Dos Aguas (11); Puerto de Garnica; Tancítaro (11); Tzitzio; Uruapan; 16 km. NW of Zacapu.
Three males and six females from the Sierra de Coalcomán have, respectively, 122-128 (125.3) and 126-136 (130.0) ventrals, and 46-47 (46.7) and 38-42 (39.1) caudals. Four males and eleven females from the Cordillera Volcánica have, respectively, 124-132 (128.5) and 127-139 (136.4) ventrals, and 43-48 (44.7) and 38-44 (40.2) caudals. These data show that, although there is little difference in the number of caudals, specimens from the Sierra de Coalcomán have fewer ventrals than do specimens from the Cordillera Volcánica. Of eleven specimens from the Sierra de Coalcomán, two have black bellies. Five others from the Sierra de Coalcomán and one from Puerto de Garnica in the Cordillera Volcánica have the bellies heavily stippled with black, giving a gray appearance. Melanistic tendencies in this species have been discussed by Anderson (1960:64), who examined the specimen from Tzitzio. In life, one specimen from Dos Aguas (UMMZ 119451) had a cream-colored belly; the edges of the ventrals were dark brick-red.
In Michoacán this snake inhabits pine-oak, pine, and fir forests at elevations between 1550 and 2800 meters in the Cordillera Volcánica and the Sierra de Coalcomán. Most specimens were found beneath rocks; the one from Tzitzio was removed from the stomach of a Mexican Motmot (Anderson, 1960:66).
Thamnophis dorsalis cyclides Cope
Thamnophis cyrtopsis cyclides Cope, Proc. Acad. Nat. Sci. Philadelphia, 13:299, December 28, 1861.—Cape San Lucas, Baja California (in error). Type locality restricted to Guanajuato, Guanajuato, México, by Smith and Taylor (1950a:330). Smith, Copeia, no. 2:140, June 8, 1951. Milstead, Texas Jour. Sci., 5:368, September, 1953.
Thamnophis eques eques (nec. Reuss), Smith, Zoologica, 27:106, October 23, 1942. Bogert and Oliver, Bull. Amer. Mus. Nat. Hist., 83:356, March 30, 1945.
Thamnophis vicinus Smith, Zoologica, 27:104, October 23, 1942.—Temazcal, Michoacán, México.
Thamnophis dorsalis cyclides, Fitch and Milstead, Copeia, no. 1:112, March 17, 1961.
Barolosa; Coalcomán; Dos Aguas (3); Los Reyes; Morelia (16); Opopeo; Pino Gordo; Tacícuaro (16); Tancítaro (14); Tangamandapio (2); Temazcal (2); Tzintzuntzan; Uruapan.
The snakes comprising the former Thamnophis eques-group have undergone extensive taxonomic and nomenclatural shuffling by Smith (1942 and 1951), Bogert and Oliver (1945), Milstead (1953), and Fitch and Milstead (1961). Smith recognized in Michoacán three members of the T. eques (= dorsalis) complex: eques eques, eques postremus, and vicinus. Later, Smith (1951) showed that the specific name eques had been misapplied, so that T. eques eques became T. cyrtopsis cyclides, and T. eques postremus became T. cyrtopsis postremus; under this arrangement T. vicinus stood unchanged. In the meantime, Bogert and Oliver (1945:359) presented a reinterpretation of Smith's data and suggested that T. vicinus, which differs from T. dorsalis cyclides only in lacking a middorsal stripe, "... is not a species, but only a pattern phase, possibly a simple mutant of T. e. eques" (= T. dorsalis cyclides, by present arrangement). Milstead (1953) agreed with Bogert and Oliver on the status of T. vicinus; furthermore, on the basis of only a few specimens, Milstead concluded that T. cyrtopsis postremus was not subspecifically distinct from T. cyrtopsis cyclides. Recently, Fitch and Milstead (1961) showed that Thamnophis dorsalis Baird and Girard (1853) was the correct name for the snakes that had been recognized as Thamnophis cyrtopsis Kennicott (1860). Consequently, the snakes referred to T. eques eques by Smith (1942) and to T. cyrtopsis cyclides by Smith (1951) and Milstead (1953) are now T. dorsalis cyclides.