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.

Geographic Distribution and Genetic Structures of the Tideland Snails Pirenella nipponica and P.asiatica in Taiwan and Japan.

The tideland snails Pirenellanipponica and Pirenellaasiatica are distributed north of the central Ryukyu Islands and in South Ryukyu, respectively, in Japan. To reveal their distribution and genetic characteristics in Taiwan, we sampled Pirenella snails along the western coast of Taiwan Island and analyzed the nucleotide sequences of their mitochondrial DNAs. Pirenella nipponica and P. asiatica inhabit the northern and southern parts of the western coast of Taiwan, respectively, and coexist only in the central part. Taiwanese and Japanese populations of P. asiatica showed significant genetic differentiation. The former showed higher genetic diversity and a larger effective population size than the latter. However, the Taiwanese population of P. nipponica was not genetically deviated from the local Japanese population on Kyushu Island. Both the Taiwan and Kyushu populations of P. nipponica showed significant genetic differences from local populations in other regions of Japan, namely, Honshu Island (the Japanese mainland) and Central Ryukyu. They also showed higher genetic diversity and a larger effective population size than the others. The Taiwanese populations of both species might be part of a large panmictic population with individuals from the Asian continent and Kyushu Island.

New records of the squat lobster genus Munidopsis Whiteaves, 1874 (Crustacea, Decapoda, Munidopsidae) from the deep sea off Taiwan.

Two species of the squat lobster family Munidopsidae, Munidopsisalbatrossae Pequegnat & Pequegnat, 1973 and M.pycnopoda Baba, 2005, are reported from Taiwan for the first time based on specimens collected from lower bathyal depths. The Taiwanese material of M.pycnopoda also represents the first record of the species from the Pacific Ocean and greatly extends this species' geographical range from the western Indian Ocean to western Pacific. The giant Munidopsis specimen from Taiwan is identified as M.albatrossae mainly by DNA barcoding even though M.albatrossae and M.aries (A. Milne-Edwards, 1880) are both morphologically and genetically extremely similar.

New subgeneric names for the most commercially important shrimp genus Penaeus Fabricius, 1798 (Crustacea, Decapoda, Penaeidae).

Although a recent comprehensive molecular phylogenetic study on Penaeus Fabricius, 1798 reinstated a single genus for these economically important shrimps, several clades in the molecular phylogenetic tree do not have formal names. Subgeneric names are given herein to five of these clades if Penaeus is to be split. A key to the subgenera in Penaeus is also provided.

On the penaeid shrimps of the genus Parapenaeopsis Alcock, 1901 (Crustacea, Decapoda) from Taiwan.

Five species in the penaeid shrimp genus Parapenaeopsis Alcock, 1901 are reported from Taiwan. Parapenaeopsis amicus V.C. Nguyn, 1971 and P. venusta De Man, 1907 are formally recorded in Taiwan for the first time. Taxonomic problems related to the species reported from Taiwan are discussed, and a key to the species of Parapenaeopsis in Taiwan is provided.

On the penaeid shrimps of the genus Metapenaeus Wood-Mason in Wood-Mason amp; Alcock, 1891 (Crustacea, Decapoda, Penaeidae) of Taiwan.

Seven speceis in the penaeid shrimp genus Metapenaeus Wood-Mason in Wood-Mason Alcock, 1891 are reported from Taiwan. Metapenaeus elegans De Man, 1907 is formerly recorded in Taiwan for the first time. A neotype is selected for the subspecies M. joyneri formosus Lee Yu, 1977 and this action synonymizes this subspecies with the nominotypical form. A key to the species of Metapenaeus in Taiwan is provided.

A new species of the deep-sea shrimp genus Glyphocrangon A. Milne-Edwards, 1880 (Decapoda: Caridea: Glyphocrangonidae) from the South China Sea off Pratas Island.

A new species of the deep-sea caridean genus Glyphocrangon A. Milne-Edwards, 1880, G. obtusis n.sp., is described and illustrated on the basis of the material collected in the South China Sea off the Pratas Island. It appears close to G. hakuhoae Takeda Hanamura, 1994 and G. robusta Komai, 2004 among the 93 described species in Glyphocrangon. From G. hakuhoae, the new species is distinguished by the rostrum with less developed convexity on the dorsolateral margin and lacking transverse septa, and the less elevated median carinae on the pleomeres 15. From G. robusta, the new species differs in lacking transverse septa at the rostrum, the fourth carina on the carapace with the two anterior parts unaligned and the posterior part divided into four lobes. Molecular genetic analysis using the barcoding segment of the mitochondrial COI gene supports the establishment of the new species.

Autochthony and isotopic niches of benthic fauna at shallow-water hydrothermal vents.

The food webs of shallow-water hydrothermal vents are supported by chemosynthetic and photosynthetic autotrophs. However, the relative importance of these two basal resources for benthic consumers and its changes along the physicochemical gradient caused by vent plumes are unknown. We used stable carbon and nitrogen isotopes (i.e., δ13C and δ15N) and Bayesian mixing models to quantify the dietary contribution of basal resources to the benthic fauna at the shallow-water vents around Kueishan Island, Taiwan. Our results indicated that the food chains and consumer production at the shallow-water vents were mainly driven by photoautotrophs (total algal contribution: 26-54%) and zooplankton (19-34%) rather than by chemosynthetic production (total contribution: 14-26%). Intraspecific differences in the trophic support and isotopic niche of the benthic consumers along the physicochemical gradient were also evident. For instance, sea anemone Anthopleura sp. exhibited the greatest reliance on chemosynthetic bacteria (26%) and photoautotrophs (66%) near the vent openings, but zooplankton was its main diet in regions 150-300 m (32-49%) and 300-700 m (32-78%) away from the vent mouths. The vent-induced physicochemical gradient structures not only the community but also the trophic support and isotopic niche of vent consumers.

A new record of the spiny lobster, Panulirusfemoristriga (von Martens, 1872) from the coastal waters of Malaysia, with revision of global distribution.

BACKGROUND: Spiny lobsters of the family Palinuridae Latreille, 1802 are known to be industrial crustaceans in the global fishing market amongst other crustacean marine species. Panulirusfemoristriga has been reported in the Maldives, Japan, Taiwan, Vietnam, the Philippines, Indonesia (Ambon, Irian Jaya, Celebes Island, Seram Island), the Polynesian Islands, Solomon Islands, New Hebrides, Wallis and Futuna and off the coast of northern Australia, but there is uncertainty about their distributions due to the morphological similarity with Panulirusfemoristriga, Panuliruslongipesbispinosus and Panulirusbrunneiflagellum. However, the identification on P.femoristiga can only be confirmed if the morphological descriptions are mentioned in literature. NEW INFORMATION: A specimen of the spiny lobster Panulirusfemoristriga Von Martens, 1872 was discovered in Semporna, located on the west coast of Sabah State, Malaysia Borneo. While the status of P.femoristriga has been classified as "least concern" on the International Union for Conservation of Nature Red List, studies on the species' population size, habitat and distribution are still inadequate. This study adopted both morphological and molecular approaches for species delimitation.The phylogenetic position of the Sabah P.femoristriga was revealed by the mitochondrial cytochrome c oxidase gene (COI) marker. This represents the first record of the species in the coastal waters of Sabah, despite its wide geographical distribution in the Indo-West Pacific. A revision on the species global distribution was also conducted by harvesting all literature with species named Panuliruslongipesfemoristriga and Panulirusfemoristriga which were available online including those prior to year 2001 before the presence of P.femoristriga is confirmed. Due to the uncertainties on the morphological distribution in previous literature, further studies are required to fill in the missing data for confirmation.

New records of spongicolid shrimps (Crustacea, Decapoda, Stenopodidea) from Taiwan.

Spongicolid shrimps of the three genera, Engystenopus Alcock & Anderson, 1894, Spongicola De Haan, 1844 and Spongicoloides Hansen, 1908 are recorded from Taiwan for the first time. The newly recorded species are Engystenopus palmipes Alcock & Anderson, 1894, Spongicola andamanicus Alcock, 1901, S. goyi Saito & Komai, 2008, S. levigatus Hayashi & Ogawa, 1987 and Spongicoloides iheyaensis Saito, Tsuchida & Yamamoto, 2006. A total of six genera and nine species of stenopodidean shrimps are now known from Taiwan. A key to the Taiwanese species of stenopodideans is provided.

A new species of the congrid eel genus Bathycongrus (Order Anguilliformes) from eastern Taiwan.

A new species of the congrid eel genus Bathycongrus is described on the basis of three specimens collected from the deep waters of eastern Taiwan. Bathycongrus melanostomus sp. nov., belongs to the few vertebrae species complex and is distinct in having a short and broad snout; a much reduced caudal fin; abdomen, mouth cavity and gill chamber blackish; small conical blunt teeth on vomer forming an elongate patch; total vertebrae 133-135, and total lateral-line pores 108-109.

Distinct suites of pre- and post-adaptations indicate independent evolutionary pathways of snapping claws in the shrimp family Alpheidae (Decapoda: Caridea).

One of the most notable evolutionary innovations of marine invertebrates is the snapping claw of alpheid shrimps (Alpheidae), capable of generating a powerful water jet and a shock wave, used for defense, aggression, excavation, and communication. Evolutionary analysis of this character complex requires the study of a suite of complementary traits to discern pre-adaptations or post-adaptations of snapping behavior. A comprehensive phylogenetic analysis of the Alpheidae based on two mitochondrial and four nuclear markers, covering 107 species from 38 genera (77.6% generic coverage), is presented. Ancestral state reconstruction analyses revealed five independent origins of snapping, two of which relate to the morphologically similar but phylogenetically distant genera Alpheus and Synalpheus, highlighting significant convergence. The evolution of the five complementary traits (adhesive plaques, tooth-cavity system, dactylar joint type, chela size enlargement, and orbital hood) did not always show a significant correlation with the evolution of snapping overall, sometimes only in a few lineages, suggesting different evolutionary pathways were involved and demonstrating the versatility in the evolution of the snapping mechanisms.

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.

Morphology of the first three zoeal stages of the deep-sea caridean shrimp Heterocarpus fascirostratus Yang, Chan & Kumar, 2018 (Crustacea, Decapoda, Pandalidae).

The larvae of the deep-sea pandalid shrimp Heterocarpus fascirostratus Yang, Chan & Kumar, 2018 were successfully hatched and cultured to the third zoeal stage. The larvae reached the third zoeal stage nine days after hatching at a water temperature of 21 ± 1 °C. Although members of Heterocarpus A. Milne-Edwards, 1881 have rather diverse body forms and are often separated into many species groups, the early zoeal morphology of H. fascirostratus follows the general developmental pattern of the species in Heterocarpus. The main differences amongst these larvae are body size, spines on the anteroventral margin of the carapace, and the endopod setation of the third maxilliped.

The Chinese mitten crab genome provides insights into adaptive plasticity and developmental regulation.

The infraorder Brachyura (true or short-tailed crabs) represents a successful group of marine invertebrates yet with limited genomic resources. Here we report a chromosome-anchored reference genome and transcriptomes of the Chinese mitten crab Eriocheir sinensis, a catadromous crab and invasive species with wide environmental tolerance, strong osmoregulatory capacity and high fertility. We show the expansion of specific gene families in the crab, including F-ATPase, which enhances our knowledge on the adaptive plasticity of this successful invasive species. Our analysis of spatio-temporal transcriptomes and the genome of E. sinensis and other decapods shows that brachyurization development is associated with down-regulation of Hox genes at the megalopa stage when tail shortening occurs. A better understanding of the molecular mechanism regulating sexual development is achieved by integrated analysis of multiple omics. These genomic resources significantly expand the gene repertoire of Brachyura, and provide insights into the biology of this group, and Crustacea in general.

First record of the rare stenopodidean shrimp Odontozona spongicola (Alcock amp; Anderson, 1899) (Decapoda: Stenopodidea: Stenopodidae) from Indonesia.

The stenopodidean shrimp Odontozona spongicola (Alcock Anderson, 1899) collected by the South Java Deep-Sea Biodiversity Expedition 2018 (SJADES 2018) is a new record from Indonesia. The specimen of O. spongicola recently listed from the South China Sea is also formally reported here in. The characteristcs and coloration of this rare species are described and illustrated.

On some squat lobsters from India (Decapoda, Anomura, Munididae), with description of a new species of Paramunida Baba, 1988.

Squat lobster specimens belonging to the family Munididae were recently collected along the southwestern coast of the mainland of India and in the Andaman Islands. The specimens belong to two known species, Agononida prolixa (Alcock, 1894) and Munida compacta Macpherson, 1997, and a new species, Paramunida bineeshi sp. nov. We here redescribe A. prolixa and describe and figure the new species. Munida compacta is newly recorded from India, and we figure the live coloration. In addition, molecular and phylogenetic analyses of two mitochondrial markers (16S rRNA and COI) revealed the phylogenetic relationships of M. compacta and P. bineeshi sp. nov. with their most closely related congeners. The genetic similarity among the individuals of M. compacta from different locations is also addressed.

On the "Plesionika martia" (A. Milne-Edwards, 1883) species group in Indian waters.

Material of the "Plesionika martia" (A. Milne-Edwards, 1883) species group from India had been reported as either P. martia or P. semilaevis Bate, 1888. Recent collection, however, revealed that both P .martia and P. semilaevis occur in Indian waters. COI barcoding gene sequence comparisons of the Indian and topotypic material of the four known species of the "P. martia" group showed that the Andaman Sea specimen is most similar to the topotypic specimens of P. martia even though there is high genetic divergence between them. For P. semilaevis, large sequence divergence is found in the topotypic material from the Philippines while the Indian specimens are genetically similar to one of the topotypic specimens. The characteristics of the Indian material of both species are described and illustrated.

Deep-sea clawed lobster Nephropsis stewarti Wood-Mason, 1872 species complex in the Indo-West Pacific (Crustacea, Decapoda, Nephropidae), with description of a new species.

Nephropsis stewarti Wood-Mason, 1872 is the most common species of the deep-sea clawed lobster genus Nephropsis Wood-Mason, 1872 in the Indo-West Pacific. Morphological comparisons and genetic analyses of extensive material referred to this lobster revealed the presence of three species. The three species differ mainly in body size, development of the intermediate carina on the carapace, position of the lateral pair of rostral teeth, whether the pleonal tergum is granulate, and the spination on the large chelipeds. Nephropsis stewarti is restricted to the western central Indian Ocean, and a neotype is selected to fix its identity. The name Nephropsis grandis Zarenkov, 2006 is revived with neotype selection for the large form found in the West Pacific and northwestern Australia. The smaller form from southern Taiwan and the Philippines is described as Nephropsis pygmaea sp. nov.