STUDIES ON NEOTROPICAL POMPILIDAE 
(HYMENOPTERA) 
II. GENUS ARIDESTUS BANKS* 
By Howard E. Evans 
Museum of Comparative Zoology 
Banks (1947, Bull. Mus. Comp. Zool., 99: 432) based the genus 
Aridestus on a single female from Paraguay. This specimen was 
identified as “bergi Brethes” although in fact bergi is a Holmberg 
species, described in 1881 from a single female from the province of 
Buenos Aires, Argentina. I have before me fifteen females and six 
males which I consider to be congeneric with bergi , and it seems ap- 
propriate to present a fuller description of the genus Aridestus on 
the basis of this additional material. 
In his generic description, Banks emphasized the transverse striae 
on the propodeum. As a matter of fact these striae are absent in the 
male bergi and in both sexes of a. Chilean species which is exceed- 
ingly similar to bergi in all other respects, including the male termi- 
nalia. I therefore find it desirable to define Aridestus somewhat 
differently than did Banks. I consider Evagetes , Aridestus , and the 
African genus A sthenoctenidia Pate (= Asthenoctenus Arnold) to 
form a closely knit generic complex characterized by the thickened 
and slightly flattened antennae, by the reduced pulvillar pad and 
comb, by having the clypeus no wider than the lower front, and by 
several other common features. Evagetes is known to be a clepto- 
parasite of other' Pompilini, and it seems to me very likely that the 
other two genera behave similarly. 
The known species of A ridestus are black with the abdomen mostly 
or entirely red, and they are especially similar to those species of 
Evagetes having the abdomen partly rufous and the pronotum sub- 
angulate behind (e.g. crassicornis Shuckard). The species of Aridestus 
differ in having the clypeus, front, and vertex narrow, the middle 
interocular distance not exceeding .58 times the transfacial distance 
in either sex, the clypeus not more than 2.5 times as wide as high 
in the female, 2.2 times as wide as high in the male. The pronotum 
is also short medially and in the female somewhat swollen antero- 
laterally, there is an unusually distinct median groove on the front, 
and the marginal cell is far removed from the wing-tip (at least 
^Published with the aid of a grant from the Museum of Comparative 
Zoology. 
Manuscript received by the editor May 15, 1966 . 
