THE AMERICAN SPIDERS OF THE GENERA 
STYPOSIS AND PHOLCOMMA 
(ARANEAE, THERIDIIDAE)* 
By Herbert W. Levi 
Museum of Comparative Zoology, Harvard University 
Several new species have been discovered since publication only a 
few years ago of a paper on Styposis (Levi, i960). One of these new 
species, S. sells, gives a clue to the relationship of the genus. The 
features characterizing Styposis are the ectally-facing embolus of the 
male palpus, and reduced or absent anterior median eyes. In only one 
other theridiid genus are there six-eyed species: Comaroma Bertkau, 
found in south-central Europe, Japan, and the western United States. 
However, the different structure of Comaroma genitalia and the 
large colulus suggest that the eye reduction evolved independently. 
The ectally-facing embolus is found also in one species of the genus 
Pholcomma (P. hirsuta Emerton, Levi 1957), members of which also 
frequently have the anterior median eyes reduced in size, and the 
colulus replaced by two setae; but, unlike most species of Styposis , 
Pholcomma species usually have denticles on the posterior margin of 
of the chelicerae. In our revision of theridiid genera (Levi and Levi, 
1962) it was suggested that there might be species intermediate be- 
tween Styposis and Pholcomma. However the female of S. rancho 
here described has the epigynum similar to that of some Chilean 
Anelosimus species, a theridiid genus of larger spiders. But the 
epigynum of S. sells from southern Brazil resembles that of the Chilean 
Anelosimus, and furthermore the complexity of the male palpus also 
suggests that it belongs to the species group of Anelosimus endemic in 
Chile. The chelicerae have teeth on the posterior margin, as in 
Anelosimus and Pholcomma species, a feature uncommon in the 
Theridiidae. But unlike Chilean Anelosmius (Levi, 1936), S. selk 
has only six eyes. Before the discovery of S. sells, it was thought that 
the ectally facing embolus in some Chilean Anelosimus (Levi, 1963), 
was a unique character, evolved independently. It is now evident 
that Styposis is intermediate between Pholcomma and the Chilean 
Anelosimus , the most abundant theridiid spiders in Chile, although 
Styposis generally lacks posterior teeth on the chelicerae. Styposis 
clausis has a rough cheliceral surface facing the fang and a carina 
ending in an indistinct tooth (Fig. 10). 
Previously Styposis was known only from America; now a small 
* Manuscript received hy the editor December 3, 1963. 
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