The species is native to the Neotropics, but was originally described from Zurich, Switzerland (Forel, 1874;1876). They were found in abundance on greenhouse orchids in a tropical botanical garden, but the population was gone (possibly replaced by Plagiolepis) by 1904 (Santschi, 1923). Brachymyrmex heeri is a widespread across Central America, South America and the Caribbean (Kempf, 1972). It was also recently reported from the Galapagos Islands, where they were found in association with introduced hemipteran Icerya purchasi Maskell, and in the agricultural zone of San Cristbal (Herrera & Longino, 2008). It is not clear the extent to which B. heeri is native (versus introduced) to many of the Caribbean islands (Wetterer & Wetterer, 2004). Thus far there have been no confirmed reports of the species establishing in the United States, but it has been intercepted at a Texas port of entry (Christopher Wilson, pers. comm.). In addition to Forels original description from Switzerland, the species has been reported from Germany, France and the Ukraine (Rasplus et al., 2010).
In Costa Rica (Jack Longino) Prior to Jan 2019 I identified these as JTL-003. This species occurs in wet forest habitats, from sea level to 1500m cloud forest. It occurs in both the canopy and on the ground. I have found nests under epiphytes, under dead wood on the ground, and in a cavity in a fern rhizome near the ground. Workers occur frequently in Winkler samples of sifted leaf litter and soil, both from the ground and from epiphytic material from the canopy. Nests are populous and there appears to be a distinct replete caste. A subset of workers have grossly distended gasters filled with clear liquid. One nest I observed contained at least two dealate queens, suggesting polygyny.
Native range. Throughout Neotropics; a widespread synanthropic species. Introduced range. Galapagos, Europe. Occasionally intercepted at US ports of entry.
Diagnosis among workers of introduced and commonly intercepted species. Antenna 9-segmented. Antennal club indistinct. Antennal scapes surpassing the posterior margin of head by more than 1/5th their length. Eyes of moderate size (greater than 5 facets). Eye length approximately equal to or slightly greater than malar distance. Head with or without distinct ocelli. Antennal sockets and posterior clypeal margin separated by a distance less than the minimum width of antennal scape. Dorsum of mesosoma lacking a deep and broad concavity. Metanotal groove present. Pronotum and mesonotum with pairs of erect hairs. Propodeum and petiolar node both lacking a pair of short teeth. Propodeum lacking posteriorly projecting protrusion. Metapleuron with a distinct gland orifice. Waist 1-segmented (may be hidden by gaster). Petiolar node appearing flattened. Gaster armed with acidopore. Gaster (especially first segment) with sparse pilosity, giving it a shiny appearance. Color yellow to brown.
The taxonomy of Brachymyrmex is in considerable need of revision before many of the current species names can confidently be applied to specimens. Brachymyrmex heeri can be distinguished from most other introduced members of the genus by the following combination of characters: (1) sparse pubescence on the first gastral tergite, (2) antennal scapes exceeding posterior margin of head by at least 1/5 their length, (3) erect hairs on the pronotum and mesonotum, and (4) eye length equal to or greater than malar distance. More yellowish specimens of B. heeri can be separated from the brown species B. patagonicus, but greater taxonomic study is required in order to separate darker B. heeri specimens. Joe MacGown (2012) suggests that dark B. heeri can be separated from B. patagonicus by the formers lack of ocelli, but the presence/absence of ocelli may be an unreliable character (Christopher Wilson, pers. comm.).
Brachymyrmex heeri is a shiny yellow to brown small, soft-bodied, nondescript species approximately 1.22 mm in length. It lives in polygynous colonies, occupies shallow nests often located in disturbed habitats, and has successfully established populations outside its native range.
Taxonomic history
Forel, 1876 PDF: 52 (q.m.).See also: Santschi, 1923b PDF: 664.Senior synonym of Brachymyrmex giardi cordobensis: Ortiz-Sepúlveda et al., 2019 10.1007/s13127-019-00406-2 PDF: 57.Senior synonym of Brachymyrmex goeldii: Ortiz-Sepúlveda et al., 2019 10.1007/s13127-019-00406-2 PDF: 57.Senior synonym of Brachymyrmex physogaster: Ortiz-Sepúlveda et al., 2019 10.1007/s13127-019-00406-2 PDF: 57.Canindeyú , Central (ALWC, BMNH, LACM, MHNG).
