NOTES ON AMERICAN THERIDIID SPIDERS 
By Herbert W. Levi 
Museum of Comparative Zoology, Harvard University 
About 195 species of theridiid spiders are known from north of 
Mexico, about 800 in all the Americas. Among them are our com- 
monest spiders but also numerous rare species. This is the first ad- 
dition to my revisions of spiders of this family. Similar additions will 
be made periodically as it becomes necessary to report on new species, 
describe the other sex of species known from only males or females, 
record habitat notes of rare species and make corrections. 
For their assistance I want to thank Miss M. E. Galiano of Buenos 
Aires, Mr. V. D. Roth of the Southwestern Research Station of the 
American Museum of Natural History, who collected specimens of 
rare Arizona species, and Dr. W. J. Gertsch, who made me aware of 
an error in my revision of the genus Tidarren and facilitated the loan 
of Latrodectus mactans hesperus. This research is in part supported 
by Public Health Research Grant AI-01944 from the National Insti- 
tute of Allergy and Infectious Diseases. 
Theridion arizonense Levi 
Figures 1-4 
Theridion arizonense Levi, 1957, Bull. Amer. Mus. Natur. Hist. 112: 49, 
figs. 137, 138, $. Female holotype from Rustler’s Camp, Chiricahua 
Mountains, Cochise County, Arizona, in the American Museum of 
Natural History. 
This species has heretofore only been known from the female. 
Description of male. Carapace yellowish with a gray line around 
carapace and a wide median gray band. Sternum gray all around. Legs 
dusky gray, darker distally. Dorsum of abdomen gray with pairs of 
white spots posteriorly, sides yellowish, venter gray. Eyes subequal 
in size. Anterior median eyes one and one-quarter diameters apart, 
their radius from laterals. Posterior median eyes less than a diameter 
apart, one diameter from laterals. Total length, 2.2 mm. Carapace, 
1. 1 mm long, 1.0 mm wide. First femur, 2.3 mm; patella and tibia, 
2.5 mm; metatarsus, 2.3 mm; tarsus, 0.8 mm. Second patella and 
tibia, 1.6 mm; third, 0.9 mm; fourth, 1.5 mm. 
The embolus of the palpus (Fig. 4) appears to be partly covered by 
a lamella like that of T. lawrencei. The shape of the radix (Fig. 3) 
and ducts within the tegulum (Fig. 4) differ. 
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