1966] 
Lawrence and Reichardt — Ptinidae 
33 
Pronotum longer than wide, constricted basally; anterior angles 
rounded ; disc somewhat flattened dorsally, with two more or less 
parallel longitudinal grooves, extending from two anterior pores pos- 
teriorly to a broad and deep, transverse impression, which is bordered 
on each side by two opposing, curved trichomes. Scutellum small, 
semicircular. Elytra more than twice as long as pronotum, almost 
twice as wide at humeri as pronoum at base; sides more or less 
parallel, expanded and broadly rounded apically; humeral callosities 
distinct; disc slightly convex dorsally, steeply sloping laterally; each 
elytron with 9 rows of fine punctures bearing short, suberect, fine, 
yellow hairs; apices of elytra individually rounded but only barely 
divergent. Hindwings fully developed. Prosternum before coxae flat, 
fairly long, intercoxal process laminate and depressed, so that the 
elongate coxae are almost touching. Mesosternum shorter than pros- 
ternum; mesocoxae separated by less than 0.25 times coxal width. 
Metasternum less than 0.50 times as long as wide and slightly longer 
than mesosternum, convex, median suture absent; metacoxae strongly 
transverse, separated by less than 0.20 times coxal width. Abdomen 
about as long as wide at base, strongly convex anteriorly; first 3 
segments fused, the sutures between them indicated only laterally; 
4th segment very narrow. Legs (Figs. 2 — 4) relatively short and 
simple; trochanters elongate-oval; femora and tibiae narrow and 
slightly flattened ( G. floridanus) or strongly flattened and expanded 
(G. formicicola and G. meinerti) ; tarsi short, the first 4 tarsomeres 
subequal. Male genitalia (Figs. 13 — 14) of the general type of 
Ptinus with median lobe articulating dorsally with bases of para- 
meres; basal piece relatively large, parameres very narrow, curved, 
converging apically. Total length : 1.70 — 2.53 mm. 
distribution: (Fig. 15): South America (Brazil, Bolivia, and 
Venezuela), Panama, Florida, and the Bahamas. 
The relatively narrow and elongate body form, presence of dis- 
tinct humeral callosities, and well developed scutellum and hindwings, 
will distinguish Gnostus from the majority of ptinid genera. From 
Ptinus and Niptinus it differs by the structure of the clypeus (which 
is more elongate), the lack of a metasternal suture, narrower pro- 
notum, and the modifications of legs and antennae. Gnostus is easily 
separated from Fabrasia by the 3-segmented antennae, position and 
size of eyes, longer and narrower prothorax, shorter legs, absence 
of metasternal suture, and partial obliteration of the first two ab- 
dominal sutures. The genus is most closely related to Ptinus and 
Fabrasia. 
All of the species of Gnostus appear to be associated with ants of 
the genus Crematogaster, and in the compilation below, at least five 
