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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.

The present communication documents the first observation of a morphologic anomaly in a juvenile Spiny Butterfly Ray Gymnura altavela. This observation is interesting for its similarity with a rostral abnormality in an adult G. altavela from the Canary Islands 10 years earlier and with the one from a juvenile Long-tailed Butterfly Ray G. poecilura from the Western Indo-Pacific. Although no firm conclusions can be drawn from these records, it reinforces the hypothesis of a congenital disorder for this type of malformation within the genus. The individual appeared to have successfully adapted for its anomaly, suggesting that these instances are not of major conservation concern. Hence, long-term studies are required to monitor anomaly occurrences and to evaluate their potential threats.

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Here, we describe the first mitochondrial genome of the angelshark, Squatina squatina. The genome is 16,689 bp in length with 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and a non-coding control region. Base composition of the mitogenome has an A + T bias (62.9%), seen commonly in other elasmobranchs. This genome provides a key resource for future investigations of the population genetic dynamics and evolution of this Critically Endangered shark.