[2] However, during the first decade of the 21st century, molecular studies have revealed that Miniopterus, a widespread genus in the Old World, is much more species-rich than previously thought.

[4] The specific name aelleni honors Prof. Villy Aellen of the Natural History Museum of Geneva, who has done much research on African bats.

[5] Within M. aelleni, Goodman and colleagues found some differentiation (3.4% sequence divergence in cytochrome b sequences) between individuals from Montagne d'Ambre in northern Madagascar and those from Anjouan and Ankarana, near Montagne d'Ambre; the cytochrome b divergence between M. aelleni and other Malagasy Miniopterus is 7 to 10%.

[6] Later in 2009, Goodman and colleagues described two more species of M. manavi-like Malagasy Miniopterus: M. brachytragos from northern Madagascar and M. mahafaliensis from the southwest.

[7] On the basis of cytochrome b sequences, they found that M. aelleni was most closely related to a clade of M. brachytragos, M. manavi, and another recently described Malagasy species, M. petersoni.

[8] The five recognized species of M. manavi-like bats are not each other's closest relatives, but apparently acquired their similarities through convergent evolution.

[17] Individuals from Anjouan have significantly shorter hindfeet than those from Madagascar, but otherwise the two populations cannot be distinguished on the basis of external characteristics.

The karyotype is conserved among species of Miniopterus; the number of chromosomes and arms is identical in M. aelleni, the Malagasy M. griveaudi and M. gleni, and even the Asian M. fuliginosus.

[5] On Madagascar, it has been recorded in forest and caves in karst areas; its distribution broadly overlaps that of M. griveaudi and the two have been found in the same roost sites on several occasions.

[23] Because M. aelleni is widespread and occurs in many protected areas on Madagascar, Goodman and colleagues inferred that its conservation status is secure.