DNA sequence information resolves taxonomic ambiguity of the common mud crab species (Genus Scylla ) in Indian waters

Abstract

For several years, mud crabs of genus Scylla have been misidentified owing to their high morphological plasticity and the absence of distinct morphological diagnostic characters. The taxonomic confusion of genus Scylla de Haan is considered to be a primary constraint to the development of aquaculture. Although genus Scylla was revised using morphological and genetic characteristics, taxonomy of Scylla species occurring in India is still not clear. In this study, partial sequences of two mitochondrial genes, 16S rRNA and CO1 (Cytochrome C oxidase subunit I) in populations of Scylla spp. obtained from eleven locations along the Indian coast were used to differentiate and resolve taxonomical ambiguity of the mud crab species in India. The sequences were compared with previously published sequences of Scylla spp. Both trees generated based on 16S rRNA and CO1 indicated that all S. tranquebarica morphotypes obtained during this study and S. tranquebarica sequences submitted previously from Indian waters reciprocally monophyletic with reference sequence of S. serrata. Both sequence data and morphological characters revealed that the species S. serrata (Forskal) is the most abundant followed by S. olivacea. Further, the 16S rRNA and COI haplotypes of Indian S. tranquebarica obtained in the study significantly differed with the known S. tranquebarica by 6.7% and 10.6% respectively whereas it differed with known S. serrata by 0.0-0.7% only, a difference that was not statistically significant. From these studies it is clear that "S. tranquebarica" commonly reported from India should be S. serrata (Forskal).

Comparison of mudcrab-based brackishwater polyculture systems with different finfish species combinations in Sundarban, India

“…Among the mudcrabs, Scylla serrata, S. olivacea , S. tranquebarica and S. paramamosain , the largest and most broadly distributed mudcrab is S. serrata (Keenan, ; Williams & Primavera, ). In India, mainly available mudcrabs are green mudcrab, S. serrata and orange mudcrab, S. olivacea (Balasubramanian et al., ). Though different techniques of mudcrab farming like grow‐out culture, crab fattening and soft shell crab production are popular (Anil & Suseelan, ; Keenan & Blackshaw, ; Trino & Rodriguez, ), grow‐out culture can yield fully grown crabs which could fetch premium price in export market.…”

Optimisation of nursery rearing for megalopa of giant mud crab Scylla serrata (Forskal, 1775)

“…Mud crab aquaculture is an emerging economic activity in the coastal areas of many south-east Asian countries, including India, and it is the focus of diversification in brackishwater aquaculture (Balasubramanian et al, 2016). High price, good demand and excellent export potential for mud crabs coupled with the ease of farming have resulted in expansion of mud crab aquaculture.…”

“…High price, good demand and excellent export potential for mud crabs coupled with the ease of farming have resulted in expansion of mud crab aquaculture. Among the four species of portunid mud crabs as described by Keenan et al (1998), only two species are present in Indian waters (Balasubramanian et al, 2016). The giant mud crab, Scylla serrata is the most preferred species for mud crab aquaculture owing to its larger size, higher price and faster growth rate (Williams and Primavera, 2001).…”