Morphological and molecular systematics of swimming crabs (Decapoda: Brachyura: Portunidae) from India collected on-board the FORV Sagar Sampada (cruise no. 378, 385 and 392), with notes on biogeography of the Indian portunid fauna.

Morphological and molecular characters of swimming crabs (Family Portunidae Rafinesque-Schmaltz, 1815) collected during one cruise each of the Fishery Oceanographic Research Vessel Sagar Sampada in the northeastern Arabian Sea (97-110 m depth), southwestern Bay of Bengal (56 m), and southeastern Bay of Bengal (56 m) and western Andaman Sea (53 m) were studied. They are referred to 17 species representing 4 subfamilies, 8 genera and 2 subgenera. Cycloachelous levigatus Koch, 2021, Monomia rubromarginata (Lanchester, 1900), Thalamita malaccensis Gordon, 1938 are first records from Indian waters. The study also reveals variations in the pleonal and genital morphology of Monomia argentata (A Milne Edwards, 1861) form B (sensu Stephenson and Rees, 1967a). Mitochondrial Cytochrome oxidase subunit I and 16S rRNA gene sequences of 14 and 16 species, respectively revealed a monophyletic subfamily Lupocyclinae Alcock, 1899, and polyphyletic subfamilies Portuninae Rafinesque, 1815 and Thalamitinae Paulson, 1875. Analysis of the biogeographic distribution patterns of Indian portunids revealed a total of 104 species representing 22 genera, thereby suggesting mixed diversity in different ecological regions. The highest number of 72 species and 2 subspecies were recorded from the West and South Indian Shelf Province followed by Andaman Province (69 species), Bay of Bengal Province (54 species) and Central Indian Ocean Islands Province (26 species). Among the individual marine ecoregions, Andaman and Nicobar Islands recorded the highest number of species (69 species), followed by South India (57), Eastern India (50), Western India (47), Northern Bay of Bengal (32) and Maldives (26).(c) 2023 Elsevier B.V. All rights reserved.