Multilocus phylogeny and historical biogeography of the Crematogaster inflata-group (Hymenoptera: Formicidae) in South-East Asia

A recent molecular phylogeny of the genus Crematogaster reclassified some members of the former subgenera Paracrema and Physocrema into the C. inflata-group, now comprised of five species: C. ampullaris, C. inflata, C. modiglianii, C. onusta and C. subcircularis. Here, a molecular analysis of the Crematogaster inflata-group and eight other species of the former subgenus Physocrema (C. aurita, C. difformis, C. mucronata, C. physothorax, C. sewardi, C. tanakai, C. vacca and C. yamanei) is conducted using a total of c. 4 kb of sequence data from six nuclear protein-coding genes and two mitochondrial genes. Monophyly of the C. inflata-group is strongly supported. A revised morphological delineation of the subgroups is proposed, supported by the molecular phylogeny: three morphologically distinct subgroups, the C. difformis-subgroup, the C. vacca-subgroup and the C. inflata-subgroup. Molecular dating and biogeographical analyses indicate that the C. inflata-group originated in the Sundaic region around the Middle Miocene 12 Mya and diversified from the Late Miocene to Pliocene. Ancestral state reconstructions indicate that the C. inflata-group diversified from an ancestor with a swollen propodeum and circular-shaped metapleural gland opening. Biogeographical reconstruction indicates that dispersal to peripheral areas and allopatry due to sea-level changes shaped the evolutionary history of the C. inflata-group.