Lepidothelphusa menneri n. sp. (Crustacea: Brachyura: Gecarcinucidae), first record of the genus from Kalimantan, Indonesia

The gecarcinucid freshwater crab genus, Lepidothelphusa Colosi, 1920, is known only from Sarawak in northern Borneo, with six recognised species i.e. Lepidothelphusa cognettii (Nobili, 1903); L. flavochela Grinang & Ng, 2015; L. limau Grinang & Ng, 2015; L. loi Grinang & Ng, 2015; L. padawan Grinang & Ng, 2015; and L. sangon Grinang & Ng, 2015. The genus is now reported from Indonesian Borneo for the first time, from specimens recently collected from Gunung Kelam in Sintang Regency, Kalimantan Barat Province. Lepidothelphusa menneri n. sp. has a very distinctive tri-coloured pattern in life, unique among congeners. It can also easily be separated from congeners by carapace, epistome, male pleonal and male first gonopod characters.

Diversification of freshwater crabs on the sky islands in the Hengduan Mountains Region, China

The numerous naturally-fragmented sky islands (SIs) in the Hengduan Mountains Region (HMR) of southwestern China constitute discontinuous landscapes where montane habitats are isolated by dry-hot valleys which have fostered exceptional species diversification and endemicity. However, studies documenting the crucial role of SI on the speciation dynamics of native freshwater organisms are scarce. Here we used a novel set of comprehensive genetic markers (24 nuclear DNA sequences and complete mitogenomes), morphological characters, and biogeographical information to reveal the evolutionary history and speciation mechanisms of a group of small-bodied montane potamids in the genus Tenuipotamon. Our results provide a robustly supported phylogeny, and suggest that the vicariance events of these montane crabs correlate well with the emergence of SIs due to the uplift of the HMR during the Late Oligocene. Furthermore, ancestrally, mountain ridges provided corridors for the dispersal of these montane crabs that led to the colonization of moist montane-specific habitats, aided by past climatic conditions that were the crucial determinants of their evolutionary history. The present results illustrated that the mechanisms isolating SIs are reinforced by the harsh-dry isolating climatic features of dry-hot valleys separating SIs and continue to affect local diversification. This offers insights into the causes of the high biodiversity and endemism shown by the freshwater crabs of the HMR-SIs in southwestern China.

Two centuries of biodiversity discovery and loss in Singapore

There is an urgent need for reliable data on the impacts of deforestation on tropical biodiversity. The city-state of Singapore has one of the most detailed biodiversity records in the tropics, dating back to the turn of the 19th century. In 1819, Singapore was almost entirely covered in primary forest, but this has since been largely cleared. We compiled more than 200 y of records for 10 major taxonomic groups in Singapore (>50,000 individual records; >3,000 species), and we estimated extinction rates using recently developed and novel statistical models that account for "dark extinctions," i.e., extinctions of undiscovered species. The estimated overall extinction rate was 37% (95% CI [31 to 42%]). Extrapolating our Singapore observations to a future business-as-usual deforestation scenario for Southeast Asia suggests that 18% (95% CI [16 to 22%]) of species will be lost regionally by 2100. Our extinction estimates for Singapore and Southeast Asia are a factor of two lower than previous estimates that also attempted to account for dark extinctions. However, we caution that particular groups such as large mammals, forest-dependent birds, orchids, and butterflies are disproportionately vulnerable.

Convergent adaptation of true crabs (Decapoda: Brachyura) to a gradient of terrestrial environments

For much of terrestrial biodiversity, the evolutionary pathways of adaptation from marine ancestors are poorly understood, and have usually been viewed as a binary trait. True crabs, the decapod crustacean infraorder Brachyura, comprise over 7,600 species representing a striking diversity of morphology and ecology, including repeated adaptation to non-marine habitats. Here, we reconstruct the evolutionary history of Brachyura using new and published sequences of 10 genes for 344 tips spanning 88 of 109 brachyuran families. Using 36 newly vetted fossil calibrations, we infer that brachyurans most likely diverged in the Triassic, with family-level splits in the late Cretaceous and early Paleogene. By contrast, the root age is underestimated with automated sampling of 328 fossil occurrences explicitly incorporated into the tree prior, suggesting such models are a poor fit under heterogeneous fossil preservation. We apply recently defined trait-by-environment associations to classify a gradient of transitions from marine to terrestrial lifestyles. We estimate that crabs left the marine environment at least seven and up to 17 times convergently, and returned to the sea from non-marine environments at least twice. Although the most highly terrestrial- and many freshwater-adapted crabs are concentrated in Thoracotremata, Bayesian threshold models of ancestral state reconstruction fail to identify shifts to higher terrestrial grades due to the degree of underlying change required. Lineages throughout our tree inhabit intertidal and marginal marine environments, corroborating the inference that the early stages of terrestrial adaptation have a lower threshold to evolve. Our framework and extensive new fossil and natural history datasets will enable future comparisons of non-marine adaptation at the morphological and molecular level. Crabs provide an important window into the early processes of adaptation to novel environments, and different degrees of evolutionary constraint that might help predict these pathways.

Shift in symbiotic lifestyle as the major process shaping the evolution of pea crabs (Decapoda: Brachyura: Pinnotheroidea)

The pea crabs, superfamily Pinnotheroidea, are exceptional among brachyuran crabs in their diverse symbiotic associations involving both inquilinism and protective symbiosis. While this group presents a rare opportunity for evolutionary comparative study of host switching and morphological evolution in marine macroinvertebrates, previous phylogenetic studies have been focused on systematics. Here, we reconstructed the most extensive phylogeny of Pinnotheroidea based on two mitochondrial and six nuclear markers, with the aim of elucidating the host switching pathways and the correlation between symbiotic lifestyles and selected morphological adaptations. Ancestral state reconstruction of host association revealed a monophyletic origin of symbiosis in the form of inquilinism. Subsequent shifts in microhabitat preference for burrows or worm tubes, and the move to protective symbiosis, primarily in the switch to mollusc endosymbiosis, contributed to radiation in Pinnotheridae. Further parallel colonisations of echinoderms and tunicates occurred but did not lead to extensive diversification, except in the Clypeasterophilus + Dissodactylus lineage, which experienced a unique switch to echinoderm ectosymbiosis. The evolution of the third maxillipeds, carapace shape and ambulatory pereiopods suggests a rather strong coupling with the symbiotic lifestyle (whether inquilinism or protective symbiosis). Phenotypic diversity of these characters was higher among species engaged in protective symbiosis, with convergence in form (or function) among those sharing the same host affiliation. Species having different host affiliations or symbiotic lifestyles might also exhibit convergence in the form of the three morphological traits, suggesting a common adaptive value of the specialisations. Pinnotherid crabs overall exhibited a lower trait diversity than the also symbiotic palaemonid shrimps with comparable species diversity. This may plausibly be attributed to differences in potential for morphological modification to serve additional functions among the traits analysed in the two groups, the less frequent host switching and the less diverse host affiliations, and thus a less complicated evolutionary history in pinnotherids.

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.

On the correct lectotype for Marmessoidea unicolor Redtenbacher, 1908 (Insecta: Phasmatodea)

Hennemann, F.H., Conle, O.V. & Brock, P.D. (2023) The types of Phasmatodea (= Phasmida) deposited in the Eidgenssisches Technisches Hochschulzentrum, Zrich, Switzerland (ETHZ). Zootaxa, 5278 (1), 176188. https://doi.org/10.11646/zootaxa.5278.1.10 Hovinga, H. (2010) The Sumatra Railroad: Final destination Pakan Baroe, 19431945. Brill, Leiden, 391 pp. https://doi.org/10.1163/9789004253711 ICZN [International Commission on Zoological Nomenclature] (1999) International Code of Zoological Nomenclature. International Commission of Zoological Nomenclature. 4th Edition. Adopted by the XXI General Assembly of the International Union of Biological Sciences. International Trust for Zoological Nomenclature, in association with the British Museum (Natural History), London, 338 pp. Redtenbacher, J. (1908) Die Insektenfamilie der Phasmiden. III. Phasmidae Anareolatae (Phibalosomini, Acrophyllini, Necrosciini). Wilhelm Engelmann, Leipzig, pp. 341589, pls. 1627. Seow-Choen, F. (2021) A Taxonomic Guide to Stick Insects of Peninsular Malaysia. Vol. 1. Natural History Publications, Borneo, Kota Kinabalu, 944 pp. Weidmann, W. (1936) Der Schweizer als Pionier und Kolonist in Sumatra. In: Der Schweizer Verein Deli-Sumatra (Ed.), Der Schweizer Verein Deli-Sumatra: Zum fnfzigjhrigen Bestehen, 18861936. Buchdruckerei der Neuen Zrcher Zeitung, Zrich, pp. 3348.

On the systematic placement of the fossil crab Lathahypossia aculeata (Busulini, Tessier & Visentin, 1984) (Crustacea: Decapoda: Brachyura)

The systematic placement of the iconic fossil crab, Lathahypossia aculeata (Busulini, Tessier & Visentin, 1984) (formerly in Titanocarcinus A. Milne-Edwards, 1864), from the Eocene of Italy is revised. The examination of two specimens that had the ventral and subcephalic features well preserved has allowed us to better understand the morphology of this species. As a result, Lathahypossia aculeata must be removed from the Hypothalassiidae (Eriphioidea), where it is now placed, and moved to the Xanthidae (Xanthoidea). The present work again highlights the importance of ventral characters in the study of fossil crabs and allows a more accurate systematic classification.

On the identities of the sesarmid crabs, Sesarma villosum A. Milne-Edwards, 1869, and Clistocoeloma suvaense Edmondson, 1951, with the description of a new species from the West Pacific (Decapoda, Brachyura, Thoracotremata)

The identities of two sesarmid crabs, Clistocoeloma villosum (A. Milne-Edwards, 1869), and C. suvaense Edmondson, 1951, both currently in Clistocoeloma A. Milne-Edwards, 1873, are poorly known and the types have not been studied in detail since their description. Clistocoeloma villosum, supposedly widespread, has been recorded from Madagascar and East Africa to Singapore, Japan, Korea, and Samoa. Clistocoeloma suvaense is only known for certain from one male collected from its type locality, Fiji. The taxonomy of C. villosum, and C. suvaense is clarified on the basis of the type specimens from Samoa and Fiji, respectively. A new species, which has long been confused with C. villosum, is described from Southeast Asia and Western Pacific.

New and rare deep-sea majoid crabs (Crustacea: Brachyura) from Papua New Guinea

Additional spider crab (superfamily Majoidea) material from four major French-led expeditions to the Papua New Guinea region were examined in this study. One new genus and four new species from the families Inachidae and Oregoniidae are described. Dorhynchus profundus n. sp. is close to D. rostratus (Sakai, 1932) but can easily be separated by the shape of the ambulatory dactylus and the proportionately lower protogastric spines. Achaeus pholcus n. sp. is unusual in that it occurs in deeper waters (beyond 500 m), and can be separated from A. lacertosus Stimpson, 1857, A. villosus Rathbun, 1916, and A. brevidactylus Sakai, 1938, by its distinctive carapace shape, structure of the frontal margin, regions of the carapace, antennular fossa, ambulatory dactylus, male pleon, and proportions of the chela. Parapleisticantha aie n. sp. is closest to P. japonica Yokoya, 1933, but differs in its proportionately longer carapace, more elongated basal antennal article, longer third maxilliped ischium and the relatively less curved male first gonopod with the distal part differently structured. A new genus (Orbicantha n. gen.) with one new species (Orbicantha sacrebleu n. gen., n. sp.) is also described; it is allied to Pleistacantha Miers, 1879, Parapleisticantha Yokoya 1933, and Pleisticanthoides Yokoya, 1933, but is distinctive in its subcircular carapace, shorter regions, short pseudorostral spines, possession of spines on the gastric, cardiac and branchial regions, some of which have rounded tips, a short ocular peduncle, a very short third antennal article, a quadrate epistome, and the more reduced P4 and P5. New records from the family Epialtidae are also reported: Griffinia gilloloensis (Rathbun, 1916), Hyastenus borradailei (Rathbun, 1907), and Oxypleurodon luzonicum (Rathbun, 1916). The taxonomy of Grypachaeus tenuicollis Takeda, 1978 (Oregoniidae) and Griffinia lappacea (Rathbun, 1918) (Epialtidae) is also discussed.

Two new species of hairy crabs (Pilumnidae) and the first record of Crinitocinus alcocki (Borradaile, 1900) (Acidopsidae) (Crustacea: Brachyura) from Taiwan

Two new species of pilumnid crabs, Heteropilumnus planus n. sp. and Pseudolitochira taiwang n. sp., are described from reefs in Taiwan. Heteropilumnus planus n. sp. is most similar to H. hirsutior (Lanchester, 1900) from Singapore and Japan, but can easily be distinguished by its distinctly flatter carapace, different anterolateral carapace armature, longer ambulatory legs, and male first gonopod structure. Pseudolitochira taiwang n. sp. is most similar to P. crinita Ng & Clark, 2022, from Papua New Guinea but can easily be separated by its carapace physiognomy, armature of the anterolateral carapace margin and proportionately shorter ambulatory legs. Heteropilumnus setosus (A. Milne-Edwards, 1873) is also transferred to Pseudolitochira; and compared with P. taiwang n. sp. The rarely reported acidopsid, Crinitocinus alcocki (Borradaile, 1900) is also recorded from Taiwan for the first time, substantially extending its known range northwards.

Revision of the Genus Lacunipotamon Dai, Song, He, Cao, Xu & Zhong, 1975 (Crustacea: Decapoda: Brachyura: Potamidae), with Descriptions of Eight New Species from Vietnam

The taxonomy of the potamid genus Lacunipotamon Dai, Song, He, Cao, Xu & Zhong, 1975, is revised. Three species are known from southern China: L. albusorbitum Dai, Song, He, Cao, Xu & Zhong, 1975 (type species); L. yuanshi Huang, Shih & Ahyong, 2020; and L. cymatile Huang, Shih & Ahyong, 2020. Eight new species are here described from northern Vietnam: L. globus, L. panda, L. contrastum, L. sublividum, L. mimicum, L. thuanchau, L. pectum and L. purpureum. This is the first record of the genus in Vietnam, with all the new species obtained from karst formations. The species are differentiated by the characters of carapace shape, anterolateral armature, posterior margin of the epistome, male sternopleonal cavity, chelipeds, ambulatory legs, male thoracic sternum, male pleon, and structures of the male first gonopods and vulvae.

On the identity of Pronotonyx laevis (Miers, 1884) (Crustacea: Brachyura: Pilumnidae)

The poorly known brachyuran crab, Pronotonyx laevis Ward, 1936, from northern Australia, is redescribed based on type and other material. We document adults of both sexes and confirm the taxonomic placement of the Pronotonyx in the Pilumnidae. Pronotonyx is most similar to the Australian Pseudocryptocoeloma parvum Ward, 1936, differing in features of the carapace and pereopods.

Two new species of semiaquatic freshwater crabs of the genera Tortomon and Aiyunamon from karst forests in northern Vietnam (Crustacea: Brachyura: Potamidae)

Two new genera of freshwater crabs (Potamidae) are recorded from northern Vietnam, Tortomon Huang, Wang & Shih, 2020, and Aiyunamon Pan, Ng & Sun, 2022. These genera had previously only been reported from southern China and eastern Myanmar. Each genus is represented by a new species. Tortomon distinctum n. sp. is markedly different from its two Chinese congeners in its proportionately wider carapace, more elongate third maxilliped, the carpus of the cheliped being armed only with a low tubercle, possessing relatively more slender and longer ambulatory legs, a gently curved male first gonopod and a more elongate male second gonopod. Aiyunamon vietnamicum n. sp. is distinct from its five congeners in its proportionately less convex dorsal surface of the carapace, relatively lower epigastric cristae, lower rugosities of the postorbital cristae, wider median lobe of the posterior margin of the epistome, relatively narrower male pleon, and a male first gonopod that has the terminal segment more distinctly curved with a wider concavity on the outer margin of the subterminal segment.

Allopatric mosaics in the Indo-West Pacific crab subfamily Chlorodiellinae reveal correlated patterns of sympatry, genetic divergence, and genitalic disparity

Molecular studies have revealed that many species once thought to be wide-ranging in the Indo-West Pacific contain allopatric mosaics of endemic lineages. These lineages provide compelling evidence that substantial time is needed to evolve isolating mechanisms sufficient to permit successful secondary sympatry, and that divergence is initiated in allopatry. In this context, questions arise regarding the nature, timing, and origin of isolating mechanisms that permit secondary sympatry. We present a phylogeny of the crab subfamily Chlorodiellinae which displays allopatric mosaics within species. These allopatric lineages typically do not have divergent male genitalia, while older sympatric lineages do. We tested the relationship between genetic distance (proxy for time), sympatry, and the divergence of male genitalic morphology. Our results suggest that male genitalic divergence is not involved in the initiation of speciation in chlorodielline crabs, having likely occurred only after isolation began in allopatry. However, morphological evolution of genitalia seemingly does play an important role in completing the process of speciation in these crabs.

Tuerkayana latens, a New Species of Land Crab from French Polynesia, with a Discussion on the Phylogeny of the Genus (Crustacea: Decapoda: Brachyura: Gecarcinidae)

The taxonomy of the gecarcinid land crab Tuerkayana rotundum (Quoy & Gaimard, 1824) is revised. The taxon, the type species of the genus, occurs from the western Indian Ocean to the western Pacific, and varies substantially in colour and various morphological features, but the male first gonopod structure is constant and the extensive genetic data from mitochondrial 16S rDNA, cytochrome c oxidase subunit 1 and control region markers confirms the recognition of one wide-ranging species. Specimens from Tuamotu in French Polynesia and Pitcairn Island, however, differ in having a smoother and slightly more swollen carapace, and significantly, the male first gonopod structure is distinctly different. The genetic data also supports their differentiation. As such, this material is here recognised as a new species, Tuerkayana latens n. sp.

A comprehensive molecular phylogeny of the brachyuran crab superfamily Xanthoidea provides novel insights into its systematics and evolutionary history

Maximum likelihood and Bayesian phylogenies for the brachyuran crab superfamily Xanthoidea were estimated based on three mitochondrial and four nuclear genes to infer phylogenetic relationships and inform taxonomy. Habitat data was then used in conjunction with several diversification rates analyses (BAMM, BiSSE, HiSSE, and FiSSE) to test evolutionary hypotheses regarding the diversification of xanthoid crabs. The phylogenies presented are the most comprehensive to date in terms of global diversity as they include all four constituent families (Xanthidae, Panopeidae, Pseudorhombilidae, and Linnaeoxanthidae) spanning all oceans in which xanthoid crabs occur. Six Xanthoidea families are recognised. Panopeidae and Xanthidae sensu stricto are the two largest family-level clades, which are reciprocally monophyletic. Pseudorhombilidae is nested within and is here treated as a subfamily of Panopeidae. Former subfamilies or tribes of Xanthidae sensu lato are basally positioned clades in Xanthoidea and are here assigned family-level ranks: Garthiellidae, Linnaeoxanthidae, Antrocarcinidae, and Nanocassiopidae. The genera Linnaeoxantho and Melybia were recovered in separate clades with Linnaeoxantho being sister to the family Antrocarcinidae, while Melybia was recovered within the family Panopeidae. The existing subfamily classification of Xanthidae and Panopeidae is drastically restructured with 20 xanthid and four panopeid subfamilies provisionally recognised. Diversification-time analyses inferred the origin of Xanthoidea and Garthiellidae in the Eocene, while the other families originated during the Oligocene. The majority of genus- and species-level diversification took place during the Miocene. Ancestral state reconstruction based on depth of occurrence (shallow vs. deep water) shows some ambiguity for the most recent common ancestor of Xanthoidea and Nanocassiopidae. The most recent common ancestors of Antrocarcinidae and Panopeidae were likely deep-water species, while those of Garthiellidae and Xanthidae were probably shallow-water species. Several shifts in net diversification rates were detected but they were not associated with depth-related habitat transitions.

Molecular phylogeny of Thoracotremata crabs (Decapoda, Brachyura): toward adopting monophyletic superfamilies, invasion history into terrestrial habitats and multiple origins of symbiosis

The Thoracotremata is a large and successful group of "true" crabs (Decapoda, Brachyura, Eubrachyura) with a great diversity of lifestyles and well-known intertidal representatives. The group represents the largest brachyuran radiation into terrestrial and semi-terrestrial environments and comprises multiple lineages of obligate symbiotic species. In consequence, they exhibit very diverse physiological and morphological adaptations. Our understanding of their evolution is, however, largely obscured by their confused classification. Here, we resolve interfamilial relationships of Thoracotremata, using 10 molecular markers and exemplars from all nominal families in order to reconstruct the pathways of lifestyle transition and to propose a new taxonomy corresponding to phylogenetic relationships. The results confirm the polyphyly of three superfamilies as currently defined (Grapsoidea, Ocypodoidea and Pinnotheroidea). At the family level, Dotillidae, Macrophthalmidae, and Varunidae are not monophyletic. Ancestral state reconstruction analyses and divergent time estimations indicate that the common ancestor of thoracotremes already thrived in intertidal environments in the Late Cretaceous and terrestrialization became a major driver of thoracotreme diversification. Multiple semi-terrestrial and terrestrial lineages originated and radiated in the Early Eocene, coinciding with the global warming event at the Paleocene-Eocene Thermal Maximum (PETM). Secondary invasions into subtidal regions and colonizations of freshwater habitats occurred independently through multiple semi-terrestrial and terrestrial lineages. Obligate symbiosis between thoracotremes and other marine macro-invertebrates evolved at least twice. On the basis of the current molecular phylogenetic hypothesis, it will be necessary in the future to revise and recognize seven monophyletic superfamilies and revisit the morphological character states which define them.

Establishment of A New Bornean Genus of Gecarcinucidae (Crustacea: Brachyura), with Descriptions of Five New Species

The freshwater gecarcinucid species from Borneo previously referred to Sundathelphusa Bott, 1969, are transferred to a new genus. Borneosa gen. nov. can be diagnosed by the presence of a distinct frontal median triangle that is shorter than the frontal margin, a relatively longer male thoracic sternum in which the sternopleonal cavity reaches more anteriorly, and a male first gonopod that has the terminal segment prominently covered with long setae. The eight species recognised-B. tenebrosa (Holthuis, 1979), B. aspera (Ng & Stuebing, 1989), B. brachyphallus (Ng, 2015), and five new species, B. niah, B. bario, B. kapit, B. sarawakensis and B. serrata-can be distinguished by characters of the frontal median triangle, epibranchial tooth, anterolateral margin, third maxillipeds, ambulatory legs, male sternum, male pleon and male first gonopod.

Alcolyra, a new genus of leucosiid crab (Crustacea: Decapoda: Brachyura) from India

The identity of Philyra alcocki Kemp, 1915 (Leucosiidae), a species described from Chilika Lake, India is clarified. The redescription of lectotype male and examination of fresh material collected from Chilika Lake, Odisha state of India revealed that P. alcocki is significantly different morphologically from members of Philyra senso stricto and other allied genera in possessing two tuberculated rows on the branchial region of carapace, and a well-developed tubercle on male thoracic sternite 5 on either side of the sternopleonal cavity. Therefore, a new genus Alcolyra n. gen. is established herewith for the species.

On two new species of deep-sea carrier crabs (Crustacea, Brachyura, Homolodromiidae, Dicranodromia) from Taiwan and the Philippines, with notes on other Indo-West Pacific species

The systematics of four species of the homolodromiid genus Dicranodromia A. Milne-Edwards, 1880, from East Asia and the Philippines is reappraised: D.danielae Ng & McLay, 2005, D.doederleini Ortmann, 1892, D.karubar Guinot, 1993, and D.martini Guinot, 1995; and key characters such as the epistome, gonopods, and spermatheca are figured in detail. Two new species, D.erinaceussp. nov. and D.robustasp. nov., are described from Taiwan and the Philippines, respectively. Dicranodromiaerinaceussp. nov. resembles D.spinulata Guinot, 1995, and D.delli Ahyong, 2008 (from New Caledonia and New Zealand) but can be separated by its distinctly spinulated carapace surfaces and proportionately shorter fifth ambulatory legs. Dicranodromiarobustasp. nov. is superficially similar to D.baffini (Alcock & Anderson, 1899) and D.karubar Guinot, 1993, but can easily be separated by possessing a broad dorsoventrally flattened infraorbital tooth. A genetic study of the species using the mitochondrial cytochrome c oxidase I gene confirms that the taxa are distinct, with D.erinaceussp. nov. coming out in a well-supported clade from congeners. The megalopa of D.doederleini is also reported for the first time.

The taxonomy of spider crabs of the genera Eurynome, Choniognathus, Seiitaiodes and Kasagia (Crustacea: Brachyura: Majidae) from southwest Indian Ocean

The taxonomy of majid spider crabs collected from recent southwest Indian Ocean cruises belonging to Eurynome Leach, 1814, and allied genera is treated. Eurynome longimana Stimpson, 1857, long synonymised with the European E. aspera (Pennant, 1777), is here recognised as a distinct species. Stimpsons (1857) species can be distinguished by the armature of granules on the third maxilliped, proportions and armature of the ambulatory merus, relatively shorter ambulatory dactylus, structure of the male sternopleonal cavity and relative proportions of the male first gonopod. The composition of Choniognathus Rathbun, 1932, is discussed and the type species, C. koreensis Rathbun, 1932, is figured. One species, C. verhoeffi (Balss, 1929), is not considered to be a member of Choniognathus and its taxonomy is discussed. A new spinose species, C. spinosus, is also described. Seiitaoides Griffin Tranter, 1986, is revised, and two new species, S. mirabilis and S. kabuto, are described and compared with S. orientalis (Sakai, 1961) and S. stimpsoni (Miers, 1884). The poorly known Eurynome elegans Stebbing, 1921 is rediscovered, its taxonomy clarified and the species is shown to belong to Kasagia Richer de Forges Ng, 2007. A second species of Kasagia, K. sudhakari Padate, Manjebrayakath Ng, 2019, recently described from the Arabian Sea is recorded from southwest Indian Ocean.

On two new species of arboreal crabs from phytotelms in Sarawak, Borneo (Crustacea: Brachyura: Gecarcinucidae: Arachnothelphusa)

Two new species of the gecarcinucid freshwater crab genus Arachnothelphusa are described from the Malaysian state of Sarawak in Borneo; one from Lanjak-Entimau Wildlife Sanctuary and another from Bako National Park. Arachnothelphusa rimba n. sp. is distinctive in possessing very long legs and a male first gonopod which has a cylindrical proximal part of the terminal segment, with the distal part sharply tapering to an acute tip. Arachnothelphusa bako n. sp. is superficially closest to A. kadamaiana from Sabah, but differs markedly by its narrower epistome, and proportionately shorter third maxillipeds and ambulatory legs.

Rediscovery of Orientotlosiishibai Sakai, 1980 (Crustacea, Decapoda, Brachyura, Leucosiidae) in Taiwan

The leucosiid crab Orientotlosiishibai Sakai, 1980 was described from one female collected off western Japan and had never been reported since. The species is now recorded from southwestern Taiwan for the first time, and is redescribed and figured at length. Although Sakai argued that Orientotlos Sakai, 1980, is closely related to Oreophorus Rüppell, 1830 and Atlantotlos Doflein, 1904, the genus is actually morphologically most similar to Merocryptus A. Milne-Edwards, 1873. The two genera, however, still differ markedly in a number of key carapace and cheliped characters.

Pseudolitochira integra (Miers, 1884) (Crustacea: Brachyura: Pilumnidae): redescribed and illustrated from micro-ct scanning the type female

The taxonomy of the poorly known pilumnid crab, Pseudolitochira integra (Miers, 1884), has been confused because the original description and figures of the type female have inaccuracies, and the specimen has not been examined in detail since the original publication. Consequently, numerous specimens from the Indo-West Pacific have been incorrectly assigned to P. integra, suggesting that this species is widely distributed. The type female was micro-CT scanned in order to provide video and accurate figures of this rare pilumnid. The female possesses a suite of carapace and pereopodal characters that distinctly distinguish it from other pilumnoid taxa. The species is redescribed, refigured and formally designated as the type species of Pseudolitochira Ward, 1942. The identities of the numerous specimens assigned to P. integra are discussed and the distribution of the species is restricted to the western Indian Ocean for the time being.

The curious case of "innies": Articles 50.1, 50.1.1 and the citation of authorities in Decapoda Crustacea-a way forward

In the majority of species and genus names in Decapoda Crustacea, the author(s) of the name equate with the author(s) of the work. In a relatively small number of cases, however, the author(s) of the name are either a subset of the authors of the work or are not an author on the work-a phenomenon herein termed "innies". We demonstrate that these two categories should be differentially interpreted according to Articles 50.1 and 50.1.1 of the ICZN Code. To promote stability in cited authorship of historical names, it is proposed that 1) if the author(s) of the name are also an author on the work, these should be universally accepted as "innies", irrespective of any further explanation in the text (including a mere attribution following the taxon name); and 2) that if the author(s) of the name are not an author(s) of the work, these should only be considered as "innies" if a more expansive explanation is given in the text, not merely an attribution of authorship to the taxon name.

Geosesarma sodalis, a new species of vampire crab (Crustacea, Brachyura, Sesarmidae) from a limestone cave in central Sarawak, Malaysia

A new species of semi-terrestrial crab of the genus Geosesarma (Sesarmidae) is described from a limestone cave in central Sarawak, Malaysian Borneo. Geosesarmasodalissp. nov. is characterised by its quadrate carapace, absence of a flagellum on the exopod of the third maxilliped, presence of 10 or 11 sharp tubercles on the dactylus of the chela and a diagnostic male first gonopod structure. This is the sixth species of Geosesarma reported from Sarawak, and the first member of the genus collected from inside caves.

emOvilyra/em, a new genus of leucosiid crab (Crustacea: Decapoda: Brachyura) from the West Pacific

The identities of two species of shallow water Southeast Asian and southern Chinese leucosiid crabs Philyra fuliginosa Targioni-Tozzetti, 1877, and P. olivacea Rathbun, 1909, are clarified; and shown to be synonyms. A new genus, Ovilyra, is established for P. fuliginosa, and it is easily distinguished from Philyra s. str. as well as allied genera by possessing an elongate carapace, a narrow and slender male pleon with somites 1 and 2 articulate, and a male first gonopod which has the distal quarter sharply bent with a well developed subdistal process.

Tritodynamia bengalensis n. sp., a new species of brachyuran crab from West Bengal state, India (Decapoda: Brachyura: Macrophthalmidae)

Tritodynamia bengalensis n. sp. is described on the basis of a male specimen dredged from the shallow coastal waters of West Bengal state, India. The new species is morphologically similar to T. bidentata Yang Tang, 2005 and T. serratipes Anker Ng, 2014, but can be distinguished by the carapace shape, dentition of the pollex, relative length of the dactylus of the third maxilliped, proportions of the propodus of the third pereopod, and structure of the male left gonopod. This is the first record of the genus Tritodynamia from India.

Revision of the freshwater crabs of the Johora tahanensis (Bott, 1966) species group (Crustacea, Brachyura, Potamidae), with a key to the genus

The taxonomy of the potamid freshwater crabs of the Johoratahanensis (Bott, 1966) species group (Potamoidea) is revised. Seven species are recognised, all from Peninsular Malaysia and southern Thailand, three of which are described as new. The three new species were previously identified as J.tahanensis but can be distinguished by characters of the carapace, male first gonopod, and vulva. A revised key to the 18 recognised species of Johora Bott, 1966, is provided.

Revision of the deep-water spider crab genus, Scyramathia A. Milne-Edwards, 1880, with the description of a new species from the Mediterranean and notes on Rochinia A. Milne-Edwards, 1875, and Anamathia Smith, 1885 (Crustacea, Decapoda, Brachyura, Epialtidae)

The taxonomy of the deep-water spider crabs of the genus Scyramathia A. Milne-Edwards, 1880, is revised and four extant species are recognised from the Atlantic and western Indian Ocean: S. carpenteri (Norman, in Thomson 1873) (type species), S. umbonata (Stimpson, 1871), S. hertwigi Doflein, in Chun 1900, and S. tenuipessp. nov.Scyramathia tenuipessp. nov. from the Mediterreanean is easily distinguished from its congeners by its slender and elongate ambulatory legs. All species are diagnosed and figured. The taxonomy of two allied genera from the Atlantic and Mediterranean, Rochinia A. Milne-Edwards, 1875, and Anamathia Smith, 1885, are also treated and their type species redescribed and figured.

On the identity of the poorly known pea crab, Pinnothera obesa Dana, 1852, and description of a new species of Arcotheres Manning, 1993 from the Southwest Pacific (Decapoda: Brachyura: Pinnotheridae)

The pinnotherid crab, Pinnothera obesa Dana, 1852, was originally described on the basis of material from Fiji, but its taxonomic status has long been obscure because the original description and figures are too brief and schematic by modern standards and the types are also lost. Examination of newly collected material from Fiji revealed the presence of two intertidal pinnotherid species assignable to the genus Arcotheres Manning, 1993, one of which is herein identified with Dana's taxon. A neotype is designated for Arcotheres obesus n. comb. in the interest of nomenclatural stability, and a detailed redescription is given. Arcotheres obesus is morphologically similar to A. exiguus (Bürger, 1895) and A. rotundatus (Bürger, 1895), and differentiating characters are discussed. The species is also reported from Peninsular Malaysia. The second species is new to science, here described as Arcotheres ocularius, and is most similar to A. palaensis (Bürger, 1895) and A. arcophilus (Bürger, 1895). The new species is also recorded from Lombok, Indonesia. Arcotheres obesus and A. ocularius n. sp. are associated with bivalve mollusks of the genera Gafrarium spp. (Veneridae) and Anadara spp. (Arcidae), respectively.

Description of the supergiant isopod Bathynomus raksasa sp. nov. (Crustacea, Isopoda, Cirolanidae) from southern Java, the first record of the genus from Indonesia

The giant isopod genus Bathynomus A. Milne-Edwards, 1879, is recorded for the first time in Indonesian waters, from deep waters off southern Java in the Indian Ocean. Bathynomusraksasasp. nov. is described and notes on juvenile specimens of an unidentified species found in the same locality are also provided. Bathynomusraksasasp. nov. is characterized by the large size (averaging at 330 mm), narrowly rounded clypeus apex, prominent longitudinal carina on the clypeus, convex lateral margins of the uropodal exopod and endopod, produced distolateral corners of the uropodal exopod and endopod which have acute ends, an uropodal exopod with a setal fringe of medium length (69%), a pleotelson 1.6 times wider than long with the posterior margin medially concave, and the large number (11–13) of spines on the pleotelson.

New species of pinnotherid crabs from Southeast Asia and Papua New Guinea (Crustacea: Decapoda: Brachyura)

Three new Indo-West Pacific species of pinnotherid crabs are described, one each of Arcotheres, Buergeres and Nepinnotheres. Arcotheres pollus, described from Paway Island, Mergui Archipelago, is most similar to A. boninensis (Stimpson, 1858), A. pernicola (Bürger, 1895) and A. purpureus (Alcock, 1900), sharing a transversely ovate carapace and long, slender, almost styliform dactyli of P4 and 5 that are about twice the length of those of P2 and 3. Buergeres choprai, described from Papua New Guinea, is most similar to B. deccanesis (Chopra, 1931) from eastern India but differentiated by segment proportions and setation of the walking legs. Buergeres tenuipes (Bürger, 1895) is synonymised with B. ortmanni (Bürger, 1895), which is also reported for the first time from Indonesia. A male of an undetermined species of Buergeres from the Philippines, possibly B. ortmanni, is figured and described, documenting the gonopod morphology in Buergeres for the first time. A key to the species of Buergeres based on females is provided. Nepinnotheres fulvia sp. nov. is also described from Papua New Guinea, and resembles N. cardii (Bürger, 1895) from the Philippines and Malaysia but can be distinguished by features of the chelipeds and maxilliped 3.

What is Sesarmops impressus (H. Milne Edwards, 1837) (Crustacea: Brachyura: Sesarmidae)?

The identity of the widely distributed mangrove and riverine sesarmid crab Sesarmops impressus (H. Milne Edwards, 1837) is clarified. The species has been reported from Madagascar to the South Pacific, but its taxonomy was previously confused. On the basis of morphological characters and available molecular evidence (using 16S rDNA and cytochrome oxidase subunit I), Sesarmops impressus is restricted to the western Indian Ocean and S. frontale A. Milne-Edwards, 1869 is confirmed to be its junior synonym. Sesarmops similis (Hess, 1865), long synonymised under S. impressus, is here recognised as a separate species and a neotype from Samoa is designated. The identity of the poorly known S. atrorubens (Hess, 1865), which has often been confused with S. impressus, is also clarified, and a neotype is selected from Fiji. Specimens from the eastern Indian Ocean and western Pacific are here identified as two new species, S. indicus sp. nov. and S. imperator sp. nov.

On the identities of Nepinnotheres vicajii (Chhapgar, 1957) and Arcotheres casta (Antony amp; Kuttyamma, 1971) from western India: conspecificity and taxonomy (Decapoda, Brachyura, Pinnotheridae)

The identity of Nepinnotheres vicajii (Chhapgar, 1957) (described as Pinnotheres vicajii) (Pinnotheridae), a pea crab associated with the bivalve Marcia recens (Holten, 1802), is clarified. On the basis of re-diagnosis of holotype male and freshly collected female specimens from its type locality, P. vicajii is now assigned to Arcotheres Manning, 1993. A second poorly known species from India, Arcotheres casta (Antony Kuttyamma, 1971), originally collected from Meretrix casta (Gmelin, 1791) is also synonymized with A. vicajii.

The Homolidae of the Hawaiian Islands, with notes on the taxonomy of Moloha major (Kubo, 1936) (Crustacea: Decapoda: Brachyura)

Based partly on a collection of homolid crabs captured from baited traps in deep waters off French Frigate Shoals, Northwest Hawaiian Islands, in October 2006, the Hawaiian species of the family Homolidae are reviewed. Known genera and species in the Hawaiian Islands now include two species of Homola (H. orientalis and H. dickinsoni), two species of Lamoha (L. williamsi and L. personata), and five genera that are each represented by a single species (Paramola japonica, Moloha major, Yaldwynopsis hawaiiana, Latreillopsis okala, and Homologenus namakae). Seven of the 14 currently recognized genera of the Homolidae and nine of the 74 known species are now known from Hawaiian waters. Colour notes are included for the first time for two species (H. dickinsoni and Y. hawaiiana). A key to the family Homolidae in Hawaiian waters is included.

Additional notes on the publication of the Narrative, Zoology and Notes from a Journal of Research into the Natural History of the Voyage of H.M.S. Samarang and its consequences for the nomenclature of decapod crustaceans and other taxa

Captain Edward Belcher was instructed by the Lords of the Admiralty to conduct a Surveying Expedition of the various coasts and islands in the Eastern Seas using H.M.S. Samarang. During this voyage from 1843-1846, Assistant-Surgeon Arthur Adams, made a significant contribution to the collection of natural history specimens, and together with fellow officers J. Richards and W. Browne, he prepared numerous drawings used by Belcher to illustrate the Narrative of the voyage. Later, Adams collaborated with Adam White (an Assistant in the Zoological Branch of the British Museum) to describe the Samarang Crustacea, published jointly with Lovell Reeve on the Samarang Mollusca, edited the Zoology of the voyage of H.M.S. Samarang and was the author of Notes from a Journal of the Natural History which was published in the Narrative of the voyage by Belcher. In his Natural History, Adams provided detailed accounts on some of the crustaceans collected with formal descriptions of species new to science thereby making these names available. The history, nomenclature and validity of the crustacean species cited in this work is discussed and a list of the available names is tabulated.

Geosesarmamirum, a new species of semi-terrestrial sesarmid crab (Crustacea, Decapoda, Brachyura) from central Taiwan

A new species of semi-terrestrial sesarmid crab of the genus Geosesarma De Man, 1892, is described from central Taiwan. Geosesarmamirumsp. nov. is distinct in possessing a strong transverse crest on the inner surface of the male chela and a diagnostic male first gonopod which is relatively long and stout, with the distal chitinous part broad and spatuliform. Like most Geosesarma species, G.mirumsp. nov. has large eggs and direct development, contrasting with the only other species known from Taiwan, G.hednon Ng, Liu and Schubart, 2004, which has small eggs and planktotrophic larvae.

Deep-sea spider crabs of the family Epialtidae MacLeay, 1838, from Papuabr />New Guinea, with a redefinition of Tunepugettia Ng, Komai amp; Sato, 2017, and descriptions of two new genera (Crustacea: Decapoda: Brachyura: Majoidea)

The deep-water epialtid spider crab (superfamily Majoidea) material collected from recent French expeditions to Papua New Guinea (BIOPAPUA 2010, PAPUA NIUGINI 2012, MADEEP 2014, and KAVIENG 2014) was studied. In addition to several new records for the country, five new species of Oxypleurodon Miers, 1885, Rochinia A. Milne-Edwards, 1875, and Tunepugettia Ng, Komai Sato, 2017, are described. The taxonomy of Tunepugettia is reappraised, and a new genus, Crocydocinus n. gen., is established, characterised by its smooth ambulatory legs and a distinct male first gonopod structure. Four species from the Bay of Bengal, Sumatra, and Réunion Island, currently placed in Rochinia and Tunepugettia are transferred to Crocydocinus n. gen. and four new species from Papua New Guinea, Philippines, and Vanuatu are described. A new genus, Neophrys n. gen., with one new species from Papua New Guinea, is established, and is characterised by the supraorbital eave being fused with the carapace and the poorly developed pre-orbital angle.

Geosesarma spectrum, a new species of semiterrestrial vampire crab (Crustacea: Decapoda: Brachyura: Sesarmidae) from Brunei Darussalam, Borneo

A new semiterrestrial vampire crab from the family Sesarmidae, Geosesarma spectrum n. sp., is described from Brunei Darussalam (Borneo). The new species is characterised by its colouration in life, relatively large size, and form of the carapace, ambulatory legs and gonopods. The new species is compared to its closest congeners from Borneo. This description brings the number of Geosesarma species to 60.

On a collection of brachyuran crabs from Lakshadweep, Indian Ocean (Crustacea: Decapoda: Brachyura)

The crab fauna (Crustacea: Brachyura) of Lakshadweep (Laccadives), a group of Indian islands in the western Indian Ocean is updated, using material from the intertidal and shallow subtidal areas collected between 2012 and 2015. Fifty-three species were recorded during this study, of which 17 species are newly recorded from the islands, and three are also new records for India. A total of 169 species of brachyuran crabs are now known from Lakshadweep. The taxonomy of Elamena gracilis Borradaile, 1903 (Hymenosomatidae) is clarified and stabilized by the designation of a lectotype.

On the identity of Sundathelphusa philippina (von Martens, 1868) (Decapoda: Brachyura: Gecarcinucidae) from the Philippines, with descriptions of two new species

The taxonomy of the Sundathelphusa philippina (von Martens, 1868) species group (Brachyura; Gecarcinucidae) from the Philippines is revised, and two new species are described. Sundathelphusa philippina sensu stricto is here restricted to the Bicol Peninsula of southern Luzon, and to the islands of Samar and Leyte. It is one of the largest freshwater crabs in the archipelago, reaching carapace widths of more than 53 mm. Sundathelphusa cebu sp. nov. from Cebu Island is superficially similar to S. philippina in morphology but can be separated by a suite of carapace characters. Sundathelphusa quirino sp. nov. from northern Luzon is the most distinct of the three taxa, with a distinctly more swollen carapace, relatively wider male pleon and a straighter male first gonopod. Sundathelphusa spelaeophila Stasolla, Abbarchi Innocenti, 2015, is also shown to be a junior synonym of S. philippina sensu stricto.

Geometric morphometric analysis in female freshwater crabs of Sarawak (Borneo) permits addressing taxonomy-related problems

The taxonomy of freshwater crabs requires a paradigm change in methodological approaches, particularly in investigations that use morphological techniques. The traditional morphometric approach (two-dimensional measurements) tends to be inappropriate for the identification of freshwater crabs due to their variable external morphology and lack of gonopods (conventionally used for the identification of male crabs) in females. In this study, we explore the potential use of the geometric morphometric technique for identification of female freshwater crabs, and identify taxonomic key characteristics of species. The shape of the carapace could be a good characteristic for the identification of female crabs, especially when the geometric morphometric technique is used. It was observed that the shape of the carapace has an advantage over the shape of the pleon and chela because its relatively flat orientation allows more consistent and easier data preparation for geometric morphometric analysis. The geometric morphometric technique is inexpensive, relatively less time consuming to employ, and accurate. This technique is convenient when dissection to examine the gonopods is not possible, which can damage the specimen in the case of endangered or rare species. Since the technique was used herein for only two species, more compelling and extensive evidence is needed before the reliability of the method can be proven.

A collection of crabs (Crustacea, Brachyura) from the southwestern coast of India, with a discussion of the systematic position of Nectopanope Wood-Mason in Wood-Mason & Alcock, 1891 (Euryplacidae)

A report on the brachyuran crabs collected from the southwestern coast of India by the Indian research vessel FORV Sagar Sampada is presented. The material consists of 13 species from three genera and five families, of which four are new records for India: Heteroplaxmaldivensis (Rathbun, 1902) (Euryplacidae), Cryptopodiacollifer Flipse, 1930 (Parthenopidae), Thalamitamacrodonta Borradaile, 1903 (Portunidae), and Paraxanthodescumatodes (MacGilchrist, 1905) (Xanthidae). The cruise also obtained the first known male of Nectopanoperhodobaphes Wood-Mason in Wood-Mason & Alcock, 1891 (type species of Nectopanope Wood-Mason in Wood-Mason & Alcock, 1891), and its characters show that it is in fact a member of the Euryplacidae Stimpson, 1871. The genus had previously been incorrectly classified in the Xanthidae MacLeay, 1838.

Redescription and new records of a poorly known leucosiid crab, Pseudophilyra punctulata Chen Ng, 2003, and description of a new species of Pseudophilyra from Japan (Crustacea: Decapoda: Brachyura)

A poorly known leucosiid crab, Pseudophilyra punctulata Chen Ng, 2003, originally described on the basis of an immature male holotype and an immature female paratype from Singapore, is rediscovered and rediagnosed on the basis of material from Thailand, the Philippines and the Ryukyu Islands (Japan). In addition, a new species closely related to P. punctulata, P. parilis, is described and illustrated on the basis of material from Mie Prefecture, Honshu mainland of Japan. The new species is distinguished from P. punctulata by the coarser granules bordering the lateral carapace margins and the different shape of the gonopods. Pseudophilyra tridentata Miers, 1879, is also compared with P. punctulata and P. parilis n. sp. because of the close similarities in the overall morphology of the carapace and appendages, but can easily be differentiated by the smoother carapace and thoracic sternum surface, different shape of the carapace and the stouter cheliped palm. It is possible that previous records of P. tridentata outside Japan might contain more than one species.

On a new species of freshwater crab, Indochinamonkhinpyae, from northern Myanmar (Crustacea, Brachyura, Potamidae)

A new species of freshwater crab of the genus Indochinamon Yeo & Ng, 2007 (family Potamidae), is described from highlands north of Myitkyina in Kachin State, Myanmar. Indochinamonkhinpyae sp. n. is distinguished from congeners by its very rugose carapace, broad male pleon and distinctively structured male first gonopod; and is the first potamid species recorded from northern Myanmar.

A new species of highland vampire crab (Crustacea: Brachyura: Sesarmidae: Geosesarma) from Serian, Sarawak

A new species of semiterrestrial highland vampire crab of the family Sesarmidae, Geosesarma larsi n. sp., is described from western Sarawak. This brings the number of Bornean Geosesarma species to 12. Geosesarma larsi n. sp. is distinguished from congeners by the structures of the carapace, third maxilliped exopod and gonopods, as well as the proportions of its ambulatory legs. The colour pattern in life is also strikingly different from allied species. Notes on its ecology are provided and conservation threats briefly discussed.

An annotated checklist of the marine brachyuran crabs (Crustacea: Decapoda: Brachyura) of India

An annotated checklist of the marine brachyuran crabs occurring in India is compiled from published literature and augmented by collections between 2005 and 2015. A total of 910 species belonging to 361 genera and 62 families are herein listed from Indian waters. Specimens representing 130 species were obtained from Gujarat state during 2005 and 2015, of which 23 are new records to Gujarat state and two species are reported for the first time from the west coast of India. The highest number of species were recorded from the Andaman and Nicobar islands (588 species) while the smallest number were from Goa and Karnataka state (82 species). The records indicate that the east coast of India, with 803 species, is more diverse than the west coast, which has 446 species.