Novel modification of the tetrapod cardiovascular system in the West African caecilian Herpele squalostoma (Amphibia: Gymnophiona: Caeciliaidae)



Aspects of the cardiovascular system of Herpele squalostoma are described and compared to other caecilians. Novel modifications of the systemic arches, anterior vertebral arteries and vertebral structures associated with the systemic arches are identified. The evolution of aortic arch diversity in caecilians is considered from the perspective of efficiency of the cardiovascular system. A speculative hypothesis is advanced concerning the evolutionary history of the systemic arches in H. squalostoma. It is argued that modification of vertebral structures is the result of epigenetic interaction between the vertebral column and the evolving systemic arch.