Morphological and functional abnormality in the spiny butterfly ray Gymnura altavela

Background: A variety of abnormalities have been described for sharks, rays and skates across different ecoregions. Morphological and functional anomalies in these species, however, were not yet documented in distributions from the Canary Islands, the spiny butterfly ray Gymnura altavela (Linnaeus, 1758) and from in situ observations. The aim of the present study is to fill these knowledge gaps. Results: A female spiny butterfly ray G. altavela with an unfused anterior part of the right pectoral fin to the neurocranium was observed in the port of Sardina del Norte (Gran Canaria Island) during a visual scuba diving census. Conclusion: The size and the observation of the activities swimming, burying and preying confirmed the adaption of the specimen for the anomaly and underdeveloped electrosensory system in its survival. The limited knowledge of teratogens and their triggering factors, and the striking similarity with an anomaly reported for G. poecilura (Shaw, 1804) from South India, suggest genetic expression aberrations or mechanical obstructions during gestation as origin for the disorder.