Parathelphusa ceophallus Ng, 1993

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 : 391-393

Parathelphusa ceophallus Ng, 1993

( Fig. 7 )

Parathelphusa ceophallus Ng, 1993: 179 , Figs. 1 , 2 .

Material examined. – Holotype: male (23.1 x 18.1mm) ( RMNH D 42418 ), Jismil Camp, a few kilometres from Labuhan Tobela, along Sungai (River) Labuhan Tobela , rivulet through hardly disturbed primary evergreen rainforest, boulder covered with calcareous deposits, 150 m, northern Pulau Buton , 4 ° 26'30"S 122 ° 59'E, Southeast Sulawesi, coll. J. van Tol, 12-18 Nov.1989.

Diagnosis. – Carapace dorsal surfaces smooth; cervical groove shallow, narrow; H-shaped central depression pronounced; branchial regions slightly inflated. Epigastric and postorbital cristae continuous, sharp, subparallel to frontal margin, with slight cleft at beginning of cervical groove; outer edge of cristae not reaching anterolateral margin, stopping before very shallow cleft separating first and second epibranchial teeth. Front slightly sinuous, entire; frontal median triangle distinct, but upper ridged margin does not join lateral margins, separated by small but distinct gap. Anterolateral margin arcuate, weakly cristae, external orbital angle broadly triangular, outer margin almost straight, about 3 times length of inner margin, first and second epibranchial teeth very low, lobiform, barely discernible. Posterolateral regions lined with distinct oblique striae. Suture between thoracic sternites 2 and 3 incomplete, gently concave towards buccal cavity. Palm of chelipeds slightly inflated, fingers longer than palm, pollex not pigmented black but dactylus 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 gently concave; lateral margins of segment 6 subparallel, gently sinuous. G1 relatively straight, directed upwards, outer margin gently sinuous along distal two-thirds, proximal part with very deep V-shaped cleft; distal part tapering. G2 with well developed distal segment, about 0.6 times length of basal segment. (Adapted from Ng, 1993)

Distribution. – Pulau Buton, Southeast Sulawesi.

Remarks. – Ng (1993), commented that P. ceophallus is most similar to species of the P. celebensis - P. pallida complex. However, it can be distinguished from the P. celebensis complex in that it possess a cleft on the postorbital cristae where the cervical groove begins ( Fig. 7A ) versus the cleft being absent in other species of the complex. The dorsal margin of the frontal median triangle of P. ceophallus is also separated from the lateral margins by a distinct gap ( Fig. 7C ). Parathelphusa ceophallus also possess a very distinct, broad and deep V-shaped cleft along the proximal outer margin of its G1, against a shallow cleft or the margin appearing entire that the other species of the complex possess ( Fig. 7H, I ).

The other two characters that Ng (1993) used to differentiate P. ceophallus from the rest of the complex, namely a low, less distinct epibranchial teeth and the outer edge of the postorbital cristae stopping well before the anterolateral margin are no longer applicable as several poorly known taxa in this group are now better understood. While they work for P. pallida and P. celebensis s. str., P. possoensis , P. crocea and P. linduensis all have very low epibranchial teeth that are almost continuous with the anterolateral margin like P. ceophallus . Parathelphusa linduensis and P. sorella also have its outer edge of the postorbital cristae stopping well before the anterolateral margin. However, P. ceophallus , can still be distinguished from these on the basis of the form of its cervical groove, frontal median triangle and G1 (see also Ng, 1993). It is also the only member of the species complex known from Pulau Buton thus far.

Figures

Fig. 7. Parathelphusa ceophallus Ng, 1993, holotype male (23.1 x 18.1mm) (RMNH D 42418): A, right dorsal view of carapace; B, frontal view of carapace; C, frontal median triangle; D, anterior thoracic sternum; E, male abdominal segmenst 4-6 and telson; F, left third maxilliped; G, right fourth ambulatory leg; H, left G1 ventral view; I, left G1 dorsal view; J, left G1 distal part, ventral view; K, left G1 distal part, dorsal view; L, left G2 (after Ng, 1993: Figs. 1, 2). Scale bars: A-G = 1.0 mm; H, I, L = 0.5 mm; J, K = 0.25 mm.

Fig. 1. Parathelphusa pantherina (Schenkel, 1902), paralectotype male (42.4 x 31.2 mm, NMB 21A): A, dorsal view; B, frontal view; C, ventral view.

Fig. 2. Parathelphusa sarasinorum (Schenkel, 1902), lectotype male (38.9 x 31.5 mm, NMB 22B): A, dorsal view; B, frontal view; C, ventral view.