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

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

First record of the Thuridilla indopacifica Gosliner, 1995 (Sacoglossa, Plakobranchidae) from the Gulf of Oman, Iran

Thuridilla indopacifica Gosliner, 1995 (Sacoglossa, Plakobranchidae) is a rare species in the Sacoglossan nudibranch that only reported from the South Africa and Western Australia. This study records T. indopacifica from the Gulf of Oman for the first time showing its expansion to the northwest of Indian Ocean

Molecular phylogeography reveals multiple Pleistocene divergence events in estuarine crabs from the tropical West Pacific

Due to the lack of visible barriers to gene flow, it was a long-standing assumption that marine coastal species are widely distributed, until molecular studies revealed geographically structured intraspecific genetic differentiation in many taxa. Historical events of sea level changes during glacial periods are known to have triggered sequential disjunctions and genetic divergences among populations, especially of coastal organisms. The Parasesarma bidens species complex so far includes three named plus potentially cryptic species of estuarine brachyuran crabs, distributed along East to Southeast Asia. The aim of the present study is to address phylogeography and uncover real and hidden biological diversity within this complex, by revealing the underlying genetic structure of populations and species throughout their distribution ranges from Japan to West Papua, with a comparison of mitochondrial COX1 and 16S rRNA gene sequences. Our results reveal that the P. bidens species complex consists of at least five distinct clades, resulting from four main cladogenesis events during the mid to late Pleistocene. Among those clades, P. cricotum and P. sanguimanus are recovered as monophyletic taxa. Geographically restricted endemic clades are encountered in southeastern Indonesia, Japan and China respectively, whereas the Philippines and Taiwan share two clades. As individuals of the Japanese clade can also be found in Taiwan, we provide evidence of a third lineage and the occurrence of a potential cryptic species on this island. Ocean level retreats during Pleistocene ice ages and present oceanic currents appear to be the main triggers for the divergences of the five clades that are here addressed as the P. bidens complex. Secondary range expansions converted Taiwan into the point of maximal overlap, sharing populations with Japan and the Philippines, but not with mainland China

<p><strong>Two new species of <em>Leptarma</em> (Decapoda, Brachyura, Sesarmidae) from the Western Indian Ocean with notes on their phylogeny</strong></p>

Two new species of Leptarma, L. dispersum n. sp. and L. reunionense n. sp. are described from Europa Island and Reunion Island, respectively. Genetically, based on the mitochondrial COX1 gene, both species are markedly divergent from other congeneric species. Phylogenetically, L. dispersum n. sp. shows close relationship with L. lenzii (De Man, 1895) while L. reunionense n. sp. clusters with L. aurifrons (Li, Ng & Shih, 2019) and the species pair L. moluccense (De Man, 1892) and L. paucitorum (Rahayu & Ng, 2009). Morphologically, the new species differ most significantly from congeners by the relative length of the ambulatory legs and the shapes of the first gonopods and carapace. After the description of these two new species, the number of species comprised in the genus Leptarma is raised to 20, four of them being distributed in and off East Africa

A checklist of the barnacles (Crustacea: Cirripedia: Thoracica) of the Persian Gulf and Gulf of Oman with nine new records

Shahdadi, Adnan, Sari, Alireza, Naderloo, Reza (2014): A checklist of the barnacles (Crustacea: Cirripedia: Thoracica) of the Persian Gulf and Gulf of Oman with nine new records. Zootaxa 3784 (3): 201-223, DOI: 10.11646/zootaxa.3784.3.

Tetraclita ehsani sp. n. (Cirripedia, Tetraclitidae), a common intertidal barnacle from the Gulf of Oman, Iran

A new species of intertidal acorn barnacle Tetraclita ehsani sp. n. was identified from the Iranian coast in the Gulf of Oman. T. ehsani sp. n. inhabits low exposed rocky shores and also attaches to shells of molluscs and the barnacle Megabalanus species. Parietes of T. ehsani ranged from white to pink which is different from T. serrata (in South African waters), which has green parietes. Morphology of the tergum and cirrus III of T. ehsani sp. n. is distinctive from other described West Indian Ocean species which have pink or white parietes (T. rufotincta, T. achituvi and T. reni). The tergum of T. ehsani is very narrow and the basal margin is slightly concave or straight, in contrast to T. rufotincta and T. reni, in which the tergum are board and with a very concave basal margin. Cirrus I anterior ramus of both T. ehsani and T. reni is antenniform and thus differing from the cirrus I of T. rufotincta (see Chan et al. 2009). Cirrus III of T. ehsani sp. n. is non-antenniform and lacks multicuspidate type setae, which is different from T. reni byan antenniform cirrus III and with multicuspidate setae

Tetraclita ehsani sp. n. (Cirripedia, Tetraclitidae), a common intertidal barnacle from the Gulf of Oman, Iran

A new species of intertidal acorn barnacle Tetraclita ehsani sp. n. was identified from the Iranian coast in the Gulf of Oman. T. ehsani sp. n. inhabits low exposed rocky shores and also attaches to shells of molluscs and the barnacle Megabalanus species. Parietes of T. ehsani ranged from white to pink which is different from T. serrata (in South African waters), which has green parietes. Morphology of the tergum and cirrus III of T. ehsani sp. n. is distinctive from other described West Indian Ocean species which have pink or white parietes (T. rufotincta, T. achituvi and T. reni). The tergum of T. ehsani is very narrow and the basal margin is slightly concave or straight, in contrast to T. rufotincta and T. reni, in which the tergum are board and with a very concave basal margin. Cirrus I anterior ramus of both T. ehsani and T. reni is antenniform and thus differing from the cirrus I of T. rufotincta (see Chan et al. 2009). Cirrus III of T. ehsani sp. n. is non-antenniform and lacks multicuspidate type setae, which is different from T. reni byan antenniform cirrus III and with multicuspidate setae

A new species of Parasesarma (Decapoda: Brachyura: Sesarmidae) from northern Australian mangroves and its distinction from morphologically similar species

A new species of mangrove crab, Parasesarma austrawati, is described from northern Australian mangroves. The new species is genetically distinct from all congeners, based on three mitochondrial (Cox1, ND1, 16S), and one nuclear (NaK) DNA markers. Morphologically, the new species is most similar to Parasesarma samawati, Parasesarma longicristatum and Parasesarma semperi with 7 or 8 rounded, well developed chelar dactylus tubercles, and appears to have been previously misidentified as P. longicristatum with which it occurs sympatrically. It differs, however, from P. longicristatum and P. semperi by having relatively shorter cheliped fingers as well as more distinct dorsal carapace regions and frontal lobes. Genetically, P. austrawati n. sp. is sister to a clade containing Parasesarma lividum from the southwest Pacific and P. samawati from East Africa. P. austrawati n. sp. is the seventh species of Parasesarma reported from northern Australian mangroves west of Torres Strait. (c) 2019 Elsevier GmbH. All rights reserved

Taxonomic reassessment of Parasesarma (Crustacea: Brachyura: Decapoda: Sesarmidae) based on genetic and morphological comparisons, with the description of a new genus

Parasesarma is a species-rich genus whose representatives are common in wetlands and mangroves of the Indo-Pacific. Morphologically, the genus is heterogeneous and has been postulated to constitute a polyphyletic taxon. In the present study, most species of Parasesarma are re-evaluated phylogenetically, using mitochondrial and nuclear molecular markers. The results show that the majority of the examined species cluster consistently with the type species Parasesarma plicatum. However, some species, among them the tree-climbing Parasesarma leptosoma, are clearly separated from this main clade of Parasesarma, forming a second stable monophyletic group, distinct from other known genera. Based on these results, and with additional support by morphological diagnoses highlighting consistent differences between the two species groups, we propose a new genus for the species clustering around P. leptosoma, proposing the new name Leptarma gen. nov

Conspicuous genetic similarity within a widely distributed and newly described species of Parasesarma De Man, 1895 from Western Pacific oceanic islands, with notes on the allied P. calypso group (Crustacea : Brachyura : Sesarmidae)

10.1071/is20046Invertebrate Systematic