1979] 
Fowler & Levi — New Quasisocial Spider 
17 
not a sufficient number of males present in the colony to inseminate 
all reproductively receptive females, only inseminated females would 
produce viable young as thelytoky is unknown in spiders (White, 
1973). Species of Anelosimus that are now considered to be 
quasisocial may thus be found to be functionally eusocial (sensu 
Wilson, 1971). However, there is still no evidence of an actual 
anatomical of physiological distinction among non-reproducing 
spiders that would qualify them as a true caste in the usual sense 
employed in the study of social insects. 
Acknowledgements 
We extend our thanks to the valuable comments that have been 
given on previous drafts by E. O. Wilson, F. M. Carpenter, R. B. 
Roberts, E. Rajotte, and R. Buskirk. 
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