Oziotelphusa ganjamensis, Pati & Sharma, 2012

Pati, S. K. & Sharma, R. M., 2012, Oziotelphusa ganjamensis, a new species of freshwater crab (Brachyura: Gecarcinucidae) from south Odisha (Orissa) state, eastern India, Zootaxa 3528, pp. 49-56 : 50-54

Oziotelphusa ganjamensis n. sp.

( Figs. 2, 3)

Type material. INDIA: adult male, holotype (cw 38.24mm, cl 28.24mm, ch 18.10mm, fw 10.44), Balakrushnapur, Berhampur-Digapahandi road, Ganjam district , Odisha [= Orissa] (19°21´27.96˝N and 84°43´44.26˝E), altitude 55m, 12 October 2011, coll. S.K. Pati (ZSI, WRC-C.767); paratypes, five male juveniles (cw 21.00– 23.70mm, cl 16.12–18.52mm, ch 10.70–12.00mm, fw 6.72–7.62mm) and five female juveniles (cw 21.62–23.38mm, cl 16.44–18.12mm, ch 10.92–12.30mm, fw 6.60–7.64mm), same collection data as holotype (ZSI, WRC-C.768) .

Diagnosis. Carapace broader than long, smooth, highly convex in frontal view; epistomal median lobe with distinct, sharp and pointed tooth; frontal margin nearly straight in dorsal view; epibranchial tooth of moderate size present slightly above postorbital cristae; epigastric cristae anterior to the postorbital cristae; branchial region inflated; frontal median triangle complete, dorsal margin fused with lateral margins; suture between thoracic sternites 2, 3 and 3, 4 indistinct; male abdomen almost triangular with concave lateral borders; sixth abdominal segment of male trapezoidal with concave lateral borders, wider than long, shorter than telson ( Figs. 2A–C). G1 terminal segment bent outwards at juncture between terminal, subterminal segments; tip of terminal segment upturned and pointed; subterminal segment relatively broad in the basal half to two-third and sharply narrows distally to look slender or even neck-like in appearance in the distal half to one-third ( Figs. 3A–C). G2 with long distal segment 0.4 times the length of basal segment ( Fig. 3D).

Description of holotype. Carapace broader than long, most of its surface smooth; dorsal surface highly convex anteriorly, posteriorly ( Figs. 2A, B); anterior lateral carapace high in frontal view ( Fig. 2B); cervical groove broadly V-shaped, very shallow and narrow; H-groove clearly visible; anterolateral margin smooth; posterolateral margin traversed by many fine oblique ridges; epistomal median lobe with distinct, sharp, pointed tooth ( Fig. 2B); frontal margin nearly straight in dorsal view ( Fig. 2A); epibranchial tooth moderate in size, located slightly above postorbital cristae, not in level with supraorbital margin ( Fig. 2A); postorbital region concave with small tubercle situated posterior to centre of supraorbital margin near to post-orbital cristae; external orbital angle acute; outer margin of external orbital tooth twice the length of inner margin; epigastric cristae anterior to postorbital cristae; postorbital cristae sharp, curved ( Fig. 2A); branchial region inflated ( Figs. 2A); frontal median triangle complete, not broader than frontal margin, dorsal margin fused with lateral margins ( Fig. 2B). Left cheliped bigger than the right cheliped ( Figs. 2A–C); pollex little longer than dactylus ( Figs. 2A, B); teeth on both fingers of cheliped small and coarse ( Fig. 2A). Ambulatory legs smooth except few bristles on lateral sides; dactylus shorter than propodus; propodus almost twice as long as broad. Suture between thoracic sternites 2, 3 and 3, 4 indistinct ( Fig. 2C); male abdomen almost triangular with concave lateral borders ( Fig. 2C); sixth abdominal segment trapezoidal, wider than long, shorter than telson, with concave lateral borders ( Fig. 2C); abdominal cavity shallow. Mandibular palp with 2 distinct joints, terminal joint bilobed. Exopods of maxillipeds with long flagellum; exopod of third maxilliped longer than ischium; ischium longitudinally grooved into deep and broad sulcus; merus broader than long. G1 terminal segment curved outwards at juncture between terminal, subterminal segments ( Figs. 3A, B); tip of terminal segment upturned and pointed ( Fig. 3C); subterminal segment relatively broad in the basal half to twothird and then sharply narrows distally to appear slender or even neck-like in the distal half to one-third ( Figs. 3A, B). G2 with long distal segment 0.4 times the length of basal segment ( Fig. 3D).

Colour. Dorsal surface yellowish brown with irregular pattern of reddish brown to dark brown spots, ventral portion light yellow.

Type Locality. Balakrushnapur , Berhampur-Digapahandi road, Ganjam district, Odisha, India (19°21´27.96˝N and 84°43´44.26˝E) (altitude 55m) .

Paratypes. The morphology of carapace and gonopods (males) is essentially the same as in the holotype except for size, colouration, the size of cheliped fingers and the finger teeth. Paratypes are smaller than the holotype. Carapace of males and females are light brown to brown in colour. The fingers of both chelipeds in males and females are of equal size and the teeth on them are small and blunt. Tubercle on the postorbital region rudimentary.

Distribution. The species is known only from type locality. It may occur in rice fields or near by areas.

Ecological notes. The species commonly lives in shallow burrows in rice field embankments. They are generally seen during the rainy season when the rice fields contain sufficient water. The population of the species in the area appears to be quite large in size.

Etymology. The specific epithet refers to its type locality, the Ganjam district in the Odisha, India.

Remarks. Oziotelphusa ganjamensis is morphologically similar to only one Indian species, Oziotelphusa wagrakarowensis ( Rathbun, 1904) , and five Sri Lankan species, O. ceylonensis ( Fernando, 1960) , O. gallicola Bahir & Yeo, 2005 , O. intuta Bahir & Yeo, 2005 , O. minneriyaensis Bott, 1970 , O. stricta Ng & Tay, 2001 , in characters like having a moderate to highly convex carapace; epistomal median lobe with distinct tooth; almost straight or gently curved frontal margin (except O. wagrakarowensis , which has a bilobed frontal margin); epibranchial tooth small to moderate in size, slightly elevated from postorbital cristae, not up to the level of supraorbital margin; concave postorbital region; almost straight to curved postorbital cristae, and almost triangular male abdomen with concave lateral borders. The new species differs in certain features from all congeners except for O. wagrakarowensis , for instance, frontal median triangle not as broad as frontal margin ( Fig. 2B; see Bahir & Yeo 2005: Fig. 14B for O. wagrakarowensis ) (versus frontal median triangle as broad as frontal margin) (see Bahir & Yeo 2005: Fig. 18B of O. ceylonensis ; Fig. 26B of O. minneriyaensis ; Fig. 28B of O. stricta ; Fig. 34B of O. gallicola ; Figs. 36B, 37C of O. intuta ) and suture between thoracic sternites 3, 4 not visible ( Fig. 2C; see Bahir & Yeo 2005: Figs. 13A, 14C for O. wagrakarowensis ) (versus visible suture between thoracic sternites 3, 4) (see Bahir & Yeo 2005: Fig. 20A for O. ceylonensis ; Figs. 23A, 24A, 25A, 26C of O. minneriyaensis ; Figs. 34C, 35A for O. gallicola ; Figs. 36C, 37A for O. intuta ; Nag & Tay 2001 for O. stricta ). The length of distal segment of G2 of congeners is same (equal to or more than 0.4 times the length of basal segment) except for O. wagrakarowensis (0.2 to 0.3 times the length of basal segment). Oziotelphusa ganjamensis is close to O. wagrakarowensis , O. intuta and O. minneriyaensis in G1 structure. Though the two Sri Lankan species ( O. intuta and O. minneriyaensis ) having distinctly bent G1 terminal segment with slightly upturned tip like that of O. ganjamensis , they can be clearly differentiated by the S-shaped G1 terminal segment with blunt tip (see Bahir & Yeo 2005: Figs. 23C–G, 24C–G, I, J, 25C–E for O. minneriyaensis , 37D–H, J for O. intuta ) (versus gently curved G1 terminal segment with pointed tip of O. ganjamensis ) ( Fig. 3A–C). The Indian species, O. wagrakarowensis can be distinguished from the new species in many features (Table–1) particularly in the shape of G1 terminal segment and G2 structure. Oziotelphusa wagrakarowensis can be separated from O. ganjamensis by its G1 having hook-like terminal segment, and distinctly broad basal two-third portion of subterminal segment and G2 with short distal segment (see Bahir & Yeo 2005: Figs. 12B–E, 13C–G) (against G1 having outwardly curved terminal segment, whose tip is upturned, and broad basal half to two-third portion of subterminal segment and G2 with long distal segment) ( Fig. 3A–D).

The Indian species of the genus, Oziotelphusa aurantia ( Herbst, 1799) , O. biloba Bahir & Yeo, 2005 , O. bouvieri ( Rathbun, 1904) , O. kerala Bahir & Yeo, 2005 and O. wagrakarowensis , were reported from southern India (Andhra Pradesh, Karnataka, Tamil Nadu, Kerala and Puducherry). Oziotelphusa aurantia was also recorded from Raniganj in West Bengal ( Wood-Mason 1871) and Ganjam in Odisha ( Henderson 1893). Since rice is the major food crop of Odisha particularly in coastal plains, discovery of a new species suggests that there is much scope for further study on biosystematics of the genus in the area.