Calumma vatosoa is a Malagasy chameleon species that has until now been known only from the male holotype and a photograph of an additional male specimen. In this paper we describe females of the chameleon Calumma vatosoa for the first time, as well as the skull osteology of this species. The analysed females were collected many years before the description of C. vatosoa, and were originally described as female C. linotum. According to external morphology, osteology, and distribution these specimens are assigned to C. vatosoa. Furthermore we discuss the species group assignment of C. vatosoa and transfer it from the C. furcifer group to the C. nasutum group. A comparison of the external morphology of species of both groups revealed that C. vatosoa has a relatively shorter distance from the anterior margin of the orbit to the snout tip, more heterogeneous scalation at the lower arm, a significantly lower number of supralabial and infralabial scales, and a relatively longer tail than the members of the C. furcifer group. These characters are, however, in line with the species of the C. nasutum group. In addition the systematic position of C. peyrierasi also discussed, based on its morphology.