Description, DNA barcode and phylogeny of a new species, Macrobrachium abrahami (Decapoda: Palaemonidae) from Kerala, India.

Macrobrachium abrahami, new species is described from Vamanapuram River, Kerala, South India. DNA bar-coding using Cytochrome B gene sequences has elucidated the taxonomic status of the new species and the ML tree reveals that M. abrahami sp. nov., is phylogenetically close to M. prabhakarani, but morphologically more similar to M. scabriculum. However, the species shares certain morphological characters with M. scabriculum, M. prabhakarani and M. lanatum, but differs remarkably from these three species in distinctive diagnostic characters: rostrum moderately long, convex, distal end directed upwards, rostral formula 12-15/2-3 with 5-6 postorbital teeth, and carapace glabrous. In larger second chelate leg, fingers stout, pubescence restricted to their base; proximal half of cutting edge with fifteen denticles. In smaller second chelate leg, cutting edge of both fingers carry six small denticles situated proximally, distal one comparatively larger. Delicate setae are seen throughout the palm. A row of dark chromatophores is present along the posterio-dorsal margin of uropodal exopods and endopods, close to the base of uropodal setae. The thickness of each band of the row is almost equal to the thickness of uropodal setae.