Parathelphusa possoensis ( Roux, 1904 )

Ng, Oliver K. S. Chia Peter K. L., 2006, The Freshwater Crabs Of Sulawesi, With Descriptions Of Two New Genera And Four New Species (Crustacea: Decapoda: Brachyura: Parathelphusidae), Raffles Bulletin of Zoology 54 (2), pp. 381-428 : 398-399

publication ID	https://doi.org/ 10.5281/zenodo.13245646
persistent identifier	https://treatment.plazi.org/id/03DF1C3D-FFB6-FFB9-7CB7-FAC1FC2FFCD1
treatment provided by	Felipe
scientific name	Parathelphusa possoensis ( Roux, 1904 )
status

Treatment

Parathelphusa possoensis ( Roux, 1904) View in CoL

( Figs. 16 View Fig , 20 View Fig A-E)

Potamon (Potamonautes) celebensis (part) - Schenkel, 1902: 528, Pl. 10 Fig. 9 View Fig , 13a View Fig .

Potamon celebense var. possoensis Roux, 1904: 564 , Fig. B.

Parathelphusa (Mesotelphusa) pallida View in CoL (part) - Bott, 1970c: 128.

Material examined. – Lectotype: male (17.3 x 13.9 mm) ( NMB 23 View Materials VIII), Lake Poso , Central Sulawesi, coll. Gesch & Sarasin, 1901 . Paralectotype: 1 female ( NMB 23 View Materials VIII), same data as lectotype. Others : 5 males, 9 females, 3 juveniles ( ZRC 2000.1682 View Materials ) , 1 male, 1 female ( MZB 1498 View Materials ), Lake Poso, Salopa Waterfall, 19 km west of Tentana , Central Sulawesi, coll. C. D. Schubart et al., 21 Jan 2000 .

Diagnosis. – Carapace inflated, dorsal surfaces smooth; cervical groove shallow, narrow; H-shaped central depression pronounced; branchial regions inflated. Epigastric and postorbital cristae continuous, sharp, subparallel to frontal margin; outer edge of cristae not reaching anterolateral margin, stopping at base of first epibranchial teeth. Front slightly sinuous, entire; frontal median triangle distinct but relatively narrow, upper ridged margin weak, lateral margins strong, distinct. Anterolateral margin smooth, external orbital angle low, broadly triangular, outer margin almost straight, about 2 times length of inner margin, first and second epibranchial teeth very low, lobiform, barely discernible. Posterolateral regions smooth, lined with weak oblique striae. Suture between thoracic sternites 2 and 3 incomplete, almost straight with respect to buccal cavity, suture between sternites 3 and 4 distinct but incomplete. Palm of chelipeds slightly inflated, fingers shorter than palm, pollex and dactylus usually unpigmented in most specimens, dactylus of major chela of large males pigmented black throughout length. Ambulatory legs relatively short, second pair longest. Dorsal margin of merus slightly cristate, gently serrated, without distinct subterminal spine. Male abdomen reaching imaginary line joining anterior edges of cheliped bases, T-shaped, segment 6 distinctly longer than segment 7; lateral margins of segment 7 concave; lateral margins of segment 6 subparallel, gently sinuous. G1 curved sharply outwards, directed upwards, outer margin convex along distal two-thirds, proximal part with deep V-shaped cleft; distal part tapering. G2 with well developed distal segment, about 0.4 times length of basal segment.

Distribution. – Lake Poso, Central Sulawesi.

Remarks. – Potamon celebense var. possoensis was first described from one small male and one female specimen from Lake Poso (also spelled Posso), Central Sulawesi, by Roux (1904) from specimens which Schenkel (1902) thought were Parathelphusa pallida . However, Roux (1904), in describing this taxon, did not designate a holotype. Bott (1970c) did not examine the specimens and regarded P. possoensis as a junior synonym of P. celebensis . However, on examination of the syntypes and the large number of topotypic specimens, P. possoensis possesses several diagnostic features and is here regarded as a valid species. The male (NMB 23VIII) is hereby designated as the lectotype of P. possoensis . The lectotype male (NMB 23VIII) is a relatively small specimen and although it is an adult male, the G1 is still relatively juvenile in form. As such, an adult G1 (male, 27.0 by 20.9 mm) (ZRC 2000.1682) is illustrated here instead ( Fig. 20 View Fig A-D).

Parathelphusa possoensis differs from P. pallida in the following characters. The outer edge of the postorbital cristae of P. possoensis does not reach the anterolateral margin, stopping at the base of the first epibranchial teeth, while for P. pallida , the outer edge of the postorbital cristae similarly does not reach the anterolateral margin but stops between the base of the first and second epibranchial teeth ( Fig. 16A View Fig vs. Fig. 12A View Fig ); the anterolateral margin of P. possoensis is smooth while that of P. pallida is finely granulated; the suture between thoracic sternites two and three is incomplete in P. possoensis while the suture for P. pallida is complete; the ambulatory legs of P. possoensis is relatively shorter while that for P. pallida is relatively longer ( Fig. 16A View Fig vs. Figs. 12A View Fig , 13A View Fig ); and most significantly, the G1 of P. possoensis is curved sharply outwards while the curvature of the same structure on P. pallida is less pronounced ( Fig. 20A, B View Fig vs. Fig. 14F, G View Fig ).