The trunk musculature of caecilians (Amphibia: Gymnophiona)

Abstract

Descriptions of the trunk musculature of six species representing sex genera and five families of caecilians reveal considerable variation, which may be useful in future systematic studies. The muscle units of the external muscular sheath (M. dorsalis trunci, M. subvertebralis) of caecilians are homologous with, and closely similar in position to, those of salamanders. The major difference in trunk musculature is the presence in caecilians of an additional muscle layer ventral to the M. subvertebralis. This muscle may be a neomorphic derivative from either the M. subvertebralis or the M. transversus. Unlike burrowing reptiles, which have ball-and-socket intervertebral joints, caecilians have retained the primitive amphicoelous centrum and compensate for stresses associated with burrowing by the presence of intercentral ligaments and interlocking basapophyses and subcentral keels. Association of Uraeotyphlus with the Ichthyophiidae and the validity of the Rhinatrematidae are supported by data from the trunk musculature.

On the Classification and Phylogeny of Caecilians (Amphibia: Gymnophiona), a Critical Review

“…The primary grooves that delimit the primary annuli of caecilians are presumably homologous to the costal grooves of salamanders. These primary grooves correspond to the myosepta of salamanders and most caecilians (Naylor and Nussbaum, 1980;Nussbaum and Naylor, 1982) and, therefore, provide a simple explanation for the 1:1 correspondence between primary annuli and vertebrae in the trunk region. This relationship breaks down under the collars, as noted above, and toward the body terminus where vertebrae are greatly reduced in size and almost always outnumber the primary annuli (Nussbaum, 1985).…”

Comparative morphology and evolution of the lungless caecilian Atretochoana eiselti (Taylor) (Amphibia: Gymnophiona: Typhlonectidae)

“…We also describe some characteristics of the anterior trunk musculature which these authors did not consider. All typhlonectids share a unique and presumably derived condition of the subvertebral muscle, in which the m. subvertebralispars ventralis originates from fascia lateral to the centra with distinctly scalloped origins (Naylor & Nussbaum, 1980).…”

A comparative study of locomotion in the caecilians Dermophis mexicanus and Typhlonectes natans (Amphibia: Gymnophiona)

“…Fritzsch, 1990;Schmidt &Wake, 1990;Wake & Schwenk, 1986;Himstedt & Simon, 1995) and morphology (e.g. Naylor & Nussbaum, 1980;Wake, 1980aWake, ,1994Nussbaum & Naylor, 1982;Bemis et al, 1983;Nussbaum, 1983) of these creatures. The functional morphology of these animals has received comparatively little attention.…”