The structure and topography of cutaneous receptors of 21 species of iguanian lizards were studied using histology and scanning electron microscopy. Sense organ...

The topography and numerical distribution of the skin receptors in 29 lizard species including 18 agamids, eight iguanids and three gekkonids, are compared and contrasted. There are no marked differences in the number of receptors in the dorsal and ventral surfaces of the body in the different groups. The maximal density of the receptors occurs on the head and decreases in the caudal direction.Iguanids and gekkonids have 5–6 times more receptors than agamids. Agamids Gonocephalus grandis from S.E. Asia, Pogona barbata, Diporiphora bilineata from Australia and Ceratophora tennentii from Sri‐Lanka, however, are distinguished by their high density of receptors, especially on the head. Species of Physignathus are similar to iguanids in this way. The agamid Phrynocephalus mystaceus shows considerable differences, in receptor number, from other species of this genus. There is a high density of receptors on the caudal scales of the Madagascan iguanid Oplurus, and a similar high density of receptors on the ventral surface of the gecko Teratoscincus scincus.

Lizards of the sunwatcher toad-headed agama species complex Phrynocephalus superspecies helioscopus, mostly distributed in Central Asia and Middle East, were examined using analysis of variation at the mitochondrial cytochrome oxidase c subunit I gene fragment and fingerprint analysis of nuclear DNA (inter-SINE PCR technique). A total of 86 individual tissue samples from 53 populations, to the full extent representing different parts of the species complex range, were subjected to molecular genetic examination, and surprisingly deep differentiation was revealed. The populations analyzed split into 12 isolated phylogroups, many of which were characterized by a narrow range and genetic isolation. Monophyly of sunwatcher (Ph. helioscopus) and Persian (Ph. persicus) toad-headed agamas was confirmed. However, both of these species probably represent the species complexes. Zoogeography of Central Asiais discussed.

Phylogenetic relationships of the agamid lizard genus Phrynocephalus are described in the context of plate tectonics. A near comprehensive taxon sampling reports three data sets: (1) mitochondrial DNA from ND1 to COI (3’ end of ND1, tRNAGln, tRNAIle, tRNAMet, ND2, tRNATrp, tRNAAla, tRNAAsn, tRNACys, tRNATyr, and the 5’ end of COI) with 1761 aligned positional sites (1595 included, 839 informative), (2) nuclear RAG-1 DNA with 2760 aligned positional sites (342 informative), and (3) 25 informative allozyme loci with 213 alleles (107 informative when coded as presence/absence). It is hypothesized that Phrynocephalus phyletic patterns and speciation reflect fault lines of ancient plates now in Asia rejuvenated by the more recent Indian and Arabian plate collisions. Molecular estimates of lineage splits are highly congruent with geologic dates from the literature. A southern origin for the genus in Southwest Asia is resolved in phylogenetic estimates and a northern origin is statistically rejected. On the basis of monophyly and molecular evidence several taxa previously recognized as subspecies are recognized as species: P. hongyuanensis, P. sogdianus, and P. strauchi as “Current Status”; Phrynocephalus bannikovi, Phrynocephalus longicaudatus, Phrynocephalus turcomanus, and Phrynocephalus vindumi are formally “New Status”. Phylogenetic evaluation indicates a soft substrate habitat of sand for the shared ancestor of modern Phrynocephalus. Size diversity maximally overlaps in the Caspian Basin and northwestern Iranian Plateau. The greatest species numbers of six in sympatry and regional allopatry are found in the southern Caspian Basin and southern Helmand Basin, both from numerous phylogenetic lineages in close proximity attributed to tectonic induced events.