Maximal caudal autotomy in Podarcis hispanica (Lacertidae): The caudofemoralis muscle is not sundered

A. P. Russell, University of Calgary
P. J. Bergmann, University of Calgary
L. J. Barbadillo, University of Calgary

Abstract

In recent years, the pattern of maximal caudal autotomy in lizards has come under consideration, with attention being focused on how nonsegmental muscles in the tail base, specifically the m. caudofemoralis longus and the m. retractor penis magnus, may limit autotomy where they cross autotomy planes or, alternatively, how they may be ruptured if maximal autotomy is practiced. In this paper, we demonstrate that in the lacertid lizard Podarcis hispanica a number of autotomic vertebrae are spanned by the m. caudofemoralis longus, that maximal caudal autotomy does occur, and that the caudofemoralis muscle dissociates from its vertebral attachments but is not torn in the process. Anatomical and histological data reveal that this muscle has a specialized structure and relationship with surrounding muscles, skeletal elements, and connective tissues that result in minimal damage upon maximal autotomy. Furthermore, upon caudal regeneration, the m. caudofemoralis longus reestablishes contact with the newly formed cartilaginous axial skeleton of the tail.