Morphological and Molecular Taxonomy of Crabs Under the Family Sesarmidae Dana 1851(BRACHYURA:SESARMIDAE) of Cochin Region,Kerala

Abstract- The present investigation is a detailed study on the common inland crabs of Cochin region. During the present study 3 species and a variety has been collected and these were subjected to detailed morphological and molecular taxonomic studies. The species identified are: Two species and a variety under the genus Neosarmatium Serène & Soh, 1970, namely, Neosarmatium kufos sp. nov. and a variety under N. kufos; Neosarmatium cochinense sp. nov and one species under the genus Parasesarma, namely, Parasesarma plicatum (Latreille, 1803).

The genus Neosarmatium Serène & Soh, 1970 has been studied thoroughly. This genus contains 19 species distributed in different parts of the world. With the addition of 2 new species reported now the number of species under this genus is increased to 21. The 2 new species are namely Neosarmatium kufos sp. nov.; Neosarmatium kufos variety nov.; Neosarmatium cochinense sp. nov. Neosarmatium kufos shows affinities with species, namely, N. indicum (A. Milne Edwards, 1868); Neosarmatium bidentatum Rahayu & Davie, 2006; N. malabaricum (Henderson, 1893) and N. punctatum (A. Milne Edwards, 1873). DNA barcode data has been generated for the first species and presented in the section on molecular taxonomy part.

Parasesarma plicatum (Latreille, 1803) has been described in detail on the basis of morphological and molecular data. But the species differs from the already reported Parasesarma plicatum (Latreille, 1803) by Rahayu & Ng, 2010 in the number of teeth on 2nd pectinated crest of male cheliped and length of proportion of somite 6 and telson of male abdomen. Parasesarma plicatum is diagnosed by squarish carapace, broader than long; upper surface of palm with 2 transverse pectinated crests, primary crest composed of 13 broad teeth, secondary crest well developed, shorter than primary, with 16 broad teeth; dorsal surface of dactylus with 11-14 tubercles, small proximally becoming large distally; male first gonopod slender, straight, apical process long, bent to form an angle of 450, produced conrneous part long, slightly sinous, tip rounded, setae originates much below the base of apical process and clustered at apical process. The phylogenetic tree was generated and presented in the thesis. According to the phylogenetic tree N. kufos and a variety showed 100% relatedness among them, 95% relatedness with the N. fourmanoiri and N. asiaticum and 81% with Parasesarma erythrodactyla. P. plicatum showed 100% relatedness among them and 72% relatedness with Perisesarma bidens.