Description of a new species of skate of the genus Malacoraja Stehmann, 1970: the first species from the southwestern Atlantic Ocean, with notes on generic monophyly and composition (Chondrichthyes: Rajidae)

Abstract

The first report of a western South Atlantic soft skate, genus Malacoraja Stehmann, 1970, is described as Malacoraja obscura, new species, from the southeastern Brazilian continental slope off the states of Espírito Santo and Rio de Janeiro, in depths ranging from 808-1105 m. The new species is known from five specimens and is distinguished from congeners by its unique dorsal coloration with small, faded white spots on disc and pelvic fins, by retaining in larger specimens an irregular row of thorns along dorsal midline of tail (extending from tail base to two-thirds of tail length in 680 mm total length female), and by presenting a ventral tail midline devoid of small denticles only at base (naked region not extending posterior to pelvic fin rear margin). Further diagnostic characters in combination include the lack of scapular thorns in larger specimens, elevated number of tooth rows (64/62 tooth rows in subadult male of 505 mm TL, and 76/74 in large female of 680 mm TL) and vertebrae (27-28 Vtr, 68-75 Vprd), ventral disc and tail with a uniform dark brown coloration, paired postventral fenestrae on scapulocoracoid, enlarged posterior postventral fenestra, circular foramen magnum and paired internal carotid foramina on braincase floor. Adult males were unavailable for study, but an anatomical description of M. obscura, n. sp., is provided. Comparisons are made with all known material of M. kreffti, literature accounts of M. senta, and with abundant material of South African M. spinacidermis; M. obscura, n. sp., most closely resembles M. spinacidermis from the eastern South Atlantic in squamation, coloration and size. Malacoraja is monophyletic due to its unique squamation and rostral appendices, and apparently comprises two species-groups, one for M. obscura and M. spinacidermis, and the other for M. kreffti and M. senta, but clarification of species-level relationships must await more anatomical information, particularly of the latter two species.<br>O primeiro registro para o Atlântico Sul ocidental de uma espécie do gênero Malacoraja Stehmann, 1970 é feita com base na descrição de Malacoraja obscura, espécie nova, proveniente do talude continental do Sudeste brasileiro dos estados do Espírito Santo e Rio de Janeiro em profundidades de 808-1105 m. A espécie nova é conhecida através de cinco exemplares e é distinta de seus congêneres pela sua coloração dorsal composta por numerosas manchas esbranquiçadas e pequenas na região do disco e nadadeiras pélvicas, por apresentar uma fileira irregular de espinhos ao longo da superfície dorsal mediana da cauda a qual persiste em espécimes maiores (desde a base da cauda até dois-terços do seu comprimento numa fêmea de 680 mm de comprimento total, CT) e uma região pequena desprovida de dentículos na base ventral da cauda (estendendo somente até a margem distal da nadadeira pélvica). Outros caracteres diagnósticos em combinação incluem a ausência de espinhos escapulares em indivíduos maiores, número elevado de fileiras dentárias (64/62 fileiras num macho subadulto de 505 m...

Deep-Water Sharks, Rays, and Chimaeras of Brazil

“…Other rare deep-water species were recorded along the Brazilian coast, but most of them are known by single records or sporadic captures, e.g., S. [15,30,36,37,58,61,75,85,[107][108][109][110]. These species probably are distributed in deeper waters and are currently inaccessible to the Brazilian deep-water fishery.…”

“…A recent increase of deep-water research along the Brazilian continental slope in the past decades [1995][1996][1997][1998][1999][2000][2001][2002][2003][2004][2005][2006][2007] has revealed a great number of new species or records of elasmobranch fishes [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31], which is changing the marine biogeographic relevance of the Neotropical realm for this group of vertebrates. Nineteen species were recorded for the first time in Brazil or described for the continental slope habitat over the past 15 years.…”

Conhecimento e conservação dos peixes marinhos e estuarinos (Chondrichthyes e Teleostei) da costa norte do Brasil

“…A maior parte das espécies descritas ocorre em ambientes recifais (e.g., Moura 1995, Sazima et al 1997, Gasparini et al 1999, Heiser et al 2000, Moura et al 2001, Pinheiro et al 2010, ou de águas profundas (e.g., Mincarone 2000, 2001, Soto 2001a,b, Gomes & Paragó 2001, Soto & Vooren 2004, Carvalho et al 2005, Anderson & Mincarone 2006, Melo 2007, Mincarone & Anderson 2008, Nielsen 2009), ambientes historicamente mal amostrados. Além disso, diversos trabalhos têm registrado novas ocorrências de espécies, até então, não assinaladas no Atlântico Sul (e.g., Barreiros et al 2004, Lima & Mincarone 2004, Mincarone & Sampaio 2004, Feitoza et al 2005, Mincarone & Smith 2005, 2010a, b, 2011, Franco et al 2009, Melo et al 2009, Lima et al 2011.…”

Biodiversity and systematics of skates (Chondrichthyes: Rajiformes: Rajoidei)

“…The western North Atlantic fauna was extensively examined by Bigelow and Schroeder who detailed this and the Gulf of Mexico regions (1948, 1950, 1951a, b, 1953, 1954, 1958, 1962, 1964, 1965). The western South Atlantic region has improved markedly in recent years with works by McEachran (1982McEachran ( , 1983, Menni and Stehmann (2000), Cousseau (Cousseau et al 2000), Gomes (2002), and de Carvalho (2005). Stehmann has reviewed the eastern North Atlantic (Stehmann 1970;Stehmann and Bürkel 1984) and the West African continental slope from Morocco to South Africa (Stehmann 1995).…”