A dorsal fold in Gymnura micrura (Bloch and Scheneider, 1801) (Chondrichthyes: Gymnuridae)

Abstract

This paper reports a dorsal fold which is a membranous structure located on the tail of two juvenile butterfly rays, Gymnura micrura (Bloch & Scheneider, 1801), caught through artisanal fishery in the shallow waters of Maranhão State (Brazil).

Morphological and functional abnormality in the spiny butterfly ray Gymnura altavela

“…The present communication is not only the first description of an elasmobranch disorder in the Canary Archipelago, but also a novel report for recording the first anomaly in G. altavela, and observing the individual in its natural habitat on several occasions, with different activities, and with a resighting after one year. Numerous anomaly reports were obtained from catch landings of free swimming elasmobranchs (Blanco-Parra and Niño-Torres 2011; Capapé et al 2015a;Capapé et al 2015b; Castro Aguirre and Torres Villegas 1979; Dalù et al 2003;El Kamel et al 2009;Forster 1967;Gudger 1933;Honma and Sugihara 1971;Metin et al 2009;Mnasri et al 2010;Moore 2015;Nunes and Piorski 2009;Orlov 2011;Ramírez-Hernandez et al 2011;Ribeiro-Prado et al 2008;Sandoval-Castillo et al 2006;dos Santos and Gadig 2014;Valle 1931), but none of them observing the specimen actively in its environment. Five out of the six reported anomaly cases in the genus Gymnura describe unfused pectoral fins.…”

“…Congenital abnormalities for the genus Gymnura (Hasselt, 1823) have been reported in the smooth butterfly ray Gymnura micrura (Bloch & Schneider, 1801) from the Amazonia (Nunes and Piorski 2009), and the long-tailed butterfly ray Gymnura poecilura (Shaw, 1804) from South India and Sri Lanka (Bennet 1964;Day 1878;Easwaran 1967;Suresh and Raffi 2012) (Table 1).…”

<b>Rostral anomaly in a juvenile Spiny Butterfly Ray <I>Gymnura altavela</I> (Linnaeus, 1758) (Elasmobranchii: Myliobatiformes: Gymnuridae) from the Canary Islands</b>

“…Three instances document an unfused right pectoral fin to the snout (Suresh & Raffi 2012;Narváez & Osaer 2016; the present study) that were similar in sex, shape, location, and texture. Two cases described a dorsal fold on the tail (Nunes & Piorski 2009) and one an absent tip of the snout (Béarez et al 2008). The low occurrence of reported anomalies in butterfly rays during the last decade in our study region and the survival of the affected individuals could suggest that these instances are not a priority conservation concern at present.…”

Morphological abnormalities in seven American round ray specimens: A review of America's batomorph anomalies

“…However, the aetiology remains inconclusive and controversial among authors, and the bibliography consulted. Abnormalities related to bicephaly, albinism, dorsal fold and hermaphroditism cases have been more or less obviously attributed to genetic and hereditary disorders (Jones et al., 2016; Lara‐Mendoza & Guerra‐Jiménez, 2020; Nunes & Piorski, 2009; Sandoval‐Castillo et al., 2006). In contrast, the aetiology of cases of anophthalmos, pectoral fins not fused to the head, spinal malformation and clasper malformation, was more general, with genetic disorders, poor nutrition, diseases, high metal concentration and water pollution being the most frequently cited (Anislado‐Tolentino et al., 2016; Ehemann & González‐González, 2018; Hauser‐Davis et al., 2020; Mancini et al., 2006; Mejía‐Falla et al., 2011; Ribeiro‐Prado et al., 2008, 2009; Soto‐López et al., 2021; Torres‐Huerta et al., 2015; Wosnick et al., 2019).…”