Brachymyrmex patagonicus Mayr
Brachymyrmex patagonicus, full face view of a worker (click image to enlarge).
Photo courtesy of http://www.antweb.org/.
A word of caution, this group is in drastic need of revision and the names are subject to change. This particular species, although distinctive from any others so far discovered in Mississippi, has been going by a couple of names, B. musculus Forel and B. patagonicus, for the last 30 years since it was first discovered to occcur in the United States in 1978 (Wheeler and Wheeler 1978). Brachymyrmex patagonicus, which is the type species, was recently redescribed (Quiran et al, 2004). A recent publication by MacGown et al (2007) and a poster by MacGown and Hlll (2007) presented the known distrubution of this species (which appears to be rapidly expanding) in the U.S., figures of all castes, biological and pest status, and brief dignoses of all castes.
Brachymyrmex patagonicus is most similar to B. obscurior, another exotic species. It differs in the size of the eye, which is much larger in B. patagonicus than in B. obscurior. Additionally, the males of these two species are quite different in color. Males of B. patagonicus are bicolored with the head and gaster dark brown and the rest of the body (see photo above), including the appendages, being pale yellowish-brown. Males of B. obscurior are concolorous dark brown. Brachymyrmex sp.-01, recorded from Florida, is also dark brown in color, but lacks erect hairs on the body. Another similar species, not yet reported from the U.S., but possible, is B. heeri. This brownish colored species differs in that the workers lack ocelli. An undescribed brown species known only from two queens collected from Arkansas (Lloyd Davis, pers. comm.) is unusual in that the queens are tiny, about the size of typical workers. All other known species present in this region are yellowish in color.
Biology and Economic Importance
MacGown, J. A., J.G. Hill, and M. A. Deyrup. 2007. Brachymyrmex patagonicus (Hymenoptera: Formicidae), an emerging pest species in the southeastern United States. Florida Entomologist 90: 457-464. [pdf]
MacGown, J. A. and J. G. Hill. 2007. Brachymyrmex patagonicus (Hymenoptera: Formicidae), an emerging pest species introduced into the southeastern United States. Mississippi Entomological Society 24-26 Oct. 2007. [power point poster]
Quiran, E. M., J. J. Martinez, and A. O. Bachmann. 2004. The Neotropical genus Brachymyrmex Mayr, 1868 (Hymenoptera: Formicidae) in Argentina. Redescription of the type species, B. patagonicus Mayr, 1868; B. bruchi Forel, 1912; and B. oculatus santschi, 1919. Acta Zoologica Mexicana 20: 273-285.
Wheeler, G. C. and J. Wheeler. 1978. Brachymyrmex musculus, a new ant in the United States. Entomological News 89: 189-190.
Wild, A. 2008. Myrmecos Blog: Rover Ants (Brachymyrmex patagonicus), an emerging pest species. http://myrmecos.wordpress.com/2008/05/27/rover-ants-brachymyrmex-patagonicus-an-emerging-pest-species/ (accessed 5 June 2008).
Links and Fact Sheets
Layton, B. and J. A. MacGown. 2008. Rover Ants: Mississippi Extension Pest Control Sheet. [pdf]
Myrmecos Blog: Rover Ants (Brachymyrmex patagonicus), an emerging pest species. http://myrmecos.wordpress.com/2008/05/27/rover-ants-brachymyrmex-patagonicus-an-emerging-pest-species/