Sahyadriana tamhini Pati & Thackeray 2021, n. sp.

Sahyadriana tamhini n. sp.

(Figs 3 F-H; 10 A-D; 11 A-H)

urn:lsid:zoobank.org:act: 70189F64-7C11-495C-96AB-42E320DFDF78

TYPE MATERIAL. — Holotype. India • ♂ (CW 9.36 mm, CL 7.37 mm, CH 4.14 mm, FW 3.63 mm); Maharashtra: Pune district: Tamhini Ghat; 18°28’37”N, 73°25’1”E; alt. 621 m; 25.VII.2017; V. D. Hegde et al. leg.; ZSI-WRC C.2010.

Paratypes. India • ♂ (CW 8.86 mm, CL 6.97 mm, CH 4.08 mm, FW 3.44 mm), ♀ (CW 9.02 mm, CL 6.96 mm, CH 3.74 mm, FW 3.53 mm); same data as for holotype; ZSI-WRC C.2011 • ♂ (CW 9.21 mm, CL 7.30 mm, CH 4.15 mm, FW 3.68 mm), ♀ (CW 11.59 mm, CL 8.80 mm, CH 5.68 mm, FW 4.38 mm); Maharashtra: Pune district: Tamhini Ghat; 18°28’22”N, 73°25’8”E; alt. 621 m; 11.VIII.2017; Tejas Thackeray leg.; ZSI-WRC C.2012 • ♂ (CW 8.77 mm, CL 6.74 mm, CH 3.74 mm, FW 3.49 mm), ♀ (CW 10.02 mm, CL 7.60 mm, CH 4.02 mm, FW 3.94 mm); Maharashtra: Pune district: Tamhini Ghat; 18°28’4”N, 73°24’46”E; alt. 584 m; same collection date and collector as for holotype; ZSI-WRC C.2013 • ♂ (CW 9.51 mm, CL 7.23 mm, CH 4.00 mm, FW 3.77 mm), ♀ (CW 11.06 mm, CL 8.11 mm, CH 4.83 mm, FW 4.17 mm); Maharashtra: Pune district: Tamhini Ghat; 18°28’1”N, 73°24’46”E; alt. 572 m; same collection date and collector as for ZSI-WRC C.2012 paratypes; ZSI-WRC C.2014.

TYPE LOCALITY. — India: Maharashtra: Pune district:Tamhini Ghat; 18°28’37”N, 73°25’1”E; alt. 621 m.

DIAGNOSIS. — Carapace in adult slightly broader than long (CW/CL = 1.3-1.4), moderately deep (CH /CL = 0.5-0.6); epibranchial tooth visible as relative distinct notch; branchial regions inflated; epistome posterior margin with strongly concave lateral lobes (Fig. 10 A-C). Third maxilliped lacking flagellum on exopod (Fig. 11A). Chelipeds with pointed fingertips (Figs 10A, D; 11B). Ambulatory legs with densely setose dactylus and propodus (Fig. 10A, D). Male sternopleonal cavity long, extending beyond imaginary line joining bases of third maxillipeds (Figs 10D; 11C). Male pleon relatively broad, T-shaped; pleonal somite 5 with concave lateral margins; pleonal somite 6 subquadrate, broader than long, subequal in length to telson, lateral margins gently convex (Figs 10D; 11C). Male telson short (Figs 10D; 11C). G1 moderately stout, almost straight; terminal segment relatively slender, subcylindrical, distally distinctly narrow and gently curved inwards, relatively long, c. 0.5 times length of subterminal segment; subterminal segment relatively slender, with sinuous inner margin (Fig. 11D, E). G2 very short, with very short distal segment (Fig. 11F). Female pleon in adult broadly subtriangular (Fig. 11G). Vulvae in adult positioned apart from each other (VD/SW = c. 0.3), each suborbicular in shape, relatively large, occupying c. 0.5 times length of S6, positioned some distance from S5/S6 (Fig. 11H).

ETYMOLOGY. — The species is named after the type locality, Tamhini Ghat, a hotspot for wildlife in Maharashtra that hosts rich biodiversity and many endemic species, including that of the freshwater crabs. The species name is used as a Latin noun in apposition.

COLOUR IN LIFE. — The species shows colour variation. The carapace and ambulatory legs are generally saddle brown, with orange coloured chelipeds on the dorsal surface (Fig. 3F); the carapace and pereiopods are relatively paler ventrally. Some crabs have orange coloured carapace and chelipeds but brownish ambulatory legs dorsally (Fig. 3G). Some individuals are completely brown (Fig. 3H), with a paler ventral surface of the carapace.

ECOLOGICAL NOTES. — Sahyadriana tamhini n. sp. was found under cobblestones near the base of rainfed cascades in an elevated mountain (above 570 m altitude). Some individuals were also seen dwelling in the crevices of mountain cliffs. These crabs are very active during the monsoon season (June to September).

GEOGRAPHICAL DISTRIBUTION. — Sahyadriana tamhini n. sp. is known only from the type locality (Tamhini Ghat) in the Western Ghats of Pune district, Maharashtra, India.

REMARKS

Among congeners, S. tamhini n. sp., is most closely related to S. alcocki (Pati in Pati, Thackeray & Khaire, 2016) mainly due to the strongly concave lateral lobes of the epistome posterior margin (Fig. 10C; see Pati et al. 2016: fig. 7B; Pati & Thackeray 2018: fig. 19B), the pointed fingertips of the chelipeds (Figs 10A, D; 11B; see Pati et al. 2016: fig. 7A- D; Pati & Thackeray 2018: fig. 19A, C), the moderately stout and almost straight G1, and the relatively slenderer, subcylindrical terminal segment of the G1, with the gently inwardly curved distal portion (Fig. 11D, E; see Pati et al. 2016: fig. 8A-C; Pati & Thackeray 2018: fig. 19D, E). These two species, however, can be differentiated by the terminal segment of the G1, which is distinctly narrow distally and relatively longer, c. 0.5 times the length of the subterminal segment in S. tamhini n. sp. (Fig. 11D, E), and gradually narrow distally and relatively shorter, c. 0.4 times the length of the subterminal segment in S. alcocki (see Pati et al. 2016: fig. 8A-C; Pati & Thackeray 2018: fig. 19D, E). Again, the shape of the subterminal segment of the G1 looks different; the inner margin of the G1 subterminal segment is sinuous in S. tamhini n. sp. (Fig. 11D, E), while it is almost straight in S. alcocki (see Pati et al. 2016: fig. 8A, B; Pati & Thackeray 2018: fig. 19D, E). Although both the species have a suborbicular-shaped adult vulva that is situated clearly away from S5/S6 (Fig. 11H; see Pati & Thackeray 2018: fig. 19H), the vulvae in adult are relatively closed positioned (VD/SW = c. 0.3) and relatively larger, occupying c. 0.5 times the length of the S 6 in S. tamhini n. sp. (Fig. 11H), whereas they are clearly positioned apart from each other (VD/SW = c. 0.4) and relatively smaller, occupying c. 0.4 times the length of the S 6 in S. alcocki (see Pati & Thackeray 2018: fig. 19H).