Resolving the confusion: <i>Amietia vertebralis</i> and <i>A. umbraculata</i> tadpole morphology

Abstract

Morphological similarities between the tadpoles of Amietia umbraculata and A. vertebralis have led to confusion and incorrect descriptions and identifications in the literature. Based on 33 body measurements and ratios we revised the morphological descriptions of the tadpoles of the two species. Tadpole identification was verified through DNA sequencing using mitochondrial (16S) gene fragments. A combination of four morphological characters proved to be informative and  consistent in distinguishing between tadpoles of the two species. Tadpoles of A. umbraculata are characterized by having four labial tooth rows in the lower jaw, extensive tail mottling, a dorsal fin that originates well behind the body, reaching a maximum depth at 50% of the tail length, and an average tail length of 1.9 times body length. Amietia vertebralis tadpoles on the other hand are characterized by having five or more labial tooth rows in the lower jaw, tail mottling that is confined to the upper half of the tail musculature, a dorsal fin that originates at the body-tail junction but retains a low profile, rising abruptly to reach a maximum depth at about 40% of the tail length, and an average tail length of 1.5 times body length. These four characters identify the two species without ambiguity.

Key words: Amietia umbraculata, Amietia vertebralis, identification key, Drakensberg, Maluti-Drakensberg, Maloti-Drakensberg, tadpole morphology.