Vogel Canyon, Comanche National Grassland, Otero County, Colorado—May 7, 2006
This was a difficult species to identify, because the taxonomy of whiptail lizards in this precise area is so complex and confusing that a number of journal articles have been written about it. There are two sexually-reproducing species in this general area: A. tigris
and A. sexlineata
. Then there several "pattern classes" of unisexual (all-female) whiptails, with tricky visible and genetic differences. These unisexual groups elicit strong philosophical debates over the definition of species, so that can make it hard to see past the terminology differences in the literature. Also, which sets of whiptails are in which precise locales seems to have changed quite a bit over the past few decades, adding to the confusion.
In 1997 herpetologists James Walker, James Cordes, and Harry Taylor published a paper carefully examining the historic confusion and disagreements and the current status of the various populations. I tracked down a copy of this paper at the always-helpful Bibliomania! herpetological literature site. It turns out that Vogel Canyon is in the only area where two very similar-looking unisexual species coexist, A. tesselata and A. neotesselata. I initially thought this was A. tessellata, but Alex Hall convinced me on iNaturalist that these were probably A. neotesselata instead. But then another whiptail expert came along and concluded that it is probably A. tesselata after all. So it's currently kind of in limbo, and I'm just calling it Aspidoscelis sp. for now.