Phrynosoma asio, the long-spined horned lizard, occurs in southern Mexico from Colima through coastal Michoacan, Guerrero, Oaxaca, to Chiapas, and in the Balsas Basin. It is the largest species of horned toad, reaching a snout-vent-length of up to 115 mm. P. asio can be distinguished from other horned lizard species by the following: two rows of abdominal fringe scales; three rows of large conical scales widely separated on the dorsum; gular scales arranged in serrated longitudinal series; and large keeled ventral scales numbering 30-35 across the widest point constituting a formidable armor.
About the Species
This specimen was collected by Dr. Wendy L. Hodges in 1999 from the southwest side of Highway 95 from the municipality of Eduardo Neri near Zumpango de Rio in the state of Guerrero, Mexico. It resides in Dr. Hodges' private collection. It was made available to the University of Texas High-Resolution X-ray CT Facility for scanning by Dr. Hodges of the Department of Biology, University of California, Riverside. Funding for scanning was provided by a National Science Foundation grant (DBI-0204459) to Dr. Hodges. Funding for image processing was provided by a National Science Foundation Digital Libraries Initiative grant to Dr. Timothy Rowe of the Department of Geological Sciences, The University of Texas at Austin.
About this Specimen
The specimen was scanned by Matthew Colbert on 22 May 2003 along the coronal axis for a total of 702 slices, each slice 0.036 mm thick with an interslice spacing of 0.036 mm.
Frost, D. R., and R. Etheridge. 1989. A phylogenetic analysis and taxonomy of iguanian lizards (Reptilia: Squamata). University of Kansas Museum of Natural History Miscellaneous Publication 81.
Pianka, E. R., and W. S. Parker. 1975. Ecology of horned lizards: A review with special reference to Phrynosoma platyrhinos Copeia 1975:141-162.
Presch, W. 1969. Evolutionary osteology and relationships of the horned lizard genus Phrynosoma (Family Iguanidae) Copeia 1969:250-275.
Reeve, W. L. 1952. Taxonomy and distribution of the horned lizard genus Phrynosoma. University of Kansas Science Bulletin 34:817-960.
Smith, H. M. 1946. Handbook of Lizards: Lizards of the United States and of Canada. Comstock Publishing Co., Ithaca, New York.
More on horned lizards from Eric Pianka and Wendy Hodges
The Horned Lizard Conservation Society