94 
Psyche 
[June 
The descriptions and measurements (Table I) utilize some ab- 
breviations kept standard in recent works on ants, particularly the 
tribe Dacetini. HL is the length of the head in full-face (dorsal) 
view, including occipital lobes and the entire clypeus. HW is the 
maximum measurable width of the head in full-face view. Cl is 
cephalic index, or HW/HL X ioo. ML is the exposed length of 
the closed mandibles beyond clypeal margin^ measured in full-face 
view. SL is the chord length of the antennal scape; SI (scape index) 
is SL/HW X ioo. MI is the mandibulo-cephalic index, or ML/HL 
X ioo. SMI, scape-mandibular index, is SL/ML X ioo. All 
measurements are in millimeters, and have an approximate error 
of d= O.Oi mm. 
Abbreviations for the main collections in which deposit has been 
made are: (MCZ) Museum of Comparative Zoology, Harvard 
University, Cambridge, Massachusetts 02138, USA; (USNM) 
United States National Museum, Washington, D. C. 20560, USA; 
(WWK) Collection of W. W. Kempf, including the Collection 
of Thomas Borgmeier, Caixa Postal 5,650, Sao Paulo, S. P., Brasil; 
(DZSP) Departamento de Zoologia, Caixa Postal 7172, Sao Paulo, 
Brasil. Other collections are given in full. The species are listed 
in alphabetical order. 
Acanthognathus brevicornis 
Acanthognathus brevicornis M. R. Smith, 1944: 150-152, worker, dealate 
queen. Type loc. ; Barro Colorado Island, Panama Canal Zone. Holo- 
type worker and paratype queen in USNM; paratype queens in 
MCZ. — Kempf, 1964:67, worker from Nova Petropolis, Rio Grande 
do Sul, Brasil. 
Worker and queen: Distinguishable from the similar A. ocellatus 
(see below) by 2 main characters: 
1. Scapes shorter than those of other species of the same size; 
scape length (chord) about equal to head width in the worker, less 
in the queen (see Table I) . Scape length markedly less than mandible 
length in both worker and queen; all other species have scapes as 
long as or longer than mandibles, except A. teledectus with its extra- 
ordinarily long mandibles. 
2. Mandibles (0.86 mm long in holotype worker, teste Smith) 
with noticeable submedian welt on inner borders and 2-5 irregular, 
separated low denticles or minute tubercles in the space between 
the welt and the apical teeth on each mandible. No other species 
has these denticles so far as known. 
In addition, the sculpture of A. brevicornis is more strongly effaced, 
more shining than in A. ocellatus , but not as much so as in A. 
