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Pseudolasius HNS Emery
Worker small, polymorphic, the head of the major being large and differently shaped from that of the minor. Mandibles well developed, with oblique apical borders furnished with 5 to 6, more rarely with 7 to 8 teeth of different sizes. Clypcus large, convex, and more or less carinate in the middle, its anterior border projecting somewhat over the bases of the mandibles. Frontal area indistinct, triangular; frontal carinae short, subparallel, rather widely separated; frontal groove indicated. Clypcal and antennary fossa; confluent. Head of major worker cordate or subrectangular, deeply emarginate posteriorly; in the minor worker much less deeply concave behind. Eyes small to very small, rarely completely lacking; ocelli absent. Antennae 12- jointed, inserted near the clypcal suture; funiculi filiform, slightly thickened towards their tips. Thorax short, stout; premesonotal and mesoepinotal sutures distinct; pro- and mesonotum convex above, mesonotum impressed; epinotum short, unarmed, with short base and long sloping declivity. Petiolar scale suberect or inclined forward, its apical border emarginate or entire. Gaster short, elliptical. Legs moderately long and stout.
Female considerably larger than the worker.- Head similar to that of the worker major but broader behind, with well-developed eyes and antennae. Thorax broader than the head, the mesonotum flattened above, the pronotum short and vertical. Wings long and ample, with a single large cubital and no discoidal cell.
Male as small as the worker and of a similar color. Mandibles dentate. Eyes and ocelli large. Antennae 13-jointed; scapes long, funiculi filiform, all their joints longer than broad. Thorax similar to that of the female; gaster more slender; external genital appendages rather narrow, hairy. Wings long and broad; venation as in the female.
Until recently these ants were supposed to be peculiar to the Indomalayan Region, but Forel has described a species from Australia and Santschi has described one from the French Congo (Map 36). Emery1 has keyed all the species known up to 1911, but several Indonesian forms have since been described. The African material before me comprises four species, one of which I refer to P. weissi Santschi HNS , the other three being undescribed. Two of the latter were taken by Lang and Chapin in the Belgian Congo, one by Mr. Gowdey in Uganda. All these forms have very poorly developed eyes, compared with the majority of Indomalayan species. Further search will probably reveal many additional species in the Ethiopian Region. The workers are hypogaeic or nocturnal and are therefore rarely seen; the males and females, however, are not infrequently taken at lights.