New Species of the Iguanian Lizard Genus Liolaemus (Squamata, Iguania, Liolaemini) from Central Patagonia, Argentina

—We describe a new species of lizard of the genus Liolaemus from northwestern Chubut Province, Argentina. This new species belongs to the fitzingerii group and is easily distinguished from other members of the group by a combination of morphological and genetic characters. The new species is diagnosable in showing the following combination of characters: dorsal pattern with a conspicuous vertebral band, presence of preand postscapular spots, prominent neck folds, and analysis of DNA sequence data from 810 base pairs of the cytochrome b gene (,4% sequence divergence from its sister taxa Liolaemus fitzingerii). The fitzingerii complex now includes three described species, all restricted to Patagonia, and the new species described here is endemic to a small lowland area in central Patagonia. RESUMEN.—Describimos una nueva especie de lagartija del género Liolaemus para el noroeste de la provincia de Chubut, Argentina. La nueva especie pertenece al grupo fitzingerii y es fácilmente distinguible de otros miembros del grupo por una combinación de caracteres morfológicos y genéticos. La nueva especie es diagnosticable con la siguiente combinación de caracteres: diseño dorsal con banda vertebral conspicua, presencia de manchas pre y post escapulares, pliegues del cuello prominentes, y análisis de datos de secuencia de ADN de 810 pares de base del gen citocromo b (,4% de divergencia de secuencia de su taxa hermano Liolaemus fitzingerii). El complejo fitzingerii incluye ahora tres especies descriptas, todas restringidas a Patagonia. Al presente, la nueva especie es endémica de un área pequeña rodeada por colinas en Patagonia central. With more than 190 species, Liolaemus Wiegmann, 1834, constitutes one of the most speciose squamate genera of South America. Several species groups can be recognized on the basis of morphological, molecular, or both types of characters, with variations according to authors (e.g., Schulte et al., 2000; Morando et al., 2003; Morando, 2004; Avila et al., 2004, 2006; Abdala, 2007). Etheridge (1995) recognized one clade of species as the boulengeri group, with several subgroups included. Other authors are in general agreement about the species included in this clade but used different names for it. Abdala (2005) used the name chacoensis group, Schulte et al. (2000) named it the boulengeri series, but Morando (2004) and Avila et al. (2006) followed the original name used by Etheridge (1995). Here, we follow Etheridge (1995) and use the name boulengeri group; we also define two complexes, boulengeri and rothi, and four species groups, donosobarrosi, darwinii, wiegmannii, and fitzingerii (Fig. 1). In a recent molecular phylogenetic analysis of several species of the boulengeri group, an assemblage of species widely distributed throughout sandy or lowlands areas of the Patagonia and Monte regions of Argentina was found to form a well-supported clade, the fitzingerii group (Avila et al., 2006). This group includes two species complexes, named as the melanops and the fitzingerii complexes by Avila et al. (2006). The fitzingerii complex includes two described species, Liolaemus fitzingerii Duméril and Bibron 1837, and Liolaemus xanthoviridis Cei and Scolaro 1980, both characterized by robust bodies and extensive ventral melanism. These species inhabit the Chubut and Santa Cruz Provinces in Argentinean Patagonia, with L. fitzingerii extending into a small area of Patagonian Steppe environment in southern Chile. Liolaemus fitzingerii is widely distributed in Patagonia as far north as the Chubut River, whereas L. xanthoviridis is apparently restricted to a relatively small area in the northeast of Chubut Province between the Rio Chubut and the Atlantic coast (Cei, 1986). As presently understood (Avila et al., 2006), the composition of the fitzingerii group is not strictly equivalent to other groupings under this name made by previous authors (Cei, 1986; Halloy et al., 1998). As a result of herpetological field surveys carried out in central Patagonia, several lizard populations 2 Corresponding Author. E-mail: avila@cenpat. edu.ar Journal of Herpetology, Vol. 42, No. 1, pp. 186–196, 2008 Copyright 2008 Society for the Study of Amphibians and Reptiles