1969] 
Brown and Kempf — Acanthognathus 
107 
5. Body prevailing smooth and shining. A few indistinct fossae 
persist on anterior part of head, especially in the region in front of 
the eyes. Parts of lower sides of alitrunk, also petiolar peduncles in 
front and behind minutely and densely punctulate. 
6. Clavate pilosity very sparse on clypeus, cheeks, mandibles, 
upper vertex, humeral angles, spines and posterior faces of both 
nodes, and more abundant on antennal scapes, legs and underside of 
head. 
Color light ferruginous; antennae, legs and gaster lighter, more 
yellowish. 
Holotype (MCZ) a unique taken in lowland rain forest on the 
property of Carton de Colombia (a paper-manufacturing firm) in 
Bajo Calima, Municipio de Buenaventura, Departamento de Valle, 
Colombia. The collection was made near the then principal logging 
road on 16 March 1967, at Kilometer 10 northward from the com- 
pany’s headquarters, R. B. Root and W. L. Brown, Jr., leg. The 
specimen was found, alive and with the incredible mandibles opened 
to approximately 180°, in thin humus immediately below a layer of 
leaf litter 1 cm. thick. No more specimens could be found in the 
vicinity. 
This is the first member of the genus found in trans-Andean South 
America. The extremely long, heavily-armed mandibles and smooth 
integument distinguish it at once from the other known species. 
Key to the Species of Acanthognathus , Based on Workers and 
Females 
1. Mandibles decidedly longer than head proper, each with 2 or 3 
long spiniform teeth before the apex (Fig. 11); dorsum of 
head smooth and shining (Colombia: Pacific lowlands) 
teledectus 
Mandibles not longer than head proper, preapical inner borders 
unarmed, or at most with low irregular denticles and/or welts 
(Fig. 1) ; dorsum of head sculptured, at least with numerous 
distinct round fossae on the disc, intervals smooth or rugulose 
2 . 
2. Petiole with very long, slender peduncle, about 3 X as long as 
its node, which is short and transverse as seen from above 
(Fig 3; Amazonia: near Manaus) stipulosus 
Petiolar peduncle slender, but less than twice as long as its node, 
which is oval and at least as long as broad as seen from above 
(Fig. 2) 3. 
