Gerrhonotus Parvus. the Pygmy Alligator Lizard of Nuevo León
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Overhead, the laughing call of a The little rattlesnake was still calmly canyon wren momentarily distracted coiled at the base of the rock where my focus from the rattlesnake I was we’d found it when Javier reappeared. watching just 2 feet in front of me. I was silently feeling thankful for our What had started off as a rock-col- good luck, and then I noticed that Javier was lecting trip through the bottom of a steep- walking very slowly and staring at his hand. walled limestone canyon south of Monterrey, When he got closer, I saw that he had caught Nuevo León (Mexico), had turned into a a lizard. “What the heck is this?” he asked, snake-collecting trip — and now I was holding it out for me to see. waiting patiently in the after- As I looked at the tiny lizard squirming in his noon sun for Javier to return hands, a sudden wave of excited disbelief from the truck. came over me. Amazingly, our luck in finding Javier Banda-Leal is a stu- the rock rattlesnake had already been sur- dent at the Universidad Autóno- passed — we had just found the third known ma de Nuevo León (UANL) in Mon- specimen of the rare, endemic pygmy alligator terrey. When we stumbled onto the tiny lizard of Nuevo León! rock rattlesnake we were carrying only one bag for rocks, so Javier made a quick Natural history beeline back to the truck for our snake collecting The pygmy alligator lizard, Gerrhonotus parvus equipment, leaving me to keep an eye on our new- Knight and Scudday, 1985, is the smallest known found friend. For several years I had been collaborat- species of anguid lizard, reaching a total length of ing with researchers at UANL on the captive breeding only 55–72.5 millimeters (one huge adult measured of montane rattlesnakes, and this new specimen would 76.5 millimeters!) snout-vent length. The tail is typi- make a great addition to the school’s captive collection. cally about twice the SVL. This species is oviparous. The Pygmy Alligator Lizard of Nuevo León, Mexico REPTILIA 69 Gerrhonotus parvus. Photo: D. Lazcano Gerrhonotus infernales is sympatric with Gerrhonotus parvus. Photo: D. Lazcano Typical Gerrhonotus parvus habitat. Photo: R. Bryson Gerrhonotus parvus. Photo: D. Lazcano The paratype was a 71.7-millimeter One was found under a dead yucca area is also home to the pine woods grahamiae lineata; the western mesquite lizard; the northern blue- (SVL) female that was maintained in a garbage dump south of shortnose skink, Eumeces brevirostris blackneck garter snake, Thamnophis belly lizard; the Nuevo Leon in captivity for 5 years and report- Galeana, the type locality of the pineus; the northern mesquite cyrtopsis cyrtopsis; the western dia- crevice swift; Ruthven’s whip- edly laid several clutches of eggs species. Three of the other four lizard, Sceloporus grammicus mondback rattlesnake, Crotalus snake, Masticophis taeniatus before her death. The species is (including the one mentioned at the disparilis; the northern bluebelly atrox; the blacktail rattlesnake, C. ruthveni; the Nuevo Leon graceful endemic to Nuevo León, Mexico, beginning of this article) were found lizard, S. parvus parvus; the spiny molossus molossus; the Mojave rat- brown snake, Rhadinaea montana; and has been collected from Feb- west of San Isidro in a canyon (ca. lizard, S. spinosus spinosus; the tlesnake, C. scutulatus scutulatus; the Texas patchnose snake; Sar- ruary to October in arid transition 5,250 feet above sea level) running Nuevo Leon crevice swift, S. the coastal plain toad, Bufo nebulifer; tor’s snail sucker, Sibon sartori Gerrhonotus parvus. Photo: D. Lazcano woodland characterized by oak, east to west, with scattered piles of torquatus binocularis; the Texas and the Rio Grande chirping frog, sartori; the arid land ribbon snake, agave, sotol, and extensive out- leaf litter, large rocks, and an inter- night snake, Hysiglena torquata Eleutherodactylus cystignathoides Thamnophis proximus diabolicus; because of its perceived close rela- crops of exposed limestone, at ele- mittent stream that leaves pools of jani; the San Luis Potosi kingsnake, campi. In the canyon near San the mottled rock rattlesnake, tionship with Lugo’s alligator vations of 5,250–5,415 feet (ca. water (most of which dry up during Lampropeltis mexicana; Jan’s bull- Isidro, the pygmy alligator lizard is Crotalus lepidus lepidus; the lizard, G. lugoi, from the Cuatro 1,600–1,650 meters). the dry season). snake, Pituophis deppei jani; the sympatric with the Texas alligator blacktail rattlesnake; the coastal Ciénegas Basin in Coahuila. Only During the course of our field- Near Galeana, the pygmy alliga- Texas patchnose snake, Salvadora lizard, Gerrhonotus infernalis — plain toad; the Rio Grande chirp- a year later, however, SMITH work on montane rattlesnakes, we tor lizard’s distribution and this distribution area is also ing frog; and the long-footed (1986) assigned the species to the have now found a total of five home to Couch’s spiny lizard, chirping frog, Eleutherodactylus genus Elgaria based on head scala- specimens of pygmy alli- Sceloporus couchi; longipes. tion. Nonetheless, recent molecu- gator lizard. the northern lar work (CONROY et al., in Taxonomic confusion press) has shown the pygmy alliga- KNIGHT and SCUDDAY (1985) tor lizard to indeed belong to the described the pygmy alliga- genus Gerrhonotus as originally tor lizard and named it described. Gerrhonotus parvus The pygmy alligator lizard is dis- — assigning the tinguished from all other species taxon to this of the family Anguidae by the fol- genus lowing combination of characteris- tics: smooth dorsal scales, the ros- tral in contact with the nasals, a second primary temporal that is in contact with the fifth medial supraocular, suboculars separated from the lower primary temporal by an upper labial, and wide pale crossbands on the tail (KNIGHT and SCUDDAY, 1985). Captive Husbandry The pygmy alligator lizard has proven to be a hardy captive. At the herpetology lab at UANL, three specimens have been kept for more than 2 years with no problems. This species seems to be less aggressive than other anguids — such as the sympatric, larger Gerrhonotus infernalis — but they do occasionally twist around and bite. REPTILIA 70 REPTILIA 71 Other species that are also found within the range of Gerrhonotus parvus Sibon sartori sartori. Photo: D. Lazcano Coluber constrictor oaxaca. Photo: D. Lazcano Coluber constrictor oaxaca. Photo: D. Lazcano Crotalus lepidus. Photo: R. Bryson Eleutherodactylus c. campi. Photo: D. Lazcano The UANL specimens have been housed individu- If we can obtain a female, we would like to breed the ally in plastic shoeboxes measuring 35 x 23 x 15 cen- species. We would hibernate the lizards for 3–4 timeters, with numerous holes drilled in the top and months at 55–60°F (13–16°C), and then put males and sides for ventilation. Each enclosure has a small females together within 2–3 weeks of removal from water bowl, a small plastic hide box, and a newspaper hibernation. We would provide overhead basking substrate that is changed daily. The lizards are usual- lights and a nest box to allow a gravid female to ther- ly fed vitamin/calcium-dusted crickets every 3–4 days, moregulate and lay eggs. and mealworms once a month. The room tempera- It is hoped that we will succeed in reproducing this ture is usually maintained at 77°F (25°C) during the species in captivity. The experience of finding the day, and 70°F (21°C) at night. During the winter, unique and rare pygmy alligator lizard of Nuevo León these temperatures drop by about 5 degrees Fahren- in the wild is thrilling, and could only be approximat- heit (about 3 degrees Celsius). No other enclosure ed by the experience of hatching babies in the lab! heating is used. No artificial lighting is used. The Note: All research has been conducted with permits enclosures are exposed to natural indirect light that issued by the Mexican government. I comes in through the windows, with the natural pho- toperiod of Monterrey. Bibliography Recently, the lizards have been transferred to all- CONROY, C. J., R. W. BRYSON, D. LAZCANO, and A. KNIGHT. In press. The phylogenetic position of the pygmy alli- glass aquariums measuring 60 x 50 x 30 centimeters, gator lizard (Elgaria parva) based on molecular data. Journal of with screen tops. The substrate is cypress mulch, and Herpetology. each enclosure has a small water dish and a hide box. KNIGHT, R. A., and J. F. SCUDDAY. 1985. A new Gerrhonotus The mulch substrate is spot cleaned and the water (Lacertilia: Anguidae) from the Sierra Madre Oriental, Nuevo León, Mexico. Southwestern Naturalist 30: 89–94. dishes are cleaned and refilled once a week. The SMITH, H. M. 1986. The generic allocation of two species of enclosures are misted lightly two or three times a Mexican anguid lizards. Bulletin of the Maryland Herpetological week. Society 22: 21–22. WADDICK, J. W., and H. M. SMITH. 1974. The significance of We have recently been able to sex the lizards, and scale characters in evaluation of the lizard genera Gerrhonotus, found that all three are males (by hemipenal “popping”). Elgaria, and Barisia. Great Basin Naturalist 34: 257–266. REPTILIA 72.