The freshwater crabs of Madagascar (Crustacea, Decapoda, Potamoidea) Author Cumberlidge, Neil Department of Biology, Northern Michigan University, Marquette, MI, 49855 (USA) ncumberl @ nmu. edu ncumberl@nmu.edu Author Sternberg, Richard V. NHB- 163, Department of Invertebrate Zoology, Smithsonian Institution, Washington D. C., 20560 (USA) Sternberg. Richard @ nmnh. si. edu. ichard@nmnh.si.edu text Zoosystema 2002 24 1 41 79 journal article 10.5281/zenodo.5401510 1638-9387 5401510 Skelosophusa gollhardi ( Bott, 1965 ) ( Figs 2A ; 4I ; 5I ; 6I ; 7M, N ; 10E, F ; 11I ) Madagapotamon gollhardi Bott, 1965: 346 , fig. 8, pl. 5, figs 19-22. Skelosophusa gollhardi – Ng & Takeda 1994: 164 , 165, fig. 1a-f, table 3. MATERIAL EXAMINED. — Madagascar . Grotte de l’Ankara, 23.VII.1939 , coll. R. Decary, 1 ad. , holotype of Madagapotamon gollhardi Bott, 1965 , cw 23, cl 16, ch 7.5, fw 6 mm ( MNHN-B 5165). TYPELOCALITY. — Grotte de l’Ankara, Madagascar . DISTRIBUTION. — Madagascar ( Fig. 11I ). This species is known only from the type locality. DIAGNOSIS. — Epigastric, postorbital crests weak, rugose, not joined. Cervical groove very short, shallow. Field of dense, short hair on carapace sidewall in pterygostomial region. Ratio length p5 merus to cw 0.63, ratio length p5 merus cl 0.91, ratio length first gonopod terminal article to subterminal segment 0.35. DESCRIPTION See Ng & Takeda (1994) . Size The adult size range is from cw 23 mm . The carapace proportions are given in Table 3. REMARKS Skelosophusa gollhardi is known only from the holotype collected from a cave near Ankara. Ng & Takeda (1994) considered S. gollhardi to be closest to S. prolixa based on carapace characters but cited “significant” differences in the form of the first gonopod and in the relative length of the merus of p5. It is difficult to discern significant differences between gonopod 1 of the two species as illustrated by Ng & Takeda (1994 : fig. 1a, c-f, 2a-f, h, i), and the proposed species boundaries defined by the relative length of the merus of p5 may not be robust ( Ng & Takeda 1994 : table 3). For example, although the ratio of the length of the merus of p5 to cl of S. prolixa is 0.75 (which is close to 0.73, 0.74 of Ng & Takeda 1994 ) the ratio of the length of the merus of p5 to cw of S. gollhardi is 0.51 (not 0.73, 0.74). Skelosophusa prolixa Ng & Takeda, 1994 ( Figs 2B ; 4J ; 5J ; 6J ; 8H ; 11J ) Skelosophusa prolixa Ng & Takeda, 1994: 166 , table 3, figs 2a-c, 3a, 5a-i, 6 k-n. MATERIAL EXAMINED. — Madagascar . Nosy-Bé, rivière de la route des lacs, 23.XI.1972 , coll. A. Crosnier, 1 ad. cw 25.6, cl 18.8, ch 9.3, fw 7.1 mm ( MNHN-B 25734). TYPELOCALITY. — Grotte nord de l’Ankara, Berges Sable, Madagascar . DISTRIBUTION. — Madagascar ( Fig. 11J ). This species is known only from the type locality. DIAGNOSIS. — Epigastric crests, postorbital crests weak, low, smooth. Cervical groove long, shallow. Dense field of hairs on carapace sidewall in pterygostomial region. Ratio length merus p5 to cw 0.51, ratio length p5 merus cl 0.75, ratio length first gonopod terminal article to subterminal segment 0.38. DESCRIPTION See Ng & Takeda (1994) . Size The adult size range is from cw 24 mm . The carapace proportions are given in Table 3. REMARKS Our recalculations of the length of the merus of p5 relative to the carapace dimensions based on diagrams and photographs of S. prolixa in Ng & Takeda (1994) (see above) indicate different values for these diagnostic dimensions from those reported by Ng & Takeda (1994 : table 3). A B C FIG. 8. — Last walking leg (pereiopod 5) of adult males of Madagascan freshwater crabs (H based on Ng & Takeda 1994 ); A , Hydrothelphusa agilis A. Milne-Edwards, 1872 ; B , H. madagascariensis (A. Milne-Edwards, 1872) ; C , H. bombetokensis ( Rathbun, 1904 ) ; D , H. goudoti (H. Milne Edwards, 1853 ) n. comb. ; E , Boreas uglowi n. gen., n. sp. ; F , Marojejy longimerus Cumberlidge, Boyko & Harvey, 2002 ; G , Madagapotamon humberti Bott, 1965 ; H , Skelosophusa prolixa Ng & Takeda, 1994 ; I , Malagasya antongilensis ( Rathbun, 1905 ) n. comb. ; J , M. goodmani (Cumberlidge, Boyko & Harvey, 2002) n. comb. Scale bar: A-D, 5.0 mm; E-L, 2.6 mm. Skelosophusa eumeces Ng & Takeda, 1994 ( Figs 2C ; 4K ; 5K ; 6K ; 11K ) Skelosophusa eumeces Ng & Takeda, 1994: 166 , 169, 171, table 3, figs 3b, 4, 6a-g, j, o. MATERIAL EXAMINED. — Madagascar . Andrafiabe, 1 ad. , holotype of Skelosophusa eumeces Ng & Takeda, 1994 cw 22.7, cl 15.8 mm ( MRSN ). TYPELOCALITY. — Andrafiabe, Madagascar . DISTRIBUTION. — Madagascar ( Fig. 11K ). This species is known only from the type locality. DIAGNOSIS. — Epigastric, postorbital crests distinct, rugose. Cervical groove broad, distinct, short. Ratio length p5 merus to cw 0.56, ratio length p5 merus to cl 0.82, ratio length first gonopod terminal article to subterminal segment 0.35. Size The adult size range is from cw 24 mm . The carapace proportions are given in Table 3. REMARKS Our recalculations of the length of the merus of p5 relative to the carapace dimensions based on the diagrams and photographs of S. eumeces in Ng & Takeda (1994) indicate different values for these diagnostic dimensions from those reported by Ng & Takeda (1994 : table 3). For example, the ratio of the length of the merus of p5 to cw in S. eumeces is 0.56 (not 0.82) and the ratio of the terminal article to subterminal segment length of gonopod 1 in S. eumeces is 0.35 (not 0.43).