Migmathelphusa olivacea, 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 : 416-418

Migmathelphusa olivacea , new species

( Figs. 35 , 36 , 37D , 38D )

Material examined. – Holotype: male (33.2 x 29.1 mm) ( MZB 1486 ), Lake Poso , Tentena, on sand of lake and outlet, Central Sulawesi, coll. C. D. Schubart et al., 20-21 Jan.2000 . Paratypes - 7 males, 1 juvenile ( ZRC 2000.1702 ), same data as holotype ; 1 male, 1 female ( ZRC 2000.1683 ), Lake Poso, Pendola south coast on sand, Central Sulawesi, coll. C. D. Schubart et al., 22 Jan.2000 ; 3 males, 3 females, 1 juvenile ( ZRC 2000.1704 ) , 1 male, 1 female ( MZB 1487 ), Lake Poso, Tindolo east coast on sand, Central Sulawesi, coll. C. D. Schubart et al., 22 Jan.2000 .

Diagnosis. – Carapace narrowly transverse to squarish, flat, branchial and gastric regions slightly inflated, dorsal surfaces smooth, deep olive-green when live; cervical groove distinct, narrow; H-shaped central depression distinct. Epigastric cristae strong, sharp, subparallel to frontal margin; postorbital cristae weak to absent. Front entire with slight depression; Remarks. – Migmathelphusa olivacea shares characters of Nautilothelphusa zimmeri and Parathelphusa sarasinorum . It is similar to N. zimmeri in that M. olivacea has a rather squarish rather than transverse carapace, a broad last ambulatory propodus, a weak to absent postorbital cristae, slender fingers in which the pollex is subequal to the palm and its third pair of ambulatory merus is longer than the rest. However, M. olivacea differs from N. zimmeri in that it has a long slender G1 with the tip directed inwards (versus short) ( Fig. 36 A-D vs. Fig. 34 A-G), a G2 with a relatively longer distal segment (0.4 times basal segment vs. 0.3 times) ( Fig. 36E vs. Fig. 34H ), the absence of a sharp distinct subterminal spine on the ambulatory merus ( Fig. 35 vs. Fig. 32 , 33 ), the external orbital angle does not extend beyond the frontal margin ( Fig. 35A vs. Fig. 32A , 33A, B ) and the frontal margin is only slightly depressed and not deeply depressed medially as in N. zimmeri ( Fig. 35B vs. Fig. 32B ).

Superficially, M. olivacea resembles P. sarasinorum which is also found in Lake Poso in that the carapace of M. olivacea has a deep olive-green coloration with a yellow tinge on the margin. M. olivacea also has an external orbital angle that does not extend beyond the frontal margin and epibranchial teeth that are blunt, low, acutely triangular, directed forwards with the outer margins slightly truncate. However, M. olivacea is different in that it has inflated branchial and gastric regions ( Fig. 35A vs. Fig. 2A ). Migmathelphusa olivacea is here recognised as a new genus as it has a distinctive long slender G1 with its tip directed inwards, a G2 with a short distal segment as well as the unique and distinct combination of characters as noted above

Figures

Fig.35. Migmathelphusa olivacea, new genus, new species, holotype male (33.2 x 29.1 mm, MZB 1486): A, dorsal view; B, frontal view; C, ventral view.

Fig. 36. Left G1 and G2. Migmathelphusa olivacea, new genus, new species, holotype male (33.2 x 29.1 mm, MZB 1486): A, G1 ventral view; B, G1 dorsal view; C, G1 distal part, ventral view; D, G1 distal part, dorsal view; E, G2. Scale bars = 1.0 mm.

Fig.37.Frontal views showing posterior margin of epistome.A, Parathelphusa pantherina (Schenkel, 1902) (38.5 x 30.3 mm, ZRC 2000.1705), unfused margin; B, Syntripsa flavichela, new species, holotype male (59.1 x 46.7 mm, MZB 1483), fused margin; C, Nautilothelphusa zimmeri (Balss, 1933), male (42.7 x 37.4 mm, ZRC 2000.1711), unfused margin; D, Migmathelphusa olivacea, new genus, new species, holotype male (33.2 x 29.1 mm, MZB 1486), unfused margin.

Fig. 38. Third maxillipeds. A, Parathelphusa pantherina (Schenkel, 1902) (38.5 x 30.3 mm, ZRC 2000.1705), without median notch on anterior margin of merus; B, Syntripsa flavichela, new species, holotype male (59.1 x 46.7 mm, MZB 1483), with median notch on anterior margin of merus; C, Nautilothelphusa zimmeri (Balss, 1933), male (42.7 x 37.4 mm, ZRC 2000.1711), without median notch on anterior margin of merus; D, Migmathelphusa, new genus, new species, holotype male (33.2 x 29.1 mm, MZB 1486), without median notch on anterior margin of merus.

Fig. 34. Left G1 and G2. Nautilothelphusa zimmeri (Balss, 1933): A, D, G1 ventral view; E, G1 dorsal view; B, F, G1 distal part, ventral view; C, G, G1 distal part, dorsal view; H, G2. A-C, holotype male (23.2 x 20.5 mm, MZB 48); D-H, male (41.8 x 35.1 mm) (ZRC 2000.1711). Scale bars = 1.0 mm.

Fig.32.Nautilothelphusa zimmeri (Balss, 1933), holotype male (23.2 x 20.5 mm, MZB 48): A, dorsal view; B, frontal view; C, ventral view.

Fig. 33. Nautilothelphusa zimmeri (Balss, 1933), female specimens: A, 38.7 x 34.7mm (MZB 643) dorsal view; B, 38.7 x 33.3 (MZB 643), dorsal view; C, 38.7 x 33.3 (MZB 643), 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.