Apterostigma epinotale, 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 : 390-391

Apterostigma epinotale , sp. nov. (Fig. 6)

Worker: Length 3.5-3.8 mm. - Head, excluding mandibles and neck, 1 1/2 times as long as wide between eyes. Neck with expanded posterior margin, over 1/3 length of head as above, much longer proportionately than in urichi . Sides sub-parallel, eyes small, convex, less than 1/6 the length of head as above. Anterior clyp'eal region straight, a distinct gap between this border and the closed mandibles. Frontal lobes large and rounded, raised at an angle of about 45°; distinct carinae extend back from these to a point posterior to the posterior margin of the eyes and are here joined by slight pre-ocular carinae, the antennal scrobes thus delimited are concave. Antennal scapes slender, gently curved, nearly as long as entire head from tip of mandibles to posterior margin of neck. Funicular joints 2-8 distinctly longer than broad, 9th joint as broad as long. Terminal joint slightly longer than joints 7-9 taken together or as the 1st funicular joint alone.

Thorax in profile as illustrated (Fig. 6.) Median longitudinal ridges on mesonotum terminating at either end in raised angles. Lateral mesonotal ridges feeble. Anterior to the mesoepinotal impression is a short pair of carinae, appearing in profile as tubercles. Basal surface of epinotum with a distinct, pair of carinae of rather uniform height; epinotum with a distinct pair of spines. Epinotal spiracles large and tubular. Petiole from above less than half as wide as postpetiole, flat on dorsal surface. Postpetiole, from above, widest behind, with sides converging to anterior margin in a slight concavity, slightly impressed postero-medially. Lateral ridges of gaster high and acute. Legs long and slender.

Covered with a gray bloom largely obscuring the somewhat iridescent, moderately shining integument which is microscopically reticulate. - Pilosity of moderately abundant long, fine blackish hairs which are largely upright. Appressed pubescence only on distal parts of appendages. - Color, beneath gray bloom, bright coppery.

Described from 5 workers taken by myself July 22, 1936, near the Oronoque River at its junction with the New River, Courantyne basin, British Guiana. The ants were in their nest in a rotted buttress of an old stump. The fungus garden, pendant, was about 15 X 20 X 5 mm. 11 cm. below this nest was the nest of Apterostigma dorotheae sp. nov.

Another small colony of workers taken by myself in this locality July 28 may be considered topotypes. Their nest was also in rotted wood but in a fallen log. The fungus garden was suspended from a root and was 41 cm. from a nest of Trachymyrmex cornetzi Forel which in turn was 15 cm. from a nest of Cyphomyrmex sp., all three being in an identical micro-habitat.

This aberrant species is unlike any known to me and is noteworthy in the possession of epinotal spines and conspicuously shining integument.