Nesomyrmex humerosus (Emery, 1896)

Garcia, Francisco Hita, Mbanyana, Nokuthula, Audisio, Tracy Lynn & Alpert, Gary D., 2017, Taxonomy of the ant genus Nesomyrmex Wheeler (Formicidae, Myrmicinae) in the Afrotropical region, with a review of current species groups and description of a new species of the N. angulatus group from Mozambique, European Journal of Taxonomy 258, pp. 1-31 : 8

Nesomyrmex humerosus species group

Definition

Antennae with 12 segments; anterior clypeal lobe short, flat-margined, and never convex, with small median triangular projection; frontal carinae present, but weakly developed; propodeal spines very well developed, long and spiniform; petiole and postpetiole without lateral spines; all dorsal surfaces of body with short, blunt pilosity.

Comments

This group contains only one species, which is morphologically quite unique in the Afrotropical region. Of special importance are the short, flat-margined anterior clypeal lobe with a small median triangular projection and the barrel-shaped petiolar node with its small, triangular node. These characters are in slightly modified ways also seen in several Neotropical and Malagasy species, while they are absent in the other Afrotropical species groups. However, the fact that N. humerosus shares these characters with species from other regions does not necessarily mean that N. humerosus is more closely related to them. It could also be an independent African lineage and similarities with species from other regions might be based on convergence. Despite the fact that N. humerosus does not resemble most species from the N. simoni group, it still shares characters with some species, such as the large eyes and the shape of the dorsal mesosomal outline, and it could be that N. humerosus is just an aberrant N. simoni group member. At present, it is not possible to deduce the biogeographical and phylogenetic affinities of this peculiar species. Currently, N. humerosus is known to occur in Kenya, Tanzania and Yemen. It is a rather rarely collected species and our scarce knowledge is based on just four collection events. Based on a sample collected in Kenya by the first author, it seems to live on vegetation, but it was also sampled from the ground in Tanzania and Yemen. It is possible that the species also occurs in other East African countries, such as Somalia and Mozambique, which are greatly under-sampled.