1978] 
Brown & Boisvert — Ant Genus Pentastruma 
205 
Habitus as shown for the paratype in Figs. 2 and 4. Note the 
depressed, flat mandibles and the 6-inerous antennae, with segments 
proportioned as in Smithistruma, and also the broadly extended, 
sharp-edged, lamelliform, free lateral margins of the clypeus, trans- 
lucent in bright light. Mandibular armament shown in detail in Fig. 
3. After the broadly rounded basal lamella there follow without a 
diastema 15 teeth, of which the first, fifth, and ninth are the longest. 
Between these, 2 groups of 3 smaller teeth each, in each such triplet, 
the middle tooth a little longer than the 2 flanking it. A similar 
triplet follows the ninth tooth, and after this 2 small subapical teeth 
and a robust apical tooth. Labral lobes at rest extending beyond the 
midlength of the mandibles. Mandibular surface very finely sculp- 
tured, weakly sericeous-shining. 
Pronotum with rounded, strongly marginate anterior margin 
(excluding cervix), faintly indicated but rounded humeri, feebly 
marginate or submarginate dorsolateral margins, widest (W about 
0.31 mm) behind midlength, tapering caudad into subparallel-sided 
posterior half of trunk (W about 0.16 mm across propodeal 
dorsum), which even widens again very slightly caudad. Meta- 
notal groove obsolete or nearly so as viewed from above; pro- 
podeal teeth approximately parallel. Faint margins extend the 
length of the dorsolateral borders of the trunk, but these are visible 
only in certain views and lights. 
Petiolar node subquadrate (rounded in front), slightly wider (W 
about 0.15 mm) than long, its dorsal surface with sculpture partly 
effaced, weakly shining. Postpetiolar disc transversely elliptical, 
nearly twice as wide as long (L 0.15, W 0.27 mm), smooth and 
shining, with a widely spaced pair of inclined hairs near posterior 
border. Gaster with weak basidorsal costulae, effaced mesad, the 
longest extending about a quarter of the length of the first terguin. 
Erect, feebly enlarged hairs: 4 near base of first gastric tergite, a pair 
near midlength, and a pair near posterior border of first tergite; 
remaining segments with 2 or 4 hairs each on tergites, and a few fine 
ventral, erect hairs also on apical half of gaster. The fine, short, 
extremely dilute, appressed and decumbent pubescence is invisible 
except at high magnifications (over 50X) and in special, strong 
lights, and is best developed on mandibles, antennae, vertex, legs, 
and gaster, though nowhere evident without a special effort to find 
it. 
Color medium testaceous; spongiform apendages sordid whitish- 
testaceous. 
