First record of coral reef-associated swimming crab from Indian waters

Phylum: Arthropoda

Class: Malacostraca Latreille, 1802

Order: Decapoda Latreille, 1802

Family: Portunidae Rafinesque, 1815

Cycloachelous levigatus Koch, 2021

Collection: Bay of Bengal, east off Nagapattinam – 10.79°N, 80.11°E, 56 m, 30.11.2019 (FORVSS 392 St. 14), Chain dredge

Voucher No.: CMLRE IO/SS/BRC/00208

Description: Small portunid crab possessing subhexagonal carapace with gently convex dorsal surface, setose, elevated granular patches on protogastric, mesogastric, metagastric, epibranchial cardiac, post-cardiac and mesobranchial regions; frontal margin with 4 teeth, medians shorter than laterals; anterolateral teeth 9, first largest, last curved, anterolaterally directed, slightly larger than preceding ones; posterolateral angle rounded. Basal antennal srticle narrow, external angle into orbital hiatus, deeply grooved. Mxp3 merus anterolateral angle extended as triangular process. Chelipeds massive, granular, merus anterior margin with 4 spines, posterior margin with 2 spines; propodus dorsal surface with 2 granular ridges, inner ridge ending in spine, outer surface with 2 granular crests, spine at carpal articulation; fingers as long as palm. P5 merus posterodistal margin serrate. Female pleonal somite 6 glabrous, lateral margins converging, telson bluntly triangular; gonopore on median part of thoracic sternite 6, axis obliquely to anterior edge of sternite.

Biological association: None.

Remarks: First record of Cycloachelous levigatus Koch, 2021 from Indian EEZ.

Distribution: Vietnam (type locality), Philippines, Japan and Bay of Bengal. Depth range: 45–77 m.

Distribution map:

Identified by: Vinay Padate

Publication: Cubelio S.S., Vishnu K.V., Subi S., Ameri S., Padate V.P., Takeda M. (2023) 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. Regional Studies in Marine Science, 62: 102879.

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