Crematogaster difformis-subgroup F. Smith 1857

The Crematogaster difformis-subgroup The relationships of the sister-species in the C. difformis -subgroup were variable with respect to their geographical distribution patterns. Crematogaster ampullaris and C. seaeardi display an allopatric distribution, whereas C. difformis and C. tanakai display a sympatric distribution. The closely related C. ampullaris and C. seaeardi illustrate an interesting distribution pattern with C. ampullaris in Sulawesi and C. seaeardi widespread elsewhere in South-East Asia. The estimated dating suggests that C. ampullaris and C. seaeardi diverged approximately 4 Mya (Fig. 4; Table 2). The divergence implies a recent split of these populations and landmass distributions in that geological time (Hall, 2002) suggesting that the ancestor of both species dispersed from the Sundaic region to Sulawesi west-to-east across Wallace’s Line. Sulawesi is considered to have taken its present form due to the collision of different islands c. 15–5 Mya (Lohman et al., 2011). As the last possible connections between Borneo and Sulawesi were during the Pliocene or the Miocene (Morales & Melnick, 1998; Mercer & Roth, 2003), the colonization of Sulawesi by the common ancestor may have occurred much later after the island collision event. The ancestor of C. seaeardi and C. ampullaris may have expanded its range to western Sulawesi (eastern Sunda Shelf) during low sea-level periods and evolved into C. ampullaris. As the Makassar Strait is a deep trench, Borneo and Sulawesi were not connected when sea levels dropped. Their diversification resulted from ‘an inter-island dispersal combined with climatic vicariance event’ (Condamine et al., 2013). Crematogaster difformis and C. tanakai are sympatric in Borneo, and their habitats are spatially close to each other. Crematogaster difformis has an obligate mutualistic relationship with Lecanopteris and Platycerium ferns in canopy trees of lowland rainforests, and C. tanakai inhabits the same nests with C. difformis (Tanaka et al., 2009, 2012; Tanaka & Itioka, 2011). This restricted distribution demonstrates distinct endemism and is, therefore, of conservation significance. Lecanopteris fern species are found in the canopies of lowland tropical rainforests. The preservation of such primary forests will lead to the conservation of the endemic species. Molecular dating indicates that C. difformis and C. tanakai diverged approximately 1 Mya (Fig. 4; Table 2). The low divergence implies a recent speciation. As in C. aurita, the dispersal event and competition can explain similarly the position of C. mucronata, which is endemic to Sumatra (Fig. 4). Klaus et al. (2013) suggested early divergence of freshwater crabs Parathelphusa and subsequent appearance on Sumatra, since much of Sumatra was still submerged during the Late Miocene. In contrast, the ancestor of C. mucronata already appeared on fragmented Sumatra during the Late Miocene. Freshwater crabs require more land area for their habitats, but ants presumably do not require large areas as Yamane (2013) listed 126 ant species having colonized Krakatau Island after eruption. Faunal and genetic similarities between the Malay Peninsula and Sumatran populations have been documented for several taxa (Gorog et al., 2004; Lohman et al., 2011; Leonard et al., 2015), as the two areas were connected at sea level 20–30 m below the present level (Voris, 2000).
Published as part of 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, pp. 901-922 in Zoological Journal of the Linnean Society 198 (3) on page 917, DOI: 10.1093/zoolinnean/zlad005, http://zenodo.org/record/8141964
{"references":["Hall R. 2002. Cenozoic geological and plate tectonic evolution of SE Asia and the SW Pacific: computer-based reconstructions, model and animations. Journal of Asian Earth Sciences 20: 353 - 431.","Lohman DJ, de Bruyn M, Page T, von Rintelen K, Hall R, Ng PKL, Shin H-T, Carvalho GR, von Rintelen T. 2011. Biogeography of the Indo-Australian Archipelago. Annual ReVieae of Ecology, EVolution, and Systematics 42: 205 - 226.","Morales JC, Melnick DJ. 1998. Phylogenetic relationships of the macaques (Cercopithecidae: Macaca), as revealed by high resolution restriction site mapping of mitochondrial ribosomal genes. Journal of Human EVolution 34: 1 - 23.","Mercer JM, Roth VL. 2003. The effects of Cenozoic global change on squirrel phylogeny. Science 299: 1568 - 1572.","Condamine FL, Toussaint EFA, Cotton AM, Genson GS, Sperling FAH, Kergoat GJ. 2013. Fine-scale biogeographical and temporal diversification processes of peacock swallowtails (Papilio subgenus Achillides) in the Indo-Australian Archipelago. Cladistics 29: 88 - 111.","Tanaka HO, Inui Y, Itioka T. 2009. Anti-herbivore effects of an ant species, Crematogaster difformis, inhabiting myrmecophytic epiphytes in the canopy of a tropical lowland rainforest in Borneo. Ecological Research 24: 1393 - 1397.","Tanaka HO, Yamane S, Itioka T. 2012. Effects of a ferndwelling ant species, Crematogaster difformis, on the ant assemblages of emergent trees in a Bornean tropical rainforest. Annals of the Entomological Society of America 105: 592 - 598.","Tanaka HO, Itioka T. 2011. Ants inhabiting myrmecophytic ferns regulate the distribution of lianas on emergent trees in a Bornean tropical rainforest. Biology Letters 7: 706 - 709.","Klaus S, Selvandran S, Goh JW, Wowor D, Brandis D, Koller P, Schubart CD, Streit B, Meier R, Ng PKL, Yeo DCJ. 2013. Out of Borneo: Neogene diversification of Sundaic freshwater crabs (Crustacea: Brachyura: Gecarcinucidae: Parathelphusa). Journal of Biogeography 40: 63 - 74.","Yamane SK. 2013. A review of the ant fauna of the Krakatau Islands, Indonesia. Bulletin of the Kitakyushu Museum of Natural History and Human History 11: 1 - 66.","Gorog AJ, Sinaga MH, Engstrom MD. 2004. Vicariance or dispersal? Historical biogeography of three Sunda shelf murine rodents (Maxomys surifer, Leopoldamys sabanus and Maxomys aehiteheadi). Biological Journal of the Linnean Society 81: 91 - 109.","Leonard JA, Den Tex R-J, Hawkins MTR, Munoz-Fuentes V, Thorington R, Maldonado JE. 2015. Phylogeography of vertebrates on the Sunda Shelf: a multi-species comparison. Journal of Biogeography 42: 871 - 879.","Voris HK. 2000. Maps of Pleistocene sea levels in South-East Asia: shorelines, river systems and time durations. Journal of Biogeography 27: 1153 - 1167."]}