Larval cranial anatomy of the Eastern Ghost Frog (Heleophryne orientalis)

Abstract

Heleophryne orientalis is endemic to the Western Cape Province of South Africa. Its tadpole lives in swift-flowing mountain streams attached to rocks and feeding on algae. Little is known about the morphology of Heleophrynids despite their important systematic position as sister taxon to all remaining Neobatrachians. Herein, I describe the external morphology as well as skeletal and muscular features of a tadpole of H. orientalis at Gosner stage 28 by using standard histology and 3D reconstruction. Derived features of this tadpole include the presence of two additional mandibular cartilages and a suprarostral cartilage without any muscular attachments. A mandibulosuprarostral ligament is absent. The presence of two M. levator mandibulae longus profundus portions and the post-orbital origination of the M. suspensorioangularis is unusual in anuran tadpoles.