Introduction
The Harnischia complex of tribe Chironomini (Diptera: Chironomidae) has been documented with 20 genera globally, among which 16 genera have been recorded from the Orient and 14 from India, including Beckidia Sæther, 1979; Cladopelma Kieffer, 1921; Cryptochironomus Kieffer, 1918; Cryptotendipes Beck and Beck, 1969; Cyphomella Sæther, 1977; Demicryptochironomus Lenz, 1941; Harnischia Kieffer, 1921; Kloosia Kruseman, 1933; Microchironomus Kieffer, 1918; Olecryptotendipes Zorina, 2007; Parachironomus Lenz, 1921; Paracladopelma Harnisch, 1923; Robackia Sæther, 1977; and Saetheria Jackson, 1977 (Mukherjee and Hazra Reference Mukherjee and Hazra2023).
The genus Cryptotendipes comprises 24 species globally, of which eight have been recorded from the Oriental region, including four from India: Cryptotendipes aculeatus Pal and Hazra, 2018; C. acutus (Goetghebuer, 1936); C. medialis Mukherjee et al., 2020; and C. nodus Yan et al., 2005. In the present study, a new species, Cryptotendipes tumidus sp. nov., is described, based on an integrated taxonomic approach, adding to the diversity of this genus in India.
To date, the genus Beckidia is represented by seven species, among which two species have been recorded from the Oriental region, including one species, Beckidia inflata Mukherjee and Hazra, 2023, from India (Mukherjee and Hazra Reference Mukherjee and Hazra2023). In the present study, we report the first faunistic record of Beckidia hirsti (Freeman, 1957) from India, previously known to be found only in the Afrotropical region.
The genus Crytochironomus contains more than 140 valid species (Liu et al. Reference Liu, Wang, Tang, Pei and Yan2024), with 20 species from the Oriental region, including 10 from India (Hazra et al. Reference Hazra, Niitsuma and Chaudhuri2016). In the present study, Cryptochironomus tamaichimori Sasa in Sasa and Kawai, 1987 is reported for the first time from India; the species was previously reported from China and the Palaearctic regions.
Materials and methods
Study area
Specimens were collected from different regions of India, including different habitats, such as moist vegetation around lakes and dense forests with scattered aquatic bodies. Detailed data on the different collection sites are listed in Table 1 and shown in Fig. 1. (Fig. 1 map was made in ArcGIS Earth, version 2.2.1.4162; https://www.esri.com/en-us/arcgis/products/arcgis-earth/overview.)
Table 1. Collection sites of the present study
Figure 1. Distribution of the examined species of the Harnischia complex in India
Collection, preservation, and imagery
Specimens were collected using open white light traps, and the chironomine midges were sorted out. The sorted samples were kept in 90% alcohol and stored at –20 °C for further studies.
For morphological taxonomy, 32 midge specimens were slide-mounted using phenol-balsam according to Wirth and Marston (Reference Wirth and Marston1968), and a few were processed for DNA extraction. The mounted specimens were identified using a Leica DM1000 microscope (Leica Microsystems GmbH, Wetzlar, Germany), and photographs were captured using a Leica K3C camera mounted on the microscope. The general terminology follows Sæther (Reference Sæther1980). The number of specimens measured is indicated by “n.” All measurements are in micrometres (µm), excluding body, wing, costa, and antenna lengths, which are in millimetres (mm), with the ranges followed by the mean. All materials examined are retained in the National Zoological Collection of the Diptera Section, Zoological Survey of India, Kolkata, West Bengal, India.
Molecular methods
For molecular analyses, a small section of tissue was dissected from beneath the thorax of the specimen without damaging the major diagnostic structures and processed further using the QIAamp Blood and Tissue Kit (Qiagen, Hilden, Germany) to extract genomic DNA. The partial mitochondrial cytochrome c oxidase 1 (CO1) gene was amplified using polymerase chain reaction with the primer pairs HCO2198: 5′-TAAACTTCAGGGTGACCAAAAAATCA-3′ and LCO1490: 5′-GGTCAACAAATCATAAAGA (Folmer et al. Reference Folmer, Black, Lutz and Vrijenhoek1994). Polymerase chain reaction was performed according to the guidelines described by Ghosh et al. (Reference Ghosh, Kar, Pramanik, Mukherjee, Sarkar and Mukherjee2022). The amplified products were subjected to Sanger sequencing, and the obtained gene sequences were uploaded to GenBank and the National Center for Biotechnology Information (NCBI) to obtain the accession numbers provided in the corresponding species descriptions.
The abbreviations used in the following text are as follows: IV, inner verticals; OV, outer verticals; Po, post orbitals; CA, head–antenna ratio; AR, antennal ratio; Acs, acrostichals; Dcs, dorsocentrals; Pa, prealars; Su, supraalars; Scts, scutellars; VR, veneral ratio; CR, costal ratio; RM, cross vein between radius and media; FCu, forked cubitus; Fe, femur; Ti, tibia; Ta, tarsomere; LR, leg ratio; BV, beinverhältnisse (leg conditions); SV, schenkel–schiene–verhältnis (thigh–splint ratio); An, anal vein; M, media vein; R, radius vein; HR, hypopygium ratio; HV, hypopygium value; BLASTn, Basic Local Alignment Search Tool for Nucleotides; NCBI, National Center for Biotechnology Information.
Sequence analysis
The BLASTn tool was used to compare the CO1 sequence of the new species of Cryptotendipes tumidus with the GenBank sequences available for the nucleotide algorithm. In the molecular analysis of Cryptotendipes, the sequences of nine species were extracted from the NCBI database, and Cryptochironomus rostratus Kieffer, 1921 was employed as an outgroup based on Cranston et al. (Reference Cranston, Hardy and Morse2012); even though Mukherjee and Hazra (Reference Mukherjee and Hazra2023) reported C. disparilis as a junior synonym of C. acutus, it is still considered as C. disparilis in the present study because of the documentation in the NCBI database. In MEGA 11 genetics analysis software (https://www.megasoftware.net/), every sequence of the taxa under study was aligned and trimmed (Tamura et al. Reference Tamura, Stecher and Kumar2021), and JModelTest (https://github.com/ddarriba/jmodeltest2) was used to select the substitution model of the chosen sequence. The GTR+I+G model (general time reversal model with invariant sites and a gamma distribution for rates across the sites) was selected for performing tree analysis with JModelTest software (Darriba et al. Reference Darriba, Taboada, Doallo and Posada2012). To construct the neighbour-joining tree, the number of bootstrap replications was 1000, and both (transition and transversion) substitutions were included, with a site coverage of 95%. Genetic divergence between taxonomic groups was estimated using MEGA 11 and Kimura’s two-parameter model (Kimura Reference Kimura1980; Tamura et al. Reference Tamura, Stecher and Kumar2021). The maximum-likelihood tree of Cryptotendipes was constructed using the CIPRES portal (https://www.phylo.org/; Miller et al. Reference Miller, Pfieiffer and Schwartz2011) using IQ-TREE software (https://iqtree.github.io/) with default parameters, and the neighbour-joining tree was constructed using MEGA 11. The tree was visualised using FigTree, version 2.10.1 (https://tree.bio.ed.ac.uk/software/figtree/). Furthermore, only the interspecific genetic distance between the available CO1 sequences of Cryptotendipes species was estimated in MEGA 11 – and not the intraspecific distance – because only single nucleotide sequences of each species were available in the global database. The GenBank accession numbers for all species in this study are listed in Supplementary material, Table S1. Because sequences for other species were lacking in the NCBI database, species delimitations were performed using Puillandre et al.’s (Reference Puillandre, Brouillet and Achaz2021) assemble species by automatic partitioning method (ASAP) and Zhang et al.’s (Reference Zhang, Kapli, Pavlidis and Stamatakis2013) multi-rate Poisson tree process (mPTP; Supplementary material, Figs. S1, S2, and S3).
Genetic divergence between taxonomic groups was estimated in MEGA-X using Kimura’s two-parameter model (Kimura Reference Kimura1980; Tamura et al. Reference Tamura, Stecher and Kumar2021).
Results
Taxonomy (morphological)
Order Diptera Linnaeus, 1758
Suborder Nematocera Dumeril, 1805
Infraorder Culicomorpha Hennig, 1948
Family Chironomidae Newman, 1834
Subfamily Chironominae Newman, 1834
Tribe Chironomini Newman, 1834
Genus Cryptotendipes Beck and Beck, 1969
Diagnosis. This small to medium-sized genus differs from other genera in the Harnischia complex in that it has an inner expansion on the basal half of the gonostylus and no apical tooth on the gonostylus.
Cryptotendipes tumidus sp. nov
ZooBank Nomenclature Act: urn:lsid:zoobank.org:act:726EB2EB-0027-442B-B43D-E2F35BB41A98
GenBank accession number: PQ663818
Type material. HOLOTYPE: India; ♂ (on slide); collected from Andhra Pradesh, Nellore district; 14.3908° N, 80.0055° E; 6.xii.2020; 26 m; R. Kumar leg. PARATYPE: India; 4 ♂ (on slide), collected from Andhra Pradesh, Nellore district; 14.3908° N, 80.0055° E; 6.xii.2020; 26 m; R. Kumar leg.
Diagnosis. Adult males are distinguished from other species of the genus Cryptotendipes by the absence of acrostichals, the presence of a prominent D-shaped protrusion on the basal part of the gonostylus, a median ridge on tergite IX, and a ridge on the anal point.
Etymology. The name “tumidus,” a Latin word, refers to a swollen expansion of the gonostylus.
Description. MALE (n = 5): total length 3.95–4.03, 3.98 mm, wing length 2.35–2.5, 2.43 mm, costal length 2.25–2.3, 2.28 mm, antennal length 0.9–0.94, 0.92 mm. Colouration: thoracic vittae present as yellowish–brown laterally, legs light brown, and abdomen yellow to light brown. Head: head width 5.25–5.30, 5.28 mm; temporal setae 3 (IV 0, OV 2, Po 1); clypeal setae 7–8; frontal tubercles are also observed; eyes bare, with dorsomedial extension of 200–210, 205 µm. Ultimate flagellomere 650–670, 660 µm long; AR 2.4–2.6, 2.5. Length of palpomeres (I–IV; in µm): 20–22.5; 37.5; 87.5–88; 115–116.5, last one not countable; CA 0.56–0.58, 0.57. Thorax: acrostichals 0, dorsocentrals 7, prealars 3, supraalars 1–2, and scutellars 4. Wing (Fig. 2A): VR 1.10–1.12, 1.11. Brachiolum with two setae. Squama with six fringed setae. FCu distinctly distal to RM. Anal lobe well developed. Legs: fore tibia with 2–3 setae; mid legs with two narrowly separated combs, each with one spur, 22.5-µm-long and 15-µm-long spurs, with 22 and 9 lateral teeth, respectively; hind legs with two narrowly separated combs, each with one spur, 25-µm-long and 20-µm-long spurs, with 32 and 9 lateral teeth, respectively; lengths (µm) and proportions of legs are shown in Table 2. Hypopygium (Fig. 2B–D): anal tergite bands Y-shaped; tergite IX with a median ridge and 5–6 apicomedian anal tergite setae. Anal point 75–77.5, 76.25 µm long, parallel-sided and rounded at the apex, having a median ridge. Transverse sternapodeme 42.5–43, 42.75 µm long; longitudinal sternapodeme 150–155, 152.5 µm long. Superior volsella (Fig. 2E) 35–37.5, 36.25 µm long, digitiform and slightly expanded at the apex, with two apical setae. Gonocoxite 160–162.5, 161.25 µm long. Gonostylus 135–137.5, 136.25 µm long, having a distinct basal protrusion with a strong inner margin, five setae distally with pointed apex. HR 1.18–1.19. 1.185; HV 2.46–2.48, 2.47.
Figure 2. Cryptotendipes tumidus sp. nov. adult male: A, wing; B, hypopygium; C, hypopygium; and D, superior volsella. Scale bars: 100 μm
Table 2. Male leg lengths (µm) and proportions of legs in Cryptotendipes tumidus sp. nov. Fe, femur; Ti, tibia; Ta, tarsomere; LR, leg ratio; BV, beinverhältnisse; SV, schenkel–schiene–verhältnis (thigh–splint) ratio; BV, beinverhältnisse (leg conditions)
Distribution. India
Remarks. The new species was confirmed to belong to the genus Cryptotendipes by characteristics such as the presence of basal expansion of the gonostylus and the absence of apical teeth on the gonostylus. Among all valid species of this genus, the new species is morphologically closer to C. acutus (Goetghebuer, 1936). It has a similar type of superior volsella but differs in the shapes of the gonostylus, anal point, and anal tergite band, along with other morphometric variations. It also resembles C. lyalichi Zorina, 2006 with respect to the absence of acrostichals but entirely differs from that species in the shape of the hypopygium and other morphometric values. To increase the taxonomic comparative resolution, the new species was carefully compared with other Oriental species (Table 3) to establish its novelty within the genus Cryptotendipes of the Harnischia complex.
Table 3. Comparison of some relevant characteristics of the Oriental species of Cryptotendipes Lenz, 1941. AR, antennal ratio; HR, hypopygium ratio; SV, schenkel–schiene–verhältnis (thigh–splint) ratio; Acs, acrostichals
Sæther (Reference Sæther1977), Yan et al. (Reference Yan, Tang and Wang2005), and Pal and Hazra (Reference Pal and Hazra2018) had prepared a key for this genus previously, and Mukherjee et al. (Reference Mukherjee, Mukherjee and Hazra2020) prepared a world pictorial key of the genus. The present study presents an updated key of the genus following the new discoveries and Mukherjee and Hazra’s (Reference Mukherjee and Hazra2023) and He and Tang’s (Reference He and Tang2025) proposed synonymic notes.
World key to the genus Cryptotendipes Beck and Beck (after Mukherjee et al. Reference Mukherjee, Mukherjee and Hazra2020)
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1. Inner margin of gonostylus with basal or median projection …………………… 2
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–. Inner margin of gonostylus without projection ……………………………. 24
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2. Inner margin of gonostylus with median projection ….………………………3
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–. Inner margin of gonostylus with basal projection ….……………….……… 13
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3. Anal point not longer than superior volsella ….….….….………….……… 4
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–. Anal point longer than superior volsella …………….……………………. 6
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4. Gonostylus with distinct concavity in apical half; Nearctic.…. C. tuberosus (Sæther, 2010)
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– Gonostylus without distinct concavity.………….………………………. 5
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5. Superior volsella columniform and straight; anal point rounded at the apex; Palaearctic ………….….…………………….…………… C. nigronitens (Edwards, 1929)
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– Superior volsella digitiform and curved; anal point pointed at the apex; Palaearctic ….………………………………,…,……….…….…C. pflugfelderi (Reiss, 1964)
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6. Anal tergite with a high ridge or keel lies dorsally ….…………………….… 7
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– Anal tergite without ridge or keel ….……………….………….………… 8
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7. Acrostichals 1–7; dorsal ridge on proximal part of T IX; Holarctic ………………….……………………………….…….…. C. casuarius (Townes, 1945)
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– Acrostichals absent; dorsal protrusion on distal part of T IX; Palaearctic . .….……………………………………………….…….…. C. lyalichi (Zorina, 2006b)
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8. Anal point with setae in basal half……………………….………….…. . . 9
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–. Anal point entirely without setae .….…….….……………….………. . . 10
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9. AR greater than 2.00; superior volsella with 2–3 apical setae and without lateral setae; Palaearctic …………………………………… C. usmaensis (Pagast, 1931)
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–. AR less than 2.00; superior volsella with one apical seta and two lateral setae; Orient …………………….……….…………. . C. tobatertius (Kikuchi and Sasa, 1990)
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10. Superior volsella with microtrichia only at base, inner margin of gonostylus sharply incised after proximal half; Holarctic………………………C. emorsus (Townes, 1945)
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–. Superior volsella with or without microtrichia, gonostylus without sharp concavity, smoothly curved …….…….….….…………….…….…………….…………… 11
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11. Superior volsella distinctly bilobed; Neotropics……C. daktylos (Walley in Curran, 1934)
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–. Superior volsella not bilobed ………………………….……………… 12
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12. Superior volsella curved, swollen at the apex and truncated; anal point tapering to point; Nearctic ….….….….…………………………. C. pilicuspis Sæther, 1977
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–. Superior volsella straight, not swollen at the apex; anal point parallel-sided to point; Palaearctic…………………………………… C. parallelus Yan et al., 2005
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13. Small digitiform lobe lies nearer to the middle of anal point .….….……….…. 14
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–. Anal point without lobe ……………………………………….……. 18
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14. Long setae of inner margin of gonostylus lie proximally; Orient ….…….…….…………………………………………… C. medialis Mukherjee et al., 2020
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–. Long setae of gonostylus present on entire inner margin .…….……………… 15
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15. Tergite IX without dorsal or ventral lobes .…………………………….… 16
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–. Tergite IX with pair of dorsal and ventral lobes ……….………………. .…17
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16. Gonostylus with basal 1/3 moderately inflated; superior volsella apically triangular; Afrotropics, Orient, Palaearctic ………….……… C. acutus (Goetghebuer, 1936)
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–. Gonostylus with basal 2/3 moderately inflated; superior volsella digitoform; Nearctic………. …………. ………………………………. . . C. rutteri (Epler, 2018)
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17. Frontal tubercles absent; superior volsella pointed at the apex, without microtrichia; Orient……………………………. C. tobasecundus (Kikuchi and Sasa 1990)
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–. Frontal tubercles present; superior volsella widened at the apex, covered by microtrichia; Palaearctic ………………………………………. C. acalcar (Reiss, 1990)
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18. Tergite IX with distinct caudolateral shoulders; Holarctic…… C. darbyi (Sublette, 1960)
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–. Tergite IX without caudolateral shoulders .………….………………….…. 19
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19. Superior volsella covered by microtrichia; gonostylus pointed at the apex; Nearctic . ……………………………………………………C. ariel (Sublette, 1960)
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–. Superior volsella without microtrichia, gonostylus with variable ending .………… 20
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20. Anal point without lateral setae; Orient………………… C. nodus Yan et al., 2005
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–. Anal point with lateral setae ….…………………….………………… 21
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21. Tergite IX with no obvious band; superior volsella with four setae; Orient …………………………………………………C. bullum (Song and Wang, 2021)
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–. Tergite IX with prominent bands; superior volsella with two apical setae………… 22
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22. Anal tergite band Y-shaped; tergite IX with a median ridge; anal point with a ridge; Orient …………………………………………… C. tumidus sp. nov
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–. Anal tergite band V-shaped; tergite IX without median ridge; anal point without ridge…………………………………………………………………23
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23. Apex of anal point truncated; superior volsella with either two apical setae or two apical and one subapical seta; Orient…………………. C. daitogeheus Sasa and Suzuki, 2001
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–. Apex of anal point swollen; superior volsella with two apical setae; Orient …………………………………………………. . …C. aculeatus Pal and Hazra, 2018
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24. Gonostylus apically pointed; superior volsella with one apical and three subapical setae; Palaearctic………………………………………. C. holsatus Lenz, 1959
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–. Gonostylus apically rounded; superior volsella with two subapical and two apical setae; Holarctic ….…………………….………C. pseudotener (Goetghebuer, 1922)
Molecular identification
The aligned dataset contains 534 base pairs of the CO1 genes of nine species in the genus Cryptitendipes, family Chironomidae, where Cryptochironomus is used as an outgroup. We observed that the CO1 gene has 380 conserved sites, 59 variable singleton sites, 95 parsimony-informative sites, and 154 variable or polymorphic sites. In a search using BLASTn and NCBI, the similarity of our sequence matched 90.82% with the Microchironomus species of the family Chironomidae.
The results of both IQ-TREE software and MEGA 11 show nonmonophyly in the maximum-likelihood and neighbour-joining trees within the Cryptotendipes genus (Fig. 3). The interspecific genetic distances between the species sequences available in the NCBI database were calculated. Among the interspecific genetic distances of Cryptotendipes species (Table 4), the highest genetic distance is between C. usmaensis and C. tumidus sp. nov. (19.91%), and the lowest is between C. darbyi and C. pflugfelderi (7.51%). The shortest distance between the new species and C. pseudotener is 13.26%. In this way, the molecular data also show the newness of this Cryptotendipes species and its closeness to C. pseudotener, whose Holarctic range and Palaearctic type locality both share important features with the Oriental realm. As only single nucleotide sequences were used for the analysis, the intraspecific genetic distances are not calculated.
Figure 3. A, The maximum-likelihood tree, and B, the neighbour-joining tree of Cryptotendipes species, and one outgroup Cryptochironomus rostratus Kieffer, 1921 inferred from the CO1 nucleotide sequence data (534 bp)
Table 4. Kimura two-parameter average (per cent) interspecific distances obtained in MEGA 11 for the Cryptotendipes species
Two species delimitation approaches were used to identify the new species: mPTP and ASAP (Supplementary material, Figs. S1, S2, and S3). The mPTP analysis shows nine individual molecular operational taxonomic units (C. darbyi, C. pflugfelderi, C. casuarius, C. pseudotener, C. disparilis, C. usmaensis, C. nodus, and C. tumidus sp. nov.), excluding the outgroup (Supplementary material, Fig. S3), and the ASAP shows the same result (Supplementary material, Fig. S1). In the ASAP analysis, the best “partitioning” is observed in the fourth rank of the ASAP score among the seventh “best” partitions, based on Kimura’s (1980) model.
In the IQ-TREE, the new species is the nearest neighbour to Cryptodentipes pseudotener. In the mPTP and ASAP analyses, all species separated perfectly, and the PhyloMap visualisation (Fig. 4) distinguished the new species. The bootstrap support of the maximum-likelihood and neighbour-joining trees was moderate due to the lack of NCBI sequences for Cryptodentipes, but the species delimitation analyses justified the molecular identification of Cryptotendipes tumidus sp. nov. as a new species.
Figure 4. PhyloMap-PTP: PhyloMap visualisation of PTP species delimitation result
New records from India
Beckidia hirsti (Freeman, 1957)
GenBank Accession No. PQ678659
Material examined. India – Maharashtra: 2 ♂ (on slide), Mumbai, 19.2289° N, 72.8691° E; 28.v.2024; 30 m; B. Mukherjee leg.
Diagnosis. The species B. hirsti is distinguished by the presence of two tibial spurs, a moderately narrow junction between gonostylus and gonocoxite, and a stout and evenly curved gonostylus.
Supplementary description. MALE (n = 2): total length 2.62 mm; wing length 1.55–1.65 mm; costal length 1.5–21.60 mm; antennal length 0.98 mm. Colouration: thorax with a light brown band, greenish–yellow abdomen. Head: width 4 mm; temporal setae 4 (IV 1, OV 2, Po 1); clypeal setae 14; frontal tubercles absent; eyes bare, with dorsomedial extension of 110–120 µm. Ultimate flagellomere 630 µm long; AR 1.7–1.8, 1.9. Length of palpomeres (I–IV; µm): 32.5; 75; 112.5; 160; last one not countable. CA 0.41. Thorax: acrostichals 0, dorsocentrals 4–5, prealars 3, supralars 1–2, and scutellars 2. Wings (Fig. 5A): VR 1.23; brachiolum with two setae; FCu distinctly distal to the RM. Anal lobe moderately developed. Legs: fore tibia with three setae and well-developed scale; mid legs with two narrowly separated comb, each with one spur, 25 µm and 17.5 µm long, with 12 and 7 lateral teeth, respectively; hind legs with two narrowly separated combs, each with one spur, 27.5 µm and 12.5 µm long, with 18 and 8 lateral teeth, respectively; lengths (µm) and proportions of legs are shown in Table 5. Hypopygium (Fig. 5B, C): anal tergite band separated medially; anal point 40 µm long, parallel-sided and rounded at the apex. Laterosternite IX with 2–3 setae on each side of anal point. Transverse sternapodeme 20 µm long; longitudinal sternapodeme 75–80 µm long. Superior volsella roughly pediform, 25–30 µm long, 32.5 µm wide at the apex, broad apically with 5–7 setae. Gonocoxite 120–125 µm long. Gonostylus 125–130 µm long, evenly curved with a seta at the apex. HR 0.96; HV 2.19.
Figure 5. Beckidia hirsti adult male: A, wing; B, hypopygium (photograph); and C, hypopygium. Scale bars: 100 μm
Table 5. Male leg lengths (µm) and proportions of legs in Beckidia hirsti. Fe, femur; Ti, tibia; Ta, tarsomere; LR, leg ratio; SV, schenkel–schiene–verhältnis (thigh–splint) ratio; BV, beinverhältnisse (leg conditions)
Remarks. Freeman (Reference Freeman1957) illustrated this species under the genus Chironomus (Cryptochironomus) with only colouration, AR, and LR1, among all the morphological characters, and Sæther (Reference Sæther1977) transferred this species within the genus Beckidia as a new combination. Following a comprehensive morphological assessment of the specimen, the species is considered to be Beckidia hirsti, based on the following combination of characters: AR 1.7–1.9, light brown marking on thorax, two tibial spurs, and evenly curved stout gonostylus. Upon examining the Indian specimen, AR 1.8 (AR 2 for the African specimen) and SV had seven setae (the illustration of the superior volsella provided in Freeman (Reference Freeman1957, fig. 13a) shows five setae). In addition to this morphological study, the CO1 sequences of the species indicate proper taxonomic corroboration. This is the first faunistic record of this species from the Orient and India, suggesting a broader distribution of the species worldwide.
Distribution. Afrotropics (Sudan, Belgian Congo); Orient (India)
Cryptochironomus tamaichimori Sasa in Sasa and Kawai, 1987
(Fig. 6A, B)
Figure 6. Cryptochironomus tamaichimori adult male: A, hypopygium (photograph); B, hypopygium. Scale bars: 100 μm
(n = 1)
Material examined. India – West Bengal: 1 ♂ (on slide), Kalimpong, 27.0601° N, 88.4666° E; 24.iii.2024; 798 m; T. Roy leg.
Diagnosis. This species is diagnosed by the presence of a pad-like superior volsella with 2–3 setae, one long seta posteriorly, and short and stout gonostylus abruptly narrowed at the apex and apically pointed.
Remarks. Sasa and Ichimori (Reference Sasa and Ichimori1983) described this species as Cryptochironomus sp. “hentona”, whereas M. Sasa documented this specimen as C. tamaichimori in Japanese notes on Cryptochironomus (Sasa and Kawai Reference Sasa and Kawai1987). The presence of the following combination of characters fully identifies the present specimen as C. tamaichimori: pad-like SV with 1–3 setae and with one long seta on posterior margin; long anal point, narrow and slender; short and stout gonostylus narrowed abruptly near apex and apically pointed; bands of ninth tergite united in the middle; frontal tubercles small; WL 2.37 mm; and AR 2.51. Other important taxonomic characters not covered in Sasa and Ichimori (Reference Sasa and Ichimori1983) include: squama with six fringed setae; gonocoxite 162.5 µm long; gonostylus 150 µm long; SV 65 µm long and 22.5 µm wide; IV 25 µm long with two setae at the apex; anal point 75 µm long; tergite IX with eight median setae; laterosternite IX with three setae on each side of anal point; longitudinal sternapodeme 175 µm long; transverse sternapodeme 87.5 µm long; CR 0.97; VR 1.02; HR 1.18; LR1 1.44; LR2 0.75; and LR3 0.73. This species is recorded for the first time in India.
Distribution. Orient (China, India); Palaearctic (Japan, Russian Far East)
Discussion. The above-noted genera of the Harnischia complex have been recorded previously in the Oriental, Afrotropical, and Holarctic regions, whereas the present study describes their distribution in India. Cryptotendipes tumidus sp. nov. and B. hirsti are recorded from the Deccan plateau, the oldest plateau in India, the chironomid biodiversity of which is little known. The Afrotropical and Oriental distribution of B. hirsti offers critical insights into faunal migration routes through the northwestern gateway (i.e., the corridor linking Afrotropical and Palaearctic faunas into India through the northwestern frontiers, especially the Western Himalaya) and the Western Syntaxial Bend of the western Himalayas, which traditionally are viewed as not conducive to faunal admixture (Mani Reference Mani1974).
Cryptochironomus tamaichimori has been recorded in the Himalayan zone of West Bengal, a well-explored region in terms of chironomid diversity. Over the years, a variety of chironomid species have been documented in the northern and northeastern regions of India, representing both Holarctic and Oriental faunal elements. The present study’s findings support the hypothesis of faunal exchange through the northeastern gateway (i.e., the Indo–Burman ranges and northeastern hill corridors linking India with Southeast Asia and the Oriental region). The distribution of these species strongly suggests that India’s chironomid fauna, much like many other animal groups, comprises a combination of species that originated from both Gondwanaland and the Holarctic region (Roback and Coffman Reference Roback and Coffman1989). This pattern reflects historical land connections and migrations that took place as the Indian subcontinent moved to its current position. However, despite the available distribution data, information on chironomid species diversity remains lacking in certain regions, particularly in Gondwana, southern, and western India. These regions remain largely unexplored, leaving gaps in our understanding of how chironomid species are distributed across these zoogeographic areas. Conducting more surveys and research in these regions is essential for building a complete picture of chironomid assemblages. In addition, morphological, geographical, and molecular taxonomic work in this group globally is incomplete. Given that the same or similar chironomid species from very different regions can have significant haplotype diversity in their conserved genes, such genetic information provides significant insights into and improved understanding of these species’ populations. An improved understanding of this diversity and of India’s faunal history and an application of an integrated taxonomical approach to the study of insect species could help to broaden discussions of the biogeography, species movement, and evolutionary processes that shape biodiversity. In addition, morphological, geographical, and molecular taxonomic studies on this group remain incomplete worldwide. Since chironomid species from different regions often show high haplotype diversity even in conserved genes, genetic data can provide important insights into their populations. Combining this genetic information with India’s faunal history and applying an integrated taxonomic approach would enhance our understanding of biogeography, species dispersal, and the evolutionary processes shaping biodiversity.
Supplementary material
To view supplementary material for this article, please visit https://doi.org/10.4039/tce.2025.10032.
Acknowledgements
The authors thank the Director of the Zoological Survey of India, Kolkata, and Dr. Gurupada Mondal, Scientist-E, H.O.O., and the divisional in charge of the Zoological Survey of India. The authors are indebted to all other members of the Diptera section of the Zoological Survey of India, particularly Mr. Oishik Kar and Ms. Debjani Ghosh. The first author thanks the Zoological Survey of India, Govt. of India, for financial assistance in the form of a postdoctoral fellowship F.210-3/2022/Tech/2636.
Competing interests
The authors declare that they have no competing interests.
