FREQUENCIES OF COLOR MORPHS IN FOUR 
POPULATIONS OF ENOPLOGNATHA OVATA (ARANEAE: 
THERIDIIDAE) IN EASTERN NORTH AMERICA* 
By David H. Wise and Paul R. Reillo 
Department of Biological Sciences 
University of Maryland Baltimore County (UMBC) 
Catonsville, Maryland 21228, U.S.A. 
Introduction 
Several types of spiders exhibit conspicuous color polymor- 
phisms. Reiskind (1970) has discovered mimetic polymorphisms 
among clubionids. Examples in which only one sex is polymorphic 
occur among the jumping spiders, which have keen vision and often 
show marked sexual dimorphism (e.g. Galiano 1981a, b). In these 
species the sex-limited polymorphisms may be related to differential 
predation pressures upon the sexes and/or sexual selection (Stamps 
and Gon 1983). Many theridiid spiders are polymorphic (Levi 1957; 
Stamps and Gon 1983), though in this group the eyes are not well 
developed and recognition of colors or patterns during courtship 
probably does not occur. Polymorphisms in theridiid species appear 
not to be sex-limited, though the frequencies of certain morphs may 
differ between the sexes (Hippa and Oksala 1977, 1981). By far the 
most extensively studied color polymorphism among spiders is that 
found in the theridiid Enop/ognatha ovata (Clerck). 
Populations of E. ovata frequently contain three distinctive types 
of adults. The most common morph has a pale yellow abdomen, 
often with several pairs of dorsolateral dark spots, but with no red 
stripes (form lineata ); another form has two dorsolateral red stripes 
running the length of the abdominal dorsum (form redimita ); and 
the least common morph has a solid red band running the length of 
the abdominal dorsum (form ovata) (Bristowe 1958). This striking 
variation in a common species has long fascinated naturalists. Early 
arachnologists considered the forms to be three species, but by early 
last century the three varieties were considered to be conspecific 
* Manuscript received by the editor October 4. 1984. 
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