Parathelphusa lokaensis (De Man, 1892 )

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 : 389-391

Parathelphusa lokaensis (De Man, 1892)

( Figs. 4-6 )

Telphusa celebensis var. lokaensis De Man, 1892: 300 .

Telphusa celebensis - De Man, 1892: 297 (part).

Potamon celebensis lokaensis - De Man, 1898: 436

Potamon (Potamonautes) celebensis lokaensis - Schenkel, 1902: 531; Rathbun, 1905: 200.

Potamon celebensis lokaensis - Roux, 1904: 561, 568.

Parathelphusa (Mesothelphusa) lokaensis - Bott, 1970c: 126, Pl. 24 Figs. 83-84.

Material examined. – Lectotype: male (24.3 x 20.0 mm) ( RMNH D 1286 ), Loka near Bonthain , South Sulawesi, ca. 5 ° 30'S 119 ° 50'E; coll. M. Weber, Oct-Nov. 1888 . Paralectotype: 1 male ( RMNH D 2586 ), same data as lectotype. Others : 1 male (24.5 x 20.2 mm) ( NMB 23 Vc); Matinangkette , South Sulawesi, coll. Sarasin , 1901; 2 females ( NMB 23 Vb), Marangka , South Sulawesi, coll. Sarasin , 1901; 1 male ( NMB 23 Va), Loka, Bonthain , South Sulawesi, coll. Sarasin , 1901; 3 females ( NMB 23 Vd), Bonthain , South Sulawesi, coll. Sarasin , 1904; 1 female (21.7 x 17.6 mm) ( RMNH D 1285 ) (syntype of Telphusa celebensis De Man, 1892 , part), Luwu district, Diagnosis. – Carapace flat, dorsal surfaces smooth; cervical groove shallow, narrow; H-shaped central depression distinct. Epigastric and postorbital cristae continuous, sharp, subparallel to frontal margin; outer edge of cristae reaches anterolateral margin, stopping just anterior of base of second epibranchial tooth. Front entire, straight; frontal median triangle distinct, incomplete, dorsal margin weak. External orbital angle broadly triangular, outer margin sinuous, serrate, about 2 times length of inner margin, first epibranchial tooth weakly demarcated from external orbital angle, appears somewhat confluent in some specimens, outer margin serrate, second epibranchial tooth low, blunt, relatively broad, directed obliquely, outer margins serrate. Anterolateral margin convex, lined with oblique striae. Posterolateral region lined with oblique striae. Suture between thoracic sternites 2 and 3 complete, almost straight. Palm of chelipeds inflated, longer than pollex. Ambulatory legs long, second pair longest. Ambulatory merus broad. Dorsal margin of merus with slight cristae, without distinct subterminal spine, although there is usually a small angle present which may be sharp. 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 gently curving outwards, directed upwards, outer margin almost straight, proximal part not clefted; distal part gently tapering; tip gently flared. G2 with well developed distal segment, about 0.6 times length of basal segment .

Distribution. – South and Central Sulawesi.

Remarks. – Parathelphusa lokaensis was first described by De Man (1892) as a variety of P. celebensis from specimens obtained from Loka, close to Bonthain. Examination of the topotype material from Bonthain, and comparing with congeneric materials, confirms that P. lokaensis is a valid species (cf. Bott, 1970c: 126). In the RMNH are two syntype males, and RMNH D 1286 is here designated as the lectotype of the species.

Parathelphusa lokaensis differs from its Sulawesi congeners by having an external orbital angle that is broadly triangular, with the outer margin uneven to sinuous. Its first epibranchial tooth is also almost confluent with the external orbital angle, and the second epibranchial tooth is relatively broad, low and blunt. The anterolateral margin of P. lokaensis is distinctively serrate, even more so when compared to P. celebensis . All these characters, combined with its relatively broad ambulatory merus, easily distinguishes P. lokaensis from the other Parathelphusa species known from Sulawesi.

The type of P. lokaensis was from Bonthain in southern Sulawesi, and the present record of it from Sungai Laempur (Malili) and near Palopo in the central part of the island is rather surprising. Yet comparisons of the specimens do not show any major differences. The only difference noteworthy is that the specimens from central Sulawesi have the first epibranchial tooth somewhat lower and less discernible. Their G 1 structures, however, are very similar. Of course, since the specimens from Central Sulawesi are not adult males (Malili: one young male and one juvenile, MZB 646; Palopo: one female specimen, RMNH D 1285, part of the type series of P. celebensis ), not that much more can be said. When adult males from this locality become available, differences may avail themselves. For the moment, despite the fact that we are dealing with an apparently more highland taxon from three disjunct localities, it seems best to regard the specimens as one species .

Figures

Fig. 4. Parathelphusa lokaensis (De Man, 1892), lectotype male (24.3 x 20.0 mm, RMNH D 1286): A, dorsal view; B, frontal view; C, ventral view.

Fig. 5. Parathelphusa lokaensis (De Man, 1892), male (24.5 x 20.2 mm, NMB 23Vc): A, dorsal view; B, frontal view; C, ventral view.

Fig. 6. Left G1 and G2. A-E, Parathelphusa lokaensis (De Man, 1892), lectotype male (24.3 x 20.0 mm, RMNH D 1286): A, G1 dorsal view; B, G1 ventral view; C, G1 dorsal part, ventral view; D, G1 distal part, ventral view; E, G2. F-J, Parathelphusa lokaensis (De Man, 1892), male (24.5 x 20.2 mm, NMB 23Vc): F, G1 ventral view; G, G1 dorsal view; H, G1 distal part, ventral view; I, G1 distal part, dorsal view; J, G2. Scale bars = 1.0 mm.