Gubernatoriana alcocki Pati, 2016

Pati, S. K., Thackeray, T. & Khaire, A., 2016, Five new species of freshwater crabs of the genera Ghatiana Pati & Sharma, 2014, and Gubernatoriana Bott, 1970 (Crustacea, Decapoda, Brachyura: Gecarcinucidae Rathbun, 1904) from the Western Ghats, India, Zootaxa 4083 (4), pp. 569-586 : 578-580

Gubernatoriana alcocki Pati n. sp.

( Figs. 7 , 8 )

Type material. INDIA: adult male, holotype (cw 12.2 mm, cl 9.66 mm, ch 6.1 mm, fw 4.6 mm), Vankusawade, near Ghanbi Vatole, Patan taluk, Satara district, Maharashtra (17.449° N and 73.829° E), altitude 1082 m, 22 July 2014, coll. S.S. Kamble & Party (ZSI, WRC-C.1513); paratypes, two males (cw 13.72–14.76 mm, cl 10.92–11.78 mm, ch 7.24–7.76 mm, fw 5.30–5.68 mm) and two females (cw 11.30–13.72 mm, cl 8.94–10.92 mm, ch 5.98–7.24 mm, fw 4.56–5.30 mm), same collection data as holotype (ZSI, WRC-C.1514).

Diagnosis. Carapace quadrate (cw/cl = 1.3); dorsal surface smooth, olive-brown coloured; anterolateral margin short, smooth, cristiform; posterolateral margin slightly convergent, with fine, oblique striations; front strongly deflexed, narrow (fw/cw = 0.4); epigastric cristae faintly visible; postorbital cristae indistinct; exorbital angle triangular, distinct, with long outer margin, ca. 2 times length of inner margin; epibranchial tooth visible as weak notch; frontal median triangle incomplete; epistomal median lobe broadly triangular with acute apex, lacking median tooth ( Figs. 7A, B ). Finger tips of chelipeds pointed ( Fig. 7D ). Suture between male thoracic sternites s2/s3 indistinct, suture between sternites s3/s4 missing except for two short lateral grooves ( Figs. 7C, F ). Male abdomen narrowly T-shaped; sixth abdominal somite slightly broader than long, nearly equal to telson length; telson short; male sternoabdominal cavity deep, long, extending beyond level of bases of third maxillipeds ( Figs. 7C, G ). G1 with slender, cone-shaped, long terminal article, ca. 0.4 times length of subterminal segment, tip slightly curving inwards ( Figs. 8A–C ). G2 with very short or vestigial terminal article ( Fig. 8D ).

Description of holotype. Carapace quadrate (cw/cl = 1.3); dorsal surface smooth; anterolateral carapace gently inflated in frontal view; anterolateral margin short, smooth, cristiform; posterolateral margin slightly convergent, with fine, oblique striations; front strongly deflexed, square cut, nearly flat, frontal margin slightly concave, narrow (fw/cw = 0.4); epigastric cristae faintly visible, smooth; postorbital cristae indistinct; exorbital angle triangular, distinct, with long outer margin, ca. 2 times length of inner margin; epibranchial tooth visible as weak notch; postorbital region shallow; branchial regions gently inflated; subhepatic region slightly rugose; cervical grooves indistinct; mesogastric groove long, with bifurcation posteriorly; H-groove visible, shallow; frontal median triangle incomplete; epistomal median lobe broadly triangular with acute apex, lacking median tooth ( Figs. 7A, B ).

Chelipeds unequal; right chela larger, smooth, fingers with two or three larger teeth, distinct gape when finger tips in contact ( Fig. 7D ); length of dactylus greater than length of upper margin of palm; carpal spine small, blunt; outer surface of merus rugose. Ambulatory legs (p2–p5) long with fine, long tuft of brownish bristles on anterior margin of merus, carpus, propodus, dactylus, posterior margin of propodus, dactylus; dactylus (p2–p5) slightly longer than propodus; longest propodus (p3) two times as long as broad ( Fig. 7E ).

Suture between male thoracic sternites s2/s3 indistinct, suture between sternites s3/s4 missing except for two short lateral grooves ( Figs. 7C, F ).

Male abdomen narrowly T-shaped; fifth abdominal somite distinctly broader than long, with concave lateral margins; sixth abdominal somite slightly broader than long, nearly equal in length to telson, with slightly concave lateral margins; telson short, broadly triangular with almost straight outer margins; male sternoabdominal cavity deep, long, extending beyond level of bases of third maxillipeds ( Figs. 7C, G ).

Mandibular palp with two joints, terminal joint bilobed; exopods of first, second maxillipeds with long flagellum; exopod of third maxilliped lacking flagellum, longer than ischium; ventral sulcus on ischium distinct, subparallel to inner margin; merus with rounded anterior external angle, depression towards inner sides ( Fig. 7H ).

G1 with slender, cone-shaped, long terminal article, ca. 0.4 times length of subterminal segment, tip broad, slightly curving inwards, joint between terminal article, subterminal segment clear; subterminal segment broader than terminal article, basal half broader than distal half ( Figs. 8A–C ). G2 conspicuously short with very short or vestigial terminal article; proximal half portion of basal segment much stouter than distal half portion ( Fig. 8D ).

Live colour. Live crabs are olive-brown but their hands are orange-brown ( Figs. 2C , 7A ).

Paratypes. Paratypes are identical to the holotype in all morphological features barring females (ZSI, WRC- C.1514), in which chelipeds are almost equal, their fingers have 12 to 14 small, blunt teeth, and the gape between fingers is comparatively small.

Etymology. Species is named in the honour of British physician, naturalist, and carcinologist Major Dr. Alfred William Alcock.

Type locality. Vankusawade, near Ghanbi Vatole, Patan taluk, Satara district, Maharashtra (17.449° N and 73.829° E) (altitude 1082 m).

Remarks. Gubernatoriana alcocki n. sp. is similar to its congeners except G. basalticola by the presence of following suite of morphological characters: carapace quadrate (cw/cl = 1.1–1.3), posterolateral margin nearly straight to slightly convergent, frontal margin narrow (fw/cw = 0.3–0.4), epistomal median lobe with an acute apex, telson short, and G2 terminal article very short or vestigial ( Figs. 7A–C, G , 8D ).

A diagnostic feature of G. alcocki n. sp. is the inwardly curved tip of the G1 terminal article ( Figs. 8A, C ). Otherwise, G. triangulus and G. gubernatoris are more similar to G. alcocki n. sp. among congeners due their long G1 terminal article, ca. 0.4–0.5 times the length of the subterminal segment (see Pati & Sharma 2014a: fig. 7E for G. triangulus ; Pati & Sharma 2014b: pl. VII, fig. 7D for G. gubernatoris ). The terminal article of the G1 of G. basalticola , G. pilosipes , G. thackerayi n. sp. and G. waghi n. sp. is short, ca. 0.3–0.35 times the length of the subterminal segment ( Fig. 10A for G. thackerayi , Fig. 12A for G. waghi ; see Klaus et al. 2014: fig. 3D for G. basalticola ; Pati & Sharma 2014b: pl. VIII, fig. 8D for G. pilosipes ). While the male sternoabdominal cavity of G. alcocki n. sp. and G. triangulus is long, extending beyond the level of the third maxilliped bases ( Fig. 7C ; see Pati & Sharma 2014a: fig. 6C for G. triangulus ), that of the G. gubernatoris is short, extending beyond the level of the cheliped bases (see Pati & Sharma 2014b: pl. VII, fig. 7C). The distal portion of the G1 terminal article is distinctly broader than its proximal portion, and the subterminal segment appears slimmer in G. alcocki n. sp. ( Fig. 8A ) when compared to the distinctly narrow distal portion of the G1 terminal article, and stout, triangular appearance of the subterminal segment of G. triangulus (see Pati & Sharma 2014a: fig. 7E for G. triangulus ). Furthermore, G. alcocki n. sp. can be distinguished from G. triangulus by the triangular, distinct exorbital angle ( Fig. 7A ) [vs. low, indistinct exorbital angle (see Pati & Sharma 2014a: fig. 6A)] and from G. gubernatoris by the long outer margin of the exorbital angle ( Fig. 7A ) [vs. short outer margin of the exorbital angle (see Pati & Sharma 2014b: pl. VII, fig. 7A for G. gubernatoris )].

Gubernatoriana basalticola has some unique morphological features [strongly transverse carapace (cw/cl = 1.8), distinctly convergent posterolateral margin, conspicuously broad frontal margin (fw/cw = 0.7), massive major chela, and elongated G2 terminal article (see Klaus et al. 2014: figs. 3A–C)] that neither its congeners nor its related genera ( Ghatiana Pati & Sharma, 2014 and Inglethelphusa Bott, 1970 ) possess, and this supports recognizing the taxon as a new genus ( Klaus et al. 2014). Molecular studies are suggested to solve the problem.

Ecological notes. Specimens of G. alcocki n. sp. were collected beneath medium sized (25–35 mm) pebbles in ephemeral streams and from the adjacent rock formations on a high mountain plateau. This species might be confined to high altitude areas of the Western Ghats since the species is not so far recorded from mountain crests or slopes (S.K. Pati, unpublished data). Individuals were found in association with Bombay Swampeel, Monopterus cf. indicus (Silas & Dawson, 1961). The new species and the eel are abundant at Vankusawade, which is the breeding ground for both. On one occasion, an eel was observed preying upon a crab (B.V. Jadhav, personal communication). Due to the small size of juvenile eels, crabs might also be predating on these young eels. Crabs are generally found in large numbers on the mountain plateau during the monsoon (June to September), but large populations were seen even during dry seasons.

Geographical distribution. Gubernatoriana alcocki n. sp. is known only from the type locality, Vankusawade near Ghanbi Vatole in Satara district of Maharashtra.

Figures

FIGURE 2. Live crabs of new species of Ghatiana and Gubernatoriana. A, Ghatiana aurantiaca n. sp. from Amboli; B, Ghatiana splendida n. sp. from Chaukul; C, Gubernatoriana alcocki n. sp. from Vankusawade; D, Gubernatoriana thackerayi n. sp. from Raghuvir Ghat; C, Gubernatoriana waghi n. sp. from Malshej Ghat. Photo credits: A, B, Arjun Kamdar; C, B. V. Jadhav; D, Shailesh Bhosale; E, Rachit Shah.

FIGURE 7. Gubernatoriana alcocki n. sp., holotype male (ZSI, WRC—C. 1513). A, dorsal view; B, frontal view; C, ventral view; D, right or major cheliped; E, right ambulatory leg (p 3); F, anterior male thoracic sternites; G, male abdomen; H, left third maxilliped. Scale bars = 5 mm (A, C), 2 mm (B, D – G), 1 mm (H).

FIGURE 8. Gubernatoriana alcocki n. sp., holotype male (ZSI, WRC—C. 1513). A, dorsal view of right G 1; B, ventral view of right G 1; C, dorsal view of right G 1 terminal article D, right G 2. Scale bar = 0.5 mm.

FIGURE 10. Gubernatoriana thackerayi n. sp., holotype male (ZSI, WRC—C. 1515). A, dorsal view of left G 1; B, ventral view of left G 1; C, dorsal view of left G 1 terminal article; D, left G 2. Scale bar = 0.5 mm.

FIGURE 12. Gubernatoriana waghi n. sp., holotype male (ZSI, WRC—C. 1517). A, dorsal view of right G 1; B, ventral view of right G 1; C, dorsal view of right G 1 terminal article; D, right G 2. Scale bar = 0.5 mm.