FIRST RECORDS OF CHIMAERA OPALESCENS ( HOLOCEPHALI : CHIMAERIFORMES : CHIMAERIDAE ) FROM MADEIRA AND NORTH-WEST AFRICAN COAST

This study reports new findings of Chimaera opalescens Luchetti, Iglésias et Sellos, 2011, which represent new records of this fish from Madeira and Morocco. The specimens were caught at the depths between 800 and 1221 m. Additional specimens deposited in the Natural History Museum of Funchal (MMF) were also studied as a comparative material and the results are reported herein. The new records of C. opalescens extend the previously known area of distribution of this fish further south.

According to Weigmann (2016) there are 40 valid species of chimaeras representing two genera, Chimaera Linnaeus, 1758 and Hydrolagus Gill, 1862.The separation of those two genera is based only on the presence or absence of a distinct anal fin (Didier andSéret 2002, Weigmann 2016).
Chimaera opalescens can be distinguished from its congener by the following combination of characters: body colour beige to tan in adults and bronzy in juveniles, unpaired fins brown to purple, uniformly coloured or with pale or whitish edges, iris black, claspers tripartite divided for one third of their length, not extending beyond pelvic fins in adults, dorsal spine equal or shorter than first dorsal fin, ventral caudal lobe equal or deeper than dorsal caudal lobe and pectoral fins just reaching origin of pelvic-fin when laid backwards, in freshly caught adult specimens (Luchetti et al. 2011).Despite the distinct morphological differences, mainly in the claspers, dorsal spine and fins, it is still commonly misidentified as Chimaera monstrosa (see Luchetti et al. 2011, Vieira andCunha 2014).
Chimaera opalescens, presented in this study, constitutes the first record of this fish from the Island of Madeira and northwest African coast, thus extending the southernmost limit of its distribution.
In this study a total of nine specimens of Chimaera opalescens from the Island of Madeira and from the northwest African coast were examined (Fig. 1).Six of them came from the black scabbardfish fishery in Madeira (800-1200 m of depth): MMF18538, 745 mm TL, male, 24/08/1961; MMF20455, 625+ mm TL, male, 23/06/1964;  The northwest African specimens were collected with bottom trawls in the framework of a Scientific Cooperation Protocol between Spain and Morocco (González et al. 2014, González andBiscoito 2015).
Two damaged specimens were not included in the morphological analysis.All voucher specimens were deposited in the collections of the Funchal Natural History Museum (MMF).
Our description of the newly found specimens is consistent with the description of Chimaera opalescens given by Luchetti et al. (2011) (Table 1).
In Fig. 3 the male sexual characters of one of the studied specimens are shown, in which the denticle arrangement in the frontal and prepelvic tenacula and the shape of the prepelvic tenaculum and claspers, are identical to the description given by Luchetti et al. (2011) for this species.
The presently reported record of Chimaera opalescens extends by 10 degrees to the South the previously known range of the species and also reduces the minimum depth (800 m) for the species as compared to the previously published range of 900-1975900- m (Weigmann 2016)).The species was simply listed with no other details in a paper by Pajuelo et al. (2016) dealing with the assemblages of deep-sea fishes from off northwest Africa.Following the recommendations of Bello et al. (2014), the present account represents the first confirmed record of C. opalescens from NW Africa.
Before this study, only two species of the family Chimaeridae were known to occur in Madeira, Chimaera monstrosa (see Maul 1949) and Hydrolagus affinis (de Brito Capello, 1868) (see Freitas et al. 2011).While reexamining the MMF specimens, originally identified as C. monstrosa, we came to the conclusion that they were in fact Chimaera opalescens.Since we were not able to locate specimens of C. monstrosa from Madeira in museum collections and Maul's (1948) reference is older than the oldest specimen in MMF, the occurrence of C. monstrosa in Madeira remains dubious.

Fig. 1 .
Fig. 1.Collection locations of Chimaera opalescens: n 30 specimens from British Isles and France (Luchetti et al. 2011), « 4 from Galicia bank (Bañon et al. 2016), and 8 from the presently reported study: ¡ 6 from the Island of Madeira and ¨ 3 from the Northwest African coast The Madeiran specimens were caught as bycatch of the traditional black scabbardfish (Aphanopus carbo Lowe, 1839 and Aphanopus intermedius Parin, 1983) deep-sea fishery, four of which had been deposited in the collections of the Funchal Natural History Museum and originally identified as C. monstrosa.The northwest African specimens were collected with bottom trawls in the framework of a Scientific Cooperation