Adult, 50′, Baja California, Mexico
Adults, 50′, Baja California, Mexico
BAJA CALIFORNIA LEGLESS LIZARD
Anniella geronimensis – Shaw 1940
IDENTIFICATION:
DISTRIBUTION:
Anniella geronimensis occurs on the Pacific coast of the Baja California Peninsula from about 3.2 mi N of Colonia Guerrero south to the vicinity of Punta Baja, near El Rosario. It also occurs in the Pacific on Isla San Geronimo and Isla San Martin.
HABITAT:
This species is found only in fine-grained dune sand within the immediate vicinity of the Pacific Ocean. It is found 4 km from the coast in a dune set within Arroyo Socorro, but is not known from any other inland locations. Within these dunes it is commonly found beneath the leaf-litter at the base of Brittlebush, Locoweed and Bursage; it may also be found beneath discarded trash such as cardboard.
Ocean Dune Habitat, Baja California, Mexico
NATURAL HISTORY:
Like A. pulchra, this lizard is viviparous and insectivorous. Unlike A. pulchra, it is found exclusively within fine-grained sandy swales and dunes within the immediate vicinity of the coast. Both species of Anniella occur together in the dunes near Colonia Guerrero, but geronimensis is far more abundant there. Gravid females have been found to contain only a single embryo; birthing is thought to occur in late summer and fall. Within the dune sets they inhabit, A. geronimensis appears to be more abundant on the windward side. Shaw (1953) reported on an individual he believed to be basking in the lower stems of a Brittlebush.
TAXONOMY:
Anniella belongs to the Family Anguidae.
TYPE:
Described as Anniella geronimensis by C. E. Shaw (1940). Holotype: SDSNH 7543. Type locality: Isla San Geronimo Island, Lower California [Baja California], Mexico.
PERSONAL NOTES:
I have found this species to be abundant and easy to unearth during the winter and spring; during summer it dives deeper in to the dune sand and is much harder to come across. In December, 2001 Chris Gruenwald, Gary Nafis and I unearthed 8 specimens in about 10 minutes at dusk at the above-pictured locality. We found several early the next morning to photograph. In June, 2002 Gary Nafis and I returned to this site and despite searching for an hour found no sign of Anniella.
CONSERVATION STATUS:
This species inhabits ecologically sensitive dune systems along a narrow coastal band that is quickly becoming populated by tourists and foriegn investors. Some residents have set up fences to keep ATV riders away from the dunes themselves, but this needs to become a more widespread practice before more habitat is destroyed. The dune sets inhabited by this species should be fully protected by Mexican law.
REFERENCES:
Shaw, C. E. 1940. A new species of legless lizard from San Geronimo Island, Lower California. Transactions of the San Diego Society of Natural History 9:225-228.
Shaw, C. E. 1953. Anniella pulchra and Anniella geronimensis, sympatric species. Herpetologica 8:167-170.