Parathelphusa ferruginea, Chia & Ng, 2006

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 : 406-408

Parathelphusa ferruginea , new species

( Figs. 25 , 26 F-J)

Material examined. – Holotype: male (36.0 x 28.5 mm) ( MZB 1491 ), Lake Towuti, Tanjung Timbala, southeast of Timampu , sand and rocks, South Sulawesi, 2 ° 42'37.7"S 121 ° 26'26.0"E, coll. C. D. Schubart et al., 25 Jan.2000 . Paratypes: 4 males, 5 females, 1 juvenile ( ZRC 2000.1715 ) , 2 males, 2 females ( MZB), same data as holotype ; 2 males, 2 females ( ZRC 2000.1687 ), Lake Towuti , Tanjung Bahasa , edge of cristae not reaching anterolateral margin, stopping distinctly before beginning of cervical groove. Front slightly sinuous, entire; frontal median triangle distinct. Anterolateral region with oblique striae, external orbital angle triangular, outer margin about 2 times length of inner margin, outer margin convex, tip of orbital angle extends to line with frontal margin, first and second epibranchial teeth sharp, acutely triangular. Posterolateral regions lined with distinct oblique striae. Suture between thoracic sternites 2 and 3 complete but weak, straight with respect to the buccal cavity. Palm of chelipeds slightly inflated, fingers shorter than palm, pollex and dactylus pigmented dark brown to black. Ambulatory legs relatively long, second pair longest. Dorsal margin of merus slightly cristate, with sharp, distinct subterminal spine. Male abdomen reaching imaginary line joining median point of anterior and posterior 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 without V-shaped cleft; distal part tapering with tip with flared opening. G2 with well developed distal segment, about 0.5 times length of basal segment .

Distribution. – Lake Towuti and Lake Mahalona, South Sulawesi.

Etymology. – “Ferruginea ” is Latin for rusty red colour. This species is so named for the rusty red carapace which is distinctive even for the three different leg-colour morphs.

Remarks. – Parathelphusa ferruginea seems to be represented by three colour morphs, namely specimens with yellow, purple and rusty red legs. Despite the differences in leg colour, all other external morphological characters and G1 characters are very similar to almost identical. Hence P. ferruginea , is recognised as a single species for the time being. It is possible that further morphological studies in the future, perhaps coupled with more extensive collections as well as molecular and other tools may provide a better resolution of the problem. Considering their distributions (in Lake Towuti and Lake Mahalona), it is quite possible that there is more than one species in what is here regarded as “ Parathelphusa ferruginea ”.

Parathelphusa ferruginea is distinct from members of the P. pallida - P. celebensis species group as well as P. lokaensis , in having a rugose, rusty-red carapace in life as well as in freshly preserved specimens, sharp, acutely triangular epibranchial teeth and a outer edge of the postorbital cristae that stops at the beginning of the cervical groove. Parathelphusa ferruginea is also distinct from the nearest geographical congener, P. pantherina , in having a rugose, rusty-red carapace, which in P. pantherina is smooth and spotted ( Fig. 25A vs. Fig. 1A ). The outer edge of the postorbital cristae of P. ferruginea stop just before the beginning of the cervical groove as compared to P. pantherina , whose postorbital cristae stops just before the base of the first epibranchial tooth ( Fig. 25A vs. Fig. 1A ). The external orbital angle of P. ferruginea reaches to a level in line with the frontal margin while that of P. pantherina does not reach the frontal margin ( Fig. 25A vs. Fig. 1A ). The epibranchial teeth of P. ferruginea are acutely triangular compared to P. pantherina which are triangular ( Fig. 25A vs. Fig. 1A ). Finally, the G1 tip of P. ferruginea has a more distinct flared opening compared to P. pantherina ( Fig. 26 FI vs. Fig. 3 A-D).

Figures

Fig. 25. Parathelphusa ferruginea, new species, holotype male (36.0 x 28.5 mm, MZB 1491): A, dorsal view; B, frontal view; C, ventral view.

Fig. 26. Left G1 and G2. A-E, Parathelphusa sorella, new species, holotype male (40.2 x 26.1 mm, ZRC 1990.490): A, G1 ventral view; B, G1 dorsal view; C, G1 distal part, ventral view; D, G1 distal part, dorsal view; E, G2. F-J, Parathelphusa ferruginea, new species, holotype male (36.0 x 28.5 mm, MZB 1491): 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.

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. 3. Left G1 and G2. A-E, Parathelphusa pantherina (Schenkel, 1902), paralectotype male (42.4 x 31.2 mm, NMB 21A): A, G1 ventral view; B, G1 dorsal view; C, G1 distal part, ventral view; D, G1 distal part, dorsal view; E, G2. F-I, Parathelphusa sarasinorum (Schenkel, 1902), lectotype male (38.9 x 31.5 mm, NMB 22B): F, G1 ventral view; G, G1 dorsal view; H, G1 distal part, ventral view; I, G1 distal part, dorsal view. Scale bars = 1.0 mm.