Molecular phylogeny, phylogeography and taxonomic revision of species of the genus Perisesarma De Man, 1895 (Crustacea: Decapoda: Brachyura: Sesarmidae)

Content Provider	Semantic Scholar
Author	Shahdadi, Adnan
Copyright Year	2018
Abstract	The present work forms part of an ongoing revision of sesarmid genera. The conspicuous and speciose genus Perisesarma De Man, 1895 is among the most taxonomically complex and problematic taxa of the family. This genus was suspected to be a polyphyletic taxon, comprising morphologically heterogeneous species. Moreover, some members of the genus have a close phylogenetic relationship with the sister genus Parasesarma De Man, 1895 and show many morphological similarities, except for the existence of an epibranchial tooth in Perisesarma. Therefore, the present study intends to evaluate the monophyly of Perisesarma and reconstruct phylogenetic relationships in comparison to Parasesarma by examining a variety of morphological characters and comparing them with results from molecular markers. Up to four genetic marker with different evolutionary mutation rates were used for different parts of this study. These include the mitochondrial genes Cox1, 16S, ND1 and the nuclear gene NaK. A comparative morphological analysis reveals that there is no unequivocal separation between species of Parasesarma and Perisesarma, because of intermediate conformations of the epibranchial tooth. In our molecular analysis, most species of Perisesarma cluster solidly with species of Parasesarma, but without being reciprocally monophyletic. Morphology and genetics also indicate that the West African species of Perisesarma and P. fasciatum are markedly different from all other species of the genus. Therefore, we here suggest with robust double support, a new classification, transferring most species of Perisesarma to Parasesarma and the v three West African representatives and P. fasciatum into two new genera, thus restricting the genus Perisesarma to the type species P. dusumieri. This study also uncovers some un-described forms of the former genus Perisesarma and presents new insight in to the phylogeography of some phylogenetic clades. Perisesarma n. sp1. is described from mangroves of southern Vietnam, differing most significantly from congeners by the tuberculation pattern of the chelar dactylus and its unique G1 morphology. Genetically, Perisesarma n. sp1. is markedly divergent from other congeneric species, both in mitochondrial and nuclear DNA. This study helps to reveal marine biogeographic barriers with restricted gene flow, among them a putative barrier between the northern Australian coastline and adjacent areas of South East Asia and the South Pacific. In agreement with these findings, we provide evidence for genetic uniqueness of representatives of the mangrove crab genus Parasesarma from northern Australian mangroves, based on three mitochondrial and one nuclear DNA marker. This distinct taxon is here described as a new species. Morphologically the new species is very similar to P. lividum from the southwest Pacific and P. samawati from East Africa. Genetically, however, it is significantly distinct from all other congeners. The same genetic disjunction is found between the two very closely related species P. semperi from S.E Asia and P. longicristatum from Australia. P. indiarum, was originally described from Ambon, Indonesia, and is assumed to be distributed all over S. E. Asian Island. But here presented genetic and morphological evidences reveal a distinct separation of Malay Peninsular populations from the types and therefore these are herein described as a new species.
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Language	English
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Resource Type	Article