The Amphibians and Reptiles of Sinaloa, Mexico - Smithsonian ...

174 UNIVERSITY OF KANSAS PUBLS., MUS. NAT. HIST.
bands on the tail (excluding KU 73537). Seven to 13 (10.6) of
the white bands on the body are complete ventrally. The dorsal
scale rows are 21 behind the head, 21 at midbody and 17-19 just
anterior to the vent. The three females and two specimens of unknown
sex (KU 63422, 40355) have the following characteristics
respectively: 216, 207, 217, ?, ? ventrals; 16, 11, 12, 15, 13 white
bands on the body; 16, 10, 12, ?, 13 of the white bands are complete
ventrally; 21 scale rows behind the head and at midbody and 19,
19, 19, 18, 19 scale rows anterior to the anus. All females have incomplete
tails. One specimen (KU 73541) from Isla Palmito del
Verde has black tips on the red scales and the snout is black with
white mottling. All of the other specimens lack black tips on the
red scales. Six specimens have white snouts that are mottled with
black, and four specimens have black snouts that are mottled with
white (excluding KU 40355, 63422). Two specimens (KU 73533-
34) have one incomplete white band on the posterior part of the
body. Another specimen (KU 73539) has two white bands that are
incomplete dorsally by four and 12 scales. A fourth specimen (KU
73536) is even more unusually marked by having three lateral blackbordered
white blotches alternating between the second and third
complete white bands. The white blotches (two on the right and
one on the left side) are 4, 14, and 7 scales long from anterior to
posterior, and are bordered by black pigment which is confluent
ventrally; dorsally the black pigment of any blotch does not contact
the vertebral scale row.
Blanchard (1921:157) suggested that nelsoni probably intergrades
with annulate, somewhere on the Mexican plateau. Fugler and
Dixon (1961:14) regarded one specimen that has only eight of the
15 white bands continuous ventrally as an indication of inter gradation
with L. t. arcifera. Five specimens with one to five white bands
discontinuous ventrally are from the southern part of the state, and
may indicate intergradation. We suspect that this color variant is
inherent in the population here referred to nelsoni. Zweifel (1960:
104-07) pointed out that the coastal population of Lampropeltis
triangulum may be distinct from nelsoni. Zweifel outlined the problem
in some detail and discussed the variation in coloration in this
species. Based on the color variation of material from Sinaloa and
the lack of knowledge of the variation and distribution of different
populations, as pointed out by Duellman (1961:102), we refer the
Sinaloan specimens to nelsoni. Only a detailed study of all specimen
of Lampropeltis triangulum from Mexico will clarify the status