Abstract
We investigated the species-level taxonomy of the Malagasy Crematogaster (Crematogaster) kelleri-group and an additional more distantly related species of the same subgenus. Morphological data from worker, queen and male ants, as well as genetic data from three nuclear genes (long wavelength rhodopsin, arginine kinase and carbomoylphosphate synthase) and one mitochondrial marker (cytochrome oxidase I) led to the recognition of six species. Within the C. kelleri-group, three new species are described: C. hazolava Blaimer sp. n., C. hafahafa Blaimer sp. n. and C. tavaratra Blaimer sp. n. The previously described taxa C. kelleri Forel and C. madagascariensis André are validated by our analysis. Conversely, our data suggests synonymy of C. adrepens Forel (with C. kelleri) and C. gibba Emery (with C. madagascariensis). A more distantly related and phylogenetically isolated species, C. tsisitsilo Blaimer sp. n., is further described. We report high levels of morphological and molecular variation in C. kelleri and illustrate that this variation can be explained partly by geography. Species descriptions, images, distribution maps and identification keys based on worker ants, as well as on queen and male ants where available, are presented for all six species. Our work highlights the elevated species richness of Crematogaster ants throughout Madagascar’s humid forests, especially in the far northern tip of the island, and the need to use multiple data sources to ensure clear demarcation of this diversity.
Highlights
The island of Madagascar is home to such a diverse array of endemic creatures that is sometimes called the ‘‘eighth continent’’
All other species are well supported by the mitochondrial data with posterior probabilities (PP) = 1 and bootstrap values
We have demonstrated high levels of continuous morphological variation within C. kelleri and concluded that the former does not correlate with observed genetic variation or geography
Summary
The island of Madagascar is home to such a diverse array of endemic creatures that is sometimes called the ‘‘eighth continent’’. We resolve and revise the taxonomy of the C. kelleri-group with a combination of morphological and genetic data, the latter comprising both mitochondrial and nuclear DNA This revision represents the penultimate taxonomic treatment of the ecologically important acrobat ants in Madagascar (see [10,11,12]), and the results have a multitude of implications and applications in ecological and conservation research. The sample size, i.e. number of specimens, submitted for extraction to the Barcode of Life Initiative was much larger, but success rates were poor overall due to the advanced age of specimens For this larger dataset, sequence data were collected for cytochrome oxidase I (COI, 578 bp used for inference) at the Biodiversity Institute of Ontario, with amplification and sequencing protocols as detailed in Smith & Fisher [24]. Minimum and maximum sequence divergences of COI within and between species were calculated under the Tamura-Nei model [32] with the software MEGA5 [33]
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