The taxonomy and biogeography of the ant subgenus Decacrema (Crematogaster) in Madagascar

In Madagascar, the ant genus Crematogaster, subgenus Decacrema, is currently represented by four nominal species. Recent extensive inventories of the Malagasy ant fauna now allow for comprehensive taxonomic revision of this species-group. In this study, species are delimited using a combination of morphological and molecular characters, informed by species distributions. Both morphology and phylogenetic analyses of three nuclear markers support only one of four of the previously described species unambiguously, while boundaries of the three remaining species remain unresolved. In addition, the data strongly suggest three new species and one raise from subspecies to species level. Results are discussed in the light of ecological biogeography and historical factors possibly shaping species diversity in Madagascar.