New horned lizard species found in southern Mexico

An article published in the current issue of the journal Herpetologica describes a new horned lizard species that lives in Mexico. Body size, tail length, and scale texture and layout distinguish this new species, which the authors propose naming Phrynosoma sherbrookei.

There are 16 recognized horned lizard species, spreading from Canada to Guatemala. Only four species have been found south of Mexico's transvolcanic belt. These distinctive reptiles have a scaly back and sides and bony horns over their brow. To avoid predators, they rely on camouflage and an ability to puff out their body. Some species squirt blood by rupturing capillaries surrounding their eyes. They adapt to dry habitats by using their tail to channel water over their back and into their mouth and by collecting solar heat through their flat, rounded body.

In Guerrero, Mexico, 14 lizards collected in the Sierra Madre del Sur appeared to be part of an unrecognized Phrynosoma species. The authors of the study analyzed tissue samples from these specimens to support their proposal of a new species. They took new DNA samples for all recognized Phrynosoma species and compared it with DNA from the newly collected lizards. They also generated a map depicting the evolution of the horned lizards to show how the newly described species has developed. Their efforts produced a family tree-style chart for the lizards that displays both close and distant relationships among the different species.

In comparing their results with previous studies and horned lizard specimens from various museums and collections, the authors found that, unlike most horned lizards, individuals representing the new species have rough scales. Their small body size, short tail, and unique horns distinguish them from the few other known rough-bellied species of horned lizards. Although they resemble a species found in southern Mexico, the authors argue that their DNA and physical appearance differ enough that they should be considered a new species.

New species of horned lizards are rarely considered threatened; however, the lizards collected in Guerrero seem to live in a small area and might benefit from protection until researchers can learn more about the population.