Two new sibling species of Mantidactylus comutus from Madagascar (Amphibia, Anura, Ranidae) Frank Glaw & Miguel Vences Glaw, F. & M. Vences (2001): Two new sibling species of Mantidactylus comutus from Madagascar (Amphibia, Anura, Ranidae). -Spixiana 24/2: 177-190 A review of the Malagasy frogs which in the past were subsumed under the name Mantidactylus redimitus, together with new field data, led to the confirmation of the specific validity of M. comutus and to the recognition of two new species: M. tschenki, spec. nov. from Ranomafana is morphologically similar to M. comutus but shows distinct differences in advertisement call and has a slightly bilobed (instead of a roundish) subgular vocal sac. M. tandroka, spec. nov. from higher elevations of the Marojezy massif is disHnguished by a wide head, distinct dorsal ridges, and colouration from M. comutus, M. tschenki, and M. redimitus. The discov-ery of close syntopy of M. redimitus and M. comutus in central eastern Madagascar corifirms that they represent valid species and that advertisement calls are good indicators for specific distinctness in Malagasy anurans. Frank Glaw, Zoologische Staatssammlung, Münchhausenstr. 21, D-81247 München, Germany. E-mail:
[email protected] Miguel Vences, Museum national d'Histoire naturelle, Laboratoire des Reptiles et Amphibiens, 25 rue Cuvier, 75005 Paris, France. E-mail:
[email protected] Introduction During the last decades it has become evident that the analysis of advertisement calls is crucial to understand the species diversity of anurans (e.g. Passmore & Carruthers 1995). This is especially true for tropical anuran communities like those in Madagascar which are poorly studied and where numerous new amphibian species are still to be discovered and described. A significant percentage of the recently discovered new species are morphologically similar to already known species and some of those sibling species pairs are hardly distinguishable when preserved (Glaw & Vences 2000). However, in all cases in which anurans with relevant differences in their advertisement calls have been investigated genet-ically, relevant genetic distances -indicative of reproductive Isolation at the species level -have been found (pers. obs. in more than 20 species pairs from Madagascar, South America, and Asia). In the present paper we review a complex of species in the Malagasy genus Mantidactylus which previously (Guibe 1978, Blommers-Schlösser & Blanc 1991) were all subsumed under the name Manti-dactylus redimitus. Glaw & Vences (1992b) noted the bioacoustic and morphological differences of low-altitude M. redimitus specimens and those of mid-altitude localities, and described the latter as new species M. cornutus. We here provide evidence that M. comutus populations as listed in the distribution map of Glaw & Vences (1994) are still composed of various species: one new sibling species was discovered during a bioacoustic survey near the village Ranomafana in south-eastern Madagascar; its morphology is very similar to M. cornutus but its advertisement calls are rather different. In contrast, specimens from the Marojezy massif in north-eastern Madagascar differ by distinct morphological features and are described as second new species, although their advertisement calls are not yet known. 177
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