Geographic Variation in the Snake Storeria occipitomaculata 
(Storer) (Serpentes: Colubridae) in Southeastern 
United States 
Douglas A. Rossman and Robert L. Erwin' 
Museum of Zoology, Louisiana State University, 
Baton Rouge, Louisiana 70893 
ABSTRACT. -The populations of Storeria occipitomaculata occurring 
in the Gulf Coastal Plain from eastern Texas to the Carolinas differ 
from the nominate subspecies in nuchal pattern, ventral coloration, 
relative tail length, and subcaudal number. To accommodate these pop- 
ulations nomenclaturally the concept of S.o. obscura Trapido is expand- 
ed and redefined. 
The Florida red-bellied snake, Storeria occipitomaculata obscura, 
was described by Trapido (1944), who distinguished it from the nominate 
race on the basis of the former having a black head, the light supralabial 
spot touching the edge of the lip, a light nuchal collar, fewer ventrals, and 
more subcaudals. He envisioned the range of S.o. obscura as encompass- 
ing peninsular Florida and coastal plain Georgia, with intergradation oc- 
curring to the north and west of this area. Subsequent authors (Wright 
and Wright 1957; Cliburn 1959; Mount 1975) reported the occurrence of 
some of the distinguishing features of S.o. obscura in Mississippi and 
Alabama populations, and we discovered them in Louisiana snakes. 
These observations, along with the more than fivefold increase in 
specimens available from the Southeast since the time of Trapido’s study, 
prompted our investigation of variation in the species throughout this 
region of the country. 
METHODS 
We examined 523 specimens of Storeria occipitomaculata from 
southeastern United States (Fig. 1), and for each specimen we recorded 
sex, ventral and subcaudal numbers, tail length as percent of total length, 
nuchal pattern, and supralabial light spot condition. To facilitate 
analysis, data for specimens from geographically proximate and 
physiographically similar localities were pooled. We also examined living 
snakes from Wisconsin, Pennsylvania, Georgia, Florida, Alabama, Mis- 
sissippi, Louisiana, Arkansas, and Oklahoma, and noted various aspects 
of their color pattern, particularly the ventral coloration. 
'Present address: Department of Molecular Virology, Abbott Laboratories, North Chicago 
IL 60064. 
Brimleyana No. 4: 95-102. December 1980. 
95 
