Sahyadriana inopinata, Pati & Thackeray, 2021

Pati, Sameer K. & Thackeray, Tejas, 2021, Five new species of freshwater crabs of the genera Ghatiana Pati & Sharma, 2014 and Sahyadriana Pati & Thackeray, 2018 from India (Decapoda: Brachyura: Gecarcinucidae), Zoosystema 43 (26), pp. 627-647 : 636-639

Sahyadriana inopinata n. sp.

( Figs 3D ; 6 A-D; 7 A-H)

urn:lsid:zoobank.org:act:A64D966D-A859-48C1-9949-092B1D7288EB

TYPE MATERIAL. — Holotype. India • ♂ (CW 10.29 mm, CL 7.86 mm, CH 4.47 mm, FW 4.16 mm); Maharashtra: Satara district: Dhobi Waterfall, Mahabaleshwar ; 17°56’13”N, 73°38’45”E; alt. 1075 m; 30.VI.2018; Tejas Thackeray leg.; ZSI-WRC C.2015 . Paratypes. India • ♂ ( CW 10.30 mm, CL 7.89 mm, CH 4.55 mm, FW 4.14 mm); ♀ ( CW 11.93 mm, CL 9.05 mm, CH 5.61 mm, FW 4.58 mm); same data as for holotype; ZSI-WRC C.2016 • 2 ♂ ( CW 9.20-10.24 mm, CL 6.92-7.78 mm, CH 4.00- 4.82 mm, FW 3.62-4.03 mm); 3 ♀ ( CW 10.97-12.33 mm, CL 8.27-9.14 mm, CH 5.13-5.56 mm, FW 4.24-4.84 mm); same data as for holotype; ZSI-WRC C.2017 .

TYPE LOCALITY. — India: Maharashtra: Satara district: Dhobi Waterfall, Mahabaleshwar; 17°56’13”N, 73°38’45”E; alt. 1075 m.

DIAGNOSIS. — Carapace in adult slightly broader than long (CW/ CL = 1.3), moderately deep ( CH /CL = 0.6); epibranchial tooth visible as relative distinct notch; branchial regions inflated; epistome posterior margin with strongly concave lateral lobes ( Fig. 6 A-C). Third maxilliped lacking flagellum on exopod ( Fig. 7A ). Chelipeds with pointed fingertips ( Figs 6A, D ; 7B ). Ambulatory legs with densely setose dactylus and propodus ( Fig. 6A, D ). Male sternopleonal cavity long, extending beyond imaginary line joining bases of third maxillipeds ( Figs 6D ; 7C ). Male pleon relatively broad, T-shaped; pleonal somite 5 with concave lateral margins; pleonal somite 6 subquadrate, slightly broader than long, subequal in length to telson, lateral margins convex ( Figs 6D ; 7C ). Male telson short ( Figs 6D ; 7C ). G1 stout, straight; terminal segment relatively less stout, proximal two-thirds stouter than distal third, inverted funnel-shaped, relatively long, c. 0.5 times length of subterminal segment; subterminal segment relatively slender ( Fig. 7D, E ). G2 very short, with very short distal segment ( Fig. 7F ). Female pleon in adult broadly subtriangular ( Fig. 7G ). Vulvae in adult positioned apart from each other (VD/SW = c. 0.3), each subovate in shape, relatively small, occupying c. 0.4 times length of S6, positioned some distance from S5/S6 ( Fig. 7H ).

ETYMOLOGY. — The species name is an adjective in the Latin nominative singular meaning unexpected, referring to the unexpected discovery of the species from the type locality of a congener, i.e., S. triangulus ( Pati & Sharma, 2014) .

COLOUR IN LIFE. — Crabs have chocolate brown coloured carapace and ambulatory legs, whereas their chelipeds are orangish brown ( Fig. 3D ). Their ventral surface is relatively paler.

ECOLOGICAL NOTES. — Sahyadriana inopinata n. sp. was found under cobblestones adjacent to a waterfall. The species dwells at higher altitude (1075 m above a.s.l.). The sympatric species, S. triangulus is so far known only from preserved specimens, with no information on its ecological requirements ( Pati & Thackeray 2018).

GEOGRAPHICAL DISTRIBUTION. — Sahyadriana inopinata n. sp. is known only from the type locality (Dhobi Waterfall, Mahabaleshwar) in Satara district of Maharashtra, India. The type locality is situated in the Western Ghats.

REMARKS

Among congeners, S. inopinata n. sp. is most similar to S. billyarjani Pati & Thackeray, 2018 and the type species, S. sahyadriensis , due to strongly concave lateral lobes of the epistome posterior margin ( Fig. 6C ; see Pati & Thackeray 2018: figs 20B; 24B), the pointed fingertips of the chelipeds ( Figs 6A, D ; 7B ; see Pati & Thackeray 2018: figs 20A, C, D; 24A, C, D), the relatively stouter, inverted funnel-shaped terminal segment of the G1 with the distal portion abruptly narrow ( Fig. 7D, E ; see Pati & Thackeray 2018: figs 20I-K, M; 24I-K), and the relatively slenderer subterminal segment of the G1 ( Fig. 7D, E ; see Pati & Thackeray 2018: figs 20I, K, M; 24I, K). Sahyadriana inopinata n. sp. is nevertheless distinguished from S. billyarjani and S. sahyadriensis by the relatively distinct notch between the epibranchial tooth and the external orbital angle ( Fig. 7A, B ) (vs indistinct notch between the epibranchial tooth and the external orbital angle; see Pati & Thackeray 2018: figs 20A; 24A), the relatively slenderer and relatively longer terminal segment of the G1, i.e., c. 0.5 times the length of the subterminal segment ( Fig. 7D, E ) (vs relatively stouter and relatively shorter terminal segment of the G1, i.e., c. 0.3-0.4 times the length of the subterminal segment; see Pati & Thackeray 2018: figs 20I-K, M; 24I-K), and the subovate-shaped vulva, which is relatively smaller, occupying c. 0.4 times the length of the S6 and is positioned a clear distance from S5/S6 ( Fig. 7H ) (vs suborbicular-shaped vulva, which is relatively larger, occupying c. 0.5 times the length of the S6 and is positioned close to S5/S6; Pati & Thackeray 2018: figs 20O; 24N).

The strongly concave lateral lobes of the epistome posterior margin and the inverted-funnel shaped terminal segment of the G1 of S. inopinata n. sp. are also similar to those of S. pilosipes (Alcock, 1909) ( Figs 6C ; 7D, E ; see Pati & Thackeray 2018: figs 22B, E, F; 23B, D, E). Both the species have a relatively broader male pleon with the concave lateral margins of the pleonal somite 5 ( Figs 6D ; 7C ; see Pati & Thackeray 2018: figs 22C; 23C). Moreover, the G1 is stout and straight, with the terminal segment relatively longer (c. 0.5 times the length of the subterminal segment) and the subterminal segment relatively slenderer in S. inopinata n. sp. and S. pilosipes ( Fig. 7D, E ; see Pati & Thackeray 2018: figs 22E, F; 23D, E). Sahyadriana inopinata n. sp., however, is easily distinguished from S. pilosipes by the pointed fingertips of the chelipeds ( Figs 6A, D ; 7B ) (vs broadly rounded or spoon-shaped fingertips of the chelipeds; see Pati & Thackeray 2018: figs 22C; 23C), the relatively stouter terminal segment of the G1, i.e., the proximal two-thirds stouter than the distal third ( Fig. 7D, E ) (vs relatively slenderer G1 terminal segment, i.e., the proximal half stouter than the distal half; see Pati & Thackeray 2018: figs 22E, F; 23D, E), and the subovateshaped and relatively smaller vulva in adult that occupies c. 0.4 times the length of the S6 ( Fig. 7H ) (vs suborbicular-shaped and relatively larger vulvae in adult, occupying c. 0.5 times the length of the S6; see Pati & Thackeray 2018: fig. 23H).

Sahyadriana inopinata n. sp. need not be confused with the sympatric species, S. triangulus , because of the relatively distinct epibranchial tooth ( Fig. 6A, B ) (vs indistinct epibranchial tooth; see Pati & Thackeray 2018: fig. 28A), the straight terminal segment of the G1 ( Fig. 7D, E ) (vs distally distinctly curved terminal segment of the G1; see Pati & Thackeray 2018: fig. 28D, E), and the basally narrow subterminal segment of the G1 ( Fig. 7D, E ) (vs basally broad subterminal segment of the G1; see Pati & Thackeray 2018: fig. 28D, E).

Figures

FIG. 3. — Colour in life: A, Ghatiana durrelli n. sp., ♀ from Amba; B, Ghatiana durrelli n. sp., ♂ from type locality; C, Ghatiana rouxi n. sp., ♂ from Chorla; D, Sahyadriana inopinata n. sp., ♂ from type locality; E, Sahyadriana keshari n. sp., ♂ from type locality; F-H, Sahyadriana tamhini n. sp., all ♂ from type locality and its vicinity. The photographed specimens could not be collected.

FIG. 6. — Sahyadriana inopinata n. sp., holotype ♂ (10.29 × 7.86 mm), ZSI-WRC C.2015: A, overall dorsal view; B, dorsal view of cephalothorax; C, frontal view of cephalothorax; D, overall ventral view. Scale bars: A, D, 5 mm; B, C, 2 mm.

FIG. 7. — Sahyadriana inopinata n. sp., holotype ♂ (10.29 × 7.86 mm), ZSI-WRC C.2015 (A-F); paratype ♀ (11.93 × 9.05 mm), ZSI-WRC C.2016 (G, H): A, left third maxilliped; B, major or right chela (outer view); C, S1-S7, pleonal somites 4-6, and telson; D, right G1 (dorsal view); E, right G1 (ventral view); F, right G2; G, pleonal somites 4-6 and telson; H, S1-S8 showing vulvae. Scale bars: A, 1 mm; B, C, G, H, 2 mm; D-F, 0.5 mm.