Apterostigma amiae, sp. nov. Worker: Length 3.3-3.7 mm. - Head, excluding mandibles and neck, 1 1/2 times as long as wide between eyes. Occipital margin evenly rounded, produced in back as a distinct neck with reflexed edges. Anterior clypeal margin convex. Frontal lobes hemispherical, sub-horizontal. Eyes small, very convex, much closer to occipital than to clypeal margin. Antennal scapes long, slender, expanded over distal half, exceeding occipital corners by a distance about equal to twice their greatest diameter. Second joint of funiculus broader than long, joints 3-7 about as broad as long, terminal joint longer than joints 7-9 taken together. Anterior margin of pronotum extended in two small lobes. Thorax, in profile, much as in the average Apterostigma in being without conspicuous projections. In profile the pronotum is slightly convex, the mesonotum high and in outline (an obtuse angle with feebly tuberculate apex and two slight convexities on the posterior descending surface. Mesoepinotal impression broad and smooth as in mayri. Basal surface of epinotum gently convex and rounding imperceptibly into the declivous surface. From above, the mesonotum and epinotum appear as two convexities, the mesonotum being the more convex and about 1/3 wider; medial longitudinal pair of carinae faintly indicated. Petiole in profile with flat anterior surface rounding into dorsal surface, and flat ventral surface, about 4/5 as high as postpetiole. Postpetiole, in profile, trapezoidal, with flat dorsal and slightly concave ventral surfaces. From above, the petiole is a little less than 1/2 as wide as postpetiole, the latter having convex sides converging anteriorly as in wasmanni. Gaster ovate, sides feebly marginate. Legs long and slender. Shining, sparsely and finely rugulose. - Pilosity not greatly obscuring integument, of moderately abundant, long, grayish hairs, originally apparently appressed, but secondarily disarranged, with sparse, fine, appressed pubescence most abundant on distal parts of appendages and gaster. - Ferruginous. Described from a series of workers taken by myself from their nest September 8, 1935, in high rain forest 23 miles west of Kartabu Point, junction of the Cuyuni and Mazaruni Rivers, British Guiana. The nest was in a rotted log resting against other trees and was 'about six feet above the ground. This species resembles mayri in general habitus but is much larger. It also resembles pilosum but the frontal lobes are different, the terminal joint of the funiculus is proportionately longer, and the mesoepinotal constriction is greater. In this same log were two colonies of Myrmicocrypta spinosa, sp. nov.

Published as part of Neal A. Weber, University of North Dakota, 1936, The biology of the fungus-growing ants. Part. I. New forms. 1, pp. 378-409 in Revista de Entomologia 7 on pages 391-392