The freshwater crabs of Madagascar (Crustacea, Decapoda, Potamoidea) Neil CUMBERLIDGE Department of Biology, Northern Michigan University, Marquette, MI, 49855 (USA) [email protected] Richard V. STERNBERG NHB-163, Department of Invertebrate Zoology, Smithsonian Institution, Washington D.C., 20560 (USA) [email protected] Cumberlidge N. & Sternberg R.V. 2002. — The freshwater crabs of Madagascar (Crustacea, Decapoda, Potamoidea). Zoosystema 24 (1) : 41-79. ABSTRACT The taxonomy of the freshwater crabs of Madagascar is revised and the num- ber of genera raised from five to six. Two new genera are erected and one genus is synonymised. Hydrothelphusa is revised with four species: H. agilis A. Milne-Edwards, 1872, H. madagascariensis (A. Milne-Edwards, 1872), H. bombetokensis (Rathbun, 1904) and H. goudoti (H. Milne Edwards, 1853) n. comb. Malagasya n. gen. is established to accommodate two species, M. antongilensis (Rathbun, 1905) and M. goodmani (Cumberlidge, Boyko & Harvey, 2002); Marojejy Cumberlidge, Boyko & Harvey, 2002 and Madagapotamon Bott, 1965 are recognised as monotypic genera, Skelosophusa remains unchanged, and Boreas n. gen. is established for one species B. uglowi KEY WORDS Crustacea, n. sp. The genus Gecarcinautes Bott, 1960 is here synonymised with Decapoda, Potamonautes Macleay, 1838 and its former taxa are referred to other genera. Brachyura, Potamoidea, All six genera of freshwater crabs found in Madagascar are endemic and all are freshwater crabs, here referred to the Potamonautidae. A new diagnosis for each of the Madagascar, 12 species is provided, many are redescribed, and most are figured from the identification keys, new genera, type. Keys to the genera and species of the Madagascan freshwater crabs are new species. provided, together with species distribution maps and a gazetteer. ZOOSYSTEMA • 2002 • 24 (1) © Publications Scientifiques du Muséum national d’Histoire naturelle, Paris. www.mnhn.fr/publication/ 41 Cumberlidge N. & Sternberg R. V. RÉSUMÉ Les crabes d’eau douce de Madagascar (Crustacea, Decapoda, Potamoidea). La taxonomie des crabes d’eau douce de Madagascar est révisée et le nombre de genres passe de cinq à six. Deux nouveaux genres sont créés et un genre entre en synonymie. Hydrothelphusa est révisé, avec quatre espèces : H. agilis A. Milne- Edwards, 1872, H. madagascariensis (A. Milne-Edwards, 1872), H. bombetokensis (Rathbun, 1904) et H. goudoti (H. Milne Edwards,1853) n. comb. Malagasya n. gen. est établi et comprend deux espèces M. antongilensis (Rathbun, 1905) et M. goodmani (Cumberlidge, Boyko & Harvey, 2002) ; Marojejy Cumberlidge, Boyko & Harvey, 2002 et Madagapotamon Bott, 1965 sont reconnus comme genres monotypiques ; Skelosophusa reste inchangé et Boreas n. gen. est établi pour une espèce B. uglowi n. sp. Le genre Gecarcinautes Bott, 1960 entre ici en MOTS CLÉS Crustacea, synonymie avec Potamonautes Macleay, 1838 et ses taxons correspondants sont Decapoda, rapportés à d’autres genres. Les six genres de crabes d’eau douce trouvés à Brachyura, Potamoidea, Madagascar sont tous endémiques et appartiennent à la famille des crabes d’eau douce, Potamonautidae. Une nouvelle diagnose pour chacune des 12 espèces est four- Madagascar, nie, beaucoup de ces espèces sont redécrites et la plupart sont figurées d’après le clés d’identification, nouveaux genres, type. Les clés des genres et des espèces des crabes d’eau douce malgaches sont don- nouvelle espèce. nées ainsi que des cartes de répartition et un répertoire géographique des espèces. INTRODUCTION thelphusa) ankaraharae Nobili, 1905, and P.(Geothelphusa) methueni Calman, 1913. Later, The present work was prompted by an examina- Pretzmann (1961) recognised the genus Bottia tion of a large previously unidentified collection of Pretzmann, 1961 with one species, H. madagas- freshwater crabs from Madagascar in the MNHN, cariensis, and a new subspecies, B. madagascariensis Paris, and by the acquisition of new specimens reticulata Pretzmann, 1961. from the island deposited in the Field Museum, Bott (1965) was the first to publish a treatment Chicago, and the AMNH, New York. The new of the Madagascan freshwater crab fauna in its material from Madagascar included three new entirety. That work (Table 1) considered 13 taxa taxa (Cumberlidge et al. 2002) and provided good from the island (as seven species, two subspecies series with excellent specimens of existing taxa. and four synonyms), but overlooked P. (P.) pit- The first three freshwater crabs to be described tarrelli. Bott (1965) placed the Madagascan from Madagascar were Thelphusa goudoti freshwater crabs in three genera. Three taxa were H. Milne Edwards, 1853, T. madagascariensis assigned to Hydrothelphusa: H. agilis agilis, A. Milne-Edwards, 1872, and Hydrothelphusa H. a. madagascariensis, and H. humbloti, three agilis A. Milne-Edwards, 1872. Rathbun’s (1904, to Gecarcinautes Bott, 1960: G. antongilensis 1905, 1906) complete revision of the taxonomy antongilensis, G. antongilensis vondrozi Bott, 1965 of the freshwater crabs of the world recognised and G. goudoti, and three to Madagapotamon seven taxa from Madagascar. That author Bott, 1965: M. humberti Bott, 1965, M. gollhardi assigned one of these to Hydrothelphusa (H. agilis) Bott, 1965 and M. ankaraharae. Bott (1965) and five to Potamon (Potamon): P. (P.) madagas- treated the remaining taxa as follows: two (P. [P.] cariensis, P. (P.) bombetokensis Rathbun, 1904, bombetokensis and P. [P.] grandidieri) were consi- P. (P.) humbloti Rathbun, 1904, P. (P.) grandi- dered to be junior synonyms of H. humbloti, dieri Rathbun, 1904, and P. (P.) goudoti, and one Bottia was viewed as a junior synonym of to Potamon (Parathelphusa): P. (P.) antongilensis Gecarcinautes, and B. madagascariensis reticulata Rathbun, 1905. Further additions included was treated as a junior synonym of H. agilis P. (Potamon) pittarelli Nobili, 1905, P. (Geo- madagascariensis. 42 ZOOSYSTEMA • 2002 • 24 (1) Freshwater crabs (Crustacea, Decapoda) of Madagascar TABLE 1. — Summary of original names of taxa from Madagascar and the names of species recognised in the present work. Original taxon name Present work Thelphusa goudoti H. Milne Edwards, 1853 Hydrothelphusa goudoti (H. Milne Edwards, 1853) Thelphusa madagascariensis A. Milne-Edwards, 1872 Hydrothelphusa madagascariensis (A. Milne-Edwards, 1872) Hydrothelphusa agilis A. Milne-Edwards, 1872 Hydrothelphusa agilis A. Milne-Edwards, 1872 Potamon (Potamon) humbloti Rathbun, 1904 Hydrothelphusa madagascariensis (A. Milne-Edwards, 1872) Potamon (Potamon) grandidieri Rathbun, 1904 Hydrothelphusa madagascariensis (A. Milne-Edwards, 1872) Potamon (Potamon) bombetokensis Rathbun, 1904 Hydrothelphusa bombetokensis (Rathbun, 1904) Potamon (Parathelphusa) antongilensis Rathbun, 1905 Malagasya antongilensis (Rathbun, 1905) n. comb. Potamon (Geothelphusa) ankaraharae Nobili, 1906 incertae sedis Potamon (Potamon) pittarrelli Nobili, 1905 ?Malagasya antongilensis (Rathbun, 1905) n. comb. Potamon (Geothelphusa) methueni Calman, 1913 Hydrothelphusa goudoti (H. Milne Edwards, 1853) Bottia madagascariensis reticulata Pretzmann, 1961 Hydrothelphusa madagascariensis (A. Milne-Edwards, 1872) Gecarcinautes antongilensis vondrozi Bott, 1965 Malagasya antongilensis (Rathbun, 1905) n. comb. Madagapotamon humberti Bott, 1965 Madagapotamon humberti Bott, 1965 Madagapotamon gollhardi Bott, 1965 Skelosophusa gollhardi (Bott, 1965) Skelosophusa prolixa Ng & Takeda, 1994 Skelosophusa prolixa Ng & Takeda, 1994 Skelosophusa eumeces Ng & Takeda, 1994; Skelosophusa eumeces Ng & Takeda, 1994 Marojejy longimerus Cumberlidge et al., 2002 Marojejy longimerus Cumberlidge et al., 2002 Gecarcinautes goodmani Cumberlidge et al., 2002 Malagasya goodmani (Cumberlidge et al., 2002) n. comb. Boreas uglowi n. gen. n. sp. Boreas uglowi n. gen., n. sp. Bott (1965) referred the three Madagascan gen- and S. eumeces Ng & Takeda, 1994, and revived era to three different subfamilies, Hydro- discussion of the taxonomic position of P. (P.) pitta- thelphusinae Bott, 1955, Gecarcinucinae relli. Recently, Cumberlidge et al. (2002) Rathbun, 1904, and Potamoninae Bott, 1955, described Marojejy Cumberlidge, Boyko & based primarily on differences in the form of the Harvey, 2002 and added two new species: terminal segment of the mandibular palp. Marojejy longimerus Cumberlidge, Boyko & According to Bott (1965) Madagapotamon Harvey, 2002 and Gecarcinautes goodmani included those taxa with a mandibular palp with Cumberlidge, Boyko & Harvey, 2002. The pres- a simple terminal segment (i.e. with no anterior ent work aims at a synthesis of the current know- process of any kind at the junction between the ledge of the freshwater crabs of Madagascar, and two segments). Hydrothelphusa included those includes a comprehensive revision of the taxono- taxa possessing a mandibular palp with a terminal my of these crabs (Tables 1; 2), together with segment with a small basal thickening, and species distribution maps (Fig. 11), a gazetteer Gecarcinautes included those taxa possessing a (Table 4), and identification keys to the genera mandibular palp with a deeply cleft, bilobed and species. terminal segment. Bott’s (1965) work remains the most recent, and HIGHER TAXONOMY indeed, the only available, comprehensive classifi- Bott’s (1970a, b) comprehensive revisions of the cation of the Madagascan freshwater crabs. higher taxonomy of the freshwater crabs of the However, since that work was written, further world recognised 11 families and three super- contributions to the knowledge of Madagascan