Crematogaster, Vacca Forel, 1911

Hosoishi, Shingo, Maruyama, Munetoshi, Yamane, Seiki, Jaitrong, Weeyawat, Hashim, Rosli, Syaukani, Syaukani, Sokh, Heng, Itioka, Takao, Meleng, Paulus & Pham, Thai Hong, 2023, Multilocus phylogeny and historical biogeography of the Crematogaster inflata-group (Hymenoptera: Formicidae) in South-East Asia, Zoological Journal of the Linnean Society 198 (3), pp. 901-922 : 917

The Crematogaster Ʋacca-subgroup

The phylogenetic relationship between the C. Ʋaccasubgroup and their ancestral state reconstruction suggests that their common ancestor occurred in the Sundaic region and its founder dispersed to Sumatra ( Fig. 4 ). During glacial periods, the populations ( C. yamanei ) retracted into glacial forest refugia. When environmental conditions became favourable for expansion, the populations recolonized, but in the Sundaic region they were restricted to higher elevation areas due to competition with the C. inflata -subgroup and the C. difformis -subgroup, which were already present in this area at lower elevations.

Crematogaster yamanei is endemic to Sumatra, but closely related to C. Ʋacca, which is distributed in the Malay Peninsula and Borneo. Meijaard’s (2004) mammal studies suggested that Sumatra shares elements of its fauna with both the Bornean/Javan and Malayan regions as a result of secondary contact. Those patterns are found in the younger taxon C. yamanei , but not in the older taxon C. mucronata . The restricted distributions of C. mucronata and C. yamanei could have resulted from another speciation event and extirpation of the relatives, respectively.

Figures

Figure 4. A, historical biogeography of the Crematogaster inflata-group based on BEAST2 and BioGeoBEARS analyses using the dispersal multiplier [Scheme (ii)] and two time slices. Blue horizontal bars depict the 95% highest posterior probability (HPD). Node labels N1–N11 correspond with denotations in Table 2. Biogeographical analysis employed a DEC model, with eight regions. The left-bottom map represents the Indo-Australian Archipelago delimited into eight areas. Colours of squares correspond to the coloured area on the map. Coloured squares indicate the most likely ancestral area recovered at each node. The present distribution of each species is given by coloured squares. B–D, palaeogeographic maps were redrawn and modified from Hall (2013): B, 15 Mya. C, 10 Mya. D, 5 Mya.