Male Gonopod Research Articles

A new species of Parahelice (Brachyura, Varunidae, Cyclograpsinae) from Sabah, Malaysia

Abstract A new species of intertidal mangrove crab, Parahelice christophi, is described from two specimens collected from Kota Kinabalu, Sabah, Malaysia. The new species can be distinguished from congeneric species by differences in the form of the suborbital ridge, carapace, chelae and male gonopod. It is the eighth species recognised in this genus. A new key to Parahelice spp. is provided.

A new species of xanthid crab, Palapedia schubarti n. sp. (Decapoda, Brachyura, Xanthoidea), from Socotra, northwestern Indian Ocean

Abstract Palapedia schubarti n. sp. is the third species of the genus Palapedia, described from the northwestern Indian Ocean. Two species, P. persica and P. apeli, had already been recorded from the Persian Gulf, and the new species is described from farther south in Socotra Island. Palapedia persica has appendages markedly ornamented with large denticles, while P. apeli has distinctly smooth appendages. Compared to the two above-mentioned species, the new species has an intermediate position regarding the spination, with small denticles on the upper margin of the palm, fingers and anterior margin of walking legs. The morphology of the first male gonopod of P. schubarti n. sp. is very close to P. rastripes, described from Ceylon, and P. truncatifrons described from Japan. The new species, however, is easily distinguishable from those two congeners in having a spade form ending and several other characteristics of chelipeds and carapace.

On the genus Flabellamon Ng, 1996, with descriptions of two new species (Crustacea: Brachyura: Potamidae).

The history, taxonomy and nomenclatural issues revolving around the genus Flabellamon Ng, 1996, are reviewed. The genus of late contained two species, F. kuehnelti (Pretzmann, 1963) and F. wanchaii Takeda, Sanpool & Intapan, 2019. In the process of this review, two new species of this genus were uncovered from historical materials that were previously misidentified, and described herein as, F. ngankee sp. nov. (from northwestern Thailand) and F. mulayit sp. nov. (from southeastern Myanmar). Flabellamon ngankee sp. nov. is most similar superficially to F. wanchaii but can be distinguished easily by morphological differences in carapace armature, external orbital tooth, male pleonal margins and male gonopod. Flabellamon mulayit sp. nov. on the other hand, is more similar morphologically to F. kuehnelti, but can also be distinguished easily by epibranchial tooth and male gonopod characters. An identification key to the species of Flabellamon is provided.

A new species of freshwater crab of the genus Hypolobocera Ortmann, 1897 from Colombia (Crustacea: Decapoda: Pseudothelphusidae), including a key to the species of the genus distributed in Colombia.

The genus Hypolobocera Ortmann, 1897, is represented by 38 species and is distributed in the south-western Panama, Venezuela, Colombia, Ecuador, and Peru, including the twenty-two registered species for Colombia. We describe and illustrate a new species of Hypolobocera Ortmann, 1897 from the foothills of the Western Cordillera, Antioquia Department, Cauca River basin, Colombia, which increases in this country the number of Hypolobocera species to twenty-three. The species distribution of this genus covers an extensive area of the Colombian territory, including most of Colombia's major river basins. We distinguished the new species from its congeners mainly by the third maxilliped, with an exopod that is 0.20 to 0.30 the length of ischium, and by the morphology of the first male gonopod, particularly by the shapes of the lateral and the mesial lobes and the outline of the apex. We include a key to species identification that uses the morphology of the first male gonopod.

Taxonomic revision and molecular phylogeny of Pisa (Decapoda: Majoidea: Epialtidae), including the description of a new genus of Pisinae

The spider crabs of the genus Pisa Leach, 1814 (Epialtidae: Pisinae) are reviewed in this study based on morphological and molecular data (16S and COI genes). From these results, a new genus, Afropisa n. gen., is established for the clade composed of Pisa carinimana Miers, 1879, Pisa calva Forest and Guinot, 1966 and Pisa sanctaehelenae Chace, 1966 based on carapace morphology, rostrum, pterygostomian tubercles and male gonopod 1. Additionally, Lissa chiragra (Fabricius, 1775) is transferred to Pisa based on morphological (adults and larvae) and molecular evidence. Furthermore, the status of Pisa hirticornis (Herbst, 1804) is discussed and clarified. The phylogenetic relationships between several Pisinae Dana, 1851 genera, as revealed by molecular data, are discussed. An illustrated identification key of eastern Atlantic and Mediterranean species of Pisinae is provided.

Stoliczia setoiyenica, a new species of freshwater crab from southern Thailand (Crustacea: Decapoda: Brachyura: Potamidae).

A new species of freshwater crab is described from southern Thailand, near the border with Peninsular Malaysia. Species of Stoliczia are characterised by their relatively flat carapace, a third maxilliped exopod that possesses no or a very short flagellum, and a conical male gonopod terminal segment that lacks or only has a very low dorsal fold. Stoliczia setoiyenica, new species, most closely resembles S. perlensis and S. kedahensis from northern Peninsula Malaysia but can be easily distinguished from congeners by differences in carapace and male gonopod morphology. Comparisons to the two known Thai Stoliczia species, S. panhai and S. ekavibhathai, are also provided for completeness.

Revision of the Indo-West Pacific crab genus Soliella (Brachyura: Xanthidae: Etisinae): ‘pseudocryptic species’ and basinal speciation

Etisine crabs are some of the most abundant cryptobionts in Indo-West Pacific coral reef systems. Despite their ecological importance and abundance in museum collections, several recent systematic studies have indicated family- to subspecies-level taxonomic problems. One such case involves the former chlorodielline genus Soliella Lasley, Klaus & Ng, 2015 (treated here as part of Etisinae), which currently comprises two valid species and three available names that have been in flux in recent literature. The validity of these taxa has only been cursorily discussed. To resolve species limits and distributions, a thorough morphological examination of hundreds of specimens was conducted, including scanning electron microscopy of male gonopods, along with analysis of sequence data of the mitochondrial marker cytochrome c oxidase subunit I (COI) from 84 exemplars across the distribution of the genus. The status of two species that have Indian Ocean versus Pacific Ocean distributions with overlap in the Indo-Australian Archipelago and adjacent regions is confirmed. While external morphology is not reliable for identification, a few discrete, although slight, differences in gonopod morphology were found, and these results are consistent with a ‘pseudocryptic species’ designation. Speciation conforms to a previously published etisine model of allopatric differentiation followed by subsequent divergence of gonopod morphology upon secondary sympatry. This pattern, the biogeography of the two species and the concept of ‘pseudocryptic species’ are discussed. http://zoobank.org/urn:lsid:zoobank.org:pub:ABEC01C7-EA5B-4BB6-87E0-405FE3895D95

Molecular species delimitation reveals hidden endemism in Faxonius placidus (Hagen 1870) (Decapoda: Astacidea: Cambaridae) in southeastern USA

Abstract Molecular surveys are critical for understanding species boundaries and evolutionary relationships of North American crayfishes, as traditional morphological characters used for taxonomy frequently misrepresent crayfish diversity. The bigclaw crayfish, Faxonius placidus (Hagen, 1870), is currently described as a widely distributed crayfish that is common throughout the Cumberland, Tennessee, and Lower Ohio river drainages. The geographic distribution of F. placidus is based on identifications using traditional morphological characters including the first-form male gonopod, chelae, and rostrum. Within F. placidus, color pattern variation is specific to populations separated by hydrogeographic barriers. We used DNA barcoding data (mtDNA-COI) and genome-wide molecular markers (nuclear SNPs) to examine geographic patterns of genetic variation in F. placidus within the Cumberland and Tennessee river drainages. The federally endangered Nashville crayfish, F. shoupi (Hobbs, 1948), was included in our analyses, as previous phylogenetic reconstructions suggest F. placidus is paraphyletic with respect to F. shoupi. Phylogenetic reconstructions and molecular species delimitation identified four genetically distinct lineages within F. placidus that are paraphyletic with respect to F. shoupi. Our results add to numerous studies demonstrating the utility of robust molecular analyses for understanding the biodiversity of North American crayfishes.

A new species of freshwater crab of the genus Chaceus Pretzmann, 1965 (Brachyura: Decapoda: Pseudothelphusidae) from La Guajira, including distribution and a key to the species of the genus.

We describe and illustrate a new species of Chaceus Pretzmann, 1965, from the Regional Natural Park of the Serranía de Perijá, La Guajira Department, Colombia. This increases the number of Chaceus species to ten, three of them with records only from Venezuela. The species of this genus are distributed in the Sierra de Santa Marta of Colombia and the Serranía de Perijá of Colombia and Venezuela. We distinguished the new species from its congeners mainly by the third maxilliped, with an exopod that is 0.60-0.62 the length of ischium, and by the morphology of the first male gonopod, particularly by the shapes of the mesial, marginal, and lateral processes. We include the distribution of the Chaceus species here and a key for the identification of the species based on the morphology of the first male gonopod.

Insights on the evolution and conservation of Appalachian burrowing crayfishes, with the description of a new species of Cambarus Erichson, 1846 (Decapoda: Astacidea: Cambaridae)

Abstract A new species of crayfish, Cambarus nyxn. sp., is described from the Kentucky/Tennessee border in the Dissected Appalachian Plateau sub-ecoregion of the US. Of the recognized species of Cambarus Erichson, 1846, it is morphologically most similar to Cambarus deweesae Bouchard & Etnier, 1979, found primarily in the Southern Limestone/Dolomite Valleys and Low Rolling Hills sub-ecoregion. Cambarus nyxn. sp., is distinguishable from other recognized congeners, except for C. deweesae, by the strongly serrated lateral margin of the propodi of the chelae, closed areola, two rows of palmar tubercles, truncate rostrum with convergent margins, and Form I male (MI) gonopod having a central projection shorter than the mesial process. The new species differs from C. deweesae in coloration (blue vs. red, respectively) and size at maturity only. There is considerable genetic, morphometric, and color variation among populations herein considered as members of the new species. The species has a limited range and highlights once more the need for increased conservation efforts for North American crayfishes. Genetic analysis of C. nyxn. sp. sheds light on the evolutionary process occurring in the crayfishes of the Appalachian Mountains after the origin of Cambarus.

A new freshwater crab species of the genus Vela Bahir & Yeo, 2007 (Decapoda: Brachyura: Gecarcinucidae) from the Western Ghats of Karnataka, India

Vela bandhavya sp. nov., a new species of gecarcinucid crab is described from the Central Western Ghats, Uttara Kannada district, Karnataka state, India. The new species can be immediately distinguished from three other species of Vela Bahir & Yeo, 2007, mainly by its short male sternopleonal cavity and a relatively shorter distal article of the male first gonopod. The diagnosis of Vela is revised to accommodate the new species, and an illustrated identification key is provided for all four species. An anomalous adult male crab, with a pair of pleopods on the pleonal somite 5 in addition to the male gonopods, is also reported.

Multigene Phylogenies of the Estuarine Sesarmid Parasesarma bidens Species Complex (Decapoda: Brachyura: Sesarmidae), with Description of Three New Species.

S Parasesarma bidens (De Haan, 1835) is a common intertidal sesarmid crab that inhabits the estuarine and mangrove regions of East Asia, as well as Vietnam and the Philippines. Previous studies have suggested that P. bidens is a species complex composed of several species. Our findings indicated that the P. bidens species complex is monophyletic with six clades, as shown by reconstructed phylogenies based on mitochondrial 16S rDNA and cytochrome c oxidase subunit I, as well as nuclear 28S rDNA. Specimens of each clade exhibited different characters, including the morphology of the cheliped, anterior carapace, male gonopod 1, and female vulvae, as well as the coloration. Three species in this complex have been previously described: P. bidens (De Haan, 1835), P. cricotum (Rahayu & Davie, 2002), and P. sanguimanus Li, Shih & Ng, 2019. Here, we describe three additional species: P. continentale n. sp., P. insulare n. sp., and P. chiahsiang n. sp. Biogeographically, the range of P. bidens includes the southern margin of Korea, the main islands of Japan, and the Ryukyus, with a comparatively northern distribution. P. continentale is widely distributed from the continental coasts of southeastern and southern China (including northern Hainan Island) to southern Vietnam and is occasionally found in Penghu, Taiwan. Parasesarma insulare is an insular species distributed from Taiwan main island, the central Philippines, to northern Borneo. Finally, P. chiahsiang is mainly limited to the Penghu Islands (Pescadores) but is also sometimes found in Taiwan main island and the offshore Gueishan Island.

Revision of the freshwater crabs of the genus Tehuana Rodríguez & Smalley in Smalley 1970 (Decapoda, Pseudothelphusidae), with the descriptions of two new species.

The freshwater crab genus Tehuana Rodríguez & Smalley in Smalley, 1970 includes eight species distributed in southeastern Mexico. A recent review of organisms belonging to this genus uncovered new variations in the male gonopod morphology. A phylogenetic analysis based on molecular characters using three genes (H3, 16S, and COI) resulted in the identification of two new species which are described herein: Tehuanaayotzintepecensis sp. nov. from Oaxaca and Tehuanacol sp. nov. from Veracruz. New diagnoses are provided for those species that had very brief descriptions lacking the treatment of important taxonomic characters and an identification key for all the species in the genus is also given. A discussion of the distribution of all the species in Tehuana in the Isthmus of Tehuantepec is presented.

Geometric morphometric analysis of gonopods in Bicoxidens flavicollis populations (Diplopoda, Spirostreptida, Spirostreptidae)

Male gonopods are useful in taxonomic diagnoses and descriptions of millipedes, although they may vary intraspecifically in shape and size. To assess this intraspecific variation, we used geometric morphometric analysis to compare gonopod morphology among eight isolated populations of the colour-polymorphic southern African millipede Bicoxidens flavicollis. Our results showed that gonopod shapes vary significantly across the examined populations, and elucidated subtle variations. CVA cross-validation test indicates an average classification rate of 75% for the five populations for which we had more than one specimen. Although we had a small number of replicates for three populations, our results still illustrate the importance of applying quantitative approaches to what would otherwise be qualitative and subjective gonopod shape categories in millipedes. As such, the taxonomic assignment of the populations of B. flavicollis may require further investigation, and further revisions would be required with an integrative approach, including molecular data, in order to re-evaluate the taxonomic diversity and distribution data of this species. Finally, we highlight the conservation potential of divergent populations as evolutionary insurance against a dynamic and unpredictable climate, whether or not they undergo full speciation.

Two new species of freshwater crabs of the genera Huananpotamon Dai & Ng, 1994 and Minpotamon Dai & Türkay, 1997 (Decapoda: Brachyura: Potamidae) from eastern China

Abstract Two new Chinese species of potamid freshwater crabs, Huananpotamon shangyouensesp. nov. and Minpotamon auritumsp. nov., are described from Fujian and Jiangxi, eastern China, respectively. The two new species can be distinguished from their closest congeners by carapace features and structures of the male first gonopods. Phylogenetic analyses based on mitochondrial 16S rDNA sequences support the establishment of the two new species.

A new genus and new species of potamid crab from Yunnan, southern China (Decapoda: Brachyura: Potamidae: Potamiscinae)

Abstract A new genus and new species of freshwater crab, Barbamon zhouigen. nov., sp. nov., belonging to the subfamily Potamiscinae Bott, 1970 (Potamidae Ortmann, 1896) is described from Wenshan Zhuangzu and Miaozu Autonomous Prefecture, Yunnan Province, China. The new genus is established based on a unique combination of characters, including the distinctive shape of the male first gonopod, and the setose ventral surface of the third maxilliped, suborbital and pterygostomial regions, and ambulatory legs. Barbamongen. nov. is similar in external appearance to AbormonMitra, Pati & Ng, 2021. The new genus, however, is distinctive in the combination of characters related to the carapace, third maxilliped, and male first gonopod. Molecular phylogenetic data derived from mitochondrial 16S rDNA sequences provides genetic support for the new genus and species.

Description of a new species of Spiralothelphusa Bott, 1968, and redescription of Spiralothelphusa wuellerstorfi (Heller, 1862) (Decapoda: Brachyura: Gecarcinucidae)

A new species of the gecarcinucid freshwater crab genus, Spiralothelphusa Bott, 1968, is described from the Andhra Pradesh State of South India, with supporting data from mitochondrial cytochrome c oxidase subunit I. This brings the number of known species of Spiralothelphusa to seven, five from India and two from Sri Lanka. The identity of S. wuellerstorfi (Heller, 1862) has remained uncertain because the former lectotype designation was not clear. Bott (1968), while designating a male lectotype of S. wuellerstorfi from the Naturhistorisches Museum Wien, Vienna, Austria, had neither stated the catalogue number nor the size of the specimen. It is now difficult to trace the particular lectotype among several paralectotypes of the depository. A new lectotype is, therefore, designated herein for S. wuellerstorfi, and the species is redescribed. The new species, S. andhra sp. nov., has morphological affinities with S. wuellerstorfi, but can be distinguished from the latter species by the shape of the male telson and outer margin of the non-twisted portion of the male first gonopod. Phylogenetic analyses of the molecular data also corroborate their separation. An illustrated identification key is provided for the species of Spiralothelphusa.

A new species of freshwater crab of the genus Barytelphusa (Decapoda, Brachyura, Gecarcinucidae) from the Eastern Ghats of India

Abstract A new species of gecarcinucid crab, Barytelphusa choprai sp. nov., is described here from the Eastern Ghats in Andhra Pradesh state of India. The new species differs from all three congeners by its convex and trapezoidal carapace, pale white colouration, and by a distinct structure of the male gonopod G1. It differs from its congeners by genetic distance (p-distance) in the range of 5.7-13.6% in partial mtCOI gene sequence. The habitat at the type locality is a slow flowing shallow stream with rocky substratum, covered with silt and debris, and devoid of aquatic vegetation.

A new genus and new species of Hymenosomatidae (Crustacea: Brachyura) from Indonesian Papua.

A new hymenosomatid crab, Chartocinus rarus n. gen. n. sp., is described from coastal waters in western Papua (formerly Irian Jaya) in Indonesia. The new genus superficially resembles Amarinus Lucas, 1980, but can easily be distinguished by its subquadrate third maxillipeds with the merus produced along the anteroexternal edge, elongate ambulatory legs, elongate male thoracic sternum, short male pleon without distinct intercalated plates on somite 5, and a short male first gonopod in which the inner margin is distinctly bilobed.

Mechanical male sterilisation in invasive signal crayfish Pacifastacus leniusculus: persistence and functionality in captive and wild conditions

Management control methods for invasive crayfish remain of limited effectiveness, resulting in ongoing invasions of high ecological impact. As management programmes integrating methods to limit juvenile recruitment could reduce population abundances, the efficacy of a sterile male release technique (SMRT) based on the manual removal of male gonopods was tested here in captive and wild conditions by comparing the survival, gonopod regeneration rates and a range of reproductive metrics of sterilised versus non-sterilised males. Sterilised male survival was high, with their removed gonopods regenerating at sizes that were always smaller than those of non-sterilised males. In captive trials, while sterilised males showed significantly lower areas of spermatophore cover than non-sterilised, and less accuracy in placement, subsequent female brood size did not differ significantly between the two male groups. The number of females retaining their clutches also did not also differ significantly between these groups. Over a seven-year period in the wild, there was no evidence suggesting SMRT significantly reduced female brood sizes and clutch retention rates. Although mechanical SMRT altered the size and delivery accuracy of sterilised male gonopods, female reproductive success of invasive crayfish was unaffected. Several potential reasons for this failure of the technique were identified and require further research.