CENTRAL BAJA CALIFORNIA ROCK LIZARD
Petrosaurus repens – Van Denburgh 1895
IDENTIFICATION:
DISTRIBUTION:
Petrosaurus repens is found from the Mesa San Carlos (Pacific Coast) south of El Rosario, east to the Sierra la Asamblea then south through the peninsula to Canyon de los Reyes, just north of La Paz, Baja California Sur. It is absent from the Viscaino Desert and Magdalena Plain regions of the western peninsula. It is also found on Isla Danzante in the Gulf of California. Elevational distribution from sea level to the high peaks of the Sierra la Asamblea and Sierra la Libertad.
HABITAT:
This wary lizard occurs in a variety of habitats, but always on large rocky structure. They may be found on lava flow escarpments, rocky cliff faces, rocky canyons, and building ruins such as Mision San Borja and Mision Santa Gertrudis.
Rocky oceanside habitat, Baja California Sur, Mexico
NATURAL HISTORY:
Grismer (2002) provides a detailed account of this species’ natural history. In the southern portion of it’s range, this species is active year-round; from roughly San Ignacio, BCS north it is generally active from March-October. Like P. thalassinus, this species often emerges from its nighttime retreats just prior to sunrise, so it may begin to thermoregulate and feed as soon as possible. While it may forage on the ground it is quick to retreat to high walls and crevices when approached. Small family groups are often found together and are generally comprised of a single adult male and several females. This species is omnivorous, with items such as Barrel Cactus and Fishhook cactus seeds (Bostic, 1971), Palo Verde flowers, leaves, and Opuntia cactus fruit (Grismer, 2002) being consumed.
Breeding takes place in the spring; eggs are layed in summer, and hatchlings first appear in late summer and early fall. Grismer states that while there is substantial latitudinal overlap between this species’ range and that of P. mearnsi, it does not occur in sympatry except at Jaraguay, BC (reported by Ottley and Murphy, 1981). An 11 km hiatus seperates the two species along the rd to Bahia de los Angeles, with P. repens being found on rock piles on the western end of the road in a cooler, higher climate.
TAXONOMY:
This species is closely related to P. thalassinus, endemic to the Cape region of Baja California Sur.
TYPE:
Described as Uta repens by J. Van Denburgh (1895). Holotype: CAS 633. Type locality: Comondu, Lower California [Baja California Sur, Mexico].
PERSONAL NOTES:
I have seen this species twice: once on a volcanic rockpile at the edge of Hwy 1 near the Chapala dry lake (south of Catavina), and also on the high rockwalls along the Gulf Coast at Canyon de los Reyes (just N of La Paz, BCS). The latter individuals were observed near a roadside shrine, and were extremely wary. Our guide attempted to noose the lizards with a 20′ long marlin fishing pole but was unable to do so. They ran effortlessly across the sheer, vertical cliff faces.
CONSERVATION STATUS:
This widespread and abundant species is in no need of any protection.
REFERENCES:
Bostic, D. L. 1971. Herpetofauna of the Pacific coast of north central Baja California, Mexico, with a description of a new subspecies of Phyllodactylus xanti. Transactions of the San Diego Society of Natural History 16:237-264.
Ottley, J. R. and R. W. Murphy. 1981. Petrosaurus thalassinus repens: Geographic distribution. Herpetological Review 12:65.
Van Denburgh, J. 1895. Review of the herpetology of Lower California. Proceedings of the California Academy of Sciences 2:77-163.