Apterostigma is a genus of New World ants of the subfamily Myrmicinae. Two species have been described from fossils preserved in Dominican amber,[1] while the others are extant. They are fungus-growing ants, though, unlike the majority of other species in Attini who grow Lepiotaceae, some species have begun cultivating Tricholomataceae.[4][5]
The genus Apterostigma was described by Gustav Mayr (1865), from winged male and female specimens collected in southern Brazil. It is a New World ant belonging to the Attina Subtribe (fungivorous ants), since they maintain the Ant-Fungus mutualism, where various species belonging to this subfamily use fungi from the Lepiotaceae family. The fungus decomposes the litter (vegetable material collected by the ants, used as a substrate), however, this is not the case of the genus Apterostigma, since it has been found that it cultivates a pterulaceous fungus of the Tricholomataceae family, which is given as a substrate. woody matter and insect excretions, along with some bits of leaf litter.
Head elongated, without isolated spines or denticles; Ventrally the eye is bordered by a convexity, the vertex extending into a sheet that delimits the occipital zone and forms a neck of variable length and width. the pronotum presents an anterior transverse edge, the cervical edge; the mesonotum presents a pair of thick longitudinal and parallel ridges of variable development and elevation; occasionally the propodeum presents a pair of isolated spines or denticles, although in some species the mesonotal ridges may form anterior triangular lobes.
Both the petiole and the post-petiole lack denticles or dorsal tubercles. the first tergus of the gaster presents on each side a longitudinal edge of variable development; the gaster generally presents a finely granulated cuticle, sometimes rough; with roughness or small piliferous papillae; never with prominent denticles or tubercles.
Body hairs consisting of flexible hairs, apically pointed, always arching or basally curved, occasionally silky, sometimes wiry; never straight, spatuliform, or squamiform.
head long; generally devoid of spines or denticles, except for some species with two low tubercles on the forehead and between the eyes. With the head in frontal view, the posteromedian profile generally presents a low emargination or at least a flat area; the posterolateral profile may be evenly convex or have a semi-hexagonal posterior profile to the eyes; a straight and vertical section posterior to each eye separated by a rounded angle from another straight and inclined section, which in turn is separated by a rounded angle, or sometimes an ridge, from the posteromedian emargination.