Previously Anolis dunni has been reported only from the vicinity of Agua del Obispo, Guerrero, a locality situated at an elevation of about 900 meters in pine-oak forest in the Sierra del Sur. All known close relatives of Anolis dunni occur only in Guerrero: A. taylori Smith and Spieler from Acapulco, A. gadowi Boulenger from Tierra Colorado, A. liogaster Boulenger, and A. omiltemanus Davis from Omiltemi. The present specimens from elevations of about 900 meters in riparian stream vegetation and oak forest represent the northern known limits of this group of Anolis.
Anolis nebulosus (Wiegmann)
Dactyloa nebulosa Wiegmann, Herpetologia Mexicana, p. 47, 1834.—México. Type locality restricted to Mazatlán, Sinaloa, México, by Smith and Taylor (1950b:66).
Anolis nebulosas, Bocourt, Mission Scientifique au Mexique et dan l'Amerique Centrale. Reptiles, livr. 2:77, 1873.
Acahuato (3); Agua Cerca; Apatzingán (4); Araparicuaro (3); 29 km. S of Ario de Rosales (3); 20 km. S of Arteaga (2); Barranca de Bejuco; Cascada Tzararacua (5); Cerro Tancítaro (13); Cherán; Chupio (5); Coalcomán (10); Cofradía; Dos Aguas (10); 18 km. E of Dos Aguas (3); El Diezmo; El Sabino (43); El Ticuiz; Jiquilpan (2); La Orilla; La Placita; La Playa (3); Los Conejos (2); Los Pozos; Nogueleras (2); Ostula; 8 km. W of Pátzcuaro (2); 8 km. NE of Pátzcuaro; Playa Azul (3); Río Cachán; Río Marquez, 10 km. S of Lombardia; Río Tepalcatepec, 27 km. S of Apatzingán; San Juan de Lima (6); San Pedro Naranjestila; Temazcal; Tuxpan (2); Tzitzio; Uruapan (74); 11 km. N of Uruapan (2); Volcán Jorullo; 16 km. E of Zacapu (2); 18 km. W of Zamora; Ziracuaretiro.
Even with the abundance of material the assignment of a specific name to these anoles is only tentative, for definite determination between Anolis nebulosus Wiegmann and A. nebuloides Bocourt is uncertain. Bocourt (1873:75) distinguished A. nebuloides from A. nebulosus by the following characters: (1) head scales keeled, not smooth; (2) snout narrower; (3) ear opening larger; (4) supraorbital semicircles separated by a row of small scales and not in contact; (5) dorsal scales larger and subequal in size to the belly scales. Boulenger (1885:77) used the same characters; Smith and Taylor (1950b:58) in their key to the Mexican species of Anolis stated that the dorsal scales are slightly smaller than the ventrals in A. nebulosus and markedly smaller in A. nebuloides. Smith (in litt.) stated that the characters of the relative sizes of the dorsal and ventral scales were incorrect in that key.
The application of the above criteria to specimens from Michoacán has not resulted in the recognition of two species. The majority of the specimens have the supraorbital semicircles separated by at least one small scale; the head scales, with the exception of those on the snout in a few individuals, are smooth; the dorsal scales are only slightly smaller than the ventrals. In other characters of scutellation the specimens are highly variable. The males in life have an orange throat fan. Anoles of this kind have been found in Michoacán, Colima, Jalisco, Nayarit, and southern Sinaloa. Near Oaxaca, Oaxaca, specimens were collected that superficially resemble those from Michoacán and farther north. These have low keels on the snout scales, dorsals somewhat larger than the ventrals, and a pink throat fan. In ten males from Oaxaca the size of the dorsal scales relative to that of the ventrals is 1.00:0.83; the same ratio for 25 males from Michoacán is 1.00:1.08. In both samples there are specimens in which the dorsal and ventral scales are about equal in size.
Investigations by Richard E. Etheridge on the osteology of Anolis, including those species here being considered, have revealed relatively constant differences in the parasternalia and in the caudal vertebrae. The application of Etheridge's findings to anoline systematics must await the completion of his study.
The carination of the scales on the snout versus smooth scales there seems to be the only significant character given by Bocourt that distinguishes A. Nebuloides from A. nebulosus. The difference in the color of the throat fan, which is apparent only in living individuals, is more striking. Obviously more than one species is represented, as is borne out by the differences in the color of the throat fan and in the osteology, but there is uncertainty about the correct name for each species. On the strength of Bocourt's diagnosis of keeled snout scales in A. nebuloides, I am applying that name to the population in Oaxaca and A. nebulosus to the specimens from Michoacán. As arranged here, the two species can be distinguished, as follows:
A. nebulosus.—Dorsal scales only slightly smaller than the ventral scales; snout scales usually smooth; throat-fan bright orange in adult males.