THE MALE OF ECHINOTHERIDION 
(ARANEAE: THERIDIIDAE)* 
By Herbert W. Levi 
Museum of Comparative Zoology, Harvard University 
Cambridge, Mass. 02138 
Introduction. A genus based on specimens of one sex only is 
unsatisfactory, even when the available specimens are so distinctive 
as to demand description. The four described species of the genus 
Echinotheridion all are known from females only. It therefore is 
important to describe the male recently found, the more so in view 
of his remarkable features. 
I would like to thank Norman Platnick, who found the male in 
American Museum of Natural History collections and recognized it 
as a possible male of Echinotheridion. 
Echinotheridion are small theridiid spiders, 2 to 3 mm in total 
length. The carapace is like that of Achaearanea and Theridion. The 
anterior median eyes of the known species are larger than others 
less than their diameter apart, almost touching the laterals. Eyes of 
the posterior row are equally spaced. Chelicerae are small with two 
anterior sclerotized teeth. Legs are short, the first longest. The 
abdomen is suboval, higher than long (Levi, 1963, fig. 120). There is 
no colulus. As in specimens of Tidarren, there usually is a vertical 
white line just above the spinnerets. Unusual for theridiid spiders is 
the enormous sclerotized epigynum. Overhanging the epigynum are 
coxal spurs which appear to be a functional part of the structure 
(Levi, 1963, fig. 120). Coxal spurs are otherwise uncommon in 
female theridiid spiders. 
Four species are known, three new in 1963: E. cartum from 
southern Brazil, E. elicolum from Venezuela, E. otlum from Ecua¬ 
dor, and E. utibile (Keyserling) from the Amazon. The recently 
collected male comes from within the range of E. cartum and 
probably belongs to that species. 
The male is remarkable in having only one palpus, and this ot 
enormous size, similar to males of Tidarren. Upon attaining adult¬ 
hood, Tidarren males attach one of their two palpi to a silk web and 
twist it off (Branch, 1942). 
* Manuscript received by the editor April 2, 1981 
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