First record of the opal chimaera, Chimaera opalescens (Holocephali: Chimaeridae) and revision of the occurrence of the rabbitfish Chimaera monstrosa in the Azores waters

Abstract

The presence of the opal chimaera, Chimaera opalescens, is reported for the first time in the deep waters of the Azores, with the capture of four specimens by fishermen and the video recording of an additional five individuals. Species identification was supported by the 646 bp sequenced fragment of the mitochondrial gene cytochrome oxidase subunit I. Because C. opalescens is a recently recognised species that had been recurrently misidentified as rabbitfish, Chimaera monstrosa, the historical data of C. monstrosa in the Azores were reviewed to assess the possible presence of both Chimaera species in the region. Although several authors have reported the occurrence of C. monstrosa in the Azorean waters since the 1800s, the majority of these are based on only three specimens caught during the late 1800s. The investigation performed using literature and examination of the museum specimens still available concluded that the most likely scenario is that C. monstrosa is absent from the Azores and past records of that species in the region are most likely misidentifications of C. opalescens.

VIII International Symposium on Marine Sciences (ISMS 2022). Libro de Abstracts

“…Recently, several new species have been described (Iglesias et al, 2022), including Chimera opalescens from deep-sea assemblages (Luchetti et al, 2011). However, previous records of C. opalescens were erroneously classified as Chimera monstrosa (Luchetti et al, 2011;Catarino et al, 2020), due to the similar morphology (Luchetti et al, 2011), which highlights the critical importance of molecular approaches to support species identification. Mitogenomes have been a powerful tool used to elucidate phylogenetic relationships, both at deep and at shallow evolutionary nodes.…”

Updated checklist of Azores Chondrichthyes (Vertebrata: Gnathostomata)

“…In the meantime, new publications have emerged regarding new records (e.g. Catarino et al 2020 ) or with new information on species already recorded for Azores (e.g. Das and Afonso 2017 , Barcelos et al 2018 ).…”

A mitochondrial genome assembly of the opal chimaera, Chimaera opalescens Luchetti, Iglésias et Sellos 2011, using PacBio HiFi long reads

“…Chimaerid are also a frequent by-catch of deep-water fisheries (Blasdale and Newton, 1998 ; Moura et al., 2004 ; Catarino et al. 2020 ). Holocephalans comprise a single surviving order, the Chimaeriformes (Wyffels et al.…”

“… 2017 ) and Azores (Catarino et al. 2020 ). The species is listed has Least Concern (LC) according with the Red List of Threatened species of the IUCN ( https://www.iucnredlist.org/species/18901743/48862329 ).…”