Identification and morphological description of tadpoles of the horned frog (Amphibia: Anura: Megophryidae) Pelobatrachus stejenegeri from the southern Philippines

The primary purpose of this study is to successfully identify and characterise the tadpoles of Pelobatrachus stejnegeri in terms of colouration, external morphology, and oral disc morphology. In this study, a detailed description of the tadpoles through photographs and sketches is provided. Their different stages from stages 25 to 41 were also identified through a stereomicroscope. They were then photographed individually, and 20 different morphometric variables were measured using ImageJ software. The results showed that tadpoles of Pelobatrachus stejnegeri are small to medium in size and have an oblong and depressed body shape, dorsolateral eye position, round pupils which are oval in shape, and a dark brown line that runs to the eye. The vent tube is medial, having a pointed dorsal fin, and a relatively longer lower fin height than its upper fin. It also has an orange to brown pigmentation and possesses jade-like green speckles on the ventral body; after preservation, it eventually turns grey and the speckles are no longer present. The total length of the tadpole ranges from 28.19 to 37.14 mm from stages 25 to 41. The oral disc structure is umbelliform, with a bi-triangular to star-like shape, which it uses to filter food and attach to debris. This makes Pelobatrachus stejnegeri tadpoles unique among the tadpoles in the area. However, they are often overlooked because most studies only concern their adult stages. As only a few tadpoles in the country have been described, this study would still greatly contribute to tadpole research in the country.