Aphaenogaster treatae Forel, 1886

Shattuck, Steve & Cover, Stefan, 2016, Taxonomy of some little-understood North American ants (Hymenoptera: Formicidae), Zootaxa 4175 (1), pp. 10-22 : 14-15

Aphaenogaster treatae Forel, 1886

Aphaenogaster treatae Forel, 1886 : xl. Syntype workers, Vineland [39°29′N 75°2′W], New Jersey (Mary Treat) (Musee d'Histoire Naturelle Genève) [https://www.antweb.org/specimen/CASENT0907701 (specimen labeled as lectotype but designation unpublished, thus syntype); https://www.antweb.org/specimen/ CASENT0900414, labeled as “cotype” is not a true type as it is not from the type locality].

Aphaenogaster treatae pluteicornis Wheeler & Wheeler, 1934: 7 . Numerous worker, 4 queen, 4 male, a few larva and pupa syntypes, Poteau [35°03′N 94°37′W], Oklahoma, 17 June 1929 (G.C. & E.W. Wheeler) (Los Angeles County Museum of Natural History , not seen). New synonym.

Wheeler and Wheeler (1934) described several taxa as “forms” of A. treatae , basing their distinctions on minor differences in sculpture, color, pilosity, head shape, and the shape of the distinctive basal antennal flange that distinguishes A.treatae from its congeners. Aphaenogaster treatae pluteicornis was established based on material collected in Oklahoma and Texas while two varieties of A. pluteicornis , “alabamensis” (from Alabama) and “oklahomensis” (with the same type locality as A. pluteicornis ) were also described. These last two names were established as infrasubspecific (quadrinomials) and are thus unavailable.

Creighton (1950) was the first to consider these forms and reduced the number of valid taxa from four to two, treating “alabamensis” as a synonym of A. treatae and “oklahomensis” as a synonym of A. treatae pluteicornis . He separated A. treatae from A. treatae pluteicornis based on differences in head shape (longer and narrower and with the posterior margin narrower and flatter in A. pluteicornis ) and sculpturing (longitudinal rugae present on the front of the head in A. treatae , only rarely present in A. pluteicornis ).

None of the differences cited by the Wheelers or by Creighton hold up, especially given the availability of new material collected in the Florida panhandle and in eastern Texas (in MCZC) . In general, workers from southern populations are reddish brown to yellowish brown in color; workers from populations from North Carolina and north tend to be darker, commonly a medium to dark brown. Cephalic sculpture tends to be a bit more prominent in northern populations, but head shape, the differences in antennal flange shape, and pilosity cited by the Wheelers are not especially convincing. From this examination we conclude that A. treatae pluteicornis is best considered a synonym of A. treatae .

Aphaenogaster treatae occurs from Maine south to the Gulf Coast (northern Florida) and west to eastern Texas, Oklahoma and north to Indiana and Illinois. Note that in the eastern states, A. treatae nests in well-drained, often sandy soils in open habitats. Nests are generally inconspicuous and are commonly found under grass clumps. In eastern Texas, the second author found the species in open, sometimes recently burned pine-oak forests and in small gaps in such forests. Of five collections, two were nests in soil, but three colonies were in red rotten pine branches or logs on the soil surface.