Type species

Conochitina claviformis Eisenack, Reference Eisenack1931; lost holotype in Eisenack, Reference Eisenack1931, p. 84, pl. 1, fig. 17, from erratic graptolitic rocks (‘Graptolithengestein’); neotype in Eisenack, Reference Eisenack1968, p. 159, pl. 25, fig. 5, from erratic graptolitic rocks, early Ludlow, Silurian (Paris et al., Reference Paris, Grahn, Nestor and Lakova1999).

Conochitina rudis new species

Figure 11.1–11.6

Holotype

Illustrated in Figure 11.4 (RBINS collection number b 10041); dimensions: L: 154 μm; D: 120 μm; Da: 84 μm; L/D: 1.28; D/Da: 1.43; sample MY-198.7 ft (60.6 m), Bull Fork Formation (Maysville, Kentucky, USA).

Diagnosis

Stout subcylindrical to subconical species with a distinctively ornamented lip, fimbriated and usually with some perforations. The vesicle wall is composed of two layers, somewhat separated, with the outer membrane being peculiarly rough, with an irregular aspect.

Occurrence

From sample MY-198.7 ft to MY-185.0 ft (60.6–56.4 m), Bull Fork Formation, MY-14-01 core, Kentucky, USA.

Description

The overall shape of the vesicle varies from subcylindrical to subconical. Flanks straight to slightly convex. The flexure can be inconspicuous, without a clear separation between the chamber and neck (Fig. 11.3). When a gentle flexure is observed, it separates the conical chamber from the subcylindrical to flaring neck (Fig. 11.6). Lip distinctively ornamented, fimbriated, and sometimes also perforated. When slightly broken, it is possible to observe that the vesicle wall is composed of two layers, somewhat individualized (Fig. 11.5). Throughout the entire vesicle, the outer layer has a rough, rugose ornamentation that, in extreme examples, can look like scales (Fig. 11.2, 11.3). This results in a homogenously irregular surface wall. In long specimens, the neck appears smooth. Rounded margin. The base has the same rough ornamentation; a pit with a mucron is situated at its center (Fig. 11.1).

Etymology

‘Rudis’ means ‘raw, rude, scratchy, or rough’ in Latin. The name refers to the diagnostic rough vesicle wall.

Materials

N = 50 specimens.

Dimensions

L: 95–164–242 μm; D: 75–99–120 μm; Da: 56–73–97 μm; L/D: 1.10–1.67–2.44; D/Da: 1.19–1.36–1.68 (n = 25).

Remarks

Although visibly ornamented, the vesicle surface of our material is still considered glabrous, one of the diagnostic features of the genus Conochitina. No other species of Conochitina is known to have this characteristic vesicle shape, and a wall with two layers that appear only to be poorly fused (Fig. 11.5), with the outer layer having a rough, rugose ornamentation.

Conochitina? pygmaea Achab, Reference Achab1987

Figure 6.1–6.3

Reference Achab1987 Conochitina pygmaea n. sp.; Achab, p. 1216–1218, pl. 9, figs. 1–10.

? Reference Ottone, Holfeltz, Albanesi and Ortega2001 Conochitina? pygmaea; Ottone et al., p. 102, pl. 3, fig. 4.

Holotype

GSC85479, sample from St-Roch n°1 core, 1700 ft (518 m), Utica Group, Katian, Upper Ordovician; near Sorel-Tracy city, SW Quebec Province, Canada (Achab, Reference Achab1987, p. 1216, pl. 9, fig. 1).

Occurrence

From sample MY-653.3 ft to MY-603.5 ft (199.1–183.9 m), Kope Formation, MY-14-01 core, Kentucky, USA. Also from upper Utica Group, near Sorel-Tracy city, SW Quebec Province (St-Roch n°1 core), and Macasty Shale, Anticosti Island (LGPL and LGCP cores), Canada (Riva, Reference Riva and Kay1969; Achab, Reference Achab1987, Reference Achab1989).

Description

The vesicle’s overall shape is stout and subconical, with convex flanks. In specimens without a neck, the vesicle is inflated and subconical, with the flanks tapering towards the aperture (Fig. 6.1). Other specimens have a gentle flexure between a short neck, tapering towards the aperture, and an inflated and subconical chamber (Fig. 6.2). At the end of the spectrum, some specimens show a more pronounced flexure separating the neck (~1/3 of the total length) from the inflated, subconical chamber (Fig. 6.3). The sealing structure has been observed close to the aperture. The lip is mildly fimbriated and can be finely and randomly perforated. Rounded margin. Vesicle wall usually smooth but can display randomly distributed granules (Fig. 6.2). Base frequently invaginated. Rarely, probable pits with a mucron were observed at the center of the base; however, these structures were very small and discrete, preventing a clear assessment of this feature.

Materials

N = 27 specimens.

Dimensions

L: 84–108–131 μm; D: 69–79–92 μm; Da: 27–36–46 μm; L/D: 1.03–1.36–1.62; D/Da: 1.84–2.22–3.00 (n = 13).

Remarks

Specimens can have a large variability in vesicle shape and outline across the population within the same sample. We consider our material to be conspecific with the specimens described and figured by Achab (Reference Achab1987) as Conochitina pygmaea. Given the overall shape of the vesicle (short and inflated, more common in genera of the Family Desmochitinidae) in both Achab’s (Reference Achab1987) and our material, the uncertainties about the apical structures, and that the sealing structure has been observed near the aperture, we have some doubt about the attribution of this species to the genus Conochitina. Although Ottone et al. (Reference Ottone, Holfeltz, Albanesi and Ortega2001) also questioned the attribution of this species to the genus Conochitina, their specimen is poorly preserved (fractures, folds, and pyrite marks present) and it appears to have randomly distributed granules and spines.

In the Province of Quebec, Co. pygmaea is one of two nominal species of a biozone defined by Achab (Reference Achab1989), in strata of the Geniculograptus pygmaeus graptolite Biozone (GBz; Riva, Reference Riva and Kay1969; Achab, Reference Achab1987).

Subfamily Tanuchitininae Paris, Reference Paris1981

Genus Hyalochitina Paris and Grahn in Paris et al., Reference Paris, Grahn, Nestor and Lakova1999

Type species

By original designation, Cyathochitina hyalophrys Eisenack, Reference Eisenack1959; holotype in Eisenack, Reference Eisenack1959, p. 11–12, pl. 2, fig. 6, from the Upper Ordovician of Cincinnati, Ohio, USA.

Hyalochitina hyalophrys? (Eisenack, Reference Eisenack1959)

Figure 11.7–11.9

Occurrence

From sample MY-319.0 ft to MY-242.9 ft (97.2–74.0 m), Grant Lake Limestone, MY-14-01 core, Kentucky, USA.

Materials

N = 36 specimens.

Dimensions

L: 336–423–500 μm; D: 84–109–134 μm; Da: 69–74–79 μm; L carina: 5–8–11 μm; L/D: 3.02–3.95–5.54; D/Da: 1.21–1.47–1.83 (n = 9).

Remarks

This species has a short original description and has not been reported frequently in the literature. The specimens in our population are frequently broken as these long vesicles seem to have a fragile wall. For identification of this morphotype, we focused on a few characteristic features (Eisenack, Reference Eisenack1959): population with an elongated subconical vesicle (total length 276–382–528 μm), neck that can be distinctly flaring, carina on the margin (L carina 5–10 μm), and lack of ornamentation. The dimensions of the specimens in our population also fall within the range of values provided for the type population.

The Hyalochitina hyalophrys? specimens are usually longer than Tanuchitina hooksae n. sp. specimens and without ornamentation on the vesicle. This population also can be separated from Tanuchitina sp. 1, given that the specimens of Tanuchitina sp. 1 are always longer and wider and their carina is always clearly below the margin. However, because of the imperfect preservation of our specimens, we decided to keep them in open nomenclature.

Miller (Reference Miller1976) identified Hy. hyalophrys in the upper Fairview Formation, Miamitown Shale, Grant Lake Limestone, Mt. Auburn, and Dillsboro formations, from Ohio, Kentucky, and Indiana, USA. In Canada, Hy. hyalophrys is the nominal species of a biozone defined by Achab (Reference Achab1989) above the Conochitina sp. 2 Biozone, the latter partially equivalent to the Paraorthograptus manitoulinensis GBz (Riva, Reference Riva and Kay1969; Achab, Reference Achab1987).

Genus Tanuchitina Jansonius, Reference Jansonius1964, emend. Paris et al., Reference Paris, Grahn, Nestor and Lakova1999

Type species

Tanuchitina ontariensis Jansonius, Reference Jansonius1964; lost holotype (Michelle Coyne, pers. comm., 2023) in Jansonius, Reference Jansonius1964, p. 910–911, pl. 1, fig. 6 (Imp. 4309-306-7-112.1 x 17), cuttings from Imperial-Calvan Anderson no. 9-6 borehole, depth 738 m (2420 ft), Maeford-Dundas Formation, Katian, Upper Ordovician, Anderdon Township, Essex County, Ontario, Canada; neotype not yet designated.

Tanuchitina hooksae new species

Figure 10

Holotype

Illustrated in Figure 10.13 (RBINS collection number b 10042); dimensions: L: 175 μm; D: 70 μm; Da: 50 μm; L carina: 4 μm; L/D: 2.50; D/Da: 1.39; sample MY-185.0 ft (56.4 m), Bull Fork Formation (Maysville, Kentucky, USA).

Diagnosis

Tanuchitina species with low but distinct ornamentation propagated throughout the entire vesicle—typically granules, that can coexist with small spines, crest-like and/or mesh-like structures. The ornamentation of the vesicle delicately spreads to the carina below the margin (< 14 μm), typically perforated and with an irregular outline.

Occurrence

From sample MY-333.0 ft (101.5 m), Grant Lake Limestone, to sample MY-055 ft (16.8 m), Bull Fork Formation, MY-14-01 core, Kentucky, USA.

Description

Vesicle’s overall shape is subcylindrical to conical, with straight to convex flanks. In specimens with an inconspicuous flexure, the vesicle is conical, with the flanks tapering towards the aperture (Fig. 10.4, 10.7, 10.9, 10.10, 10.12, 10.13). When a gentle flexure is present, it separates the subcylindrical, somewhat short neck from the conical chamber (Fig. 10.1, 10.3). The maximum width is located at the rounded margin or closely above it. The lip is always fimbriated and can also display perforations and spines (Fig. 10.1, 10.7). Low-rise but distinctive ornamentation spread over the whole vesicle. The most prevalent type comprises vesicles with randomly distributed, individualized granules (Fig. 10.1, 10.10, 10.13–10.15). Rarely, vesicles with granules display bands of densely distributed, thicker granules and spines, alternating with areas with more spaced, small granules (Fig. 10.2, 10.3). There are rare specimens with granules connected by lines, giving the ornamentation a polygonal-mesh appearance (Fig. 10.4, 10.5, 10.9). In some vesicles, the granules can be well-developed and coexist with small spines (Fig. 10.12). Some specimens show fine lines, sub-parallel to the long axis of the chitinozoan vesicle, creating a crest-like appearance (Fig. 10.7, 10.8). The ornamentation on the vesicle delicately spreads to the carina below the margin, with a variable length (3–14 μm), commonly perforated and always with an irregular outline (Fig. 10.5, 10.8, 10.16–10.18). The base is gently ornamented with granules, with a pit with a mucron at its center, surrounded by concentric rings (Fig. 10.6, 10.18).

Etymology

Named after the pen name ‘bell hooks’ used by Gloria Jean Watkins, an African-American educator, author, and social critic born in Kentucky.

Materials

N = 821 specimens.

Dimensions

L: 98–195–367 μm; D: 56–82–116 μm; Da: 44–59–100 μm; L carina: 3–7–14 μm; L/D: 1.44–2.42–4.07; D/Da: 1.13–1.40–1.68 (n = 46).

Remarks

Frequently, Tanuchitina specimens with distinct ornamentation coexist in the same sample and are considered part of the same population. The intraspecific variation of dimensions and ornamentation in this morphotype is notable, as demonstrated in Figure 10.

Tanuchitina alborzensis Ghavidel-Syooki, Reference Ghavidel-Syooki2017, of the Ghelli Formation, Iran, resembles the new species described here due to its granulate ornamentation. However, T. alborzensis usually is longer than our material, the density of its granules decreases towards the aperture, the ornamentation on the lip is not described or observed, no perforations are observed in the carina, and, while the carina length is not provided, we calculated it from the plate with the type material as no longer than 5 μm. Additionally, intraspecific variation in the ornamentation of specimens is not mentioned for T. alborzensis. From our material, the specimens with a gentle flexure (e.g., Fig. 10.1, 10.3) may display an overall shape similar to Tanuchitina ontariensis Jansonius, Reference Jansonius1964, first described from the Maeford-Dundas Formation, currently assigned to the Georgian Bay Formation (Ontario, Canada; Liberty, Reference Liberty1969; Zhang et al., Reference Zhang, Tarrant and Barnes2011). In contrast, T. ontariensis has a more pronounced hourglass shape, with the flaring neck approximately half of the total length of the vesicle, and, importantly, the vesicles are not described as having ornamentation nor is it observed in the specimen figured by Jansonius (Reference Jansonius1964). Although T. ontariensis is the type species of the genus Tanuchitina, it was succinctly described, only one complete specimen was figured, and no SEM images were ever made, which hinders assessing the morphological characters of the entire population and their variation. It remains possible that, in the absence of SEM studies of the type assemblage of T. ontariensis, these type specimens do contain subtle ornamentation, which could make them fall within the intraspecific variability we describe here for Tanuchitina hooksae n. sp. Unfortunately, further studies are impossible, as the holotype of T. ontariensis is considered lost (Michelle Coyne, pers. comm., 2023), and the type stratum (collected in well cuttings) is inaccessible. Thus, we separate our ornamented specimens from T. ontariensis to emphasize the presence of ornamentation.

Another species showing similarities with the material described here is Tanuchitina laurentiana Soufiane and Achab, Reference Soufiane and Achab2000b, given its outline and dimensions. However, the T. laurentiana population has clear convex flanks, giving the vesicles an inflated aspect, and, while this is not described, the longitudinal axis of the type specimens figured is slightly curved. Also, for T. laurentiana, the ornamentation on the lip, vesicle, or carina and the presence of apical structures have not been described or observed.

Tanuchitina sp. 1

Figure 12.1, 12.2, 12.10

Occurrence

Sample MY-114.8 ft (35.0 m), Bull Fork Formation, MY-14-01 core, Kentucky, USA.

Description

Elongated, subcylindrical vesicle shape. Gentle flexure between the short, slightly flaring neck, and long, subcylindrical and inflated chamber (Fig. 12.1, 12.2). Maximum width at the lower half of the chamber. Carina below the rounded margin. Lip gently fimbriated. Vesicle wall glabrous, varying from smooth to rugose in appearance, the latter especially noticeable in the lowermost part of the chamber of some specimens. At the transition between chamber and carina, fine folds can be observed, parallel or oblique to the longitudinal axis of the vesicle (e.g., Fig. 12.10). In parts where the carina is well preserved, it is long and complete (i.e., without perforations), without distinct ornamentation. The carina seems to tear easily (Fig. 12.10); therefore, the carina wall is considered thin and fragile, and the irregular outline of the carina is not considered diagnostic since it could be damaged. In a few specimens, the carina seems multi-layered (Fig. 12.2). When observed, the base of the vesicle always displays a rugose aspect, with a pit with a mucron at its center (Fig. 12.10).

Materials

N = 5 specimens.

Dimensions

L: 602–659 μm; D: 145–156 μm; Da: 116–118 μm; L carina: 16–18 μm; L/D: 4.16–4.22; D/Dp: 1.24–1.33 (n = 2).

Remarks

Our specimens display similarities with Tanuchitina anticostiensis (Achab, Reference Achab1977a) and Tanuchitina agrestis (Jenkins, Reference Jenkins1970a) in terms of vesicle and carina length and vesicle shape. The maximum diameter and absence of rough ornamentation in our material are more compatible with the features of T. anticostiensis than with T. agrestis. However, some ornamentation has been observed in our specimens, which is incompatible with T. anticostiensis: the vesicle wall appears rugose, particularly at the lowermost part of the chamber (Fig. 12.1), carina, and base (Fig. 12.10). In contrast to our material, the carina of T. anticostiensis appears robust, not damaged and with a wavy outline. Additionally, many characteristics of T. anticostiensis and T. agrestis display significant overlap (vesicle shape, dimensions, age), and their main difference (i.e., the rough ornamentation of T. agrestis) cannot be fully evaluated given that there are no SEM images known of this taxon. Given our limited population and all the uncertainties expressed, the use of open nomenclature is preferred.

Subfamily Belonechitininae Paris, Reference Paris1981

Genus Acanthochitina Eisenack, Reference Eisenack1931

Type species

Acanthochitina barbata Eisenack, Reference Eisenack1931; lost holotype in Eisenack, Reference Eisenack1931, p. 82–83, pl. 1, fig. 10, from erratic limestone from the Baltic (‘Ostseekalk’); neotype in Nõlvak, Reference Nõlvak1980, pl. 29, fig. 1, Hullo borehole, 21.0 m, Baltoscandian late Vormsi Stage, Katian, Upper Ordovician, Estonia (Paris et al., Reference Paris, Grahn, Nestor and Lakova1999).

Remarks

The genus Acanthochitina was erected as monospecific, with Acanthochitina barbata as the type species (Eisenack, Reference Eisenack1931). Before the 1970s, it was difficult to fully understand the details of ornamentation without advanced imaging techniques. For decades, many specimens with a second layer elevated from the vesicle were attributed to Ac. barbata (see below, in the remarks of the Acanthochitina species, mention of possible misidentifications). Now that SEM is a standard technique in chitinozoan studies, differentiation among species of Acanthochitina is easier and advances are being made (see Vandenbroucke, Reference Vandenbroucke2008b).

Acanthochitina cancellata Martin, Reference Martin1983

Figure 4.2–4.7, 4.9

Reference Martin1983 Acanthochitina? cancellata Martin, p. 11, pl. 3, fig. 19; pl. 4, figs. 14, 28, 29.

Reference Achab1987 Acanthochitina cancellata; Achab, p. 1213, pl. 2, figs. 1–4.

? Reference Asselin, Achab and Soufiane2000 Acanthochitina cancellata; Asselin et al., pl. 1, figs. 4, 5, 7, 8.

? Reference Asselin, Achab and Soufiane2004 Acanthochitina cancellata; Asselin et al., pl. 1, fig. 10.

Holotype

CGC 55810, sample NEP-9-2, Delisle unit, Lotbinière Formation, Utica Group, Portneuf County, Quebec, Canada (Martin, Reference Martin1983, p. 11, pl. 4, fig. 14).

Occurrence

Discontinuously from samples MY-761.0 ft (232.0 m) to MY-642.9 ft (196.0 m), Point Pleasant and Kope formations, MY-14-01 core, Kentucky, USA. Acanthochitina cancellata also occurs from the Neuville Formation (Trenton Group) to the Lotbinière Formation (Utica Group), St-Lawrence Lowlands, Quebec, and in the Macasty Formation, Anticosti Island, Canada (Martin, Reference Martin1983; Achab, Reference Achab1987).

Materials

N = 87 specimens.

Dimensions

L: 253–390–645 μm; D: 91–110–150 μm; Da: 65–83–106 μm; H mesh: 2–4–5 μm; L/D: 1.97–3.58–5.21; D/Da: 1.10–1.34–1.71 (n = 33).

Remarks

Despite some specimens of our population surpassing the dimensions of the type material of Martin (Reference Martin1983) and the specimens attributed by Achab (Reference Achab1987) to this species, the remaining morphological characters fit within the diagnostic range given by Martin (Reference Martin1983). The variability of dimensions we encountered in our population likely is related to the greater number of specimens found (n = 87), in contrast with the number of specimens studied by Martin (Reference Martin1983, n = 4) and Achab (Reference Achab1987, n = 8).

Achab (Reference Achab1987) reassigned specimens identified as Acanthochitina barbata Eisenack, Reference Eisenack1931, from the Kope Formation, Kentucky (Miller, Reference Miller1976), to Ac. cancellata. However, we suggest those specimens fit better within Acanthochitina latebrosa Vandenbroucke, Reference Vandenbroucke2008b. Additionally, we question the specific attribution of the specimens figured in Asselin et al. (Reference Asselin, Achab and Soufiane2000, Reference Asselin, Achab and Soufiane2004). On the specimens from the lower Amadjuak Formation (south Baffin Island, Canada; Asselin et al., Reference Asselin, Achab and Soufiane2000), the mesh ornamenting the vesicle seems considerably elevated from the vesicle wall, particularly in Asselin et al. (Reference Asselin, Achab and Soufiane2000, pl. 1, figs. 7, 8 [corrected from the original figure caption]), a feature more compatible with Ac. latebrosa. However, due to the limited resolution of the published images, this suggestion cannot be confirmed. These specimens, as well as the one represented in Asselin et al. (Reference Asselin, Achab and Soufiane2004, pl. 1, fig. 10) are incomplete and broken, which prevents us from fully evaluating their dimensions. While the latter-mentioned specimen has a vesicle and ornamentation outline suggestive of Ac. cancellata, its image was obtained in transmitted light microscopy and does not allow clear observation of its diagnostic mesh.

In Quebec Province, Ac. cancellata is the index species of a biozone defined by Achab (Reference Achab1989) and occurs in levels that have yielded fossils of the Orthograptus ruedemanni GBz and of the lower part of the Diplacanthograptus spiniferus GBz (Riva, Reference Riva and Kay1969; Martin, Reference Martin1983), which is partially correlative with the Diplacanthograptus caudatus GBz (Maletz, Reference Maletz, Part and revision2021[2023]), the international marker of the GSSP for the base of the Katian (Goldman et al., Reference Goldman, Leslie, Nõlvak, Young, Bergström and Huff2007).

Acanthochitina latebrosa Vandenbroucke, Reference Vandenbroucke2008b

Figure 7.1–7.5, 7.10

Reference Jenkins1967 Acanthochitina barbata Eisenack in Jenkins, p. 443–445, pl. 68, figs. 1–9, text-fig. 3.

Reference Miller1976 Acanthochitina barbata; Miller, p. 98–105, pl. 1, figs. 1–7.

? Reference Knabe1980 Acanthochitina barbata; Knabe, p. 62–64, pl. 1, figs. 1, 3, 5, 6 (non pl. 1, figs. 2, 4).

Reference Ancilletta1997 Acanthochitina barbata; Ancilletta, p. 9, pl. 6, fig. 12; pl. 11, figs. 2–5; pl. 20, figs. 1–12, pl. 22, fig. 12.

Reference Vandenbroucke2008b Acanthochitina latebrosa Vandenbroucke, p. 31–33, pl. 15, figs. 1–14; pl. 25, figs. 1, 2, 12–15.

Reference Vandenbroucke, Ancilletta, Fortey and Verniers2009a Acanthochitina latebrosa; Vandenbroucke et al., fig. 14(e).

Holotype

UGent repository number: SV9-0009; RBINS repository number: b5049; sample 90-17, stub II; Cliff section, Onny Valley, Shropshire, UK; Onny Formation, British Streffordian Stage, lower Katian (Vandenbroucke, Reference Vandenbroucke2008b, p. 31–33, pl. 15, fig. 1).

Occurrence

In the USA, Ac. latebrosa has been identified with certainty in the Kope Formation, Kentucky (Miller, Reference Miller1976; this work, samples MY-584.6 ft/178.2 m, MY-555.7 ft/169.4 m, and MY-487.0 ft/148.4 m). In England, Ac. latebrosa occurs in the Onny Formation, British Streffordian Stage, lower Katian (Vandenbroucke, Reference Vandenbroucke2008b, and references therein). In Turkey, this species has been identified in well cuttings CEYLANPINAR 1 and GIRMELLI 1, Katian (Paris et al., Reference Paris, Le Hérissé, Monod, Kozlu, Ghienne, Dean, Vecoli and Günay2007).

Materials

N = 30 specimens.

Dimensions

L: 186–268–353 μm; D: 76–88–109 μm; Da: 53–65–83 μm; H mesh: 5–10–13 μm; L/D: 2.36–3.06–3.72; D/Da: 1.11–1.36–1.61 (n = 13).

Remarks

The specimens of the Kope Formation from the MY-14-01 core display the same claviform-cylindrical vesicle outline, with its maximal width more or less halfway up the chamber, as Ac. latebrosa from the Onny Valley (England; Vandenbroucke, Reference Vandenbroucke2008b; Vandenbroucke et al., Reference Vandenbroucke, Ancilletta, Fortey and Verniers2009a). In addition, the polygonal mesh-like ornamentation considerably elevated from the vesicle by small spines, the carina-like structure (Fig. 7.10), and their dimensions are all similar to the characteristics of the type assemblage.

Specimens from the Kope Formation in Maysville, Kentucky, have been identified as Acanthochitina barbata Eisenack, Reference Eisenack1931 (Miller, Reference Miller1976, pl. 1, figs. 1–7). Later, these were reassigned by Achab (Reference Achab1987, p. 1213) to Acanthochitina cancellata Martin, Reference Martin1983. However, given their vesicle outline, ornamentation characteristics, and dimensions (similar to the specimens from the upper Kope Formation in the MY-14-01 core), we propose reassigning these to Ac. latebrosa. Additionally, Knabe (Reference Knabe1980) identified Ac. barbata from the Lexington Limestone, Point Pleasant, Clays Ferry, and Kope formations (Kentucky), but the described morphological features are more aligned with the diagnosis of Ac. latebrosa. Unfortunately, the images of the figured specimens are not sharp enough to allow a certain reassignment.

In the British Avalonia, Ac. latebrosa is one of two nominal species of a biozone defined by Vandenbroucke (Reference Vandenbroucke2008a), in strata correlated with the Dicellograptus morrisi Subzone of the Dicranograptus clingani Biozone (lower Katian; e.g., Zalasiewicz et al., Reference Zalasiewicz, Rushton and Owen1995).

Genus Belonechitina Jansonius, Reference Jansonius1964

Type species

By original designation, Conochitina micracantha subsp. robusta Eisenack, Reference Eisenack1959; holotype in Eisenack, Reference Eisenack1959, p. 9–10, pl. 3, fig. 4, from the Saku Member of the Wasalemma Formation, Katian, Upper Ordovician, Estonia.

Belonechitina duplicitas (Martin, Reference Martin1983) new combination

Figure 3.1, 3.2

Reference Martin1983 Hercochitina? duplicitas Martin, p. 17, pl. 1, fig. 11; pl. 2, figs. 8, 11, 12; pl. 3, fig. 2; pl. 4, figs. 5, 33; pl. 5, figs. 15, 37.

Reference Achab1987 Hercochitina? duplicitas; Achab, p. 1224, pl. 8, figs. 1, 2 (non pl. 8, figs. 3, 4).

? Reference Malo, Cousineau, Sacks, Riva, Asselin and Gosselin2001 Hercochitina? duplicitas; Malo et al., p. 31, 34, pl. 1, figs. 5, 6.

? Reference Asselin, Achab and Soufiane2004 Hercochitina duplicitas; Asselin et al., p. 494, pl. 1, fig. 15.

Holotype

CGC 55874, sample CBE-2, Saint-Casimir unit, Neuville Formation, Trenton Group, Charlesbourg Ltée quarry, Quebec County, Canada (Martin, Reference Martin1983, p. 17, pl. 4, fig. 33).

Occurrence

In this work, Belonechitina duplicitas n. comb. occurs discontinuously from sample MY-778.3 ft to MY-682.3 ft (237.2–208.0 m), Point Pleasant Formation and Kope Formation, MY-14-01 core, Kentucky, USA. Belonechitina duplicitas n. comb. also occurs in several formations of the Trenton, Ottawa, and Utica groups, Québec City, Montréal, and Ottawa regions (Martin, Reference Martin1983; Achab, Reference Achab1987), and in the Macasty Shale of the LGPL core, Anticosti Island (Riva, Reference Riva and Kay1969; Achab, Reference Achab1987), Canada.

Materials

N = 11 specimens.

Dimensions

L: 215–242–272 μm; D: 78–91–98 μm; Da: 55–63–67 μm; H spines: 11–18–23 μm; L/D: 2.45–2.67–2.8; D/Da: 1.42–1.45–1.47 (n = 3).

Remarks

Belonechitina duplicitas n. comb. was originally assigned to the genus Hercochitina with doubt (Martin, Reference Martin1983), and in subsequent studies as well (Achab, Reference Achab1987, Reference Achab1989; Achab and Asselin, Reference Achab and Asselin1995; Malo et al., Reference Malo, Cousineau, Sacks, Riva, Asselin and Gosselin2001). Asselin et al. (Reference Asselin, Achab and Soufiane2004) seem to confirm its attribution to that genus (i.e., Hercochitina). However, in the type material of this species, the multirooted spines are randomly distributed, a feature compatible with the diagnosis of the genus Belonechitina. We consider attribution of the specimens in Malo et al. (Reference Malo, Cousineau, Sacks, Riva, Asselin and Gosselin2001, pl. 1, figs. 5, 6) to this species questionable since we do not distinguish ornamentation in their vesicles. We also doubt that the specimen of Asselin et al. (Reference Asselin, Achab and Soufiane2004, pl. 1, fig. 15) could be B. duplicitas due to the limited height of its ornamentation, contrasting with the type material (e.g., Martin, Reference Martin1983, pl. 2, figs. 11, 12).

In the Province of Quebec, B. duplicitas n. comb. is one of the nominal species of a biozone defined by Achab (Reference Achab1989).

Belonechitina laciniata new species

Figures 11.10–11.16, 14.7

Figure 14. Morphological lineages 1 (1–5) and 2 (6–8), emphasizing the characteristic ornamentation of each species (original SEM images with the respective illustrations, slightly idealized, to better display the vesicle outlines and ornamentation details), and their stratigraphic ranges in the MY-14-01 core (Kentucky, USA). Hercochitina anningae n. sp. (9) is the only new Hercochitina species not included in one of the morphological lineages; however, it is added as additional information, to better illustrate its diagnostic ornamentation.

Holotype

Illustrated in Figure 11.12, 11.16 (RBINS collection number b 10043); dimensions: L: 189 μm; D: 88 μm; Da: 73 μm; H spines: 4 μm; L/D: 2.14; D/Da: 1.22; sample MY-233.3 ft (71.1 m), Grant Lake Limestone (Maysville, Kentucky, USA).

Occurrence

From sample MY-233.3 ft (71.1 m; Grant Lake Limestone) to MY-185.0 ft (56.4 m; Bull Fork Formation), MY-14-01 core, Kentucky, USA.

Diagnosis

Stout Belonechitina species with an exceptionally ornamented lip, deeply lobed, (sub)cylindrical vesicle densely ornamented with randomly distributed simple spines—fine, short, with pointy tips and broad bases, usually longitudinally aligned but never connected with the surrounding spines.

Description

Stout cylindrical to subcylindrical vesicles with generally straight flanks. Flexure inconspicuous (Fig. 11.14, 11.16). Exceptionally ornamented lip, deeply lobed, with the lobes being drawn out and giving the lip an overall pitchfork appearance. Usually, the lip also displays numerous large perforations (Fig. 11.12, 11.16) and/or long spines (Fig. 11.10, 11.13). Maximum width situated at the rounded margin. Entire vesicle densely ornamented with randomly distributed simple spines. These spines are fine, with broad bases, usually longitudinally aligned, but never connecting to the surrounding spines, and ending in pointed tips. The spines are typically short in most of the vesicle (< 5 μm), slightly thicker at the margin, and become shorter towards the aperture or are substituted by granules (Fig. 11.10). The spiny ornamentation on the base becomes scarcer and smaller towards the center of the base, where a pit with a mucron, surrounded by concentric rings has been observed (Fig. 11.15).

Etymology

Named after its lip ornamentation, resembling laciniate leaves with deep lobes.

Materials

N = 145 specimens.

Dimensions

L: 131–192–266 μm; D: 71–101–133 μm; Da: 50–75–101 μm; H spines: 2–3–5 μm; L/D: 1.46–1.92–2.38; D/Da: 1.13–1.35–1.62 (n = 23).

Remarks

A line drawing of the holotype, to illustrate the ornamentation of this new species more clearly, can be found in Figure 14.7. Belonechitina laciniata n. sp. is the second element of the morphological lineage 2 (Fig. 14) containing, from older to younger: Hercochitina andresenae n. sp., B. laciniata n. sp., and Hercochitina polygonia n. sp. These species have similar size ranges and mostly discrete ornamentation. However, H. andresenae n. sp. can be differentiated by having crests ornamented with several spines and perforations, which resemble lacework in the more elaborate cases (Fig. 9.4, 9.10, 9.11). Additionally, specimens of H. andresenae n. sp. usually have subconical vesicles, gentle but well-marked flexures, and mildly ornamented lips.

Belonechitina laciniata n. sp. differs from H. polygonia n. sp. as the latter has small crests connecting the short spines and thorn-like projections (frequently < 2 μm in height) and dense and complex ornamentation on the margin, resulting in a polygonal mesh appearance (Fig. 12.9). Also, the ornamentation (shape, size, and density) of B. laciniata n. sp. is similar to Belonechitina brittanica Vandenbroucke, Reference Vandenbroucke2008b (Sandbian and lower Katian, UK). However, the latter species is characterized by its claviform vesicle and ovoid to ovoid-conical, swollen chamber and commonly has lambda spines, which are absent in our material.

Belonechitina senta? (Achab, Reference Achab1978a)

Figure 13.1

Occurrence

Sample MY-065.4 ft (19.9 m), Bull Fork Formation, MY-14-01 core, Kentucky, USA.

Dimensions

L: 97 μm; D: 74 μm; Da: 34 μm; H spines: 2 μm; L/D: 1.30; D/Da: 2.18 (n = 1).

Materials

N = 1 specimen.

Remarks

Like the type material, this specimen has a narrow and short neck, well differentiated from the subconical chamber with convex flanks, short and conical spines randomly distributed on the entire vesicle, which give it a grainy appearance, and the greatest width located at the rounded margin. This specimen is smaller than the eight specimens measured by Achab (Reference Achab1978a). However, due to the limited populations measured by Achab (Reference Achab1978a) and found here, and the fact that the ratios of our specimen fall within the ratios of the type material, we consider it possible that our material could represent a short specimen of this taxon.

Belonechitina sp. 1

Figure 5.1, 5.2, 5.8

Occurrence

Sample MY-691.5 ft (210.8 m), Point Pleasant Formation, MY-14-01 core, Kentucky, USA.

Description

Subconical vesicle. Gentle to inconspicuous flexure. When the flexure is present, it separates the gently conical chamber from the subcylindrical neck. Maximum width is situated at the rounded margin. Straight flanks. Lip finely fimbriated. The lowermost part of the chamber and margin are ornamented with granules and numerous simple, two-legged, or thin, multirooted spines (around 40), ending in a simple tip (Fig. 5.8). The remaining vesicle is smooth. A pit with a mucron has been observed in the base, also ornamented with randomly distributed, small granules.

Materials

N = 12 specimens.

Dimensions

L: 73–142–216 μm; D: 57–70–84 μm; Da: 32–43–64 μm; H spines: 2–6–9 μm; L/D: 1.07–1.99–2.99; D/Da: 1.06–1.73–2.08 (n = 6).

Remarks

Our material is very similar to the specimens described as Conochitina sp. 2 by Achab (Reference Achab1987), of the Lorraine Group, near Sorel-Tracy city, SW Quebec Province, Canada, which defines a Katian biozone (Achab, Reference Achab1989). Our specimens differ by having seemingly thinner walls and more complex spines. Both Achab’s (Reference Achab1987) and our specimens are not glabrous, having spines (> 2 μm) randomly distributed on the lower chamber and margin, fitting better instead within the genus Belonechitina. Nevertheless, given the image resolution of the Conochitina sp. 2 type material and the poor preservation of the specimens studied here, we prefer to not consider these populations conspecific for now and leave our population in open nomenclature.

Belonechitina sp. 2

Figure 7.6, 7.7

Occurrence

From samples MY-555.7 ft to MY-487.0 ft (169.4–148.4 m), Kope Formation, MY-14-01 core, Kentucky, USA.

Description

Subconical vesicle. A gentle flexure separates the conical chamber with convex flanks from the neck, which flares discreetly. Lip finely fimbriated. Maximum width at the bluntly rounded margin or slightly above. Concerning its ornamentation, the vesicles can be divided into four areas. At the margin and lowermost part of the chamber, the ornamentation is more developed, in the form of long (< 14 μm) and fine multi-rooted spines that come together in a rounded tip. Most of the chamber is decorated with few, minor granules, randomly distributed and very dispersed. On the flexure, the granules are larger, more abundant, and spaced closer. The neck wall can be smooth or ornamented with few, small and dispersed granules. In only one exposed base, some short spines and granules were observed but no apical structure was recognized.

Materials

N = 12 specimens.

Dimensions

L: 94–153–181 μm; D: 73–84–98 μm; Da: 41–52–59 μm; H spines: 3–8–14 μm; L/D: 1.28–1.82–2.30; D/Da: 1.46–1.63–1.90 (n = 5).

Remarks

Belonechitina micracantha (Eisenack, Reference Eisenack1931) is well known for its spines concentrated on the lower part of the chamber, originally only characterized as short. We consider that the spines of the figured type assemblage, including holotype and neotype, can also be described as having thick roots and simple tips (e.g., Eisenack, Reference Eisenack1931, pl. 1, figs. 19–21; Eisenack, Reference Eisenack1959, pl. 1, fig. 5). The specimens attributed here to Belonechitina sp. 2 also have spines concentrated on the lower part of the chamber, although they are considerably longer than those of B. micracantha, and multi-rooted, which is neither observable nor described in the type assemblage of the latter species. In addition to the differences in spine morphology, B. micracantha usually has a greater L/D ratio than Belonechitina sp. 2. No other Belonechitina species are known with similar ornamentation, consisting of only multi-rooted spines, restricted to the margin and area immediately above it, coexisting with granules in the vesicle and no other type of spine. Given that only a couple of well-preserved specimens were found in this reduced population, we prefer to use open nomenclature until more material is found.

Genus Hercochitina Jansonius, Reference Jansonius1964

Type species

Hercochitina crickmayi Jansonius, Reference Jansonius1964; holotype in Jansonius, Reference Jansonius1964, p. 908–909, pl. 1, fig. 9, core sample from 210 m (690 ft), Gamache Princeton Lake 1 borehole, Vauréal Formation, Upper Ordovician, Anticosti Island, Canada.

Remarks

The large number of Hercochitina species identified here agrees with decades of work by Achab and her colleagues in Canada. Achab (Reference Achab1988) previously mentioned that many species of Hercochitina defined in Laurentia have not been reported from other paleocontinents. Hercochitina seems to be a genus that encompasses a great intraspecific total length variability, as discussed at length by Liang et al. (Reference Liang, Bernardo, Goldman, Nõlvak, Tang, Wang and Hints2019), reported in the dimensions section, figured by several other authors (e.g., Jenkins, Reference Jenkins1967; Achab, Reference Achab1977b; Melchin and Legault, Reference Melchin and Legault1985), and demonstrated within different species described here.

Hercochitina andresenae new species

Figures 9.1–9.8, 9.10, 9.11, 14.6

Holotype

Illustrated in Figure 9.8 (RBINS collection number b 10044); dimensions: L: 212 μm; D: 96 μm; Da: 78 μm; H crests: 4 μm; L/D: 2.21; D/Da: 1.23; sample MY-457.3 ft, 139.4 m, Kope Formation (Maysville, Kentucky, USA).

Diagnosis

Hercochitina species with 20–25 discontinuous, long, and spiny crests on the visible face. The crests lie directly on the vesicle, are frequently perforated, and are ornamented with closely spaced, blunt spines, with broad bases. When the crests are elevated and intensely perforated, they resemble lacework.

Occurrence

From sample MY-487.0 ft (148.4 m; Kope Formation) to MY-319.0 ft (97.2 m; Grant Lake Limestone), MY-14-01 core, Kentucky, USA.

Description

The overall shape of the vesicle is subconical. A gentle and broad flexure separates the conical chamber from the subcylindrical to slightly flaring neck. Maximum width occurs at the lower half of the chamber. Lip finely fimbriated and can have a few spines and perforations (Fig. 9.7, 9.8). Numerous discontinuous, long, and spiny crests densely ornament the entire vesicle: the estimated total number of crests is 40–50 (based on the 20–25 crests counted on the visible face). The crests rest directly on the vesicle, are closely spaced, frequently perforated, and ornamented with blunt spines, with broad bases, and round tips. In parts where the crests are elevated and intensely perforated, the vesicle seems adorned with lacework (Fig. 9.4, 9.10, 9.11). In specimens where the ornamentation has been mildly eroded, the crests look wavy (Fig. 9.6). Usually, the crests are more continuous and ornamented on the lower half of the vesicle and become more discontinuous and simpler towards the aperture; granules can coexist with the small crests, immediately below the lip (Fig. 9.7, 9.8). On the rounded margin, the crests may end on a prominent simple spine (Fig. 9.5, 9.10). The base is ornamented with granules, and a discrete pit with a mucron, surrounded by concentric rings has been observed at its center (Fig. 9.3, 9.6, 9.10).

Etymology

Named after Sophia de Mello Breyner Andresen, a Portuguese poet and writer.

Materials

N = 964 specimens.

Dimensions

L: 63–171–238 μm; D: 67–91–118 μm; Da: 43–63–83 μm; H crests: 2–3–6 μm; L/D: 0.62–1.91–2.54; D/Da: 1.21–1.45–1.64 (n = 22).

Remarks

While in some specimens the ornamentation can be very discontinuous (e.g., Fig. 9.8), it is easy to spot many crests when looking at the details, thus this species fits with the diagnostic features of the genus. A line drawing of the holotype, to depict the ornamentation of Hercochitina andresenae n. sp. more clearly, can be found in Figure 14.6. Hercochitina andresenae n. sp. is the oldest element of the morphological lineage 2, containing (older to younger, Fig. 14): H. andresenae n. sp., Belonechitina laciniata n. sp., and Hercochitina polygonia n. sp. Hercochitina andresenae n. sp. can be differentiated from B. laciniata n. sp., which has the vesicle ornamented by individual spines, that are never connected to the surrounding spines (i.e., no crests present). Additionally, B. laciniata n. sp. has an inconspicuous flexure and an intensely ornamented lip that can have long spines and several perforations. Hercochitina andresenae n. sp. differs from H. polygonia n. sp. as the latter has an inconspicuous flexure, a higher number of crests, and the ornamentation is lower (frequently < 2 μm), so the crests connect spines and thorn-like projections. Importantly, the most diagnostic feature of H. polygonia n. sp. is the dense ornamentation at the margin, forming a polygonal mesh, which is absent in H. andresenae n. sp.

Although H. andresenae n. sp. and Hercochitina sp. 2 (in this study) have a somewhat similar outline and discontinuous crests, the latter specimens always have an inconspicuous flexure and fewer, lower, and more continuous, non-spiny crests. The more ornamented specimens of H. andresenae n. sp., with lacework-like crests (e.g., Fig. 9.10), can resemble some very ornamented Hercochitina species from Anticosti Island: Hercochitina filamentosa Achab, Reference Achab1977b (Vauréal Formation, Paraorthograptus prominens GBz, upper Katian), and Hercochitina florentini Achab and Asselin in Achab et al., Reference Achab, Asselin, Desrochers and Riva2013 (Ellis Bay Formation, uppermost Katian?–Hirnantian). However, H. filamentosa has a narrower neck, the flanks are distinctively convex, the crests are more continuous, and the height of the crests can reach 28 μm. In H. florentini, the crests are more continuous and are raised from the vesicle by spines, while in our material the crests are clearly discontinuous and lie directly on the vesicle, with the spines above them.

Hercochitina anningae new species

Figures 5.3–5.7, 5.9–5.10, 14.9

Holotype

Illustrated in Figure 5.5 (RBINS collection number b 10045); dimensions: L: 306 μm; D: 122 μm; Da: 70 μm; H crests: 3 μm; L/D: 2.51; D/Da: 1.76; sample MY-672.3 ft (204.9 m), Kope Formation (Maysville, Kentucky, USA).

Diagnosis

Hercochitina species characterized by its numerous discontinuous, poorly individualized, and multi-rooted crests, predominantly located in the lower two-thirds of the subconical vesicle. These complex crests are composed of about 2–5 low ridges, one of them being thicker, longitudinal, and longer, like a main stem; these structures meet antiaperturalwards in a multi-rooted spine with a simple tip.

Occurrence

From sample MY-701.6 ft (213.8 m; Point Pleasant Formation) to MY-555.7 ft (169.4 m; Kope Formation), MY-14-01 core, Kentucky, USA.

Description

The overall shape of the vesicle is conical, without a clear separation between the neck and the chamber (i.e., the flexure is inconspicuous). Maximum width situated at the rounded margin. The flanks are roughly straight. In the longer specimens, there is a gentle constriction above the margin (Fig. 5 .6, 5.7), which is absent or inconspicuous in small and medium specimens (Fig. 5.3, 5.4). Lip always fimbriated. The lower two-thirds of the vesicle covered by sets with about 2–5 low ridges, connected to the vesicle by multiple roots. These ridges coalesce antiaperturalwards, where they culminate in a multi-rooted spine with a simple tip, perpendicular to the vesicle (Fig. 5.9, 5.10). One of these 2–5 ridges is always thicker, fairly longitudinal, and longer, like the main stem of a plant. This group of features (main longitudinal stem, smaller ridges, and spine) is considered a complex, discontinuous, and poorly individualized crest. On the visible face, around 7–10 crests were counted (an estimated 14–20 crests in the whole vesicle). The crests are longer, more continuous, and complex in the lower third of the vesicle. The margin is ornamented with usually long (< 27 μm) and intensely multi-rooted spines, in a similar number to the number of crests on the vesicle. Towards the aperture, the crests become very short and evolve first into isolated multi-rooted spines and then into simple spines and granules. In the base, the ornamentation continues, first as multi-rooted and then simple spines towards the pit, which has been observed with a mucron and concentric rings (Fig. 5.10).

Etymology

Named after Mary Anning, a self-taught English paleontologist.

Materials

N = 124 specimens.

Dimensions

L: 138–296–506 μm; Dp: 98–125–155 μm; Da: 55–70–90 μm; H crests: 3–7–12 μm; L/D: 1.41–2.37–5.18; D/Da: 1.18–1.80–2.39 (n = 44).

Remarks

A line drawing of the holotype, to represent the ornamentation of this new species more clearly, can be found in Figure 14.9. Among all the Hercochitina species, this population presents more similarities to Hercochitina violana Nõlvak and Liang in Liang et al., Reference Liang, Bernardo, Goldman, Nõlvak, Tang, Wang and Hints2019: the low and multi-rooted crests, the multi-rooted spines on the base, margin and upper third of the vesicle, and the apical structures. However, the crests of our specimens are longer, more complex, and extend farther towards the aperture on the vesicle. In H. violana, we counted more crests (around 12–14 on the visible face, 28 on the whole vesicle) than the ones counted in our population, the constriction near the base of H. violana is considered a diagnostic feature (i.e., present in most or all vesicles), while the constriction in our specimens is only recognizable in longer vesicles, and the neck of H. violana develops a flaring collar, a feature not present in our material. Across the literature, other specimens in open nomenclature have ornamentation similar to our population but their crests are raised higher above the vesicle wall than in our material. This is the case for one of the specimens identified as Hercochitina aff. spinetum Melchin and Legault, Reference Melchin and Legault1985, by Grahn and Nõlvak (Reference Grahn and Nõlvak2007b, fig. 4O; Baltoscandian Keila Stage/ ca. Sandbian–Katian boundary, from Estonia) and one specimen also identified as Hercochitina aff. spinetum by Bauert et al. (Reference Bauert, Nõlvak and Bauert2014, fig. 2G; Baltoscandian Keila Stage/ ca. Sandbian–Katian boundary, from Estonia). Liang et al. (Reference Liang, Tang, Wang, Yan and Wang2023, fig. 6R) identified a specimen as Hercochitina sp. 1 from the Huadan Formation (Katian, South China) with very similar ornamentation to our specimens but the outline of their specimen is very different: a conspicuous flexure separates the short, flaring neck from the chamber with convex flanks. Due to the limited SEM images available in the literature of these similar specimens, we cannot evaluate the outline and ornamentation variability of those populations and we cannot assess if these morphotypes could be conspecific with our material.

Hercochitina edingerae new species

Figures 3.5–3.17, 14.1

Holotype

Figure 3.11, 3.17 (RBINS collection number b 10046); dimensions: L: 220 μm; D: 97 μm; Da: 62 μm; H crests: 6 μm; L/D: 2.27; D/Da: 1.55; sample MY-770.3 ft (234.8 m), Point Pleasant Formation (Maysville, Kentucky, USA).

Occurrence

From sample MY-770.3 ft (234.8 m; Point Pleasant Formation) to MY-682.3 ft (208.0 m; Kope Formation), MY-14-01 core, Kentucky, USA.

Diagnosis

Hercochitina species bearing 6–10 main crests that are sinuous, thick, and continuous from margin to lip, many of them bifurcating towards the aperture. Smaller, simpler, and discontinuous crests can also be present, between the main crests. Presence of complex multirooted spines at the margin.

Description

The vesicle’s overall shape is conical. When a gentle flexure is present, it separates the conical chamber with mildly convex flanks from the subcylindrical to slightly flaring neck. Gently (Fig. 3.5, 3.14) to strongly (Fig. 3.8, 3.11) fimbriated lip. Maximum diameter above the rounded margin. Ornamentation consists of 6–10 thick and sinuous main crests (extrapolated from the 3–5 crests counted on the visible face) connected to the vesicle by spines, single or in pairs. The crests are continuous, extending from the margin to the lip. The main crests can be identified by being thicker, more complex, and elevated from the vesicle (< 9 μm). Smaller, simpler, and discontinuous crests can occur between the main crests (Fig. 3.9, 3.15). Rarely, the main crests extend beyond the lip, in the form of complex spines (Fig. 3.8, 3.11). Many crests bifurcate towards the aperture, on the chamber, and neck (e.g., Fig. 3.5, 3.7, 3.8). One of the crests resulting from the bifurcation commonly is abandoned (e.g., Fig. 3.10, 3.13–.17). There can be more crests on the upper half (aperturalwards) of the vesicle than on its lower half (antiaperturalwards; Fig. 3.5, 3.12). The crests are thicker, more complex, and more elevated on the lower half of the vesicle. At the margin, the crests develop into complex, multirooted spines (< 18 μm long; Fig. 3.7, 3.17). The ornamentation extends to the base in the form of multirooted spines and to simple spines towards the center of the base, where a pit without a mucron can be observed (Fig. 3.10).

Etymology

Named after Johanna ‘Tilly’ Edinger, German-American paleontologist and the founder of paleoneurology.

Materials

N = 386 specimens.

Dimensions

L: 108–164–240 μm; D: 67–86–107 μm; Da: 42–54–70 μm; H crests: 4–6–9 μm; L/D: 1.34–1.91–2.57; D/Da: 1.15–1.62–2.00 (n = 30).

Remarks

A line drawing of the holotype, to better illustrate the ornamentation of this new species, can be found in Figure 14.1. Our material can be easily separated from most of the other species of Hercochitina given that its crests extend continuously from the margin to the aperture. In Hercochitina crickmayi Jansonius, Reference Jansonius1964, the crests may also reach the aperture, but the number of crests is higher, the crests are more regular, and they do not bifurcate. Also, the vesicle of that species is generally longer than our material (total length of H. crickmayi: 230–450 μm), and its aperture is less ornamented. In H. downiei Jenkins, Reference Jenkins1967, and H. aff. H. downiei (in this paper), the crests might reach the aperture, but the ornamentation elevates higher above the vesicle’s surface than in the species described here. In contrast to our material, H. normalis Achab, Reference Achab1977b, has full membranous crests (rarely with perforations on the lower half of the chamber). Hercochitina edingerae n. sp. is the oldest element of the morphological lineage 1. Hercochitina edingerae n. sp. and Hercochitina krafftae n. sp. have similar vesicle dimensions and both have thick crests that can bifurcate and be sinuous. However, H. krafftae n. sp. can be differentiated by its stout vesicle and inflated chamber, having more crests but only located on the chamber, and those crests are discontinuous, ending antiaperturalwards in a multirooted spine perpendicular to the vesicle wall, becoming smaller towards the aperture, and being substituted at the neck by spines and granules. Additionally, when present, the flexure in specimens of H. krafftae n. sp. is more marked, and the spines at the margin are usually shorter and have fewer roots than the ones of H. edingerae n. sp.

Hercochitina krafftae new species

Figures 6.4–6.10, 14.2

Holotype

Illustrated in Figure 6.7 (RBINS collection number b 10047); dimensions: L: 187 μm; D: 98 μm; Da: 55 μm; H crests: 7 μm; L/D: 1.90; D/Da: 1.80; sample MY-642.9 ft (196.0 m), Kope Formation (Maysville, Kentucky, USA).

Occurrence

From samples MY-642.9 ft to MY-477.0 ft (196.0–145.4 m), Kope Formation, MY-14-01 core, Kentucky, USA.

Diagnosis

Hercochitina species with a stout and inflated vesicle. The chamber has 5–8 low and discontinuous crests on the visible face that become higher and better developed antiaperturalwards. Each crest developed on the chamber that does not reach the margin ends in a multirooted spine that is perpendicular to the vesicle wall and has a simple tip (< 10 μm). The crests become smaller towards the aperture and are substituted by simple spines and granules in the neck. Discrete, multi-rooted spines on the margin.

Description

Stout and overall conical vesicle with convex flanks. Within the same sample, a population of this species can have considerable variability of vesicle shape and outline. In specimens without a neck, the vesicle is inflated and subconical, with the flanks tapering towards the aperture (Fig. 6.5, 6.6, 6.10). Most specimens have a gentle flexure between a subcylindrical neck and an inflated and subconical chamber (Fig. 6.7–6.9). Gently fimbriated lip. The chamber is covered by 10–16 rows of low and discontinuous crests (5–8 crests counted on the visible face), that can commonly be sinuous and bifurcate aperturalwards (Fig. 6.4, 6.7). The crests are connected to the chamber by spines, single or in pairs (Fig. 6.4), and increase in height and ornamentation in an antiapertural direction. If they do not reach the margin, the crests end in a multirooted, thick spine, somewhat perpendicular to the chamber wall, and with a simple tip (< 10 μm; Fig. 6.7–6.10). Few crests reach the rounded margin, ending as discrete, multirooted spines (L spines margin < 14 μm); the latter can be in higher numbers than the number of crests on the chamber (Fig. 6.4). The crests get smaller towards the aperture, being substituted by small spines and granules. The base is ornamented with small spines and granules, and a pit with a mucron has been observed at its center (Fig. 6.9).

Etymology

Named after Catherine ‘Katia’ Krafft, a French volcanologist who, together with her husband Maurice Krafft, captured videos and imagery of volcanic eruptions, raising awareness and inspiring many young women to study geology.

Materials

N = 230 specimens.

Dimensions

L: 48–142–255 μm; D: 66–84–117 μm; Da: 28–47–72 μm; H crests: 4–7–10 μm; L/D: 0.72–1.67–2.17; D/Da: 1.45–1.83–2.62 (n = 22).

Remarks

A line drawing of the holotype, to depict the ornamentation of this new species more clearly, can be found in Figure 14.2 (the arrows highlight the crests bifurcating aperturally). Similar to our material, Hercochitina changi Achab and Asselin in Achab et al., Reference Achab, Asselin, Desrochers and Riva2013 (Ellis Bay Formation, uppermost Katian?–Hirnantian) has discontinuous, short crests coalescing in spines. However, H. changi is differentiated by its subcylindrical vesicles, weak flexure, more crests (not provided in the original description but counted in the type material from the plates; Achab et al., Reference Achab, Asselin, Desrochers and Riva2013), around 11–15 on the visible face, and those crests coalesce in longer spines than in the new species described here.

Hercochitina krafftae n. sp. is the second element of morphological lineage 1. Hercochitina edingerae n. sp. can be differentiated from H. krafftae n. sp. by its slender vesicle, having fewer crests, continuous from margin to lip, and those crests never display spines on the chamber. Additionally, the crests of H. edingerae n. sp. are usually thicker, more sinuous, and have more bifurcations per crest, and the spines at the margin are commonly longer and more intensely multi-rooted. Hercochitina tharpae n. sp. only has discontinuous crests in the flexure area; its crests are continuous on the chamber and more homogeneously raised from the vesicle (H crests < 12 μm), while the crests of H. krafftae n. sp. are mostly low and only increase in height in the antiapertural direction, peaking at their multi-rooted spine (H crests < 10 μm). Also, H. tharpae n. sp. displays sets of spines at the margin: usually longer (< 22 μm) than those of H. krafftae n. sp., intensely multi-rooted, anastomosed, that extend laterally on the margin.

Hercochitina polygonia new species

Figures 12.3–12.6, 12.9, 14.8

Holotype

Illustrated in Figure 12.3 and 12.9 (RBINS collection number b 10048); dimensions: L: 256 μm; D: 98 μm; Da: 80 μm; H crests: 1.6 μm; L/D: 2.61; D/Da: 1.23; sample MY-085.5 ft (26.1 m), Bull Fork Formation (Maysville, Kentucky, USA).

Diagnosis

Stout Hercochitina species with fine, very discontinuous but distinctive, 76–84 crests (about 38–42 on the visible face). Crests lie on the surface of the vesicle and connect the simple or two-legged, broad-based ornaments—short spines and thorn-like projections (< 2 μm). At the margin, this ornamentation gets denser, thicker, and more complex, with a polygonal mesh appearance.

Occurrence

From sample MY-185.0 ft to MY-085.5 ft (56.4–26.1 m), Bull Fork Formation, MY-14-01 core, Kentucky, USA.

Description

Vesicle overall shape is subcylindrical to subconical, and stout. The flanks are generally straight. Inconspicuous flexure. The uppermost part of the vesicle may flare. Lip fimbriated and can have small perforations (Fig. 12.3, 12.6). The entire vesicle is densely ornamented with fine, very discontinuous, 76–84 crests (inferred from around 38–42 crests counted in the observable face). Lying directly on the vesicle, the crests connect a few short spines and thorn-like projections (< 2 μm): these can be simple or two-legged, with broad bases (Fig. 12.3, 12.5, 12.9). On the margin, the ornamentation gets bigger and more abundant, and the connections between spines get thicker and more complex—more lines occur, propagating in different directions, between the crests and spines, uniting these elements randomly; this ornamentation has the appearance of a polygonal mesh connected to the vesicle (Fig. 12.9). The ornamentation extends to the base, getting smaller towards its center, where a pit with a mucron is observed.

Etymology

From Greek πολύς - polys, ‘many’, and γωνία - gōnia, ‘angle’, the name refers to the polygonal mesh appearance of the ornamentation on the margin.

Materials

N = 31 specimens.

Dimensions

L:110–176–262 μm; D: 65–91–122 μm; Da: 51–67–87 μm; H crests: 1–1–3 μm; L/D: 1.38–1.95–2.74; D/Da: 1.23–1.35–1.51 (n = 14).

Remarks

Although the ornamentation of this species is low and fine, it is easily recognized even in eroded specimens, due to the polygonal mesh-like ornamentation on the margin (Fig. 12.4). A line drawing of the holotype, to represent the ornamentation of this new species more clearly, can be found in Figure 14.8. Hercochitina polygonia n. sp. is the youngest element of morphological lineage 2, with Hercochitina andresenae n. sp. and Belonechitina laciniata n. sp., as the oldest and second elements, respectively (Fig. 14). These species have similar size ranges, and their ornamentation is mostly discrete. Hercochitina polygonia n. sp. can be differentiated from H. andresenae n. sp., which has fewer spiny crests (40–50 in the entire vesicle, 20–25 in the observable face), that are generally higher (H crests < 6 μm) and can be intensely perforated, resembling lacework (Fig. 9.4, 9.10, 9.11). Additionally, the specimens of H. andresenae n. sp. usually have more subconical vesicles and a gentle but well-marked flexure.

Belonechitina laciniata n. sp. is distinguished by the individual spines ornamenting the entire vesicle, never connected to the surrounding spines (i.e., no crests present). Additionally, B. laciniata n. sp. has an intensely ornamented lip that can have long spines and several perforations (Fig. 11.10, 11.12). While the ornamentation of H. andresenae n. sp. and B. laciniata n. sp. gets thicker on the margin, it never gets complex and interconnected as in H. polygonia n. sp., gaining the appearance of a polygonal mesh.

Lastly, the complex ornamentation on the margin of H. polygonia n. sp. resembles Hercochitina? bromidensis Grahn and Miller, Reference Grahn and Miller1986 (Darriwilian–Sandbian; Oklahoma, USA; Laurentia). However, the mesh in H.? bromidensis has a wavy pattern while H. polygonia n. sp. has a more random polygonal mesh. In other differences, H.? bromidensis has broadly concave flanks, and the neck will be granulated or smooth in the specimens in which the crests stop at the upper part of the vesicle.

Hercochitina tharpae new species

Figures 7.8, 7.9, 7.11–7.15, 14.3

Holotype

Illustrated in Figure 7.11 (RBINS collection number b 10049); dimensions: L: 202 μm; D: 118 μm; Da: 70 μm; H crests: 10 μm; L/D: 1.71; D/Da: 1.67; sample MY-506.4 ft (154.4 m), Kope Formation (Maysville, Kentucky, USA).

Diagnosis

Hercochitina species with a wide conical vesicle. Six to ten continuous crests are situated only on the chamber. On the margin, these crests become sets of numerous long, multi-rooted, and anastomosing spines, which propagate antiaperturally, beneath the vesicle, and extend laterally on the margin, without connecting to the adjacent sets of spines.

Occurrence

From sample MY-565.8 ft to MY-487.0 ft (172.5–148.4 m), Kope Formation, MY-14-01 core, Kentucky, USA.

Description

Overall vesicle shape is conical, with a wide base. Maximum width at the margin. The marked flexure separates the conical chamber with convex flanks from the subcylindrical neck. Lip with discrete ornamentation, finely fimbriated to wavy (Fig. 7.14). Neck usually smooth but can have some randomly distributed, small granules. On and around the flexure, randomly distributed granules and short, small spines, with bases widening longitudinally (parallel to the long axis of the vesicle) are present. Rarely, in the flexure area, small discontinuous crests that are connected to the vesicle by simple spines bifurcate aperturalwards and end antiaperturalwards in a simple spine (Fig. 7.11, 7.13). On the chamber, 6–10 continuous crests (extrapolated from the 3–5 crests observed on the visible face) are connected to the chamber by spines, individually or in pairs (Fig. 7.15). Some of the crests on the vesicle commonly bifurcate aperturalwards and are gently sinuous, always ending at more or less the same height as the flexure. On the rounded margin, the crests are elevated from the chamber by their spines, which propagate antiaperturally (< 22 μm), beneath the base of the vesicle, and extend laterally on the margin—becoming sets of numerous long, multi-rooted, and anastomosed spines (Fig. 7.15). These complex spines on the margin are differentiated and they do not connect laterally with the adjacent sets of spines. The base is ornamented with some small spines and granules and, at its center, a pit with a mucron, sometimes surrounded by concentric rings has been observed.

Etymology

Named after Marie Tharp, an American geologist and oceanographic cartographer who made the first scientific map of the Atlantic Ocean floor.

Materials

N = 213 specimens.

Dimensions

L: 100–173–252 μm; D: 64–93–118 μm; Da: 43–53–70 μm; H crests: 6–8–12 μm; L/D: 1.11–1.86–2.67; D/Da: 1.41–1.75–2.16 (n = 20).

Remarks

A line drawing of the holotype, to illustrate the ornamentation of this new species more clearly, can be found in Figure 14.3. Hercochitina tharpae n. sp. is the third element of morphological lineage 1, composed of (older to younger, Fig. 14): Hercochitina edingerae n. sp., Hercochitina krafftae n. sp., H. tharpae n. sp., and Clathrochitina mangle n. sp. Hercochitina krafftae n. sp. can be differentiated from this new species by its discontinuous crests in the flexure area and chamber, which are low for most of their length but becoming higher antiaperturalwards and culminating in a spine that is perpendicular to the vesicle wall (< 10 μm), and by its spines on the margin, which are simpler and usually shorter (< 12 μm) than those of H. tharpae n. sp., and do not extend laterally. While H. tharpae n. sp. and Cl. mangle n. sp. have a similar outline and remarkable ornamentation on the margin, the latter has less to no ornamentation on the chamber and neck, and a crown of anastomosing processes on the margin (i.e., the ornamentation elements are densely packed and connected), while H. tharpae n. sp. has sets of spines that are well differentiated and do not connect laterally to other sets of spines.

Hercochitina cf. H. cristata Achab, Reference Achab1987

Figure 9.9, 9.12–9.14

Occurrence

Sample MY-389.0 (118.6 m), Fairview Formation, MY-14-01 core, Kentucky, USA.

Description

The overall shape of the vesicle is conical. The gentle flexure separates the conical chamber with straight to mildly convex flanks from the short, subcylindrical neck that can sometimes slightly flare towards the aperture (Fig. 9.12, 9.14). Lip gently fimbriated. Greatest width at the rounded margin or closely above. Thick, complex, and multi-rooted crests, poorly individualized (around 8–12 on the visible face), and very well-developed on the chamber. Towards the aperture, the crests decrease in size and complexity and frequently bifurcate (Fig. 9.12, 9.14). The crests are continuous on the chamber and discontinuous on the neck, and can even change to multi-rooted, small spines or granules (Fig. 9.14). On the contrary, towards the basal margin, the crests get thicker, more elevated from the chamber, and intensely multi-rooted. The crests end on the margin in the form of complex, multi-rooted but short spines, with simple tips (< 13 μm). The ornamentation of the chamber propagates to the base, decreasing in direction to its center, where a pit with a mucron has been observed (Fig. 9.13).

Materials

N = 12 specimens.

Dimensions

L: 134–251–345 μm; D: 109–125–143 μm; Da: 59–80–96 μm; H crests: 5–6–7 μm; L/D: 1.12–1.97–2.48; D/Da: 1.31–1.60–2.01 (n = 5).

Remarks

All the specimens strongly resemble Hercochitina cristata Achab, Reference Achab1987, from the Utica Formation (G. pygmaeus GBz), Montréal, Canada. However, in our small population, only occurring in one sample, the crests seem thicker, slightly higher, and more intensely multi-rooted than the ones observed in the type material. These differences favor the use of open nomenclature.

Hercochitina aff. H. downiei Jenkins, Reference Jenkins1967

Figure 3.18–3.20

Occurrence

Discontinuously present in samples MY-778.3 ft (237.2 m; Point Pleasant Formation) to MY-682.3 ft (208.0 m; Kope Formation), MY-14-01 core, Kentucky, USA.

Description

The vesicle’s overall shape is conical. The chamber is conical to pyriform, with convex flanks. The neck can be inconspicuous or short and subcylindrical. When present, the flexure is gentle. The sealing structure can be close to or at the aperture (Fig. 3.19). Fimbriated lip. Maximum diameter between the middle of the chamber and the rounded margin. The ornamentation consists of continuous crests: simple, wishbone, and multirooted spines (up to 15 μm in height), arranged in 10–14 longitudinal rows around the whole vesicle (5–7 on the visible face), connected at their tips by longitudinal bars. The crests start on the neck (Fig. 3.18) or at the lip (Fig. 3.19, 3.20) and it is inferred that they extend to the margin since the crests are never entirely preserved. The crests can bifurcate aperturalwards (Fig. 3.18). The ornamentation extends to the base, in multirooted spines turning into simple spines towards the center of the base, where a pit without a mucron can be observed (Fig. 3.20).

Materials

N = 11 specimens.

Dimensions

L: 72–107–135 μm; D: 61–76–86 μm; Da: 33–46–55 μm; H crests: 11–13–15 μm; L/D: 1.18–1.41–1.69; D/Da: 1.39–1.73–2.57 (n = 11).

Remarks

The long spines are aligned in longitudinal rows, with their tips connected by continuous crests suggesting similarity to H. downiei Jenkins, Reference Jenkins1967. This characteristic ornamentation enables this taxon to be distinguished from other Hercochitina species with similarly long spines such as H. multiansata Paris et al., Reference Paris, Verniers, Miller, Melvin and Wellman2015, from the Qasim and Sarah formations of Saudi Arabia, or H. filamentosa Achab, Reference Achab1977b, from the upper part of the Vauréal Formation (upper Katian) of Anticosti Island, which do not develop these characteristic crests. Hercochitina turnbulli Jenkins, Reference Jenkins1969, from the Viola Limestone (Pa. manitoulinensis GBz), Oklahoma, has shorter and more abundant spines arranged in a greater number of longitudinal rows, and the crests only occur in four or five longitudinal rows connecting a few of the spine tips (i.e., the crests are not continuous across the whole length of the vesicle; see Fig. 5.11–5.14). However, some morphological features hamper an unambiguous assignment of our material to the species H. downiei Jenkins, Reference Jenkins1967: (1) the total length of specimens in our population is shorter than the type assemblage of H. downiei (72–107–135 μm vs. 135–153–188 μm); (2) our specimens can have fewer crests than the ones from the type assemblage (10–14 vs 12–16); (3) besides simple and wishbone spines, our specimens also have multirooted spines, not described by Jenkins (Reference Jenkins1967) and impossible to discern in the images of the type assemblage; and (4) the spines in our specimens have a maximum height of 15 μm while in the assemblage described by Jenkins (Reference Jenkins1967), the spines had a height of up to 59 μm. These four features suggest a population somewhat different from H. downiei (i.e., a different morphospecies).

Hercochitina aff. H. longi Achab and Asselin in Achab et al., Reference Achab, Asselin, Desrochers and Riva2013

Figure 13.2–13.7

Occurrence

From samples MY-065.4 and MY-055.0 (19.9–16.8 m), Bull Fork Formation, MY-14-01 core, Kentucky, USA.

Description

Vesicle shape cylindrical to subconical. Flanks straight to slightly convex. Flexure inconspicuous. Two to four crests in the observable face. The crests are slightly sinuous, and they can be thick (connected to the vesicle by pairs of spines) and display perforations (Fig. 13.3, 13.7). A considerable variation in the total length of the specimens has been observed: longer (Fig. 13.4, 13.5), shorter (Fig. 13.2), and intermediate specimens have been found in the population. This characteristic seems to condition certain morphological and ornamentation features. In longer specimens, the vesicle shape is (sub)cylindrical, the crests are continuous until around the middle part of the vesicle, then evolve towards the aperture into broad-base spines, simple spines, and granules, and the vesicle finally displays a smooth collarette that may flare (Fig. 13.4); the ornamentation on the lip is gently fimbriated (Figs. 13.4, 13.5). In the short specimens, the vesicles are subconical, the crests are continuous from the marginal spines to the lip and extend beyond it, giving a spiny ornamentation to the lip, and the flanks taper towards the aperture (Fig. 13.2, 13.3). In all specimens, the spines on the margin can be long (< 37 μm) and have an approximated triangular shape due to their broad base and simple tip (Fig.13 .2, 13.7); commonly, the number of spines at the margin is superior to the number of crests on the vesicle (Fig. 13.6). At the center of the base, which has gently rugose ornamentation, a pit with a mucron was observed, surrounded by concentric rings (Fig. 13.7).

Materials

N = 119 specimens.

Dimensions

L: 90–269–384 μm; D: 69–86–107 μm; Da: 54–70–94 μm; H crests: 1–3–4 μm; L/D: 1.03–3.15–4.44; D/Da: 0.92–1.25–1.72 (n = 25).

Remarks

Our material has some morphological characteristics in common with Hercochitina longi Achab and Asselin in Achab et al., Reference Achab, Asselin, Desrochers and Riva2013, from the Vauréal Formation (Pa. prominens GBz), eastern Anticosti Island: cylindroconical vesicle; ornamentation consisting of a few relatively long and distinct crests observed on the visible face; discontinuous crests that evolve to simple spines towards the aperture, culminating in an ornamented lip; a row of spines at the margin. However, when compared with the type material of H. longi, our population has a greater range of dimensions, the vesicles are usually more cylindrical, the crests are thicker and more ornamented, and the spines on the margin are longer, larger, more numerous, and complex. These differences favor the use of open nomenclature, at least until more H. longi specimens are illustrated, preferentially from the type locality.

Hercochitina sp. 1

Figure 3.21, 3.22

Occurrence

From samples MY-778.3 ft and MY-770.3 ft (237.2–234.8 m), Point Pleasant Formation, MY-14-01 core, Kentucky, USA.

Description

Vesicle’s overall shape is conical to pyriform. Conical chamber with convex flanks. Gentle flexure. Short, subcylindrical neck. Aperture fimbriated. Ornamentation on the neck and upper half of the chamber consists of discontinuous crests of connected thorn-like and λ-spines (< 5 μm). The discontinuity of the crests makes it difficult to give an exact number but between 18 and 20 crests were counted with certainty on the visible face of the vesicles. On the lower half of the chamber, the ornamentation decreases in complexity: the discontinuous crests are shorter and smaller. At the margin, simple and λ-spines, sometimes multi-rooted spines, are observed and they propagate to the base (Fig. 3.21). The ornamentation transitions occur gradually. Maximum diameter located slightly above the rounded basal margin. Apical structures were not observable.

Materials

N = 20 specimens.

Dimensions

L: 93–108–129 μm; D: 65–74–88 μm; Da: 37–46–55 μm; H crests: 2–3–5 μm; L/D: 1.18–1.47–1.71; D/Da: 1.36–1.65–2.17 (n = 14).

Remarks

No other species of Hercochitina is known to have such a clear decrease in the ornamentation complexity on the lower half of the chamber. However, due to the small number of specimens recovered, we decided to keep this morphotype in open nomenclature until more material is found.

Hercochitina sp. 2

Figure 5.15–5.18, 5.21

Occurrence

From sample MY-701.6 ft (213.8 m; Point Pleasant Formation) to MY-603.5 ft (183.9 m; Kope Formation), MY-14-01 core, Kentucky, USA.

Description

The overall shape of the vesicle is subcylindrical to subconical. No clear separation between chamber and neck (i.e., flexure inconspicuous). Rounded margin. The flanks are overall straight. The lip is gently fimbriated. Low, fine, and numerous crests (12–18 crests on the visible face) were observed across the entire vesicle. The crests rise up to 3 μm above the vesicle wall. Fairly continuous in the lower half of the vesicle, the crests get tenuous and discontinuous in its upper half and usually do not reach the lip (e.g., Fig. 5.15). The crests are sometimes replaced by randomly distributed, simple spines and granules on the uppermost part of the vesicle. At the margin, the crests end in the form of simple or two-legged spines (Fig. 5.21, < 4 μm in length). The base is lightly ornamented with granules and a pit with a mucron has been observed (Fig. 5.17).

Materials

N = 140 specimens.

Dimensions

L: 148–259–348 μm; D: 64–85–104 μm; Da: 52–65–84 μm; H crests: 0.7–1.4–2.5 μm; L/D: 1.86–3.04–3.85; D/Da: 1.08–1.30–1.53 (n = 18).

Remarks

While Hercochitina lindsayensis Melchin and Legault, Reference Melchin and Legault1985, has similar ornamentation to our material, that species presents a more subconical vesicle (Dp of H. lindsayensis: 100–129–170 μm), a gentle flexure, and complex spines up to 8 μm long at the margin. Our material can also be differentiated from Hercochitina longi Achab and Asselin in Achab et al., Reference Achab, Asselin, Desrochers and Riva2013, a species with a lower number of crests, and spines on the margin. Although Hercochitina sp. 2 shares some features with Hercochitina crickmayi Jansonius, Reference Jansonius1964 (vesicle shape and low crests), our material is differentiated by its crests becoming discontinuous towards the aperture and being replaced by spines on the uppermost part of the vesicle, low crests that barely rise above the vesicle wall, and by the absence of complex spines at the margin. These differences were also noted previously in specimens identified as “Hercochitina sp. aff. H. crickmayi” (Knabe, Reference Knabe1980, p. 99–101) from the Lexington Limestone, Point Pleasant, Kope, and Clays Ferry formations, from different sections in Kentucky, and thus could be conspecific with our material. In conclusion, the ornamentation in our specimens is faint, fine, and low, and we are unsure if this is an original feature or a result of poor preservation/abrasion. Therefore, this morphotype is kept in open nomenclature until more material is found from coeval levels, in other sections, and we can confirm if the delicate ornamentation is in fact an original feature.

Subfamily Spinachitininae Paris, Reference Paris1981

Genus Spinachitina Schallreuter, Reference Schallreuter1963, emend. Paris et al., Reference Paris, Grahn, Nestor and Lakova1999

Type species

By original designation, Conochitina cervicornis Eisenack, Reference Eisenack1931; lost holotype in Eisenack, Reference Eisenack1931, p. 89, pl. 2, fig. 12, erratic calcareous sandy siltstones; neotype, Spinachitina cervicornis, in Nõlvak and Grahn, Reference Nõlvak and Grahn1993, pl. 3, fig. A, from the Kahula Formation, Baltoscandian Keila Stage, ca. Sandbian–Katian boundary, Upper Ordovician, Estonia (Paris et al., Reference Paris, Grahn, Nestor and Lakova1999).

Spinachitina sp. 1

Figure 11.17–11.22

Occurrence

From sample MY-273.2 ft (83.3 m; Grant Lake Limestone) to MY-191.4 ft (58.3 m; Bull Fork Formation), MY-14-01 core, Kentucky, USA.

Description

The overall shape of the vesicle is subconical. A gentle flexure separates the subcylindrical to slightly flaring neck from the conical chamber with straight to mildly convex flanks. Lip fimbriated. Vesicle ornamented with randomly distributed granules of small to moderate size. Small, broad-based spines with a blunt tip may be observed on the chamber, in addition to the granules (Fig. 11.19). Crown of numerous (about 32–48), roughly aligned processes on the rounded margin (< 16 μm). These processes are multirooted, two-legged, or simple spines, thick at their roots, fine most of their length, with simple and blunt tips. The granular ornamentation extends to the base, decreasing in size towards its center, where a pit with a mucron has been observed (Fig. 11.18).

Materials

N = 302 specimens.

Dimensions

L: 83–132–211 μm; D: 57–79–103 μm; Da: 37–47–65 μm; L processes: 2–6–16 μm; L/D: 1.02–1.68–2.72; D/Da: 1.35–1.72–2.18 (n = 36).

Remarks

Although the processes on the margin do not always perfectly align in a crown, there is a significant length difference between these and the ornamentation on the lower half of the chamber. Therefore, in our opinion, it is justified to attribute this species to Spinachitina, instead of Belonechitina (Paris et al., Reference Paris, Grahn, Nestor and Lakova1999). In the Katian Stage, there are two clear groups of Spinachitina species: (1) the ones with thick, long, and ornamented processes (e.g., Spi. alaticornis Jenkins, Reference Jenkins1967, Spi. cervicornis (Eisenack, Reference Eisenack1931), and Spi. katherinae Vandenbroucke, Reference Vandenbroucke2008b); and (2) the ones with numerous fine, short spiny processes with simple tips (e.g., Spi. bulmani Jansonius, Reference Jansonius1964, and Spi. fossensis Vanmeirhaeghe and Verniers, Reference Vanmeirhaeghe and Verniers2004). Spinachitina sp. 1 shares more morphological characteristics with the species of the second mentioned group: conical chamber and subcylindrical to slightly flaring neck, similar total length range (~100 to < 300 μm), commonly ornamented lip, and occasionally with granules present on the vesicle wall. There is substantial intraspecific variation in the ornamentation of Spinachitina sp. 1 specimens, including many transitional forms. This morphotype is easy to differentiate from other Spinachitina species only when its features are intensely developed and well preserved: thick granules coexisting with spines on the chamber and long processes on the margin (< 16 μm; e.g. Fig. 11.19). In the same population, specimens with subtle ornamentation (i.e. with small granules and shorter processes; e.g., Fig. 11.17, 11.21) may be difficult to separate from other Spinachitina species. Therefore, we do not consider our material to have sufficiently diagnostic characteristics to erect a new species and it is kept in open nomenclature.

Family Lagenochitinidae Eisenack, Reference Eisenack1931, emend. Paris, Reference Paris1981

Subfamily Ancyrochitininae Paris, Reference Paris1981

Genus Ancyrochitina Eisenack, Reference Eisenack1955

Type species

Conochitina ancyrea Eisenack, Reference Eisenack1931, by original designation; lost holotype in Eisenack, Reference Eisenack1931, p. 88–89, pl. 4, fig. 4, erratic limestones of the Baltic (‘Ostseekalk’); neotype in Eisenack, Reference Eisenack1955, p. 163–164, pl. 2, fig. 7, erratic Beyrichia limestones from the Baltic seafloor, Přídolí, Silurian (Paris et al., Reference Paris, Grahn, Nestor and Lakova1999).

Ancyrochitina barbescens? Martin, Reference Martin1975

Figure 5.19, 5.20, 5.22

Occurrence

From sample MY-722.6 ft (220.2 m; Point Pleasant Formation) to MY-242.9 ft (74.0 m; Grant Lake Limestone), MY-14-01 core, Kentucky, USA.

Description

Vesicle’s overall shape is conical. The inflated, conical chamber is separated from the subcylindrical neck by a marked flexure without shoulders. Flanks convex. Lips fimbriated. Vesicle wall glabrous. Numerous thin and spongy processes, simple or bi-rooted, and simple, bifurcating or branching tips (Fig. 5.19, 5.22). Apical structures or ornamentation on the base have not been observed.

Material

N = 144 specimens.

Dimensions

L: 78–98–124 μm; D: 73–86–105 μm; Da: 33–42–54 μm; Lch: 34–60–79 μm; Ln: 28–38–70 μm; L processes: 9–15–24 μm; L/D: 0.79–1.16–1.41; D/Da: 1.67–2.07–2.98 (n = 20).

Remarks

While this species is rarely imaged and has only briefly been described in the literature, it has diagnostic characteristics that differentiate it from other species of Ancyrochitina: inflated chamber, vesicle wall smooth, and 10–27 cylindrical, spongy, and fine processes, length of 15–28 μm, with a simple or bifurcated base, and branched at the tip. The ornamentation is often broken in the specimens of this population, therefore we can rarely assess the total number of processes and observe their branching tips.

Our material is different from Ancyrochitina merga Jenkins, Reference Jenkins1970a (Sylvan Shale, Pa. manitoulinensis and Dicellograptus complanatus GBzs, Oklahoma) as Anc. merga has a longer neck, can have spiny ornamentation on the vesicle, the processes can be longer, and usually are more elaborate and organized (“generally 1–3, rarely 4, orders of Y- or T-shaped branching into 2 sharply diverging, equal distal limbs” Jenkins, Reference Jenkins1970a, p. 267).

Ancyrochitina aff. Anc. corniculans Jenkins, Reference Jenkins1969

Figure 5.23–5.25

Occurrence

From sample MY-722.6 ft (220.2 m; Point Pleasant Formation) to MY-253.1 ft (77.1 m; Grant Lake Limestone), MY-14-01 core, Kentucky, USA.

Description

The overall shape of the vesicle is conical. The conical chamber is separated from the subcylindrical or flaring neck by a marked flexure without shoulders. Flanks straight to concave. Lip fimbriated. At the rounded margin, 8 thick processes (4 on the visible face) that may have simple or bifurcating tips were counted. The vesicle can be smooth but, in most specimens, some ornamentation is present on the chamber and neck, particularly intense in the flexure area, in the form of simple and two-legged spines (Fig. 5.25) and/or granules of different sizes (Fig. 5.23, 5.24). Apical structures were not observed, only tenuous concentric rings at the center of the base (Fig. 5.24).

Materials

N = 115 specimens.

Dimensions

L: 74–107–131 μm; D: 64–74–91 μm; Da: 33–41–50 μm; Lch: 44–71–93 μm; Ln: 23–36–60 μm; L processes: 17–30–45 μm; L/D: 1.03–1.46–1.79; D/Da: 1.51–1.83–2.2 μm (n = 20).

Remarks

Among all Ancyrochitina species, this material resembles Ancyrochitina corniculans Jenkins, Reference Jenkins1969, from the Viola Limestone (Pa. manitoulinensis GBz, Oklahoma, USA), based on the following features: dimensions and ratios, presence of thick processes that may bifurcate, and some specimens in this population have gentle ornamentation on the vesicle. However, it differs from this species by not having the range of ornamentation present in the type population (simple, λ, and π spines) and most specimens of our population have more processes than originally described and figured. This morphotype also clearly differs from other Katian, gently ornamented Ancyrochitina species. Ancyrochitina barbescens Martin, Reference Martin1975, from the Utica Formation (SW Quebec Province, Canada), has an inflated chamber/convex flanks, with a greater number of cylindrical and narrow processes (10–27). Ancyrochitina merga Jenkins, Reference Jenkins1970a, from the Sylvan Shale (Paraorthograptus manitoulinensis and Dic. complanatus GBz, Oklahoma, USA) has thinner and commonly more (8–24) processes at the margin, which can have several orders of bifurcation.

Genus Clathrochitina Eisenack, Reference Eisenack1959

Type species

Clathrochitina clathrata Eisenack, Reference Eisenack1959; holotype in Eisenack, Reference Eisenack1959, p. 15, pl. 1, fig. 3, from Dalhem canal, Pentamerus gotlandicus beds from southeast Slite Marls, late Sheinwoodian, Silurian, Gotland, Sweden.

Clathrochitina mangle new species

Figures 8, 14.4, 14.5

Reference Miller1976 Trochochitina multiramosa Miller, p. 172–176, pl. 16, figs. 1, 2, 4–7, text-fig. 20.

Reference Knabe1980 Trochochitina multiramosa; Knabe, p. 111–112, pl. 6, figs. 16, 18.

Reference Velleman2016 Clathrochitina multiramosa; Velleman, p. 69–70, pl. 5, figs. 16, 17, 21–23.

Holotype

Figure 8.19 (RBINS collection number b 10050); dimensions: L: 142 μm; D: 98 μm; Da: 56 μm; Lch: 88 μm; Ln: 54 μm; L processes: 22 μm; L/D: 1.45; D/Da: 1.74; sample MY-477.0 ft (145.4 m), Kope Formation (Maysville, Kentucky, USA).

Diagnosis

A Clathrochitina species with a dense crown of uncountable processes on the margin. The processes are multi-rooted, fine, and solid. The sets of numerous processes anastomose in a mangrove-like aspect and join distally in a simple tip or a partial ring.

Occurrence

In this work, from sample MY-477.0 ft (145.4 m; Kope Formation) to MY-282.0 ft (86.0 m; Grant Lake Limestone), MY-14-01 core, Kentucky, USA. In several other sections of Kentucky and Cincinnati, Ohio, Cl. mangle n. sp. was identified in the upper part of the Clays Ferry Formation, the upper part of the Kope Formation, the Fairview Formation, and the lower part of the Grant Lake Limestone (Miller, Reference Miller1976; Knabe, Reference Knabe1980).

Description

Vesicle’s overall shape is conical. When a flexure is conspicuous (i.e., chamber and neck are well differentiated), the chamber is conical and the neck is subcylindrical (e.g., Fig. 8.1). In most specimens, the chamber flanks are straight to convex, but specimens with slightly concave flanks (Fig. 8.4) are also found. When present, the flexure is usually gentle, but it can be sigmoidal and have discrete shoulders (Fig. 8.8, 8.12). In most specimens, the length of the neck is almost half of the total length of the vesicle; however, the neck can also be short (Fig. 8.15) or inconspicuous (Fig. 8.7, 8.14). The lip is gently fimbriated. A prosome has been observed inside the neck (Fig. 8.6). On the margin, there are numerous fine and solid processes, densely packed, resulting in a thick crown. We estimate that the number of processes should be between many dozens and fewer than 200. However, the processes are so numerous and are distributed in such a complex and compact way that their exact number is uncountable. Sets of processes come together in simple tips (Fig. 8.20) and/or partial rings (Fig. 8.14, 8.16), at a maximum distance from the margin of 38 μm. Even when vesicles were intensely eroded, the many spines and granules (resulting from the broken processes) and the complex roots on the margin allowed the identification of this species. Gentle ornamentation can be present on the vesicle, in the form of discontinuous crests on the lower part of the chamber, connected to the sets of processes on the margin (e.g., Fig. 8.6, 8.16, 8.20), and granules randomly distributed on the chamber and neck (Fig. 8.1). At the base, concentric rings and a pit with a mucron have been observed (Fig. 8.5, 8.18).

Etymology

The specific epithet relates to the red mangrove (Rhizophora mangle, described by Linnaeus) as the arrangement of the processes on the margin of this chitinozoan species resembles the numerous roots of mangrove trees.

Materials

N = 728 specimens.

Dimensions

L: 89–144–238 μm; D: 76–102–143 μm; Da: 35–52–65 μm; Lch: 63–101–150 μm; Ln: 11–43–88 μm; L processes: 11–20–38 μm; L/D: 0.89–1.41–2.30; D/Dc: 1.51–1.97–2.58 (n = 55).

Remarks

This species was first described from the Maysville area as Trochochitina multiramosa, but never formally defined (Miller, Reference Miller1976). Trochochitina is a nomen nudum and was not retained by Paris et al. (Reference Paris, Grahn, Nestor and Lakova1999). The taxon’s conical chamber and the crown of compact, anastomosing processes on the margin justify its attribution to the genus Clathrochitina. We could not retain the original species name either given that the species Ancyrochitina multiramosa Taugourdeau and de Jekhowsky, Reference Taugourdeau and de Jekhowsky1960, was later reassigned to the genus Clathrochitina (Taugourdeau, Reference Taugourdeau1967) and has nomenclature priority. Therefore, a new species name was selected for our population.

Two line drawings to clearly show the diagnostic features and variability in the ornamentation of this new species can be found in Fig. 14.4, 14.5. Clathrochitina mangle n. sp. is the fourth and youngest element of morphological lineage 1, composed of (older to younger; Fig. 14): Hercochitina edingerae n. sp., Hercochitina krafftae n. sp., Hercochitina tharpae n. sp., and Cl. mangle n. sp. Hercochitina tharpae n. sp. can be distinguished from Cl. mangle n. sp. by always having continuous crests on the chamber and well-differentiated sets of spines that do not connect laterally (i.e., never forming a continuous crown of anastomosing processes). The complexity and density of processes on the margin of the studied specimens are unique within the genus Clathrochitina. Species originally attributed to the genus Clathrochitina from Middle Ordovician strata have been reassigned to Sagenachitina (e.g., Jenkins, Reference Jenkins1970a). After the reassignment of Cl. concinna Achab Reference Achab1978b, and Cl. sylvanica Jenkins, Reference Jenkins1970a, to the genus Plectochitina, only one species in open nomenclature, Clathrochitina sp. 1 Achab and Asselin in Achab et al., Reference Achab, Asselin, Desrochers and Riva2013, has been reported from the Upper Ordovician (Hirnantian, Anticosti Island). Clathrochitina sp. 1 can be differentiated by its diagnostic small granules randomly distributed throughout the entire vesicle, and its processes on the margin being shorter, less numerous, and more sporadically distributed than those of Cl. mangle. n. sp. To date, Cl. mangle n. sp. appears to be the oldest reported species of the genus Clathrochitina.

Genus Plectochitina Cramer, Reference Cramer1964

Type species

Plectochitina carminae Cramer, Reference Cramer1964; lost holotype in Cramer, Reference Cramer1964, p. 346–347, pl. 20, fig. 21, from the La Vid de Gordón section, upper San Pedro Formation, Přídolí, Silurian, NW Spain; neotype in Priewalder, Reference Priewalder1997, p. 77, pl. 2, fig. 1, pl. 4, figs. 1, 7, 8, from type stratum.

Plectochitina spongiosa (Achab, Reference Achab1977b)

Figure 5.26–5.28

Reference Achab1977b Ancyrochitina spongiosa Achab, p. 2195–2197, pl. 1, figs. 1–9, 12.

Reference Achab1978a Ancyrochitina spongiosa; Achab, p. 299–300, pl. I, figs. 1–3.

Reference Achab1978b Ancyrochitina spongiosa; Achab, pl. I, figs.11, 12 (non pl. III, figs. 15–17).

? Reference Molyneux and Paris1985 Plectochitina spongiosa; Molyneux and Paris, pl. 5, figs. 8, 9.

Reference Achab1987 Ancyrochitina spongiosa; Achab, p. 1214–1216, pl. I, figs. 1–3.

? Reference Soufiane and Achab2000a Plectochitina spongiosa; Soufiane and Achab, pl. II, fig. 3.

non Reference Ghavidel-Syooki and Vecoli2007 Plectochitina spongiosa; Ghavidel-Syooki and Vecoli, p. 181, pl. I, fig. 1.

? Reference Loydell, Nestor and Männik2010 Plectochitina spongiosa; Loydell et al., fig. 12h.

? Reference Al-Shawareb, Miller and Vecoli2017 Plectochitina spongiosa; Al-Shawareb et al., pl. 9, fig. 3 (non pl. 9, fig. 4).

Holotype

GSC49055, core sample 1500 ft (457 m), Vauréal Formation, NACP core, Anticosti Island, Canada (Achab, Reference Achab1977b, p. 2195–2197, pl. 1, fig. 6).

Occurrence

From sample MY-722.6 ft (220.2 m; Point Pleasant Formation) to MY-253.1 ft (77.1 m; Grant Lake Limestone), MY-14-01 core, Kentucky, USA. Also from the Utica and Lorraine groups, SW Quebec Province (Achab, Reference Achab1987), and the Vauréal and Ellis Bay formations, Anticosti Island (Achab, Reference Achab1977b, 1978a, b; Achab et al., Reference Achab, Asselin, Desrochers and Riva2013), Canada.

Materials

N = 28 specimens.

Dimensions

L: 62–92–112 μm; D: 62–73–80 μm; Da: 29–40–47 μm; Lch: 41–59–73 μm; Ln: 18–33–70 μm; L processes: 18–27–31 μm; L/D: 0.83–1.26–1.46; D/Da: 1.59–1.84–2.21 (n = 13).

Remarks

This species was originally assigned to the genus Ancyrochitina (Achab, Reference Achab1977b). However, in the type assemblage of this species, a crown of cell-like processes can be observed, which justifies its reattribution to the genus Plectochitina. Some authors (e.g., Priewalder, Reference Priewalder1997) have questioned if this species could be a junior synonym of Plectochitina sylvanica (Jenkins, Reference Jenkins1970a). Many characteristics overlap: vesicle shape, size range, organization of the processes, and type assemblages originate from units of similar age. However, a few differences exist between these species: Pl. spongiosa has no more than 10 processes, which can be shorter (< 50 μm) than those of Pl. sylvanica (< 90 μm), and they seem thicker. We have not reviewed the type material of these species and we are not studying samples from their type strata, so we keep these species separate.

Attribution of the specimens of Molyneux and Paris (Reference Molyneux and Paris1985, pl. 5, figs. 8, 9) to Pl. spongiosa is questioned since their processes seem thinner and more complex than the ones of the type assemblage, resembling the features of Pl. concinna (Achab, Reference Achab1978b). We are also uncertain if the specimen of Soufiane and Achab (Reference Soufiane and Achab2000a, pl. II, fig. 3) could be Pl. spongiosa since it only preserves one set of two processes joined at the tip and has abundant granules on the vesicle, a characteristic not observed in the type material or described by Achab (Reference Achab1977b). The specimen attributed to this species by Loydell et al. (Reference Loydell, Nestor and Männik2010, fig. 12h), has a neck length greater than half of the total length of the vesicle, an ornamentation of abundant small granules, and only two preserved processes with uneven thickenings, features inconsistent with the diagnosis of Pl. spongiosa and that resemble the characteristics of Pl. nodifera (Nestor, Reference Nestor1980). One of the specimens of Al-Shawareb et al. (Reference Al-Shawareb, Miller and Vecoli2017, pl. 9, fig. 3) identified as Pl. spongiosa has fewer and longer (> 50 μm) processes than expected for this species.

Other specimens in the literature may have been erroneously identified as Pl. spongiosa. Three of the specimens figured by Achab (Reference Achab1978b, pl. III, figs. 15–17) have an ovoid and elongated chamber, fewer and thinner processes, without evidence of joining at the tip, contrasting with the type material of this species (Achab, Reference Achab1977b). The specimen pictured by Ghavidel-Syooki and Vecoli (Reference Ghavidel-Syooki and Vecoli2007, pl. I, fig. 1) has processes bifurcating at the tip, a feature incompatible with the diagnosis of Pl. spongiosa and, in our opinion, more similar to those of Ancyrochitina merga Jenkins, Reference Jenkins1970a. The specimen of Al-Shawareb et al. (Reference Al-Shawareb, Miller and Vecoli2017, pl. 9, fig. 4) only has one preserved process that is longer than 100 μm, inconsistent with the dimensions of the type population of Pl. spongiosa (Achab, Reference Achab1977b).

In Quebec, Pl. spongiosa is the nominal species of a biozone defined by Achab (Reference Achab1989), occurring in levels that yielded graptolites of the basal G. pygmaeus GBz (Riva, Reference Riva and Kay1969; Achab, Reference Achab1987), correlated with the lower part of the Pleurograptus linearis GBz (Maletz, Reference Maletz, Part and revision2021[2023]).

Plectochitina cf. Pl. sylvanica (Jenkins, Reference Jenkins1970a)

Figure 4.10–4.16

Occurrence

From samples MY-770.3 ft (234.8 m; Point Pleasant Formation) to MY-487.0 ft (148.4 m; Kope Formation), MY-14-01 core, Kentucky, USA.

Description

The overall shape of the vesicle is conical. The well-developed flexure, without shoulders, separates the conical chamber from the neck, subcylindrical or flaring towards the aperture. Usually, small and discrete granules are randomly distributed on the neck and lip (Fig. 4.10, 4.11). A maximum of 20 process roots were observed on the margin. The processes have a cell-like structure (i.e., internally, the processes have partitions/divisions, which cause their irregular outline and thickness variation) and anastomose: sets of 2–9 anastomosed processes have been observed; they may unite and split again, making a complex net (Fig. 4.14–4.16). Distally from the vesicle, the processes commonly finish in a simple tip (Fig. 4.12), or they can rarely unite in a ring-like structure (Fig. 4.13). When the base of the vesicle is exposed, discrete concentric rings are sometimes observed (Fig. 4.14). No apical structures were observed.

Materials

N = 846 specimens.

Dimensions

L: 59–100–131 μm; D: 56–76–91 μm; Da: 26–38–53 μm; Lch: 37–64–86 μm; Ln: 21–36–69 μm; L processes: 19–33–50 μm; L/D: 0.84–1.32–1.89; D/Da: 1.38–2.05–2.94 (n = 23).

Remarks

Our material is conspecific with the material described as Trochochitina radiata Miller, Reference Miller1976, nomen nudum (Miller, Reference Miller1976) from the upper Kope Formation at Maysville, Kentucky. However, all these specimens have a conical chamber and cell-like processes on the margin, suggesting their attribution to the genus Plectochitina. All of the specimens strongly resemble Plectochitina sylvanica (Jenkins, Reference Jenkins1970a) (Sylvan Shale, Pa. manitoulinensis and Dic. complanatus GBzs, Oklahoma, USA, Goldman and Bergström, Reference Goldman and Bergström1997), Plectochitina spongiosa (Achab, Reference Achab1977b) (Utica Group to Ellis Bay Formation, G. pygmaeus to Metabolograptus persculptus GBzs, Canada; Achab, Reference Achab1978b; Melchin, Reference Melchin2008) and Plectochitina concinna (Achab, Reference Achab1978b) (upper Vauréal to Ellis Bay Formation, Pa. prominens to M. persculptus GBzs, Anticosti Island; Melchin, Reference Melchin2008; Achab et al., Reference Achab, Asselin, Desrochers, Riva and Farley2011) by having the characteristic long and complex processes, a similar outline and dimensions. In our abundant, well-preserved specimens, we observe a large variability, with all the intermediate forms, surpassing the type populations of both species. For example, unlike Pl. concinna, the necks in our specimens can be longer than the chamber, reaching up to two-thirds of the total length of the vesicle; and the anastomosing processes can be longer than 30 μm (Fig. 4.16). The length of the processes of our specimens falls within the range of those of Pl. sylvanica and they are longer, thinner, and more numerous than type specimens of Pl. spongiosa. However, our specimens can have even more processes than type specimens of Pl. sylvanica and rarely have a continuous ring connecting their distal ends, which is common within that species. Also, Pl. sylvanica, Pl. spongiosa, and Pl. concinna were never described as having granules on the neck and the resolution of the images of their type material does not provide that degree of detail. Given this degree of complexity, our specimens are described in open nomenclature.

Subfamily Angochitininae Paris, Reference Paris1981

Genus Angochitina Eisenack, Reference Eisenack1931

Type species

Angochitina echinata Eisenack, Reference Eisenack1931; lost holotype in Eisenack, Reference Eisenack1931, p. 82, pl. 1, fig. 7, from erratic Beyrichia limestones (‘Beyrichia-kalk’); neotype in Eisenack, Reference Eisenack1964, p. 319, pl. 29, fig. 10, from the topmost part of the Hemse beds, early Ludfordian, Silurian, Gotland, Sweden (Paris et al., Reference Paris, Grahn, Nestor and Lakova1999).

Angochitina bascomae new species

Figure 6.12–6.17

Holotype

Illustrated in Fig. 6.14, 6.17 (RBINS collection number b 10051); dimensions: L: 129 μm; D: 83 μm; Da: 47 μm; Lch: 94 μm; Ln: 35 μm; H spines: 6 μm; L/D: 1.55; D/Da: 1.77; sample MY-603.5 ft (183.9 m), Kope Formation (Maysville, Kentucky, USA).

Diagnosis

Ovoid to pear-shaped Angochitina species with thick spines of different morphologies coexisting in the same specimens: bases can be simple, two-legged, or thorn-like; tips can be simple, pointed, or broad, or they can bifurcate.

Occurrence

Sample MY603.5 ft (183.9 m), Kope Formation, MY-14-01 core, Kentucky, USA.

Description

Vesicle small, subconical to pear-shaped. Chamber ovoid to subconical, with the convex flanks tapering towards the gentle flexure. Maximum width at the lower half of the chamber. Shoulders absent. Neck subcylindrical to gently flaring. A tubular prosome has been observed partially ejected from the vesicle (Fig. 6.13). Lip fimbriated. Ornamentation of randomly distributed, thick spines: simple, two-legged, and/or thorn-like. At the tip, the spines can be simple or bifurcated (few per specimen but easy to spot; indicated with arrows in Fig. 6.17). The spines get shorter, finer, and scarcer towards the aperture and can be replaced by granules close to the lip. The same decrease of ornamental complexity occurs towards the center of the base, where no apical structures were observed.

Etymology

Named after Florence Bascom, an educator and the first woman geologist hired by the U.S. Geological Survey (1896).

Materials

N = 153 specimens.

Dimensions

L: 78–114–190 μm; D: 75–83–101 μm; Da: 29–46–70 μm; Lch: 58–81–110 μm; H spines: 4–7–11 μm; L/D: 0.94–1.37–1.88; D/Da: 1.45–1.87–2.81 (n = 20).

Remarks

Angochitina dicranum Jenkins, Reference Jenkins1967 (Onnia beds, correlated with the Dicellograptus morrisi Subzone of the Dicranograptus clingani Biozone, lower Katian, UK; Zalasiewicz et al., Reference Zalasiewicz, Rushton and Owen1995) is the only other Upper Ordovician Angochitina species that is known to have bifurcating spines. However, the ornamentation in that species is more spaced, the spines are longer, and the vesicle is more elongated than our material.

Angochitina oklahomensis Taugourdeau, Reference Taugourdeau1965

Figure 12.7, 12.8, 12.11, 12.12

Reference Taugourdeau1965 Angochitina? oklahomensis n. sp.; Taugourdeau, p. 466, pl. I, fig. 6.

? Reference Rauscher and Doubinger1967 Angochitina oklahomensis; Rauscher and Doubinger, p. 315, pl. 1, fig. 9.

Holotype

N°32 J, from the Viola Limestone (= Viola Springs Formation), P. manitoulinensis GBz (Goldman and Bergström, Reference Goldman and Bergström1997), Katian, Criner Hills, Carter County, Oklahoma, USA (Taugourdeau, Reference Taugourdeau1965, p. 466, pl. I, fig. 6).

Occurrence

Upper Ordovician of: US Midwest, Viola Limestone (= Viola Springs Formation) of Oklahoma; in this work, from sample MY-319.0 (Grant Lake Limestone) to sample MY-075.0 (Bull Fork Formation), MY-14-01 core, Kentucky, USA.

Materials

N = 337 specimens.

Dimensions

L: 98–138–172 μm; D: 65–80–88 μm; Da: 35–45–56 μm; Lch: 68–101–127 μm; H spines: 2–3–4 μm; L/D: 1.37–1.73–2.09; D/Da: 1.51–1.78–2.17 (n = 24).

Remarks

This species was originally assigned with doubt to the genus Angochitina (Taugourdeau, Reference Taugourdeau1965). In the following years, authors confirmed this assignment (e.g., Rauscher and Doubinger, Reference Rauscher and Doubinger1967) and we agree with that decision. While this species has been rarely imaged and only succinctly described, it has diagnostic characteristics that differentiate it from other Angochitina species: short, wide, and subcylindrical neck; cylindro-ovoid chamber; and a vesicle densely ornamented with small, simple, pointed spines (Fig. 12.12) We cannot confidently agree that the specimen of Rauscher and Doubinger (Reference Rauscher and Doubinger1967, pl. 1, fig. 9) belongs to the species Ang. oklahomensis: while the shape of the neck and chamber is compatible with the features of this species, the image was obtained with transmitted light microscopy and does not have the necessary resolution to confirm the size and organization of the spines.

Angochitina cf. Ang. capillata Eisenack, Reference Eisenack1938

Figures 9.15–9.18, 12.13–5.17

Occurrence

From sample MY-457.3 (Kope Formation) to sample MY-075.0 (Bull Fork Formation), MY-14-01 core, Kentucky, USA.

Description

Overall shape of the vesicle is conical. Flexure well developed. Chamber ovoid to subconical with convex flanks. Maximum width situated at the half-length or within the lower half of the chamber. Neck subcylindrical to flaring. Lip fimbriated (Fig. 12.14) and can have small perforations (Fig. 12.16). Vesicle densely ornamented with fine spines, less than or equal to 8 μm in length, always with pointed tips and broad and elongated bases, typically two-legged and aligned with the long axis of the vesicle (e.g., Fig. 9.15, 9.18). The spines are longer in the middle area of the vesicle and decrease both aperturalwards and antiaperturalwards. A pit without a mucron has been observed at the center of the base (Fig. 12.17).

Materials

N = 1348 specimens.

Dimensions

L: 93–128–179 μm; D: 65–76–91 μm; Da: 36–44–56 μm; Lch: 65–94–141 μm; Ln: 17–35–55 μm; H spines: 3–5–8 μm; L/D: 1.26–1.70–2.17; D/Da: 1.48–1.73–1.97 (n = 20).

Remarks

The type material of Ang. capillata Eisenack, Reference Eisenack1938 (erratic block, Upper Ordovician, Baltica) appears to display thicker and longer spines (dimensions not provided and the original images are too low resolution to recalculate some measurements of this material), described as thorn-shaped and not as two-legged or lambda spines. However, the original vesicle dimensions and its outline are similar to the characteristics of our material. Given the uncertainties, it is appropriate to apply open nomenclature.

Order Operculatifera Eisenack, Reference Eisenack1931

Family Desmochitinidae Eisenack, Reference Eisenack1931, emend. Paris, Reference Paris1981

Subfamily Desmochitininae Paris, Reference Paris1981

Genus Desmochitina Eisenack, Reference Eisenack1931

Type species

Desmochitina nodosa Eisenack, Reference Eisenack1931; lost holotype in Eisenack, Reference Eisenack1931, p. 92, pl. 3, fig. 1, from erratic Ordovician calcareous sandy siltstone; neotype in Laufeld, Reference Laufeld1967, p. 330–332, fig. 26, from the ‘Skagen’ Formation, Baltoscandian Keila Stage, ca. Sandbian–Katian boundary, Upper Ordovician, Fjäka section, Dalarna, Sweden.

Desmochitina cf. D. holosphaerica Eisenack, Reference Eisenack1968

Figure 4.19

Occurrence

From samples MY-741.1 ft and MY-701.6 ft (225.9–213.8 m), Point Pleasant Formation, MY-14-01 core, Kentucky, USA.

Description

Overall shape of the vesicle subspherical. Greatest width at the upper half of the vesicle. Very wide aperture (Da = 67% of Dp). Short, straight collarette. The operculum is thick and not ornamented. Vesicle wall smooth. The operculum of the preceding specimen is still attached to the base of the following vesicle (Fig. 4.19).

Materials

N = 4 specimens.

Dimensions

L: 71–71–72 μm; D: 64–69–72 μm; Da: 43–46–48 μm; L collarette: 5–6–7 μm; L/D: 0.99–1.04–1.13; D/Da: 1.48–1.49–1.50 (n = 3).

Remarks

Of all the Desmochitina species known to have an operculum of the preceding specimen still attached to the base of the following vesicle, our material presents many similarities with D. holosphaerica from glacial erratics of the Baltic region, which Eisenack (Reference Eisenack1968) considered Caradocian in age (Sandbian–lower Katian), in having a subspherical vesicle, a very short collarette, and a wide aperture. In the type material of D. holosphaerica, the short collarette flares gently while in our material the collarette is approximately straight. Also, no structure that could resemble a copula between the base of the vesicle and the operculum of the preceding specimen, as described by Eisenack (Reference Eisenack1968), was observed in our specimens: the way the vesicle was folded could be hiding this structure or it might not be present at all. These differences, the low abundance of specimens of this morphotype in our samples, and the lack of published images of D. holosphaerica after its definition favor the use of open nomenclature. Desmochitina holosphaerica has been reported but not figured from the Baltoscandian Uhaku to Keila stages (e.g., Nõlvak, Reference Nõlvak and Põldvere2008; Goldman et al., Reference Goldman, Nõlvak and Maletz2015).

Subfamily Eisenackitininae Paris, Reference Paris1981

Genus Eisenackitina Jansonius, Reference Jansonius1964, restrict. Paris, Reference Paris1981

Type species

Eisenackitina castor Jansonius, Reference Jansonius1964; holotype in Jansonius, Reference Jansonius1964, p. 912–913, pl. 2, fig. 16, core sample from 253 m (758 ft), Hume Formation, Givetian, Devonian, northern Canada.

Eisenackitina cf. E. ripae Soufiane and Achab, Reference Soufiane and Achab2000b

Figure 13.8–13.13

Occurrence

Samples MY-065.4 ft and MY-055.0 ft (19.9–16.8 m), Bull Fork Formation, MY-14-01 core, Kentucky, USA.

Description

Vesicles can be elongated and subcylindrical (Fig. 13.8) to short (Fig. 13.11), subconical, and stout (Fig. 13.9). Flexure commonly inconspicuous (Fig. 13.8, 13.10). When recognizable, the gentle flexure separates the conical chamber from the mildly flaring, short neck (Fig. 13.9). Lip moderately (Fig. 13.9, 13.13) to intensely fimbriated, sometimes also displaying perforations (Fig. 13.10). Maximum width at the rounded margin or slightly above. Vesicle densely and homogeneously ornamented with granules. The outer half of the base is similarly ornamented, but the ornamentation decreases towards the center of the base, where a pit with a mucron and concentric rings can be observed (Fig. 13.12), when the base is not invaginated (Fig. 13.9–13.11).

Materials

N = 289 specimens.

Dimensions

L: 120–189–277 μm; D: 84–104–122 μm; Da: 64–77–93 μm; L/D: 1.25–1.81–2.40; D/Da: 1.16–1.36–1.51 (n = 26).

Remarks

Eisenackitina ripae type material (Paraorthograptus pacificus and Metabolograptus extraordinarius GBzs, from central Nevada and Arctic Canada; Finney et al., Reference Finney, Berry, Cooper, Ripperdan, Sweet, Jacobson, Soufiane, Achab and Noble1999; Štorch et al., Reference Štorch, Mitchell, Finney and Melchin2011; Maletz, Reference Maletz, Part and revision2021[2023]) and our material have important features in common: vesicle shape and dimensions, and dense, small ornamentation. Yet, in contrast to the E. ripae type material, our population is ornamented with granules (tubercles or cones absent), and the presence and size of the ornamentation appear uniform throughout the entire vesicle. These differences favor the use of open nomenclature.

Within the Family Desmochitinidae, the genus Bursachitina is characterized by its glabrous and conical chamber, while specimens of the genus Eisenackitina have an ovoid chamber with randomly distributed spines (Paris et al., Reference Paris, Grahn, Nestor and Lakova1999). The holotype and paratypes of E. ripae display a conical chamber and this species is described as having tubercles and cones without indicating dimensions, and spines were not mentioned or observed. These features seem more compatible with the genus Bursachitina. However, given the doubt that our material even is conspecific with this species, we only mention the possibility of reassigning the mentioned species to the genus Bursachitina without making a formal suggestion.

Eisenackitina sp. 1

Figure 6.18–6.21

Occurrence

Sample MY-603.5 ft (183.9 m), Kope Formation, MY-14-01 core, Kentucky, USA.

Description

Vesicle stout, ovoid to pear-shaped. The pear-shaped vesicles have a gentle flexure separating the ovoid chamber from the neck that tapers towards the aperture (Fig. 6.20, 6.21). Convex flanks. Maximum width mid-chamber or on its lower half. The lip is usually poorly preserved but seems to be gently fimbriated (Fig. 6.18). The sealing structure seems to be an operculum at the aperture of the vesicle (Fig. 6.18). The vesicle is ornamented with randomly distributed, small, pointed, and broad-based spines. Base invaginated in most specimens: ornamentation of granules and discrete concentric rings were observed on the base, but it was impossible to observe the presence of apical structures.

Materials

N = 62 specimens.

Dimensions

L: 64–97–117 μm; D: 70–81–95 μm; Da: 29–38–48 μm; H spines: 2–3–5 μm; L/D: 0.92–1.19–1.50; D/Da: 1.65–2.19–2.74 (n = 21).

Remarks

Eisenackitina sp. 1 can be very similar to some specimens of Angochitina bascomae n. sp., present in the same sample. However, Ang. bascomae n. sp. typically has longer spines with more variable morphologies coexisting on the same vesicle, commonly with bifurcating tips. Also, specimens of Ang. bascomae n. sp. usually are longer. No other Eisenackitina species from the Upper Ordovician is known to have such an ovoid vesicle.

Genus Nevadachitina Soufiane and Achab, Reference Soufiane and Achab2000b

Type species

Nevadachitina vininica Soufiane and Achab, Reference Soufiane and Achab2000b; holotype in Soufiane and Achab, Reference Soufiane and Achab2000b, p. 175, pl. I, fig. 2, from the uppermost Vinini Formation, Vinini Creek section, Hirnantian (Upper Ordovician), Roberts Mountains, Nevada, USA.

Remarks

The genus Nevadachitina was erected after the revision work of Paris et al. (Reference Paris, Grahn, Nestor and Lakova1999), and therefore was not included there. Since then, this genus has been consistently used by different authors (e.g., Sinha et al., Reference Sinha, Vandenbroucke and Verniers2011; Paris et al., Reference Paris, Thusu, Meinhold, Howard, Rasul, Strogen, Abutarruma, Elgadry and Whitham2012; Achab et al., Reference Achab, Asselin, Desrochers and Riva2013). Until now, only three species were attributed to Nevadachitina, one of them in open nomenclature (Soufiane and Achab, Reference Soufiane and Achab2000b). The number of crowns and longitudinal rows, together with spine characteristics, have been considered key features for discerning between species (Soufiane and Achab, Reference Soufiane and Achab2000b). Before the current study, species belonging to the genus Nevadachitina were identified and reported only from central Nevada, within the Dic. ornatus (upper Katian), M. extraordinarius, and M. persculptus (Hirnantian) GBzs (Finney et al., Reference Finney, Berry, Cooper, Ripperdan, Sweet, Jacobson, Soufiane, Achab and Noble1999; Soufiane and Achab, Reference Soufiane and Achab2000b; Maletz, Reference Maletz, Part and revision2021[2023]).

Nevadachitina soufianei new species

Figure 13.14–13.18

Holotype

Illustrated in Figure 13.18 (RBINS collection number b 10052); dimensions: L: 132 μm; D: 74 μm; Da: 54 μm; H spines: 19 μm; L/D: 1.77; D/Da: 1.39; sample MY-065.4 ft (19.9 m), Bull Fork Formation (Maysville, Kentucky, USA).

Diagnosis

Nevadachitina species with spaced spines on the whole vesicle, organized in 15–16 crowns and 10–12 longitudinal rows regularly distributed on the visible face. The spines appear to be stiff to slightly flexible, subcylindrical, and long (< 19 μm), their bases are frequently perforated and elongated longitudinally, and their rounded tips sporadically bifurcate.

Occurrences

Sample MY-065.4 ft (19.9 m), Bull Fork Formation, MY-14-01 core, Kentucky, USA.

Description

The overall shape of the vesicle is conical. In a few specimens, the chamber and neck are not differentiated, and the vesicle gets narrower towards the aperture with convex flanks. When separated by a gentle flexure, the chamber is conical to subcylindrical, with convex to straight flanks, and the neck is short and subcylindrical. Lip finely fimbriated. Sealing structures were not observed. Ornamentation consists of spaced spines on the whole vesicle, regularly organized in 15–16 crowns and 10–12 longitudinal rows on the visible face. The spines appear to be stiff to slightly flexible, subcylindrical, widening slightly towards the vesicle wall, and tapering to blunt, rounded tips at their distal end. The bases of the spines are frequently perforated and elongated longitudinally, and distally, the tips may bifurcate—rarely but observable at least once in all the studied specimens of the population (Fig. 13.14, 13.18). The spines are long (< 19 μm) on the margin and the chamber, getting shorter towards the aperture, and evolving to thorns and granules near the lip, where they lose their regular distribution. Rounded margin. Base ornamented with spines in concentric rings around the apical structure: a simple pit (Fig. 13.18), or a pit with a discrete mucron (Fig. 13.16).

Etymology

This species is dedicated to Azzedine Soufiane for his work on Ordovician and Silurian chitinozoans and his heroic behavior during the Québec City mosque attack in 2017.

Materials

N = 17 specimens.

Dimensions

L: 95–133–158 μm; D: 71–79–90 μm; Da: 46–50–56 μm; H spines: 9–14–19 μm; L/D: 1.34–1.69–1.97; D/Da: 1.39–1.60–1.88 (n = 9).

Remarks

The presence of spines on the whole vesicle regularly organized in crowns and longitudinal rows warrants the inclusion in the genus Nevadachitina. The studied material differs from Nevadachitina praevininica Soufiane and Achab, Reference Soufiane and Achab2000b, and N. vininica Soufiane and Achab, Reference Soufiane and Achab2000b, from the Hanson Creek (upper Katian, Dic. ornatus GBz) and uppermost Vinini (Hirnantian, M. extraordinarius and M. persculptus GBz) formations, respectively (Nevada, USA). Nevadachitina soufianei n. sp. has a vesicle and/or chamber more conical than ovoid, more crowns and rows of spines, and rare bifurcated spines. The specimens of our population also are usually longer and always wider than the specimens of N. praevininica and N. vininica. These differences justify erection of a new species. The number of crowns and longitudinal rows of spines of the specimens in our population, as well as their dimensions, partially overlaps with those attributed to Nevadachitina sp. Soufiane and Achab, Reference Soufiane and Achab2000b, from the lower part of the Vinini Formation. However, in the latter, most of the spines seem shorter (no measure provided), the number of crowns and longitudinal rows are mostly inferred by the scars of broken spines, and spines with bifurcated tips were not observed. Those distinct characteristics may be either a result of taphonomical processes or morphological differences between two species. Given this uncertainty, we do not synonymize our material with Soufiane and Achab’s (Reference Soufiane and Achab2000b) specimens attributed to Nevadachitina sp.