Apterostigma dorotheae, Neal A. Weber, University of North Dakota, 1936

Neal A. Weber, University of North Dakota, 1936, The biology of the fungus-growing ants. Part. I. New forms. 1, Revista de Entomologia 7, pp. 378-409 : 389-390

Apterostigma dorotheae , sp. nov. (Fig. 5)

Worker: Length 2.6-2.8 mm. - Head, excluding mandibles slightly over 1 1/2 times as long as wide between eyes. Neck very slight, with expanded margin. Sides sub-parallel, occipital margin rounded, feebly but distinctly impressed in middle. Eyes hemispherical, situated closer to posterior than to clypeal margin, slightly less than 1/5 in diameter the length of head. Anterior clypeal margin evenly convex and extending to cutting edge of mandibles when the latter are closed. Frontal lobes broad, rounded and sub-horizontal, frontal area slightly impressed. Antennal scapes moderately stout, inflated at distal 1/2 and slightly curved, not as long as head, excluding mandibles. Joints 2-9 of funiculus distinctly broader than long, terminal joint slightly shorter than joints 6-9 taken together.

Thorax in side view as illustrated (Fig. 5). Anterior margin of pronotum extended in a pair of low, rounded lobes. Mesonotum, from above, with a pair of carinae produced posteriorly as rounded lobes. These carinae of variable development. Basal surface of epinotum with a pair of median, inconspicuous ridges. Epinotal stigmata prominent. Dorsal surface of petiole laterally produced as blunt tubercles. Petiole slightly over 1/2 as wide as postpetiole. Postpetiole, from above, hexagonal, broadly impressed postero-medially. Gaster feebly marginate.

Opaque, surface largely obscured by pilosity. - Pilosity of abundant, appressed, grayish hairs and finer and sparser appressed pubescence. Dark red-brown.

Described from a few workers of a colony taken by myself July 22, 1936 near the Oronoque River at its junction with the New River, tributary of the Courantyne River, British Guiana. The nest of the ants was 11 cm. below the nest of A. epinotale sp. nov. , in a cavity in a mass of humus inside the rotted buttress of a stump. The fungus garden differed from that of epinotale in being larger, uniformly dark gray, the mycelia were more diffuse, and there were no bromatia.

The nest was pendant and also attached at the sides. There was no evidence of an envelope of fungus around the garden.

This species resembles A. mayri but differs in stouter habitus, higher mesoepinotal region, in having carinae on declivous surface of mesonotum produced as lobes, and in darker color.