The status of Myotis ater and Myotis muricola in south-east Asia is reviewed. Both species appear to occur sympatrically in several localities including Sulawesi, Borneo and peninsular Malaysia. Peninsular Malaysian specimens referred to M. ater are larger than those from elsewhere and are allied with ater with some doubt. M. ater nugax from Borneo appears to be the Bornean representative of M. ater, but specimens formerly referred to that form by Hill and Francis (1984) and Payne et al. (1985) prove to be a previously undescribed species which is described here. M. oreias from Singapore is quite distinct from any of these species, but the type and only known specimen is in poor condition, and its true affinities are difficult to determine.Resume. -Le Statut de Myotis ater et de Myotis muricola en Asie du Sud-Est est evalue. Les deux especes sont trouvees en sympatrie dans plusieurs localites incluant Sulawesi, Borneo ct la Malaisie peninsulaire. Les specimens de la peninsule malaise consideres comme M. ater sont plus grands que partout ailleurs, et sont associes a ater avec quelques doutes. M. ater nugax de Borneo est bien le representant local de M. ater, mais des specimens attribues precedemment a cette forme par Hill et Francis (1984) et Payne et al. (1985 representent en fait une espece nouvelle. decrite ici. M. oreias de Singapour est nettement distincte de ces autres especes, mais le specimen-type, qui est le seul specimen connu de 1'espece, est en mauvais etat, et ses reelles affinites sont difficiles ä determiner.

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