OF THE U N I VERSITY or ILLINOIS 590-S v.34 BIOLOGY Return this book on or before the Latest Date stamped below. Theft, mutilation, and underlining of books arc reasons for disciplinary action and may result in dismissal from the University. University of Illinois Library L161— O-1096 FIELDIANA . ZOOLOGY Published by CHICAGO NATURAL HISTORY MUSEUM - Volume 34 MARCH 15, 1956 No. 39 A NEW SNAKE OF THE GENUS TANTILLA FROM WEST TEXAS SHERMAN A. MINTON, JR. INDIANA UNIVERSITY MEDICAL CENTER, INDIANAPOLIS, INDIANA Among some 300 reptiles and amphibians collected in Trans- Pecos Texas is an apparently undescribed snake of the genus Tan- tilla. It is sufficiently distinct from other members of the genus to warrant description, although it is represented in the collection by only a single specimen. In preparation of this description I have profited from the helpful advice of Hobart M. Smith, of the University of Illinois, and Philip W. Smith, of the Illinois Natural History Survey. The new form is to be known as: Tantilla cucullata1 sp. nov. Type. — Chicago Natural History Museum no. 74384, adult male from six miles south-southeast of Alpine, Brewster County, Texas, at an elevation of about 5,000 feet. Collected by S. A. Minton, Jr., on July 1, 1955. Diagnosis. — A Tantilla with an almost uniformly black head, the pigmentation including the chin and labials and terminating 3 to 4 scales posterior to the parietal; no light nuchal collar; mental barely in contact with anterior chin-shields; ventrals 167, subcaudals 82. Description of type. — Head somewhat depressed, slightly but distinctly wider than the neck; snout wide, rounded when seen from above, projecting slightly beyond the lower jaw. Rostral slightly wider than high, visible when viewed from above; internasals smaller than prefrontals, common internasal suture about half the length of the common prefrontal suture; greatest length of frontal almost twice the common prefrontal suture; common parietal suture about two-thirds of the length of the frontal; posterior tips of parietals separated by a single rhomboid scale. Nasal almost 1 From cucullus, a hood, referring to the form of the black head pigmentation. No-789 449 A?R l» 1955 450 FIELDIANA: ZOOLOGY, VOLUME 34 equally divided by a vertical suture; naris central; preocular single and barely in contact with nasal; 2 postoculars, the upper slightly smaller than the lower; temporals 1-1, elongate, subequal; 7 supra- labials, 1-2-3-4-6-5-7 in increasing order of size, third and fourth entering the orbit. Mental an equilateral triangle, its posterior apex just in contact with the anterior chin-shields; 6 infralabials, 2-3-1- 6-5-4 in increasing order of size, the fourth much the largest; ante- rior four in contact with anterior chin-shield ; only fourth in contact with posterior chin-shield. Body slender and almost cylindrical, with slight, even taper; tail tapering gradually to a fine tip. Dorsal scales in 15 rows; ventrals 167; anal divided; subcaudals 82. Total length after preservation 336 mm.; tail 83 mm. Dorsal color in life light tan; after preservation paler and more grayish; free margins of most dorsal scales finely stippled with black, this feature being more pronounced posteriorly; ventral color very pale greenish white. Top and sides of head entirely black save for a small, pale brown area at the tip of the snout; black color terminates irregularly 3 to 4 scale lengths behind parietals and last supralabials; no light collar posterior to dark area. Mental, infralabials, and chin-shields black, with minute light flecks on anterior chin-shields and first infralabial; light ventral color encroaching irregularly in the midline to within about one scale length of the posterior chin- shields; laterally the dark color of the throat includes the tips of the second ventral. Comparisons. — Following the arrangement of Smith (1942), this species' closest relatives appear to be nigriceps and eiseni. From both it differs in the intense black pigmentation of virtually the entire head and in the high subcaudal count of 82. The distinctive head pattern of cucullata is better derived from an expansion of the black cap of nigriceps than from that of eiseni or yaquia, in which the tendency is toward formation of a black collar at the angle of the jaw bordered posteriorly by a light collar. In number of ventrals, cucullata exceeds nigriceps but falls within the range of variation in eiseni and probably yaquia. In nigriceps the first infralabial nor- mally separates the mental from the anterior chin-shield; this con- dition is closely approached in the type of cucullata. The relatively large size of cucullata points to relationship with both eiseni and nigriceps. The white venter affords another point of distinction; in the few fresh eiseni and nigriceps examined the venter is suffused with orange or pinkish. Head pattern, larger size, and greater FIG. 98. Tantilla cucullata sp. nov.; head of type, CNHM 74384. Photo- graphs by Illustration Department of Indiana University Medical Center. 451 452 FIELDIANA: ZOOLOGY, VOLUME 34 number of ventrals and subcaudals separate cucullata from snakes of the atriceps-utahensis complex. The type locality of cucullata lies within the ranges of both atriceps and nigriceps, although the probability of ecological segregation is great. Remarks. — The type of cucullata was collected alive on a highway about an hour before sunset and soon after a light shower. The terrain at the site is hilly but not especially rugged. The soil is a much comminuted reddish lava sparsely grown with grass, junipers (Juniperus monosperma), and cholla (Opuntia imbricata). If this habitat is typical, the expected range probably does not extend much more than 20 miles to the south and east of Alpine, where the grassy hills give way to a more arid Lower Sonoran association. To the north, the range may extend to the foothills of the Davis Mountains. REFERENCES BLANCHARD, FRANK N. 1938. Snakes of the genus Tantilla in the United States. Field Mus. Nat. Hist., Zool. Ser., 20: 369-376. BROWN, BRYCE C. 1950. An annotated check list of the reptiles and amphibians of Texas, xii + 257 pp. Baylor University Press, Waco, Texas. SMITH, HOB ART M. 1942. A resume of Mexican snakes of the genus Tantilla. Zoologica, 27: 33-42. UNIVERSITY OF ILLINOIS-URBANA