The generic status of Toluca is unsettled. Taylor and Smith (1942b) separated Toluca from Conopsis by the presence of enlarged and grooved posterior maxillary teeth in Toluca and their absence in Conopsis. Bogert and Oliver (1945:378) suggested synonymizing Toluca with Conopsis. Smith and Laufe (1945:12) defined the generic position of Toluca. Actually, in deciding the generic position of these snakes, five genera (Ficimia, Gyalopion, Pseudoficimia, Conopsis, and Toluca) must be considered. Of these Ficimia and Gyalopion are closely related; they have been placed in one genus by some workers. Pseudoficimia is intermediate between Ficimia-Gyalopion and Toluca-Conopsis. A workable definition of the supraspecific classification of these snakes must await a thorough review of the species.
Trimorphodon biscutatus biscutatus (Duméril, Bibron, and Duméril)
Dipsas biscutata Duméril, Bibron, and Duméril, Erpétologie genérale, 7 (pt. 2):1153, 1854.—México. Type locality restricted to Tehuantepec, Oaxaca, México, by Smith and Taylor (1950a:340).
Trimorphodon biscutatus biscutatus, Smith, Proc. U. S. Natl. Mus., 91:159, November 10, 1941.
Apatzingán (11); Cofradía; Cuatro Caminos; El Sabino (2); La Placita; La Playa (2); Lombardia (2); Nueva Italia (2); Río Tepalcatepec, 27 km. S of Apatzingán; Tafetán.
In the arid lowlands of the Tepalcatepec Valley and presumably also in the scrub forest of the coastal lowlands, this is an abundant snake, which is active only at night. Usually snakes of this species are found on the ground, but one large individual was observed at night in a low tree. That individual defied capture by widely opening its mouth and striking repeatedly at the collector. The excreta of one specimen contained feathers of an unidentified species of bird.
Trimorphodon latifascia Peters
Trimorphodon biscutata latifascia Peters, Monats. Akad. Wiss. Berlin, p. 877, 1869.—Puebla, México. Type locality restricted to Izúcar de Matamoros, Puebla, México, by Smith and Taylor (1950a:341).
Trimorphodon latifascia. Taylor, Univ. Kansas Sci. Bull., 25:364, July 10, 1939.
Apatzingán (5); Casada Tzararacua; Coalcomán (2); Lombardia; 14 km. S of Lombardia; Nueva Italia; San Salvador.