86 
William E. Sanderson 
RESULTS 
SCALATION 
Mean numbers of preocular, postocular, subocular, supralabial, 
infralabial, and temporal scales do not distinguish N. cyclopion from 
N. floridana. Regression analysis revealed no significant difference 
between the two taxa in relative tail length. 
Ventral scute counts do not appear to be related to a signifi- 
cant degree to either sexual dimorphism or geographic variation. 
However, the mean number of ventrals for cyclopion (x = 141.6, 
range = 133-145, n = 249) is significantly higher than that of 
floridana (x = 136, range = 129-141, n = 130, P < 0.01). As in 
most species of snakes, there is sexual dimorphism in the number 
of subcaudal scales. This difference is significant in both cyclopion 
and floridana ( P < 0.01); males of both taxa have 5-11 more 
subcaudals than females from the same localities. In both sexes 
cyclopion has fewer subcaudals than floridana. In cyclopion , north- 
ern populations have fewer subcaudals than southern populations, 
whereas there is no discernible geographic variation in floridana. 
Subcaudal counts in floridana show no significant geographic varia- 
tion. Samples from the vicinity of the presumed zone of parapatry 
are significantly different ( P < 0.01). The mean subcaudal number 
for male cyclopion from southern Alabama and Escambia County, 
Florida, is 73.9 (range = 70-76, n = 8), whereas that of male 
floridana from the western panhandle is 77.5 (range = 77-78, n = 
2). Mean values for female cyclopion and floridana from the same 
areas are 66.7 (range = 61-69, n = 15) and 70 ( n = 1), respec- 
tively. The ranges of these values for the two taxa do not overlap, 
and the differences are significant even with the small sample sizes 
for floridana. 
Table 1. Most frequent dorsal scale row formulae for Nerodia cyclopion and N. 
floridana. See Sanderson (1983) for complete scale row data. 
Dorsal scale rows 
(anterior-midbody- 
posterior) 
Males 
Females 
cyclopion 
floridana 
cyclopion 
floridana 
%of 
Number sample 
% of 
Number sample 
% of 
Number sample 
% of 
Number sample 
25-23-19 
15 
31.3 
0 
0 
0 
0 
0 
0 
27-25-21 
33 
68.8 
15 
34.1 
57 
70.4 
0 
0 
29-25-21 
0 
0 
15 
34.1 
10 
12.3 
11 
22.9 
29-27-21 
0 
0 
11 
25.0 
12 
14.8 
15 
31.3 
29-27-23 
0 
0 
3 
6.8 
2 
2.5 
22 
45.8 
