Two new, long-legged species of the freshwater crab genus Sundathelphusa Bott, 1969, are describe... more Two new, long-legged species of the freshwater crab genus Sundathelphusa Bott, 1969, are described from the island of Negros in the central Philippines. These are Sundathelphusa orsoni, new species, from the forested foothills of Mount Kanlaon in the northern region of the island, and S. niwangtiil, new species, a troglophilic species from the hilly southern region. These two species are similar to Philippine congeners such as S. longipes (Balss, 1937), S. wolterecki Balss, (1937), S. sutteri (Bott, 1970), S. celer (Ng, 1991), and S. holthuisi Ng, 2010, but can be distinguished from these, and from each other, by the morphology of the carapace, pereopods, male thoracic sternum, pleon, and gonopods.
Recent marine surveys in Christmas Island and the Cocos (Keeling) Islands yielded two species of ... more Recent marine surveys in Christmas Island and the Cocos (Keeling) Islands yielded two species of Pseudozius Dana, 1851. Pseudozius caystrus (Adams & White, 1849) is briefly treated. Pseudozius pacificus Balss, 1938, is recorded for the first time from Christmas Island and the Indian Ocean.
The xanthid crab fauna of Christmas Island and the Cocos (Keeling) Islands, Australian territori... more The xanthid crab fauna of Christmas Island and the Cocos (Keeling) Islands, Australian territories in the Indian Ocean, is documented. A total of 107 species of xanthid crabs are recorded, with 30 new species records from either or both territories. Two potentially new species are included in this listing, and the taxonomy of Paractaea rufopunctata plumosa Guinot, in Sakai, 1976, and Leptodius planus Ward, 1934, is discussed.
This present series of scientific exploration and expeditions was carried out from 2010 to 2012, ... more This present series of scientific exploration and expeditions was carried out from 2010 to 2012, totalling six and two weeks, and covering 153 and 50 field stations (some repeated) in Christmas Island and Cocos (Keeling) Islands respectively. The expeditions were carried out by a principal team of 11 from Singapore, with participants from Australia, Japan and Taiwan.
The genus Isolapotamon Bott, 1968 (Brachyura: Potamidae) is represented in the Philippines ny fou... more The genus Isolapotamon Bott, 1968 (Brachyura: Potamidae) is represented in the Philippines ny four poorly known species, all found on the large southern island of Mindanao. Isolapotamon mindanaoense (Rathbun, 1904) is re-described based on newly collected material, and an update on its distribution is also provided. A fifth species, I. maranao sp. nov., is here described from the northwestern region of Mindanao. It differs from its congeners primarily in the morphology of the male first pleopods, although minor external differences are also observed in the form of the carapace, ambulatory legs and of the male thoracic sternum and abdomen. A key to the Philippine species of Isolapotamon Bott, 1968, is provided.
A new species of xanthid crab (Brachyura: Xanthidae) is described from the Bohol Sea in the centr... more A new species of xanthid crab (Brachyura: Xanthidae) is described from the Bohol Sea in the central Philippines. Xanthias joanneae sp. nov. is most similar in morphology to X. maculatus Sakai, 1961 (type locality: Sagami Bay, Japan), particularly in the presence of distinctive ocelli on the carapace and pereopods. It can be separated from this species by the greater number of ocelli on the dorsal surface of the carapace, wider teeth separated by narrow notches on the carapace anterolateral margin, absence of longitudinal ridges on the external surface of the chelar palm, shorter and stouter ambulatory legs, narrower male anterior thoracic sternum, and stouter G1.
The xanthid crab Leptodius exaratus (H. Milne Edwards, 1834) has been widely reported from the In... more The xanthid crab Leptodius exaratus (H. Milne Edwards, 1834) has been widely reported from the Indo-West Pacific, where it is a ubiquitous component of the intertidal and shallow subtidal fauna. The taxonomy of this species, however, is complex and there are many synonyms, most of which have not been adequately treated or discussed in the past. A close examination of a series of specimens throughout its range shows that L. exaratus should be restricted to the western Indian Ocean. Populations from the eastern Indian and western Pacific oceans should be referred to Leptodius affinis (De Haan, 1835), a species originally described from Japan. While their carapaces are superficially similar, the male first gonopod structure is a reliable character to distinguish these two species. Cancer (Xantho) lividus De Haan, 1835, Leptodius nigromaculatus Serène, 1962, as well as some of the varieties of L. exaratus established by Stimpson (1907), are considered to be junior subjective synonyms of L. affinis (De Haan, 1835). Where necessary, lectotypes or neotypes are designated to stabilise the taxonomy of the two species treated herein.
A new species of hymenosomatid crab of the genus Elamena H. Milne Edwards, 1837, is described fro... more A new species of hymenosomatid crab of the genus Elamena H. Milne Edwards, 1837, is described from the island of Samal, in the Davao Gulf, Mindanao, southern Philippines. Elamena samalensis sp. nov. belongs to the Elamena truncata species-group and is most similar to E. simplidenta Ng & Chuang, 1996, in the general form of the carapace and in the presence of only one subdistal tooth on the ambulatory dactyli. It can be distinguished from this species, however, by its more projecting rostrum, relatively longer and more slender ambulatory legs, and by the pointed apex of the female pleotelson.
This study asked whether reductive traits in cave organisms evolve at a slower pace (suggesting n... more This study asked whether reductive traits in cave organisms evolve at a slower pace (suggesting neutral evolution under relaxed selection) than constructive changes, which are likely to evolve under directional selection. We investigated 11 subterranean and seven surface populations of Sundathelphusa freshwater crabs on Bohol Island, Philippines, and examined constructive traits associated with improved food finding in darkness (increased leg and setae length) and reductive traits (reduced cornea size and eyestalk length). All changes occurred rapidly, given that the age of the most recent common ancestor was estimated to be 722–271 ka based on three mitochondrial markers. In order to quantify the speed of character change, we correlated the degree of morphological change with genetic distances between surface and subterranean individuals. The temporal pattern of character change following the transition to subterranean life was indistinguishable for constructive and reductive traits, characterized by an immediate onset and rapid evolutionary change. We propose that the evolution of these reductive traits just like constructive traits—is most likely driven by strong directional selection.
Examination of the holotype and other specimens of the type species of Garthiella , G. aberrans (... more Examination of the holotype and other specimens of the type species of Garthiella , G. aberrans (Rathbun, 1906, reveals that this genus must be excluded from Chlorodiellinae Ng & Holthuis, 2007, due to the absence of the diagnostic morphological features of the subfamily such as spoon-tipped chelae, prominent dactylo-propodal locks on the ambulatory legs, and subdistal teeth on the ambulatory dactyli. Garthiellinae subfam. nov. is therefore established for this genus, as molecular and morphological evidence show that it cannot be classified in any other subfamily of Xanthidae MacLeay, 1838. A new species of Garthiella from the Bohol Sea, central Philippines, is also described. Garthiella sikatuna sp. nov. can be distinguished from G. aberrans by its relatively flatter and less granular carapace, more pronounced and curved anterolateral teeth, longer and more slender pereopods and by the form of the male first gonopods.
The identity of the rare xanthid crab, Pilumnoplax acanthomerus Rathbun, 1911, originally describ... more The identity of the rare xanthid crab, Pilumnoplax acanthomerus Rathbun, 1911, originally described from the Amirante Islands in the western Indian Ocean, is elucidated. Števčić (2005) transferred the species from Pilumnoplax Stimpson, 1858, to a new genus, Linnaeoxantho. This monotypic genus is re-diagnosed and new morphological characters are highlighted. New records from Ryukyu and Line Islands, in the western and central Pacific, respectively, are reported. Linnaeoxantho is compared with the morphologically similar Melybia Stimpson, 1871, from the western Atlantic, and their affinities are discussed. Linnaeoxanthinae Števčić, 2005, is here recognised as a valid xanthid subfamily for Linnaeoxantho and Melybia, and is considered to have priority over Melybiidae Števčić, 2005.
Two rare species of xanthid crab (Brachyura: Xanthidae) are reported for the first time in the te... more Two rare species of xanthid crab (Brachyura: Xanthidae) are reported for the first time in the territorial waters of Pakistan. Odhnea echinus and Paraxanthodes cumatodes were collected from Sonmiani Bay, on the coast of Pakistan. These species are known from only a few specimens and localities globally. The male gonopods are figured for the first time for these two species, and updates on their taxonomy are also provided.
The xanthid subfamily Polydectinae Dana, 1851, is recorded for the first time in the Philippines,... more The xanthid subfamily Polydectinae Dana, 1851, is recorded for the first time in the Philippines, being represented by four species: Polydectus cupulifer (Latreille, in Milbert, 1812), Lybia tessellata (Latreille, in Milbert, 1812), L. leptochelis (Zehntner, 1894), and L. hatagumoana Sakai, 1961. The taxonomy of L. hatagumoana is discussed at length, and a new genus, Tunebia gen. nov., established for it and the allied L. tutelina Tan & Ng, 1994, from New Caledonia. The new genus is diagnosed and compared with other polydectine genera.
The xanthid genus Glyptoxanthus A. Milne-Edwards, 1879, known from the tropical eastern Pacific, ... more The xanthid genus Glyptoxanthus A. Milne-Edwards, 1879, known from the tropical eastern Pacific, western and eastern Atlantic, and the Red Sea, is revised as part of an ongoing revision of the subfamily Euxanthinae Alcock, 1898. Analysis of morphological characters shows that Glyptoxanthus must be excluded from the subfamily Euxanthinae and placed in a distinct subfamily, Glyptoxanthinae nov. subfam. The new subfamily has affinities to Euxanthinae, Actaeinae Alcock, 1898, and Zalasiinae Serène, 1968, but it is distinguished from these by a suite of characters in the thoracic sternum, third maxillipeds, epistome, chelipeds, and male abdomen and gonopods. All the included species are re-diagnosed, with additional comments and updates on their biology and distribution. In an effort to stabilize the taxonomy of the genus and some of its species, neotypes were selected for G. erosus (Stimpson, 1859) (type species), G. labyrinthicus , and G. meandricus . A key to the genus is included.
Currently, 13 subfamilies are recognised in the brachyuran family Xanthidae: Actaeinae, Antrocarc... more Currently, 13 subfamilies are recognised in the brachyuran family Xanthidae: Actaeinae, Antrocarcininae, Chlorodiellinae, Cymoinae, Etisinae, Euxanthinae, Kraussiinae, Liomerinae, Polydectinae, Speocarcininae, Xanthinae, Zalasiinae and Zosiminae. This classification has been based on shared adult features like a transversely ovate carapace, well defined dorsal carapace regions, usually with lateral dentition, stout chelipeds and relatively short ambulatory legs. Such characters are now considered to be convergent. Consequently a number of higher xanthid taxa may be artifical and not monophyletic. A broad sample of 147 xanthid species representing 75 out of 124 genera from all 13 xanthid subfamilies were sampled in a multi-gene analysis. Four markers (three mitochondrial and one nuclear) were used and yielded a tree with ca. 30 xanthid clades. Monophyletic support was demonstrated for the Antrocarcininae (although substantially redefined), Cymoinae, and Polydectinae. Almost every other subfamily was para- or polyphyletic. Furthermore, the two other families of the Xanthoidea, Pseudorhombilidae and Panopeidae, were found nested within the Xanthidae. The molecular results were consistent with phylogenetic relationships implied by a suite of novel and/or neglected “ventral” adult characters including sternal characters, position of genital openings and morphology of the first zoea, instead of “dorsal” characters traditionally used to infer xanthid relationships.
A new genus and new species of pilumnid crab is described from marine encrusting communities in S... more A new genus and new species of pilumnid crab is described from marine encrusting communities in Singapore. Leelumnus gen. nov. is morphologically similar to Latopilumnus Aniptumnus Ng, 2002, in the general shape of the carapace, chelipeds, ambulatory legs and morphology of the male thoracic sternum, but can be distinguished by the morphologies of the front and anterolateral margin of the carapace, as well as the unique structure of the male first gonopod. Only the type species, L. radium sp. nov. is currently assigned to the new genus.
Relatively few studies have been done to define or assess rarity in the marine environment. Publi... more Relatively few studies have been done to define or assess rarity in the marine environment. Published studies have focused on shallow-water and intertidal habitats, and the available information appears to reflect the same pattern observed in terrestrial environments, i.e., that there are many rare species and few common species in any one given area. However, our studies of the abundance of new and/or supposedly rare taxa of decapod crustaceans from the deep, steep slopes of the island of Balicasag, in the central Philippines, have raised questions on how rarity should be defined in marine invertebrates. Examples of such supposedly rare species of crabs and lobsters (Crustacea: Decapoda) are presented here. That these animals come from deep, steep slopes, a relatively under-studied habitat, highlights the major gaps in current knowledge of marine biodiversity that are in part due to the inadequacy of both traditional and high technology sampling methodologies and the limited habitat types that the former can target. Low-technology, artisanal tangle nets have proved to be an optimal capture technique for deep-water decapod crustaceans on deep, steep slopes; many new taxa have been discovered and, in other cases, perceptions of rarity and endemicity have been corrected.
A new species of Lipkemera Davie, 2010 (Xanthidae, Liomerinae) collected by tangle nets in the is... more A new species of Lipkemera Davie, 2010 (Xanthidae, Liomerinae) collected by tangle nets in the islands of Balicasag and Panglao, central Philippines, is described. Lipkemera holthuisi sp. nov., is closely allied to L. acutidens , but can be distinguished from it and other congeners by the characters of its carapace, pereopods, male abdomen, male gonopods and by its live coloration. The new species is only the second species of the genus to be reported from the Philippines, and brings to four the total number of species known. RÉSUMÉ Une nouvelle espèce de Lipkemera Davie, 2010 (Xanthidae, Liomerinae) récoltée par tangle net dans les îles de Balicasag et de Panglao, dans les Philippines centrales est décrite. Lipkemera holthuisi sp. nov. est étroitement apparenté à L. acutidens (Sakai, 1969) mais s'en distingue ainsi que de ses autres congénères par les caractères de sa carapace, ses peréopodes, son abdomen male, ses gonopodes males et par sa coloration sur le vivant. La nouvelle espèce est seulement la seconde espèce du genre à être trouvé aux Philippines et porte à quatre le nombre total des espèces connues.
A new species of xanthid crab of the genus Medaeus Dana, 1852, is described from the Bohol Sea in... more A new species of xanthid crab of the genus Medaeus Dana, 1852, is described from the Bohol Sea in the central Philippines. Medaeus danielita new species, is similar to Medaeus aztec Davie, 1997, but can be easily differentiated from it by the structure of its carapace, ambulatory legs, and male first gonopods. It is only the second species of the genus known from the Philippines.
Two new, long-legged species of the freshwater crab genus Sundathelphusa Bott, 1969, are describe... more Two new, long-legged species of the freshwater crab genus Sundathelphusa Bott, 1969, are described from the island of Negros in the central Philippines. These are Sundathelphusa orsoni, new species, from the forested foothills of Mount Kanlaon in the northern region of the island, and S. niwangtiil, new species, a troglophilic species from the hilly southern region. These two species are similar to Philippine congeners such as S. longipes (Balss, 1937), S. wolterecki Balss, (1937), S. sutteri (Bott, 1970), S. celer (Ng, 1991), and S. holthuisi Ng, 2010, but can be distinguished from these, and from each other, by the morphology of the carapace, pereopods, male thoracic sternum, pleon, and gonopods.
Recent marine surveys in Christmas Island and the Cocos (Keeling) Islands yielded two species of ... more Recent marine surveys in Christmas Island and the Cocos (Keeling) Islands yielded two species of Pseudozius Dana, 1851. Pseudozius caystrus (Adams & White, 1849) is briefly treated. Pseudozius pacificus Balss, 1938, is recorded for the first time from Christmas Island and the Indian Ocean.
The xanthid crab fauna of Christmas Island and the Cocos (Keeling) Islands, Australian territori... more The xanthid crab fauna of Christmas Island and the Cocos (Keeling) Islands, Australian territories in the Indian Ocean, is documented. A total of 107 species of xanthid crabs are recorded, with 30 new species records from either or both territories. Two potentially new species are included in this listing, and the taxonomy of Paractaea rufopunctata plumosa Guinot, in Sakai, 1976, and Leptodius planus Ward, 1934, is discussed.
This present series of scientific exploration and expeditions was carried out from 2010 to 2012, ... more This present series of scientific exploration and expeditions was carried out from 2010 to 2012, totalling six and two weeks, and covering 153 and 50 field stations (some repeated) in Christmas Island and Cocos (Keeling) Islands respectively. The expeditions were carried out by a principal team of 11 from Singapore, with participants from Australia, Japan and Taiwan.
The genus Isolapotamon Bott, 1968 (Brachyura: Potamidae) is represented in the Philippines ny fou... more The genus Isolapotamon Bott, 1968 (Brachyura: Potamidae) is represented in the Philippines ny four poorly known species, all found on the large southern island of Mindanao. Isolapotamon mindanaoense (Rathbun, 1904) is re-described based on newly collected material, and an update on its distribution is also provided. A fifth species, I. maranao sp. nov., is here described from the northwestern region of Mindanao. It differs from its congeners primarily in the morphology of the male first pleopods, although minor external differences are also observed in the form of the carapace, ambulatory legs and of the male thoracic sternum and abdomen. A key to the Philippine species of Isolapotamon Bott, 1968, is provided.
A new species of xanthid crab (Brachyura: Xanthidae) is described from the Bohol Sea in the centr... more A new species of xanthid crab (Brachyura: Xanthidae) is described from the Bohol Sea in the central Philippines. Xanthias joanneae sp. nov. is most similar in morphology to X. maculatus Sakai, 1961 (type locality: Sagami Bay, Japan), particularly in the presence of distinctive ocelli on the carapace and pereopods. It can be separated from this species by the greater number of ocelli on the dorsal surface of the carapace, wider teeth separated by narrow notches on the carapace anterolateral margin, absence of longitudinal ridges on the external surface of the chelar palm, shorter and stouter ambulatory legs, narrower male anterior thoracic sternum, and stouter G1.
The xanthid crab Leptodius exaratus (H. Milne Edwards, 1834) has been widely reported from the In... more The xanthid crab Leptodius exaratus (H. Milne Edwards, 1834) has been widely reported from the Indo-West Pacific, where it is a ubiquitous component of the intertidal and shallow subtidal fauna. The taxonomy of this species, however, is complex and there are many synonyms, most of which have not been adequately treated or discussed in the past. A close examination of a series of specimens throughout its range shows that L. exaratus should be restricted to the western Indian Ocean. Populations from the eastern Indian and western Pacific oceans should be referred to Leptodius affinis (De Haan, 1835), a species originally described from Japan. While their carapaces are superficially similar, the male first gonopod structure is a reliable character to distinguish these two species. Cancer (Xantho) lividus De Haan, 1835, Leptodius nigromaculatus Serène, 1962, as well as some of the varieties of L. exaratus established by Stimpson (1907), are considered to be junior subjective synonyms of L. affinis (De Haan, 1835). Where necessary, lectotypes or neotypes are designated to stabilise the taxonomy of the two species treated herein.
A new species of hymenosomatid crab of the genus Elamena H. Milne Edwards, 1837, is described fro... more A new species of hymenosomatid crab of the genus Elamena H. Milne Edwards, 1837, is described from the island of Samal, in the Davao Gulf, Mindanao, southern Philippines. Elamena samalensis sp. nov. belongs to the Elamena truncata species-group and is most similar to E. simplidenta Ng & Chuang, 1996, in the general form of the carapace and in the presence of only one subdistal tooth on the ambulatory dactyli. It can be distinguished from this species, however, by its more projecting rostrum, relatively longer and more slender ambulatory legs, and by the pointed apex of the female pleotelson.
This study asked whether reductive traits in cave organisms evolve at a slower pace (suggesting n... more This study asked whether reductive traits in cave organisms evolve at a slower pace (suggesting neutral evolution under relaxed selection) than constructive changes, which are likely to evolve under directional selection. We investigated 11 subterranean and seven surface populations of Sundathelphusa freshwater crabs on Bohol Island, Philippines, and examined constructive traits associated with improved food finding in darkness (increased leg and setae length) and reductive traits (reduced cornea size and eyestalk length). All changes occurred rapidly, given that the age of the most recent common ancestor was estimated to be 722–271 ka based on three mitochondrial markers. In order to quantify the speed of character change, we correlated the degree of morphological change with genetic distances between surface and subterranean individuals. The temporal pattern of character change following the transition to subterranean life was indistinguishable for constructive and reductive traits, characterized by an immediate onset and rapid evolutionary change. We propose that the evolution of these reductive traits just like constructive traits—is most likely driven by strong directional selection.
Examination of the holotype and other specimens of the type species of Garthiella , G. aberrans (... more Examination of the holotype and other specimens of the type species of Garthiella , G. aberrans (Rathbun, 1906, reveals that this genus must be excluded from Chlorodiellinae Ng & Holthuis, 2007, due to the absence of the diagnostic morphological features of the subfamily such as spoon-tipped chelae, prominent dactylo-propodal locks on the ambulatory legs, and subdistal teeth on the ambulatory dactyli. Garthiellinae subfam. nov. is therefore established for this genus, as molecular and morphological evidence show that it cannot be classified in any other subfamily of Xanthidae MacLeay, 1838. A new species of Garthiella from the Bohol Sea, central Philippines, is also described. Garthiella sikatuna sp. nov. can be distinguished from G. aberrans by its relatively flatter and less granular carapace, more pronounced and curved anterolateral teeth, longer and more slender pereopods and by the form of the male first gonopods.
The identity of the rare xanthid crab, Pilumnoplax acanthomerus Rathbun, 1911, originally describ... more The identity of the rare xanthid crab, Pilumnoplax acanthomerus Rathbun, 1911, originally described from the Amirante Islands in the western Indian Ocean, is elucidated. Števčić (2005) transferred the species from Pilumnoplax Stimpson, 1858, to a new genus, Linnaeoxantho. This monotypic genus is re-diagnosed and new morphological characters are highlighted. New records from Ryukyu and Line Islands, in the western and central Pacific, respectively, are reported. Linnaeoxantho is compared with the morphologically similar Melybia Stimpson, 1871, from the western Atlantic, and their affinities are discussed. Linnaeoxanthinae Števčić, 2005, is here recognised as a valid xanthid subfamily for Linnaeoxantho and Melybia, and is considered to have priority over Melybiidae Števčić, 2005.
Two rare species of xanthid crab (Brachyura: Xanthidae) are reported for the first time in the te... more Two rare species of xanthid crab (Brachyura: Xanthidae) are reported for the first time in the territorial waters of Pakistan. Odhnea echinus and Paraxanthodes cumatodes were collected from Sonmiani Bay, on the coast of Pakistan. These species are known from only a few specimens and localities globally. The male gonopods are figured for the first time for these two species, and updates on their taxonomy are also provided.
The xanthid subfamily Polydectinae Dana, 1851, is recorded for the first time in the Philippines,... more The xanthid subfamily Polydectinae Dana, 1851, is recorded for the first time in the Philippines, being represented by four species: Polydectus cupulifer (Latreille, in Milbert, 1812), Lybia tessellata (Latreille, in Milbert, 1812), L. leptochelis (Zehntner, 1894), and L. hatagumoana Sakai, 1961. The taxonomy of L. hatagumoana is discussed at length, and a new genus, Tunebia gen. nov., established for it and the allied L. tutelina Tan & Ng, 1994, from New Caledonia. The new genus is diagnosed and compared with other polydectine genera.
The xanthid genus Glyptoxanthus A. Milne-Edwards, 1879, known from the tropical eastern Pacific, ... more The xanthid genus Glyptoxanthus A. Milne-Edwards, 1879, known from the tropical eastern Pacific, western and eastern Atlantic, and the Red Sea, is revised as part of an ongoing revision of the subfamily Euxanthinae Alcock, 1898. Analysis of morphological characters shows that Glyptoxanthus must be excluded from the subfamily Euxanthinae and placed in a distinct subfamily, Glyptoxanthinae nov. subfam. The new subfamily has affinities to Euxanthinae, Actaeinae Alcock, 1898, and Zalasiinae Serène, 1968, but it is distinguished from these by a suite of characters in the thoracic sternum, third maxillipeds, epistome, chelipeds, and male abdomen and gonopods. All the included species are re-diagnosed, with additional comments and updates on their biology and distribution. In an effort to stabilize the taxonomy of the genus and some of its species, neotypes were selected for G. erosus (Stimpson, 1859) (type species), G. labyrinthicus , and G. meandricus . A key to the genus is included.
Currently, 13 subfamilies are recognised in the brachyuran family Xanthidae: Actaeinae, Antrocarc... more Currently, 13 subfamilies are recognised in the brachyuran family Xanthidae: Actaeinae, Antrocarcininae, Chlorodiellinae, Cymoinae, Etisinae, Euxanthinae, Kraussiinae, Liomerinae, Polydectinae, Speocarcininae, Xanthinae, Zalasiinae and Zosiminae. This classification has been based on shared adult features like a transversely ovate carapace, well defined dorsal carapace regions, usually with lateral dentition, stout chelipeds and relatively short ambulatory legs. Such characters are now considered to be convergent. Consequently a number of higher xanthid taxa may be artifical and not monophyletic. A broad sample of 147 xanthid species representing 75 out of 124 genera from all 13 xanthid subfamilies were sampled in a multi-gene analysis. Four markers (three mitochondrial and one nuclear) were used and yielded a tree with ca. 30 xanthid clades. Monophyletic support was demonstrated for the Antrocarcininae (although substantially redefined), Cymoinae, and Polydectinae. Almost every other subfamily was para- or polyphyletic. Furthermore, the two other families of the Xanthoidea, Pseudorhombilidae and Panopeidae, were found nested within the Xanthidae. The molecular results were consistent with phylogenetic relationships implied by a suite of novel and/or neglected “ventral” adult characters including sternal characters, position of genital openings and morphology of the first zoea, instead of “dorsal” characters traditionally used to infer xanthid relationships.
A new genus and new species of pilumnid crab is described from marine encrusting communities in S... more A new genus and new species of pilumnid crab is described from marine encrusting communities in Singapore. Leelumnus gen. nov. is morphologically similar to Latopilumnus Aniptumnus Ng, 2002, in the general shape of the carapace, chelipeds, ambulatory legs and morphology of the male thoracic sternum, but can be distinguished by the morphologies of the front and anterolateral margin of the carapace, as well as the unique structure of the male first gonopod. Only the type species, L. radium sp. nov. is currently assigned to the new genus.
Relatively few studies have been done to define or assess rarity in the marine environment. Publi... more Relatively few studies have been done to define or assess rarity in the marine environment. Published studies have focused on shallow-water and intertidal habitats, and the available information appears to reflect the same pattern observed in terrestrial environments, i.e., that there are many rare species and few common species in any one given area. However, our studies of the abundance of new and/or supposedly rare taxa of decapod crustaceans from the deep, steep slopes of the island of Balicasag, in the central Philippines, have raised questions on how rarity should be defined in marine invertebrates. Examples of such supposedly rare species of crabs and lobsters (Crustacea: Decapoda) are presented here. That these animals come from deep, steep slopes, a relatively under-studied habitat, highlights the major gaps in current knowledge of marine biodiversity that are in part due to the inadequacy of both traditional and high technology sampling methodologies and the limited habitat types that the former can target. Low-technology, artisanal tangle nets have proved to be an optimal capture technique for deep-water decapod crustaceans on deep, steep slopes; many new taxa have been discovered and, in other cases, perceptions of rarity and endemicity have been corrected.
A new species of Lipkemera Davie, 2010 (Xanthidae, Liomerinae) collected by tangle nets in the is... more A new species of Lipkemera Davie, 2010 (Xanthidae, Liomerinae) collected by tangle nets in the islands of Balicasag and Panglao, central Philippines, is described. Lipkemera holthuisi sp. nov., is closely allied to L. acutidens , but can be distinguished from it and other congeners by the characters of its carapace, pereopods, male abdomen, male gonopods and by its live coloration. The new species is only the second species of the genus to be reported from the Philippines, and brings to four the total number of species known. RÉSUMÉ Une nouvelle espèce de Lipkemera Davie, 2010 (Xanthidae, Liomerinae) récoltée par tangle net dans les îles de Balicasag et de Panglao, dans les Philippines centrales est décrite. Lipkemera holthuisi sp. nov. est étroitement apparenté à L. acutidens (Sakai, 1969) mais s'en distingue ainsi que de ses autres congénères par les caractères de sa carapace, ses peréopodes, son abdomen male, ses gonopodes males et par sa coloration sur le vivant. La nouvelle espèce est seulement la seconde espèce du genre à être trouvé aux Philippines et porte à quatre le nombre total des espèces connues.
A new species of xanthid crab of the genus Medaeus Dana, 1852, is described from the Bohol Sea in... more A new species of xanthid crab of the genus Medaeus Dana, 1852, is described from the Bohol Sea in the central Philippines. Medaeus danielita new species, is similar to Medaeus aztec Davie, 1997, but can be easily differentiated from it by the structure of its carapace, ambulatory legs, and male first gonopods. It is only the second species of the genus known from the Philippines.
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