Parathelphusa sorella, 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 : 403-406

Parathelphusa sorella , new species

( Figs. 24 , 26 A-E)

Material examined. – Holotype: male (40.2 x 26.1 mm) ( ZRC 1990.490 ), Gua Saripah, near Teduang village , Maros, South Sulawesi, coll. P. Leclerc, 25 Jul.1989 . Paratypes: 1 male (47.4 x 30.7 mm) ( ZRC, ex. MZB 006 ), Gua Saripa, lake, Samanggi, Kabupaten Maros , South Sulawesi, 5 ° 2'35.2"S 119 ° 42'9"E, coll. C. Rahmadi & F. Brehier, 2 Aug.2001 ; 1 female (39.7 x 26.4 mm) ( MZB 13 ) , 1 female (23.0 x 15.4 mm) ( ZRC, ex MZB 13 ), Gua Saripa, Samanggi, Kabupaten Maros , South Sulawesi, 5 ° 2'35.2"S 119 ° 42'9"E, coll. L. Deharveng, I. Andayani & A. Bedos, 2 Aug.2001 ; 1 female (43.0 x 28.6 mm) ( ZRC ex MZB 2002.006 ), Gua Saripa, gallery Cacing, Kecamatan Simbang , Kabupaten Maros , South Sulawesi, coll. C. Rahmadi, 18 Apr.2002 ; 1 male (43.1 x 28.0 mm) ( MZB 2002.0001 ), Gua Saripa, lake, Kecamatan Simbang, Kabupaten Maros , coll. Y. R. Suhardjono & C. Rahmadi, 18 Apr.2002 ; 1 male (22.9 x 15.0 mm) ( ZRC, ex MZB), spring of Saripa, Samanggi, Kabupaten Maros , South Sulawesi, coll. A. Bedos, 25 Aug.2002 .

Diagnosis. – Carapace convex, branchial regions highly inflated, dorsal surfaces smooth; cervical groove deep and distinct; H-shaped central depression shallow. Epigastric and postorbital cristae continuous, shallow but distinct, subparallel to frontal margin; outer edge of cristae not reaching anterolateral margin, stopping at start of cervical groove. Front sinuous, entire, median point with distinct depression; frontal median triangle distinct, dorsal ridge absent. Cornea of eye reduced. Anterolateral margin smooth, diverges sharply after external orbital angle, external orbital angle broadly triangular, low, outer margin almost straight, about 3.0 times length of inner margin, first and second epibranchial teeth very low almost continuous with anterolateral margin. Posterolateral regions lined with distinct oblique striae. Suture between thoracic sternites 2 and 3 incomplete, concave towards buccal cavity. Suture between thoracic sternites 3 and 4 complete, forming 2 convex semicircles towards buccal cavity, resembling a “W” shape, reaching suture between sternites 2 and 3. Palm of chelipeds slightly inflated, fingers longer than palm. Ambulatory legs relatively short, second pair longest. Dorsal margin of merus slightly cristate, without distinct subterminal spine. Male abdomen reaching imaginary line joining anterior edges of cheliped bases, T-shaped, segment 6 subequal to segment 7; lateral margins of segment 7 gently concave; lateral margins of segment 6 subparallel, gently sinuous. G1 relatively long, slender, distinctly curved, directed upwards, outer margin concave along distal two-thirds, proximal part without cleft; distal part sharply tapering. G2 with well developed distal segment, about 0.6 times length of basal segment.

Distribution. – Caves in the vicinity of Maros, South Sulawesi.

Etymology. – “Sorella ” is Greek for an old man with a foot in the grave. This species is so named alluding to it being found in caves, which is often associated in Greek myths as the entrance to the underworld. The name is used as a noun in apposition.

Remark s. – The sole male holotype of Parathelphusa sorella was collected from within a cave. This species is likely to be a cavernicolous species as it possess reduced corneas similar to the cavernicolous freshwater crabs described by Holthuis (1979, 1980) from Borneo and New Guinea and Ng and Sket (1996) from Bohol, Philippines. This species is closely allied to P. pallida and P. celebensis and is a member of this complex. It is closer to P. pallida in that its first and second epibranchial teeth are very low and almost continuous with the anterolateral margin. It resembles P. celebensis in that its dorsal ridge of the frontal median triangle is absent. It is also similar to P. pareparensis in that the fingers of its cheliped are also longer than the palm and that the outer edge of the postorbital cristae ends at the start of the cervical groove.

However, it differs from P. pallida , P. celebensis and P. pareparensis in a number of distinctive characters. Firstly, the branchial regions of P. sorella are highly inflated, to the extent that the anterolateral margin diverges sharply even after the second epibranchial teeth ( Fig. 24A, B ). The branchial regions of its three closest congeners, P. pallida , P. celebensis and P. pareparensis are not as inflated and swollen ( Figs. 8A , 9-13A , 17-19A ). Secondly, the frontal margin of P. sorella is sinuous, with a distinct depression in its median point as compared to those of P. pallida , P. celebensis and P. pareparensis , which are straight ( Fig. 24A vs. Figs. 9- 13A , 17-19A ). However, the value of the character of the sinuous frontal margin is difficult to ascertain. Ng and Tan (1998) in their remarks for Isolapotamon naiadis Ng, 1986 , from Borneo, mentioned that the form of the frontal margin varies with size and becomes more sinuous and lower in large specimens. This is especially so in specimens with inflated or swollen branchial regions (as in the case of P. sorella ), and the frontal margin could then be more sinuous. The lack of a large series of specimens of P. sorella for examination of the frontal margin for size variation makes a clearer conclusion difficult.

large rocks (south of Timampu), South Sulawesi, 2 ° 40'53.5"S 121 ° 26'06.9"E, coll. C. D. Schubart et al., 25 Jan.2000; 8 males, 1 female ( ZRC 2000.1690 ), Lake Towuti, Timbala, southeast Timampu , sand and rocks, South Sulawesi, coll. C. D. Schubart et al., 25 Jan.2000 ; 3 males, 2 females ( ZRC 2000.1689 ), Lake Towuti, Timbala, southeast Timampu , sand and rocks, South Sulawesi, coll. C.D Schubart et al., 25 Jan.2000 ; 4 females ( ZRC 2000.2558 ), Lake Towuti, about 8 km south of Timampu , between Tandjung Subalaoteh and Tandjung Petea (Station 8), South Sulawesi, coll. M. Kottelat, 2 Jul.1988 ; 1 female ( ZRC 2000.2559 ), Lake Towuti, station 1, about 3 km south of Timampu, estuary of Sungai Batuopa , South Sulawesi, coll. M. Kottelat, 22 Jun.1988 ; 1 male, 2 females ( ZRC 2000.2560 ), Lake Towuti, about 8 km south of Timampu , between Tandjung Subalaoteh and Tandjung Petea (Station 8), South Sulawesi, coll. M. Kottelat, 2 Jul.1988 ; 1 male ( MNHB 27373 ), Lake Towuti , South Sulawesi, 2 ° 50.74'S 121 ° 26.09'E, coll. M. Glaubrecht & T. von Rintelen, 21 Aug.1999 ; 1 male, 1 female ( MNHB 27370 ), Lake Towuti , South Sulawesi, 02 ° 40.89'S 121 ° 41.49'E, coll. Brinkmann & T. von Rintelen, 1 Apr.2000 . Others : 3 males, 2 females ( ZRC 2000.1692 ) , 1 female ( MZB 1492 ), Lake Mahalona (north and northwest coast), under rocks and sandstone terraces, South Sulawesi, 2 ° 33'54.3"S 121 ° 29'44.1"E and 2 ° 34'42.2"S 121 ° 29'06.2"E, coll. C. D. Schubart et al., 27 Jan.2000 ; 1 female ( ZRC 2000.1693 ), Sungai Mahalona, ca. 2 km from Lake Mahalona , clinging to rock in strong current, South Sulawesi, 2 ° 36'38.1"S 121 ° 31'51.7"E, coll. C. D. Schubart et al., 27 Jan.2000 .

Diagnosis. – Carapace slightly inflated, rusty-red in life, dorsal surfaces rugose; cervical groove shallow, indistinct; H-shaped central depression distinct. Epigastric and postorbital cristae continuous, sharp, subparallel to frontal margin, with slight cleft at beginning of cervical groove; outer The cornea of the eye of P. sorella is very much reduced in comparison to P. pallida , P. celebensis and P. pareparensis . The cornea of the eye can show slight variability within some species of Sundathelphusa (see Ng & Sket, 1996) from the Philippines, but not to the degree observed here for P. sorella . The suture between thoracic sternites three and four of P. sorella is complete, forming two convex semicircles towards the buccal cavity, resembling a “W” shape, that reaches the suture of sternites two and three. Although it shares some characters with P. pareparensis , P. sorella differs in having comparatively shorter ambulatory dactyli ( Fig. 24 ), similar in condition to P. celebensis and P. pallida but different from the proportionately longer ambulatory dactyli of P. pareparensis ( Fig. 18 , 19A, B ). Lastly, compared to P. pallida , P. celebensis and P. pareparensis , P. sorella possesses, relatively, the longest and most slender G1, which curves distinctively outwards ( Fig. 26 A-D).

Figures

Fig. 24. Parathelphusa sorella, new species, holotype male (40.2 x 26.1 mm, ZRC 1990.490): 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. 8. Parathelphusa celebensis (De Man, 1892), lectotype male (18.8 x 15.2 mm, RMNH D 2385): A, dorsal view; B, frontal view; C, ventral view.

Fig. 9. Parathelphusa celebensis (De Man, 1892), paralectotype female (26.6 x 20.9 mm) (RMNH D 2385): A, dorsal view of carapace; B, frontal view.

Fig. 10. Parathelphusa celebensis (De Man, 1892), male (33.3 x 26.1 mm, NMB 23IVa): A, dorsal view; B, frontal view; C, ventral view.

Fig. 11. Parathelphusa celebensis (De Man, 1892), 1 male (33.3 x 26.1 mm) (lectotype of Potamon (Potamonautes) celebense var. immaculata Schenkel, 1902): A, dorsal view; B, frontal view; C, ventral view.

Fig. 12. Parathelphusa pallida (Schenkel, 1902), lectotype male (23.9 x 18.3 mm, NMB 23VIb): A, dorsal view; B, frontal view; C, ventral view.

Fig. 13. Parathelphusa pallida (Schenkel, 1902), female (NMB 23 Ia) (lectotype of Potamon (Potamonautes) celebensis var.annulipes Schenkel, 1902): A, dorsal view; B, frontal view; C, ventral view.

Fig. 17. Parathelphusa pareparensis, lectotype male (22.3 x 17.6 mm) (RMNH D 2587): A, dorsal view; B, frontal view.

Fig. 18. Parathelphusa pareparensis (De Man, 1892), male (29.5 x 22.9 mm, ZRC 2000.2570): A, dorsal view; B, frontal view; C, ventral view.

Fig. 19. Parathelphusa pareparensis (De Man, 1892), young female (25.8 x 19.9 mm) (ZRC 2000.2570), photographed shortly after preservation showing fresh coloration pattern: A, dorsal view; B, dorsal view of carapace; C, frontal view.