Morphological abnormalities in the Chilean Eagle ray Myliobatis chilensis (Myliobatiformes: Myliobatidae) off the Peruvian coast, Southeast Pacific

Abstract

Records about morphological abnormalities in rays of the genus Myliobatis are scarce worldwide. In the present study, three specimens exhibiting different malformations were identified during the monitoring of the reproductive biology of the Chilean eagle ray Myliobatis chilensis, conducted from 2017 to 2018 in the fishing port of Salaverry (northern Peru). The identified specimens included: (i) a female with split pectoral fins, (ii) a male with an unfused-to-the-head pectoral fin, and (iii) a female with a short and thick tail. Here we report and discuss the implications and likely causes of these first three cases of morphological abnormalities in M. chilensis from the western Pacific.

RETRACTED: Aerial imagery reveals abnormal stingrays, Taeniura lymma (Myliobatiformes: Dasyatidae), in the central Red Sea

“…In both cases, the posterior pectoral fin was completely cleft giving a fringe‐like appearance, which starkly contrasts the symmetrical deformity presented here. Perhaps, the most similar deformity previously reported is a Chilean eagle ray, Myliobatis chilensis Philippi, 1892, whose pectoral fin was symmetrically split in the middle (Valderrama‐Herrera et al., 2022). Somewhat similar are the most severe, symmetrical cases of an incomplete fusion of the pectoral fin to the head, which is relatively common in batomorphs (Bureau, 1889; Clarke, 2021; Ehemann et al., 2022; Legendre, 1935; Ribeiro‐Prado et al., 2008; Templeman, 1965; Valderrama‐Herrera et al., 2022).…”

“…Perhaps, the most similar deformity previously reported is a Chilean eagle ray, Myliobatis chilensis Philippi, 1892, whose pectoral fin was symmetrically split in the middle (Valderrama‐Herrera et al., 2022). Somewhat similar are the most severe, symmetrical cases of an incomplete fusion of the pectoral fin to the head, which is relatively common in batomorphs (Bureau, 1889; Clarke, 2021; Ehemann et al., 2022; Legendre, 1935; Ribeiro‐Prado et al., 2008; Templeman, 1965; Valderrama‐Herrera et al., 2022). The prevalence of incomplete disk closures in batomorphs is likely a result of the fact that the pectoral disk develops out of two separate pectoral fins that first grow in length and width and then gradually fuse with the body (Thorson et al., 1983).…”

“…Reports of fin deformities include the absence of fins (Capape et al., 2015; Ehemann et al., 2022), the presence of aberrant fins (Ben Brahim & Capapé, 1997; Deli Antoni et al., 2012), and deformed pectoral disk (Ramaiyan & Sivakumar, 1988; Ribeiro‐Prado et al., 2008; Valderrama‐Herrera et al., 2022). Anterior incomplete disk closure, in which the pectoral fins failed to completely fuse with the head, is the most commonly reported defect (Ehemann et al., 2022; Ribeiro‐Prado et al., 2008; Valderrama‐Herrera et al., 2022). Malformations along the posterior side of the pectoral disk are much rarer, but completely cleft posterior pectoral fins with a fringe‐like appearance have been reported in Pateobatis jenkinsii (Annandale, 1909) and Dasyatis hypostigma Santos & Carvalho, 2004 (Ramaiyan & Sivakumar, 1988; Ribeiro‐Prado et al., 2008).…”

“…Morphological defects in batomorphs have been reported for over 130 years (Bureau, 1889), encompassing a wide range of deformities including misshapen genitalia, dental abnormalities, hermaphroditism, bicephaly, anophthalmia, albinism, and fin defects (Ehemann et al., 2022; Ribeiro‐Prado et al., 2008). Reports of fin deformities include the absence of fins (Capape et al., 2015; Ehemann et al., 2022), the presence of aberrant fins (Ben Brahim & Capapé, 1997; Deli Antoni et al., 2012), and deformed pectoral disk (Ramaiyan & Sivakumar, 1988; Ribeiro‐Prado et al., 2008; Valderrama‐Herrera et al., 2022). Anterior incomplete disk closure, in which the pectoral fins failed to completely fuse with the head, is the most commonly reported defect (Ehemann et al., 2022; Ribeiro‐Prado et al., 2008; Valderrama‐Herrera et al., 2022).…”