THE SPIDER GENUS STYPOSIS 
(ARANEAE, THERIDIIDAE) 1 
By Herbert W. Levi 
Museum of Comparative Zoology, Harvard University 
Theridiid spiders usually have eight eyes. Only recently the genus 
Archerius Levi (1957, Trans. Amer. Micros. Soc., 76: 114) was 
described from some California specimens having only six eyes. Since 
then an eight-eyed species from Japan was seen, a species having the 
anterior median eyes small. The number of eyes, then, may not be of 
generic importance. 
Since the work on Archerius , another theridiid genus has been found 
in which the eye number is variable. In some species the anterior 
median eyes are present but small ; other species lack them entirely. 
Judging by their similar appearance and by the genital structure, the 
species are closely related and belong to the genus Styposis. 
A grant from the National Institutes of Health (E-1944) and a 
National Science Foundation grant (G-4317) made the completion 
of this paper possible. I would like to thank Dr. W. J. Gertsch and 
Dr. A. M. Chickering for specimens used and Professor M. Vachon 
for permitting me to examine S. flavescens in the Museum National 
d’Histoire Naturelle in Paris. 
Styposis Simon 
Styposis Simon, 1894, Histoire Naturelle des Araignees, 1: 592. Type species 
by original designation and monotypy: S. flavescens Simon. 
Small unpigmented spiders, less than 2 mm. total length. In some 
species carapace almost circular, weakly sclerotized, with six large 
eyes (except all eyes relatively small in S. ajo, Figure 27) arranged 
in two groups of three eyes touching each other (Figs. 1, 5, 10, 11). 
In other species ( S . flavescens , S. scleropsis) carapace longer than wide, 
sclerotized, with raised reticulate pattern (Figs. 18, 24). In all spe- 
cies anterior median eyes absent or minute, their maximum diameter 
equal to radius of posterior medians. Chelicerae weak with one or two 
teeth on anterior margin (Fig 11), probably none on posterior. Legs 
fairly long; in some species patella and tibia 2.7 times carapace length 
(S. clausis) , in others shorter 1.4 times carapace length (S. ajo , S. 
flavescens) . Legs with many setae; comb on fourth tarsus greatly 
reduced, its setae almost smooth. Abdomen soft, sometimes wider 
than long, or high. Colulus two minute hairs slightly anterior of 
Tublished with the aid of a grant from the Museum of Comparative Zoology 
at Harvard College. 
13 
