Description of the neuroanatomy of the brachial plexus in South American lizards. Phylogenetic implications.

Few studies considered the anatomy of the nerve plexuses and musculature associated with them in ectothermic sauropsids. Based on differentiated Sudan Black B staining and conventional dissections, we describe the neuroanatomy of the brachial plexus, its main associated nerves, and muscles. For that, representatives of the genera Diplolaemus, Liolaemus, Phymaturus, and Tropidurus were selected. Based on this, potentially useful characters for phylogenetic analysis were described. Our results show that the brachial plexus can be formed by four, five, or six nerve branches. The brachial flexor trunk, circumflex, interosseous, median, radial, subscapulocoracoid, supracoracoid, and ulnar nerves were identified. Regarding the muscles innervated by the main nerves, the following muscles were identified: biceps brachii, deltoideus scapularis, latissimus dorsi, levator scapulae, pectoralis, serratus thoracis, trapezius, triceps longus caudalis, and triceps longus lateralis. Phylogenetic analyzes revealed 31 potential synapomorphies. There exists evidence that neuroanatomy studies in a phylogenetic context could provide useful information helping to elucidate the relationships between taxonomic groups.

A New Species of Lizard Endemic to Sierra de Fiambalá, Northwestern Argentina (Iguania: Liolaemidae: Phymaturus). Integrated Taxonomy Using Morphology and DNA Sequences: Reporting Variation Within the antofagastensis Lineage.

The northernmost distributed group of lizards belonging to Phymaturus occurs in rocky outcrops of the Puna region between 3600-4200 m in Argentina. In a recent phylogenetic study based on morphological and genetic information, the monophyly of this small lineage was corroborated. This group is formed by Phymaturus antofagastensis, P. laurenti, P. denotatus, P. mallimaccii and a population of uncertain taxonomic status until the present study. After obtaining new samples and observations, we described a new species belonging to this lineage that is known only from Sierra de Fiambalá, being the species of Phymaturus living at the highest elevation ever recorded (4500 m). Males have a homogeneous yellow dorsum and lack melanic coloration over their heads, a phenomenon found in males of most species of the palluma group. We provide a detailed diagnosis, including characters from the squamation, coloration and significant differences found among continuous characters (ANOVA). Furthermore, we present genetic distances among members of the mallimaccii subclade based on sequences of the cytb marker. We provide color photos showing pattern variation of males and females. We reanalyze the phylogenetic relationships within the entire palluma group and update info on all members of the antofagastensis lineage based on new samples and make a better supported hypothesis. We also evaluate the phylogenetic position of the new taxon.