TAXONOMIC CONFIRMATION AND SPECIES COMPOSITION OF MUD CRAB Scylla spp. AVAILABLE IN BANGLADESH

Abstract

Bangladesh is riverine country located in South Asia along with a coastline about 710 km including 618,780 ha mangrove with tidal flats which are greatly suitable for distribution and good composition for mud crab population. In past many researchers worked on the mud crab for aquaculture purpose in the real field without knowing their proper species recognition including with their composition in the coastal regions of Bangladesh. Recently some researchers dealt with taxonomic work on crab for species clarification based on molecular techniques which required highly modern equipped laboratory that is known to be difficult for general people including illiterate fishermen. This research was conducted for measuring species composition of the mud crab (Scylla spp.), in the particular area of Bangladesh. The present study was conducted at Bagerhat, Cox’s Bazar and Chittagong districts of Bangladesh for taxonomic confirmation and species composition of mud crab (Scylla). About 70-100 mud crab specimens were collected from each of those regions. From primary identification, 46%, 59% and 75% crabs were considered as S. olivacea, while 54%, 41%, and 25% crabs were S. serrata at Bagerhat, Cox’s Bazar and Chittagong, respectively. For more clarification, all crabs were observed external morphology including with the description of first and second male gonopods and measured 24 morphological characters for morphologically distinct samples. From the measured characters were calculated into 27 morphometric ratio to recognise each single species. The present study confirmed the existence of two species of mud crabs namely S. olivacea and S. serrata where 59% was S. olivacea and 41% was S. serrata from the collected sample in Bangladesh. The study revealed that S. olivacea is dominant mud crab species among four Scylla spp. after that S. serrata also well distributed in the coastal regions of Bangladesh.