Acropyga are small ants known for tending mealybugs (Hemiptera: Pseudococcidae) underground on plant roots (Bünzli 1935). In a recent worldwide revision of the genus LaPolla (2004) recognized 17 species for the Neotropical region. The genus might be much more diverse than currently known because crpytic, underground ants are notoriously undersampled. Acropyga are quite common in Cachoeira Nature Reserve in soil samples extracted in Berlese funnels.
Workers and queens of many species show a great range of variation in size and shape of various characteristics which makes it difficult to establish species boundaries on morphological grounds. For example, it is not uncommon that the number of antennal segments varies from one antennae to the other in a single specimen. Characteristics of the mandibles are important for species diagnosis. Therefore I included a picture of the manibles for each species.
10-segmented antennae; mandible with 5 teeth; 3rd tooth is the smallest tooth; short diastema between basal tooth and other teeth; dorsal surface of mandibles with many (sub-)erect hairs; scapes reach to posterior marging of head; head broader than long.
8-segmented antennae; mandible with 4 triangular teeth; diastema between basal tooth and other teeth; eyes relatively large and close to anterior margin of head; dorsal face of propodeum with long, erect hairs.
11-segmented antennae; mandible with 3 triangular teeth; mandibular teeth decreasing in size from apical to basal; long, erect hairs on dorsal face of propodeum sparse.
Acropyga JHB03 Bihn ms.
10-11-segmented antennae; mandible with 4 triangular teeth; in frontal view of head; eyes situated on extreme lateral border of head (i.e. distance between outer eye margin and lateral border of head smaller than eye diameter); dorsal face of propodeum with long, erect hairs.
Acropyga JHB04 Bihn ms.
9-segmented antennae; mandible with 4 teeth; first tooth much longer than second tooth; short diastema between basal tooth and other teeth; eyes minute.
Offline References for Acropyga
Bünzli, G.H. (1935): Untersuchungen über coccidophile Ameisen aus den Kaffeefeldern von Surinam. Mitteilungen der Schweizerischen Entomologischen Gesellschaft 16:455-593.
LaPolla, J.S. (2004): Acroypyga (Hymenoptera: Formicidae) of the world. Contributions of the American Entomological Institute, 33(3):1-130.