A Taxonomic Study of the Middle American Snake, Pituophis Deppei

Part 1

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UNIVERSITY OF KANSAS PUBLICATIONS MUSEUM OF NATURAL HISTORY

Vol. 10, No. 10, pp. 599-610, 1 pl., 1 fig. May 2, 1960

A Taxonomic Study of the Middle American Snake, Pituophis deppei

WILLIAM E. DUELLMAN

UNIVERSITY OF KANSAS LAWRENCE 1960

UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

Editors: E. Raymond Hall, Chairman, Henry S. Fitch, Robert W. Wilson

Volume 10, No. 10, pp. 599-610, 1 pl., 1 fig. Published May 2, 1960

UNIVERSITY OF KANSAS Lawrence, Kansas

PRINTED IN THE STATE PRINTING PLANT TOPEKA, KANSAS 1960

28-2493

PLATE 45

A Taxonomic Study of the Middle American Snake, Pituophis deppei

WILLIAM E. DUELLMAN

INTRODUCTION

As a part of a study of the herpetofauna of the Mexican state of Michoac['a]n an attempt was made to ascertain the interspecific and intraspecific relationships of the various populations of Pituophis there. Field work in Michoac['a]n revealed that two supposed subspecies of Pituophis deppei were sympatric. This discovery led to the examination of all available (124) museum specimens of these snakes.

I am grateful to the following persons who permitted me to examine specimens in their care: Charles M. Bogert, American Museum of Natural History (AMNH); Doris M. Cochran, United States National Museum (USNM); Norman Hartweg, University of Michigan Museum of Zoology (UMMZ); Robert F. Inger, Chicago Natural History Museum (CNHM); Arthur Loveridge, Museum of Comparative Zoology (MCZ); Hobart M. Smith, University of Illinois Museum of Natural History (UIMNH); and Edward H. Taylor, E. H. Taylor--H. M. Smith collection (EHT-HMS). Specimens in the accounts of the species are listed after the abbreviations of the institutions given in parentheses above.

HISTORICAL REVIEW

Part 2

Dum['e]ril (1853: 453) described Elaphis deppei from a specimen in the Leiden Museum from "Mexico." This specimen, according to the type description, has 233 ventrals and 67 caudals. In 1863 Jan described Pituophis deppei var. pholidostictus, also with "Mexico" as the type locality. Subsequent authors (see synonymy of P. deppei deppei in Stull, 1940: 25) have treated pholidostictus as a synonym of deppei. Smith and Taylor (1950: 334) restricted the type localities of deppei and pholidostictus to San Juan Teotihuac['a]n, M['e]xico. Cope (1860: 369) described Arizona jani on the basis of a specimen in the United States National Museum from Buena Vista, Coahuila. Stull (1932: 2, 1940: 42), Smith (1944: 145) and Smith and Taylor (1945: 107) considered jani as a northern subspecies of Pituophis deppei. Arizona lineaticollis was described by Cope (1861: 300); the type, which originally was in the Academy of Natural Sciences of Philadelphia and is now lost, was said to have come from Jalapa, Veracruz. This locality probably is in error. Smith (1943: 460) placed lineaticollis as a southern subspecies of deppei. Schmidt and Shannon (1947: 79) described Pituophis deppei brevilineata on the basis of five specimens from Tanc['i]taro, Michoac['a]n, and Stuart (1954: 172) described Pituophis deppei gibsoni from seven specimens from Departamento Chimaltenango, Guatemala. Thus, at present five subspecies of Pituophis deppei are recognized.

CHARACTERS STUDIED

Snakes currently assigned to Pituophis deppei differ from other members of the genus by possessing two instead of four prefrontal plates. The subspecies of P. deppei have been defined on characters of coloration and scutellation.

Scutellation.--The only scale characters utilized in the present study are the numbers of ventrals and caudals. The number of ventrals varies in the total sample from 210 to 246 (Table 1); usually the variation in one locality is no more than 15. Number of caudals varies from 52 to 72. There is slight sexual dimorphism in the number of ventrals and somewhat greater differences in the number of caudals.

TABLE 1.--Variation in the Numbers of Ventrals and Caudals in Four Subspecies of Pituophis.

==============================+====================+================== SUBSPECIES | Ventrals | Caudals +---------+---------+---------+--------- | Range | Mean | Range | Mean ------------------------------+---------+---------+---------+--------- deppei deppei | | | | 34 | 210-231 | 220.4 | 53-69 | 61.5 16 | 209-232 | 218.2 | 52-61 | 57.2 | | | | deppei jani | | | | 12 | 215-235 | 225.1 | 56-68 | 62.6 3 | 228-231 | 229.0 | 52-60 | 56.0 | | | | lineaticollis lineaticollis | | | | 13 | 231-258 | 239.5 | 54-72 | 64.9 9 | 229-249 | 241.3 | 55-68 | 60.6 | | | | lineaticollis gibsoni | | | | 2 | 234 | 234.0 | 61-65 | 63.0 4 | 241-246 | 243.7 | 57-63 | 59.0 ------------------------------+---------+---------+---------+---------

Coloration.--The dorsal ground color is tan or straw; the dorsal pattern consists basically of dark middorsal blotches and dark lateral intercalary spots. Number of blotches, color of blotches posteriorly, width of pale interspaces between anterior blotches, and color of lateral intercalary spots vary considerably geographically. In some populations (lineaticollis and gibsoni) the anterior blotches are divided medially forming either a pair of dark stripes on the anterior part of the body or a series of paired spots. Details of coloration are described in the following accounts.

ACCOUNTS OF THE SPECIES AND SUBSPECIES

Study of Pituophis deppei (auctorum) revealed the presence of sympatric populations of two distinct species of Pituophis differing from each other in scutellation and coloration. The nomenclature resulting from the required rearrangement necessitates the recognition of 1) deppei as a species, 2) jani as a subspecies of deppei, 3) lineaticollis (with brevilineata as a synonym) as a species distinct from deppei, and 4) gibsoni as a subspecies of lineaticollis. Known geographic distributions of these named taxa are shown in Figure 1.

=Pituophis deppei deppei= Dum['e]ril

Elaphis deppei Dum['e]ril, Mem. Acad. Inst. France, vol. 23, p. 453, 1853; Dum['e]ril and Bibron, Erp['e]tologie g['e]n['e]rale, vol. 7, p. 268, February 25, 1854.

Pituophis deppei, Jan, Elenco sistematico degli ofidi, p. 59, 1863; G[:u]nther, Biologia Centrali-Americana, Reptilia, p. 124, February, 1894.

Elaphis pleurostictus Dum['e]ril, Mem. Acad. Inst. France, vol. 23, p. 453, 1853 [Type.--Museum d'Histoire Naturelle Paris, No. 6616; type locality--"Monte Video" (restricted to San Juan Teotihuac['a]n, M['e]xico, by Smith and Taylor, 1950: 334)].

Pituophis pleurostictus, Jan, Elenco sistematico degli ofidi, p. 59, 1863.

Pituophis deppei, var. pholidostictus Jan, Elenco sistematico degli ofidi, p. 59, 1863 [Type.--Zoologisches Museum Berlin, No. 1738; type locality.--"Mexico" (restricted to San Juan Teotihuac['a]n, M['e]xico, by Smith and Taylor, 1950: 334)].

Pituophis deppei deppei, Stull, Occas. Papers Mus. Zool. Univ. Michigan, no. 250, p. 1, October 12, 1932; Bull. U. S. Natl. Mus. 175, p. 25, April 23, 1940; Smith and Taylor, U. S. Natl. Mus., no. 187, p. 107, 1945.

Type.--Rijksmuseum van Natuurlijke Historie, Leiden, No. ???, obtained by Ferdinand Deppe. The type locality was originally given as "Mexico"; this was restricted to San Juan Teotihuac['a]n, state of M['e]xico, by Smith and Taylor (1950: 334).

Diagnosis.--This subspecies is characterized by the presence of solid body-blotches and lateral intercalary spots, dorsal interspaces less than five scales in length, and the absence of paired stripes or rows of blotches, on the anterior part of the body. There are 209 to 232 ventrals and 52 to 62 caudals. The body-blotches number 27 to 49. In adults the anterior and posterior body-blotches are black; the lateral intercalary spots are solid black. In many individuals black dashes connect the adjacent corners of the dorsal body-blotches (Pl. 45, Fig. 1). In juveniles the anterior, dorsal body-blotches are black, whereas those at the midbody and posteriorly are brown.

Variation.--Geographically, scutellation varies only slightly. Comparison of specimens from the northern part of the Mexican Plateau (Chihuahua, Coahuila, and Durango--5 specimens), the central part of the plateau (Aguascalientes, San Luis Potos['i], and Zacatecas--13 specimens), the southern part of the plateau (Guanajuato, Jalisco, M['e]xico, and Michoac['a]n--18 specimens), and Puebla and southern Veracruz (12 specimens) shows the average number of ventrals for these samples to be, respectively, 221.6, 216.7, 221.3, and 220.0. The average number of dorsal body-blotches for the same samples are, respectively, 36.6, 37.7, 38.4, and 34.6. Only in the southernmost sample is there a noticeable difference in the number of blotches.

The specimen from P['a]rajo Verde, Veracruz, was considered to be an intergrade between P. deppei and P. lineaticollis by Smith (1943: 461), who stated that, although the snake had 231 ventrals and dark lateral streaks as does deppei, it had light-centered dorsal blotches and stripes on the neck as does lineaticollis. This specimen (USNM 110892) has a high number of ventrals for deppei; one from Jalisco has 232, and one each from Guanajuato and Veracruz have 229. The blotches posteriorly are lighter than those anteriorly and are slightly lighter in the center than at the periphery. Two anterior blotches are divided medially and narrowly connected by black streaks. Although these are somewhat suggestive of the pattern of lineaticollis, they are more nearly like that of deppei. Four other specimens from the same area are typically deppei. There is some doubt as to the actual provenance of the snake stated to have come from P['a]rajo Verde, for, according to Smith (1943: 460), the snake had been tied to a truck and dragged halfway down the slopes of the Cumbres de Acultzingo, where he found it. He surmised that it probably was dragged no farther than the settlement, P['a]rajo Verde, at the Cumbres de Acultzingo.

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