A New Gerrhonotus (Lacertilia: Anguidae) from the Sierra Madre Oriental, Nuevo Leon, Mexico

Abstract

-A new species of alligator lizard from Galeana, Nuevo Le6n, Mexico is described. The new species is the smallest gerrhonotine lizard known, and differs from other species in the following combination of characters: smooth dorsal scales, nasals in contact with rostral, second primary temporal in contact with fifth medial supraocular, suboculars separated from the lower primary temporal by an upper labial, and wide pale crossbands on the tail. It is an oviparous species, and is found in transition woodland. The new species is intermediate to Gerrhonotus kingi and G. lugoi, but is closest to G. lugoi. A number of species of gerrhonotine lizards are known for north-central Mexico. Gerrhonotus liocephalus ranges from Texas through the Sierra Madre Oriental southward. Barisia imbricata also occurs in the Orientals. Gerrhonotus lugoi is found in the Cuatro Cienegas Basin of Coahuila, and G. kingi occurs to the west in the Sierra Madre Occidental. Two gerrhonotine lizards collected in the vicinity of Galeana, Nuevo Le6n (24? 49' North, 100? 05' West, elevation 1650 m) possess a combination of characters that sets them apart from G. liocephalus, B. imbricata, G. lugoi, G. kingi and all other known forms of Anguidae. These two specimens represent a new species for which we propose the name: Gerrhonotus parvus, new species Holotype.-Sul Ross State University 5538. Female (Fig. 1), collected 3 km SE Galeana, Nuevo Leon, Mexico, 21 March 1983, by R. Alec Knight. Paratype.-SRSU 5537. Female (Fig. 2) collected 1 km S Galeana, Nuevo Leon, Mexico, 23 June 1977, by Kelvin Scott. Diagnosis.-A species of Gerrhonotus that differs from all other known species in having the following combination of characters: small adult size, smooth dorsal scales, nasals in contact with rostral, second primary temporal in contact with fifth medial supraocular, suboculars separated from lower primary temporal by an upper labial, and wide pale crossbands on the tail. Description of the holotype.-Measurements in mm: snout-vent length, 55.0; length of tail, 97.0; tail-body ratio, 1:1.76; greatest width of body, 8.7; width at base of tail; 5.0; width of head, 7.5; length of head (anterior margin of ear opening to tip of snout), 10.4; depth of head, 4.8; axilla to groin, 30.0; length of arm, 7.0; length of leg, 10.0; fourth finger, 3.0; fourth toe, 4.9. The head is small and not distinct from the neck. Head color is grayishbrown with scattered dark spots and the lips are peppered with pigment. Chin and throat are a pearly white. Head scales are smooth and glossy: primary temporals, 4-4; the second in contact with the fifth medial supraocMARCH 27, 1985 E SOUTHWESTERN NATURALIST 30(1):89-94 This content downloaded from 157.55.39.112 on Wed, 07 Sep 2016 04:38:17 UTC All use subject to http://about.jstor.org/terms The Southwestern Naturalist FIG. 1.-Gerrhonotus parvus, new species. Dorsal view of the holotype (SRSU 5538) in life. Snout-vent length is 55.0 mm. ular; secondary temporals 4-4; postoculars, 3-3; suboculars, 2-2; superciliaries, 5-4; loreals, 1-1; postnasals, 2-2; frontonasal enlarged and separated from the frontal by contact of paired prefrontals; supranasals, 1-1; posterior internasals, 1-0; cantholoreals, 1-1; canthals, 1-1; upper labials, 12-13; infralabials, 12-12; sublabials, 7-7; postmentals paired. The body is slender and examination of the ovaries indicates a mature female. Dorsal scales are smooth, glossy, and arranged in 16 longitudinal and 53 transverse rows. There are 12 longitudinal and 62 transverse rows of smooth ventral scales. Body scales were counted following the method of Tihen (1949). The lateral fold consists of 5 or 6 rows of small granular scales. The grayish brown dorsum and sides are transversed by pale gray crossbands, 11 complete and 4 incomplete. The crossbands are two scale rows wide, and defined by dark edges, especially along the posterior margins. The venter is pearly white. Limbs are small. Scales are larger on anterior of limbs and granular on posterior of limbs. There are 9 rows of enlarged scales on anterior of thigh and 14 rows of granular scales on posterior of thigh. The limbs are mottled and paler than the dorsal ground color. The tail is complete with 88 scale whorls. Tail color is grayish-brown as is the body, but a shade lighter. The tail has 10 pale gray crossbands. Proximally the crossbands are narrow, two scale whorls in width and distally enlarged to three, four, then five whorls in width. The distal 27 mm of the tail is pale gray. Description of the paratype.-The paratype was maintained alive in capcivity for five years. During this time the specimen changed hands among 90 vol. 30, no. 1 This content downloaded from 157.55.39.112 on Wed, 07 Sep 2016 04:38:17 UTC All use subject to http://about.jstor.org/terms Knight and Scudday-New Gerrhonotus FIG. 2.-Dorsal view of the paratype of G. parvus (SRSU 5537) in alcohol. Snout-vent length is