Species diversity and molecular taxonomy of symbiotic crustaceans on Portunus pelagicus (Linnaeus, 1758) in Vietnam, with remarks on host records and morphological variation

Abstract The blue swimming crab (Portunus pelagicus (Linnaeus, 1758)) is an economically and ecologically important species in Vietnam, and a potential subject for aquaculture as well. More than 400 individual crabs were collected along the Vietnamese coastline and examined for ectosymbiotic crustaceans. Two molecular markers (28S rRNA and COI mtDNA) were applied for species delineation. Seven species were reported and described, of which six are cirripede barnacles (Thecostraca, Thoracia); and one parasitic copepod Choniosphaera indica Gnanamuthu, 1954 (Copepoda, Podoplea). Four species (Chelonibia testudinaria (Linnaeus, 1758), Semibalanus sp., Octolasmis neptuni (MacDonald, 1869), and Dianajonesia tridens (Aurivillius, 1894)) were the first records for both host and location. The symbiotic crustaceans occupy specific niches on the crab body, and vary in their infestation status. Molecular taxonomy of symbiotic crustaceans was classified and confirmed based on sequence similarity and phylogenetic analyses.

摘要：远海梭子蟹（Portunus pelagicus (Linnaeus, 1758)）是越南兼具经济与生态重要性的物种，同时亦是水产养殖的潜在研究对象。本研究沿越南海岸线采集了400余只该种蟹类，针对其体表共生甲壳类开展调查。研究采用28S核糖体RNA（28S rRNA）与细胞色素C氧化酶亚基I线粒体DNA（COI mtDNA）两种分子标记进行物种界定，共报道并描述了7种共生甲壳类：其中6种为蔓足类藤壶（Thecostraca, Thoracia），剩余1种为寄生桡足类印度刺球桡足虫（Choniosphaera indica Gnanamuthu, 1954, Copepoda, Podoplea）。本次研究涉及的4个物种（Chelonibia testudinaria (Linnaeus, 1758)、Semibalanus sp.、Octolasmis neptuni (MacDonald, 1869)、Dianajonesia tridens (Aurivillius, 1894)）均为该宿主物种与本次研究分布区域的首次记录。共生甲壳类在蟹体占据专属生态位，且侵染程度存在显著差异。本研究基于序列相似性与系统发育分析，完成了共生甲壳类分子分类学地位的归类与确认。