A female of this species was collected in the Parque Nacional at the north edge of Uruapan in 1899, and a male was taken there in 1947; these specimens were used by Hartweg in his description of the species. Floyd L. Downs obtained another specimen in the Parque Nacional on July 19, 1960. It has 164 ventrals and 46 caudals; in life, the ground color of the neck was brown with a purplish tint; the dorsal markings were black; the chin was a cream-color, and the belly was white. This specimen is distinguished from those of all other species of Geophis in Michoacán in that it has dark irregular cross-bars on the dorsum and a row of dark spots on the venter.
Hypsiglena torquata ochrorhyncha Cope
Hypsiglena ochrorhyncha Cope, Proc. Acad. Nat. Sci. Philadelphia, 12:246, November 15, 1860.—Cape San Lucas, Baja California, México.
Hypsiglena torquata ochrorhyncha, Bogert and Oliver, Bull. Amer. Mus. Nat. Hist., 83:378, March 30, 1945.
Tupátaro.
The systematic status of the geographic variants of Hypsiglena in México and southwestern United States has been commented on by several authors. Tanner (1944) considered H. torquata and H. ochrorhyncha to be distinct species; Bogert and Oliver (1945:379) and Duellman (1957b:238) presented evidence indicating that H. torquata and H. ochrorhyncha intergrade in Sinaloa and southern Sonora. In Hypsiglena the scutellation, including the numbers of labials, dorsals, ventrals, and caudals, seem to vary in a clinal manner. Nevertheless, these snakes can be divided into two distinct populations on the basis of the nuchal color pattern, consisting of an ochrorhyncha-type (a broad dark nape-band, the lateral edges of which extend anteriorly and fuse with a postorbital stripe, and a narrow nape stripe extending from the posteromedian edges of the parietals to the dark nape band) and a torquata-type (a somewhat narrower dark nape-band bordered anteriorly by a pale nuchal area, and no dark nape stripe). Snakes having the ochrorhyncha-type of nuchal pattern are found on the Mexican Plateau from Michoacán northward into the desert regions of Sonora and the southwestern United States. Snakes having the torquata-type of pattern are found on the coastal lowlands and adjacent slopes of the Sierra Madre Occidental from southern Sinaloa to Colima and thence inland in the Balsas-Tepalcatepec Basin to Morelos and Guerrero. An exception is Hypsiglena torquata dunklei from Forlón and San Fernando, Tamaulipas; it has the torquata-type of nuchal pattern. The distributional picture is somewhat complicated because some individuals having the torquata-type of nuchal pattern also have a faint nape stripe. If these are taken as exceptions, the general picture of distribution in México is H. t. torquata on the Pacific lowlands from Sinaloa southward to the Balsas Basin and H. t. ochrorhyncha on the Mexican Plateau.
Smith (1943:433) resurrected Hypsiglena jani Dugès for the snakes of the ochrorhyncha-type on the southern part of the Mexican Plateau. He stated that the southern specimens differed from northern ones in having a nuchal spot 9 or 10 scales in length, as compared with a spot 2 to 6 scales in length in northern specimens. A cursory examination of specimens from the areas between Arizona and Michoacán showed that there is a gradual increase in the size of the spot from north to south. If no other characters can be found to distinguish the populations, they should be considered as a single subspecies.
Hypsiglena affinis differs from H. torquata in possessing 19 instead of 21 rows of dorsal scales. Additional material is needed from the western slopes of Jalisco and the Barrancas in Zacatecas and Durango, before definite allocation of affinis can be made.
Bogert and Oliver (1945:379) discussed the status of certain named populations in Baja California and concluded that only one species occurs there, and that the species probably is conspecific with H. torquata. A careful review of the genus Hypsiglena might show that there is only one species.
The one specimen from Michoacán (USNM 46513) is from an elevation of about 2300 meters near the southern edge of the Mexican Plateau.