Lungs and mesopneumonia of scincomorph lizards (Reptilia: Squamata)

Abstract

Mesopneumonia of 28 and lungs of 44 species of scincomorph lizards are described, representing mesopneumonia in six of the seven scincomorph families and lungs of all seven families of this taxon. Except for gymnophthalmids and scincids, a family typical organization of mesopneumonia occurs. In cordylids, gerrhosaurids, xantusiids and lacertids the complete right ventral mesopneumonium (VMp) inserts cranially on the posterior vena cava and caudally on the dorsal surface of the right liver lobe. The left VMp is attached to the ventrolateral body wall in cordylids and lacertids; in gerrhosaurids the left VMp is short and inserts on the pericardium and the posterior vena cava; in xantusiids the left VMp is reduced and the lungs are fused cranially with the pericardium. In scincids the VMp of both sides vary in length and insert on the ventral mesentery, or may be lacking completely. The visceral topology of the gymnophthalmids Calyptommatus and Notobachia differs from the general scincomorph pattern, with the liver and stomach elongated and situated on the right and left side of the body cavity, respectively. The left and the right VMp extend over the entire length of the lungs and insert on the ventral mesentery. All lungs examined in the study are single-chambered and show no major structural variability of the inner surfaces, except in lacertids, some gerrhosaurids, Cordylus, and two genera of gymnophthalmids (Echinosaura and Neusticurus). In these groups, rows of dorsomedial niches are present. r 2005 Elsevier GmbH. All rights reserved.