Myrmicinae, Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
Colombia (type loc.), Costa Rica. Costa Rica: Atlantic lowlands, moist Pacific slope near Monteverde.
Antennae 9-segmented, so small it is hard to count the five segments between the two-segmented club and the larger first funicular segment; mesosoma strongly ankylosed; propodeal suture not impressed; propodeum short and sloping, without distinct dorsal face; petiole lacking anteroventral tooth; mesosomal dorsum with about 4 pairs of erect setae, fourth abdominal tergite with abundant short erect setae; mesosomal and metasomal dorsa with underlying pubescence absent or so short and appressed as to be invisible; color brown.
These ants are so extremely tiny that they are probably more common than we think. I know this species from CATIE near Turrialba, Hitoy Cerrere Biological Reserve, La Selva Biological Station, and a Pacific slope site at 900m elevation just west of Monteverde. All the collections I have seen have been from either Winkler or Berlese samples of litter from the forest floor.
Fernández described this species from a Colombian collection and deposited a paratype in my collection. The paratype is identical to material I have from Costa Rica. However, there are errors in the published description. The description states "Body nearly naked of long hairs, with only a few (about 0.05 mm) distributed as follows: four in the clypeal area; two on each frontal lobe; four on promesonotum, none on propodeum, none on legs; two on petiole, two on the postpetiole, two on first tergal dorsum." This is repeated in the key, which refers to "two [setae] in first tegum gaster." The paratype I have and all my Costa Rican material has abundant erect setae, more than ten, on the first gastral tergite.
Fernández described another species, C. semistriata, with holotype from Colombia and a paratype series from Nicaragua. The description states "Body nearly naked of long hairs, with only a few (about 0.05 mm) distributed as follows: four in the clypeal area; two on each frontal lobe; two on the head (each one near occipital corner), eight on promesonotum, two on propodeum, none on legs; two on petiole, four on the postpetiole, several on first tergal dorsum." This is more like the correct description of C. reina. In the key, C. semistriata is differentiated from C. reina by having the promesonotal striation incomplete, not extending to the posterior margin. Given the widespread occurrence of C. reina in Costa Rica and no evidence of multiple sympatric species with striate promesonotum, my suspicion is that the extent of promesonotal striation is variable, and the Nicaraguan paratypes of C. semistriata are misidentified C. reina. In the publication, C. reina is described from one collection and C. semistriata from two, so it would not suprise me if these were revealed to be synonyms.
Fernández C., F. 2004. The American species of the myrmicine ant genus Carebara Westwood (Hymenoptera: Formicidae). Caldasia 26:191-238.
John T. Longino, The Evergreen State College, Olympia WA 98505 USA. firstname.lastname@example.org
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