This study describes the reproductive systems of male and female Johngarthia lagostoma, a land crab endemic to South Atlantic oceanic islands, focusing on spermatozoa production and storage. Specimens from Trindade Island (Brazil) were analysed for anatomy, histology, and histochemistry. The male system includes a pair of tubular testes showing different stages of spermatogenesis and spermiogenesis, leading to mature spermatozoa. These move to the anterior vas deferens (AVD), which has proximal and distal portions, the latter containing coenospermic spermatophores surrounded by secretion type I, reactive to proteins and acidic and neutral polysaccharides. The median (MVD) and posterior (PVD) vas deferens produce type II (strongly protein-reactive) and type III (weakly protein-reactive) secretions. Accessory glands between the MVD and PVD produce the same secretions plus a secretion type IV, reactive to neutral polysaccharides. These mix with the spermatophores and other vas deferens secretions, increasing the PVD’s secretion volume, crucial for the initial release of spermatophores into the seminal receptacle. The female reproductive system features voluminous seminal receptacles connected to the ovary, comprising mesodermal and ectodermal regions classified as ventral-type connection. Plugs and sperm packets are absent, with the seminal receptacles filled with free spermatozoa, suggesting dehiscence occurs shortly after sperm transfer. The influence of male and female secretions on this process is suggested, alongside their roles in sperm maintenance and fertilization facilitation.

The genus Apharyngostrigea comprises a group of diplostomoidean digeneans that parasitize birds of the family Ardeidae (herons), with approximately 20 species described worldwide. Despite numerous efforts, a robust phylogenetic framework to delimit species within the genus is still lacking, mainly due to the limited morphological variation among its members. This study employed an integrative taxonomic approach, combining nuclear and mitochondrial DNA sequences with morphological data to assess species boundaries within Apharyngostrigea based on specimens collected from southeastern Mexico. Using a combination of species discovery (Automatic Barcode Gap Discovery, Assemble Species by Automatic Partition, General Mixed Yule Coalescent and Poisson Tree Processes) and validation methods based on Bayesian gene tree topologies (BPP and PHRAPL). We found high diversity within this genus in southeastern Mexico. Our analyses supported the delimitation of four nominal species that were previously described and validated in this study, along with the redescription of three of them. In addition, through species delimitation methods and morphological examination, we identified two candidate species and/or lineages that require further evidence to be formally described. This study demonstrates that an integrative taxonomic approach provides a robust framework for species delimitation in taxonomically complex groups such as Apharyngostrigea.

The Liolopidae (Diplostomoidea) are a small family of digeneans that parasitize reptiles and amphibians as adults. Knowledge of intermediate hosts in this family remains scarce, leaving a major gap in the understanding of liolopid biology. To date, the only fully elucidated life cycle is that of Liolope copulans Cohn 1902, a species infecting Asian salamanders, with no other cercarial or metacercarial stages known. This study aimed to identify potential intermediate hosts for Paraharmotrema karinganiense, found in several chelonian species from southeastern Mozambique and South Africa. African apple snails of the genus Lanistes and Nothobranchius killifish were sampled from temporary pools in Karingani Game Reserve, southern Mozambique. Snails were screened over 9 months for cercarial shedding, and encapsulated metacercariae recovered from the spotted killifish (N. orthonotus, Peters) (Cyprinodontiformes: Nothobranchiidae) were excysted for morphological and molecular analyses. Fork-tailed cercariae from Lanistes sp. and 1 metacercaria found in the spotted killifish were genetically identical to the adult of P. karinganiense. This study provides the second documented life cycle of a liolopid trematode and presents the first life cycle for the family based on natural infections, being the first completely documented life cycle for freshwater trematodes from southern Africa. This linkage of larval and adult specimens signifies the importance of Nothobranchius killifish as intermediate hosts as well providing insight in parasite transmission dynamics within temporary aquatic ecosystems.

A new genus and species of trematode, Paratestophis gelicolus gen. nov., sp. nov., is described from the large intestine of the rainbow water snake, Enhydris enhydris, collected from several provinces in southern Thailand. Morphological analyses reveal distinct characteristics that differentiate P. gelicolus gen. nov., sp. nov. from related echinochasmid taxa, specifically its elongated bottle-shaped body, presence of 22 collar spines, parallel testes and parasitism of snakes–features not observed in other echinochasmid genera. Multi-marker phylogenetic analyses (28S rRNA, 18S rRNA, ITS2 and COI) strongly support its taxonomic placement within Echinochasmidae while confirming its genetic distinction from known genera such as Echinochasmus, Stephanoprora, and Microparyphium, thereby warranting the establishment of Paratestophis gen. nov. The species exhibited a 24% prevalence of infection (25/106) in E. enhydris, and was found co-infecting with four other helminths, including Tanqua siamensis, Encyclometra bungara, and two additional trematode species currently under examination, all occupy distinct ecological niches. Principal Component Analysis based on 19 morphological characters revealed morphological homogeneity among the specimens. This study represents the first record of a new genus and species within Echinochasmidae infecting snakes, and provides an updated systematic framework for the family, including a revised key to genera. The findings emphasise the need for further research into parasite taxonomy, host specificity and evolutionary relationships in Southeast Asian ecosystems.

The yellowfin, Thunnus albacares (Bonaterre), is one of the most important resources for commercial fisheries along the Mexican Pacific coast. The parasite fauna of this important marine resource has been documented in different regions across its global distributional range. However, few studies have been conducted on parasites of tuna populations in the Cortezian Marine Ecoregion (CME) in northwestern Mexico, despite the development of the fresh and frozen sushi/sashimi-grade tuna market in recent decades. Our study aimed at identifying the metazoan parasite fauna of T. albacares in the CME. Between 2023 and 2024, 17 individuals were studied for parasites before being processed. Parasites were collected and identified using morphological and molecular data. One hundred twenty-five metazoan parasites were collected, representing 10 species, including the monogeneans Hexostoma thynni (Delaroche, 1811) Rafinesque, 1815, Neobenedenia girellae (Hargis, 1955) Yamaguti, 1963, and Capsala sp., the digenean Hirudinella ahi (Pallas, 1774) Baird, 1853, the larval cestode Heterosphyriocephalus tergestinus (Pintner, 1913) Dallarés, Carrassón and Schaeffner, 2016, larval forms of the nematode Anisakis typica (Diesing, 1860) Baylis, 1920, the acanthocephalan Rhadinorhynchus laterospinosus Amin, Heckmann, and Ha, 2011, and three species of copepods, Euryphorus brachypterus (Gerstaecker, 1853), Pseudocycnus appendiculatus Heller, 1865 and Brachiella thynni Cuvier, 1830. Anisakis typica reached the highest prevalence of infection in our samples, and along with R. laterospinosus, it reached the highest mean intensity values. This study reports a species that represents a zoonotic risk (A. typica) and contributes to the understanding of the parasite diversity of commercially important fish in the CME.

A redescription of Cloeosiphon aspergillus is presented based on the type material and additional specimens from Madagascar, South Africa, and New Caledonia. Cloeosiphon aspergillus is characterized by its pineapple-shaped anal shield, bidentate hooks arranged in rings, and a continuous longitudinal muscle layer. Additionally, a new species, Cloeosiphon mexicanus sp. nov. is described from the southern Mexican Pacific. This new species differs from C. aspergillus by having an inconspicuous secondary tooth on posterior hooks and the absence of spherical units along the basal margin of the anal shield. Furthermore, a discussion on the synonyms of C. aspergillus is included. This study expands the taxonomic knowledge of the genus Cloeosiphon and highlights the importance of the detailed description for accurate species recognition.

Lund’s fly, Cordylobia rodhaini (Calliphoridae), is an African blowfly considered to be an uncommon cause of furuncular myiasis. Far less is known about C. rodhaini than about the more frequently reported tumbu fly, Cordylobia anthropophaga. From 2011 to 2020, fly larvae were collected and analysed from 11 independent infestations of wild non-human primates and 10 independent infestations of humans (including 1 from this author) in Kibale National Park, Uganda. All 21 larvae were identified morphologically and genetically as C. rodhaini. Larvae from non-human primates were on average 4·5 times larger than larvae from humans. Non-human primates had empty furuncles, indicating recent egress of mature third instar larvae and completion of the larval stage of the lifecycle; however, eastern chimpanzees (Pan troglodytes schweinfurthii) were photographed removing larvae from furuncles of grooming partners. A total of 4 closely related mitochondrial haplotypes were identified, 2 of which were shared by larvae from humans and non-human primates. Genetic variation within C. rodhaini from this single location was comparable to that within other calliphorid species. Non-human primates may play a larger role in the maintenance of C. rodhaini than previously known, and in certain forested locations C. rodhaini may be the predominant cause of furuncular myiasis. The sylvatic lifecycle of C. rodhaini may explain its differentiation from Cordylobia anthropophaga, which has a peridomestic lifecycle. In general, these findings shed new light on how myiasis-causing flies can adapt to different ecological settings and be regionally rare but locally abundant.

This study provides the first case reported of Paraprionospio treadwelli (Hartman, 1951) in the Gulf of Mexico. Based on 242 individuals collected between 20.8 and 176 m depth during three oceanographic expeditions, we describe in detail the morphology of the identified specimens, including the description of the pygidium, so far unknown in this species, and provide SEM photographs to support their identification. Paraprionospio treadwelli was originally found in Chesapeake Bay, Northwestern Atlantic, and we now extend its distribution southwards to the Western Gulf of Mexico. Remarks on the environmental conditions where this spionid species was found and the observed abundance seasonal pattern are also provided.

The family Brachycladiidae (Digenea) is a species-rich taxon restricted to marine mammals, well-known for its associated pathogenic load, but otherwise poorly understood. A major gap in our knowledge is their circulation pathways, as the life cycle has been elucidated only for a single brachycladiid species, Orthosplanchnus arcticus, a parasite of pinnipeds. Our goal was to determine whether small ocellate metacercariae previously reported from the Barents Sea edible cockles (Cerastoderma edule) belong to the brachycladiids. We searched for brachycladiid metacercariae in nine bivalve species across three sub-Arctic Seas. They were found in three cardiid species (Ciliatocardium ciliatum, C. edule, and Serripes groenlandicus) and a scallop, Chlamys islandica. Surprisingly, we discovered numerous brachycladiid metacercariae in a single infected whelk, Buccinum undatum. Obtained molecular genetic data (mitochondrial and nuclear ribosomal) indicated that all these metacercariae belong to O. arcticus. We used statistical analysis to explore potential preferences for the second intermediate hosts in this brachycladiid species. The results suggest that bivalve size, rather than species, more accurately predicts infection patterns with O. arcticus metacercariae. We also found no significant differences in morphology between metacercariae from different bivalve species. As such, O. arcticus exhibits broad specificity for the second intermediate hosts, with larger bivalve individuals showing higher infection rates. We discuss the factors underlying this broad specificity, the benefits of larger bivalve preference, and the unequal contribution of different hosts in the transmission of a parasite. Finally, we highlight the potential zoonotic risk associated with O. arcticus due to human consumption of its intermediate hosts.

Ideas about morphological complexity have been used to classify languages and to link complexity to language age and social structure. Creoles and sign languages are often framed as younger and structurally simpler than other languages. Concurrently, sign language morphology has been described as paradoxical, as both simple and complex. This paper is a critical examination of claims about morphological complexity and its relationship to language age and social structure. We show that the theoretical and empirical foundations of claims that sign language morphology is paradoxical are flawed. Specifically, argumentation and evidence supporting analogies between creole and sign language complexity adopt theoretically contested and ideologically problematic assumptions about creoles and uncritically apply them to sign languages. We identify four flaws in argumentation: (i) use of limited morphological data to generate claims about global complexity, (ii) association of binary language categories with categorical complexity differences, (iii) use of language age to motivate predictions about morphological complexity, and (iv) extrapolating from creole complexity to sign language complexity. Based on these flaws, we develop nine theoretical and practical recommendations for working with morphological complexity and discuss uncritical cross-disciplinary transfer of ideas.

This study examined how word identification is influenced by interword spacing and morphological complexity in Thai, a script without interword spacing. While previous research supported the facilitative effect of interword spacing on Thai word identification, they did not account for the potential effects of the words’ morphological structure. The challenge of word identification becomes more pronounced when readers have to identify compound words (e.g., bathroom) when reading sentences without interword spacing. In an eye-tracking experiment that manipulated interword spacing (unspaced, spaced) and noun type (bimorphemic compound, monomorphemic) in Thai sentences, we confirmed previous findings that interword spacing has a facilitative effect on word identification, as evidenced by shorter first fixation duration, gaze duration and total fixation time. Furthermore, we observed an interaction effect indicating that interword spacing had a larger facilitative effect on the identification of compounds compared to monomorphemic words. Our results also revealed that the morphological structure of Thai words can influence saccadic movements, e.g., the first fixation landing position was closer to the beginning of compounds than to simple words. We suggest that the orthography-language interface, a language-specific feature, should be considered a major component in eye movement models of reading.

Non-native languages tend to be acquired through a combination of explicit and implicit learning, where implicit learning requires coordination of language information with referents in the environment. In this study, we examined how learners use both language input and environmental cues to acquire vocabulary and morphology in a novel language and how their language background influences this process. We trained 105 adults with native languages (L1s) varying in morphological richness (English, German, Mandarin) on an artificial language comprising nouns and verbs with morphological features (number, tense, and subject-verb [SV] agreement) appearing alongside referential visual scenes. Participants were able to learn both word stems and morphological features from cross-situational statistical correspondences between language and the environment, without any instruction. German-speakers learned SV agreement worse than other morphological features, which were acquired equally effectively by English or Mandarin speakers, indicating the subtle and varied influence of L1 morphological richness on implicit non-native language learning.

The present study describes a new Ditylenchoides species, isolated from Meknès, Morocco, during nematode surveys conducted to investigate the biodiversity of plant-parasitic nematodes in Mediterranean olive groves and adjacent patches of natural vegetation. Application of integrative taxonomical approaches clearly verified that it is a new species designated herein as Ditylenchoides morocciensis sp. nov., also representing the first report of the genus in Morocco. The new species is parthenogenetic, characterised by a short body 460 (373–528 μm); stylet delicate, relatively short, 8.7 (8.0–9.0) μm long with rounded basal knobs; six lines in the lateral fields; median bulb of pharynx oval, muscular and valvate; secretory-excretory pore located at the level of basal pharyngeal bulb region; vulva located at 79.9 (76.9–81.3) % of body length; relatively long post-vulval uterine sac 29.1 (20.0–39.0) μm; and a subcylindrical tail 24.4 (22.0–28.0) μm long, with a bluntly rounded tip. The results of molecular analysis of D2-D3 28S rRNA, ITS rRNA, partial 18S rRNA, and cytochrome oxidase c subunit 1 (COI) gene sequences support for the new species status and clearly separated D. morocciensis sp. nov. from all other species within Ditylenchoides. Phylogenetic analyses of ribosomal markers (D2-D3 28S rRNA and partial 18S rRNA) of this study confirms that Ditylenchoides is a monophyletic genus, clearly separated from other genera within Anguinoidea.