Coral reef-associated brachyuran fauna (Crustacea: Decapoda: Brachyura) from Angria Bank off the west coast of India Author Padate, Vinay P. 0000-0002-2244-8338 Centre for Marine Living Resources & Ecology, Ministry of Earth Sciences, Government of India, Atal Bhavan, LNG Terminus Road, Puthuvype, Kochi, 682508, India. & vinaypadate @ gmail. com; https: // orcid. org / 0000 - 0002 - 2244 - 8338 vinaypadate@gmail.com Author Periasamy, Rengaiyan 0000-0001-6941-4074 CSIR - National Institute of Oceanography, Dona Paula, Goa, 403004, India. & periasamy @ ncpor. res. in; https: // orcid. org / 0000 - 0001 - 6941 - 4074 periasamy@ncpor.res.in Author Rivonker, Chandrashekher U. 0000-0002-5828-5032 School of Earth, Ocean and Atmospheric Sciences, Goa University, Goa, 403206, India. & curivonker @ unigoa. ac. in; https: // orcid. org / 0000 - 0002 - 5828 - 5032 curivonker@unigoa.ac.in Author Ingole, Baban S. 0000-0001-6096-6980 CSIR - National Institute of Oceanography, Dona Paula, Goa, 403004, India. & babaningole @ ncpor. res. in; https: // orcid. org / 0000 - 0001 - 6096 - 6980 & National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Government of India, Headland Sada, Vasco-Da-Gama, Goa, 403804, India. babaningole@ncpor.res.in text Zootaxa 2023 2023-10-19 5357 3 398 422 http://dx.doi.org/10.11646/zootaxa.5357.3.4 journal article 274290 10.11646/zootaxa.5357.3.4 44033c16-d494-439a-b750-71b16fb90247 1175-5326 10063288 75944208-37BF-484C-9917-F9376027C31E Thusaenys irami ( Laurie, 1906 ) ( Fig. 2E–I ) Halimus irami Laurie, 1906: 379 , pl. 1 figs. 4, 4a ( type locality: Gulf of Mannar, Muttuvartu Par, Sri Lanka ).— Rathbun 1924: 5 . Thusaenys irami . — Griffin & Tranter 1986: 193–196 , fig. 66c–d.— Ng et al . 2008: 106 [list]. Material examined. Male (3.0 × 4.3 mm ) ( NIO /BOD/AB/BRY/00002), RVSS 2 , west of Vijaydurg , Arabian Sea , 16.44°N , 72.07°E , 37 m depth , Van Veen grab, coll. R . Periasamy , 6 January 2014 . Diagnosis. Carapace pyriform, longer than wide, smooth, covered with short, stiff setae, intestinal region with low tubercle ( Fig. 2E, F ). Rostrum length nearly 0.5 × post-rostral CL; rostral spines slender, horizontal, divergent from the base, lacking accessory spine; dorsal carapace smooth; Orbits reduced, supraorbital eave produced into indistinct preorbital spine, cupped postorbital process with an extension on posterior margin of upper orbital hiatus ( Fig. 2F, G ). Supraorbital eave margin weakly concave. Basal antennal article broad, anterolateral angle produced into strong spine separated from flagellar base by notch (indicated by arrowhead in Fig. 2G ); lateral margin convex ( Fig. 2G ). Maxilliped 3 merus quadrilateral, as long as wide, length 0.5 × ischial length ( Fig. 2G ). Pterygostomian region with 2 tubercles ( Fig. 2G ). Chelipeds slender ( Fig. 2H ). Male pleon terminally tapering, telson sub-triangular, not inserted deeply into somite 6 ( Fig. 2H ). G1 expanded at distal tip, groove present near lateral margin near pleonal surface ( Fig. 2I ). Colouration. Fresh specimen: reddish, chelae greyish ( Fig. 2E ). Preserved specimen: light brown ( Fig. 2F ). Biology. Known to occur underneath sub-tidal rocks, inside pearl oysters, over muddy substrates, vicinity of corals and Lithothamnion ; 36–37 m ( Griffin & Tranter 1986 ; present study). Laurie (1906) reported Sacculina infestation from Sri Lanka . The present specimen was collected from rocky substrate, at 37 m depth, in the vicinity of Favites corals. Remarks. Laurie (1906) described Halimus irami from an ovigerous female collected from Muttuvartu Par, in the Gulf of Mannar ( Sri Lanka ). Griffin & Tranter (1986) included Halimus irami in a new genus, Thusaenys , owing to the strongly produced basal antennal article with anterior notch and the broad, weakly lobed supraorbital eave. Thusaenys irami differs from its closest congener T. calvarius ( Alcock, 1895 ) in having basal antennal article with weakly convex lateral margin (vs. strongly produced lateral margin in the latter species (cf. Takeda 2023 : fig. 1B)), and low tubercle on the intestinal region (compared to short, strong median spine in the latter (cf. Takeda 2023 : fig. 1A)). The Indian specimen conforms to the holotype description ( Laurie 1906 ) in the nearly smooth dorsal surface of the carapace, the presence of a low tubercle on the intestinal region, a relatively long rostrum nearly half as long as the remaining carapace, supraorbital eave anteriorly projecting into triangular tooth, and a gently convex lateral margin of the basal antennal article which is produced into strong spine separated from flagellar base by a notch. On the other hand, the present specimen differs from the holotype in the absence of an epibranchial tubercle. Geographical distribution. Australia , New Guinea , Indonesia , and Gulf of Mannar off Sri Lanka ( Griffin & Tranter 1986 ); eastern Arabian Sea off India (present study). The present observation is the first record from Indian waters indicating westward extension of the known geographical range.