Paratrechina

LaPolla, J. S., Brady, S. G. & Shattuck, S. O., 2010, Phylogeny and taxonomy of the Prenolepis genus-group of ants (Hymenoptera: Formicidae)., Systematic Entomology 35, pp. 118-131 : 127-128

Paratrechina

Figures of worker. Head: Fig. 5D; mesosoma: Fig. 6D; mandible: Fig. 7C.

Synopsis of taxonomic history (for full description see Bolton et al., 2006): Paratrechina Motschoulsky 1863: 13 . As junior synonym of Prenolepis, Dalla Torre, 1893: 177 ; revived as genus, Emery, 1925: 216. Type species: Paratrechina currens (junior synonym of Paratrechina longicornis ); by subsequent designation of Wheeler (1911).

Diagnosis. Mandible with 5 teeth; maxillary palps 6- segmented; labial palps 4-segmented; erect setae on dorsum of head randomly placed; scapes lacking erect hairs; abundant erect setae on legs and dorsum of mesosoma. Eyes well developed and convex, surpassing outline of head in full frontal view, placed midlength and laterally on head. Dorsal mesosomal setae arranged loosely in pairs; propodeum lacking erect setae; propodeum with a low-domed dorsal face; overall mesosoma shape long and slender.

Distribution. (Fig. 9A). Paratrechina longicornis is a well-known invasive species that now has a pantropical distribution. It has also become established in more temperate localities by living in buildings and other man-made structures. Greenhouses in North America are sometimes infested with Pa. longicornis ( Wetterer et al., 1999) .

Notes. Taxonomists have long commented on the unusual morphology of Pa. longicornis , such as its elongated scapes and tibiae and unusual mesosomal setal pattern compared to other ‘ Paratrechina , s.l. ' ( Trager, 1984). Our results here confirm that it is in fact a separate, distinct lineage from other Prenolepis genus-group members. In his reorganization of the genus, Emery (1925) recognized Pa. longicornis as distinct from the rest of the genus by placing it in its own monotypic subgenus. Here we recognize Paratrechina as a monotypic genus.

This is a notoriously invasive species that has spread worldwide around the tropics and subtropics. It is interesting to note that our analysis places it within a clade containing Pseudolasius and Euprenolepis , two genera that are restricted to southeastern Asia. Therefore, it may be reasonable to assume that Pa. longicornis is native to this region, and not to Africa as has been previously suggested. It is also interesting to note that to date no Euprenolepis or Pseudolasius are known to have been introduced by human activities, so whatever characteristics of Paratrechina that make it a good invader seem restricted to this single lineage.

Paratrechina longicornis currently contains the subspecies Pa. l. hagemanni ( Forel, 1901), described from worker(s) collected at Boma, Democratic Republic of Congo. Wheeler (1922) treated this form as a junior synonym of longicornis (without comment), whereas Emery (1925) removed it from synonymy as a variety of longicornis (again without comment). In his original description, Forel (1901) states that this taxon is very similar to longicornis and differs in being ‘perhaps ' slightly smaller and with the metanotum slightly more convex. All other characters mentioned match longicornis , and, upon examination of type material, Pa. l. hagemanni (Forel) is here returned to synonymy with Pa. longicornis (syn. nov.), leaving Paratrechina with a single valid species.