Abstract
A new species of chimaerid, Hydrolagus erithacus sp. nov., is described from nine specimens collected from the southeast Atlantic and southwest Indian oceans from depths of 470–1,000 meters. This species is distinguished from all other Hydrolagus species based on the following characteristics: head bulky, relatively large, followed by stocky body; head and body height from about pectoral fin origin to pelvic fin origin similar, then tapering rapidly to filamentous tail; first dorsal fin spine height about equal to, or slightly less than first dorsal fin apex height; second dorsal fin up to 81% of total body length and uniform in height; trifurcate claspers forked for approximately 20% of total length; robust frontal tenaculum nearly uniform in width, prepelvic tenaculae with five to seven medial spines, and a uniform black coloration with robust, non-deciduous skin. Comparison of mitochondrial NADH2 gene sequences with other morphologically similar Hydrolagus species suggests that H. erithacus is a distinct species.
References
Angulo, A., Lopez, M.I., Bussing, W.A. & Murase, A. (2014) Records of chimaeroid fishes (Holocephali: Chimaeriformes) from the Pacific coast of Costa Rica, with the description of a new species of Chimaera (Chimaeridae) from the eastern Pacific Ocean. Zootaxa, 3861 (6), 554–574.
https://doi.org/10.11646/zootaxa.3861.6.3Barnett, L.A.K., Didier, D.A., Long D.L. & Ebert, D.A. (2006) Hydrolagus mccokseri sp. nov., a new species of chimaeroid fish from the Galápagos Islands (Holocephali: Chimaeriformes: Chimaeridae). Zootaxa, 1328, 27–38.
Compagno, L.V.J. (1999) An overview of chondrichthyan systematic and biodiversity in southern Africa. Transactions of the Royal Society of South Africa, 45 (1), 75–120.
https://doi.org/10.1080/00359199909520406Didier, D.A. (2008) Two new species of the genus Hydrolagus Gill (Holocephalii: Chimaeridae) from Australia. In: Last, P.R., White, W.T. & Pogonoski, J.J. (Eds.), Descriptions of New Australian Chondrichthyans. CSIRO Marine and Atmospheric Research Paper Number 022, 349–356.
Didier, D.A. & Séret, B. (2002) Chimeroid fishes of New Caledonia with description of a new species of Hydrolagus (Chondrichthyes, Holocephali). Cybium, 26 (3), 225–233.
Didier, D.A., Kemper, J.M. & Ebert, D.A. (2012) Phylogeny, biology and classification of extant holocephalans. In: Carrier, J.C., Musick, J.A. & Heithaus, M.R. (Eds.), The Biology of Sharks and Their Relatives 2nd Edition. CRC Press, Boca Raton, pp. 97–122.
https://doi.org/10.1201/b11867-6Ebert, D.A. &. Stehmann, M.F.W. (2013) Sharks, batoids, and chimaeras of the North Atlantic. FAO Species Catalogue for Fishery Purposes. No. 7. Rome, FAO., 523 pp.
Ebert, D.A. & van Hees, K.E. (2015) Beyond Jaws: rediscovering the ‘lost’ sharks of southern Africa. African Journal of Marine Science, 37 (2), 141–156.
https://doi.org/10.2989/1814232X.2015.1048730Hardy, G.S. & Stehmann, M. (1990) A new deep-water ghost shark, Hydrolagus pallidus n.sp. (Holocephali, Chimaeridae), from the Eastern North Atlantic, and redescription of Hydrolagus affinis (Brito Capello, 1867). Archiv für Fischereiwissenschaft, 40, 229–248.
James, K., Ebert, D.A., Long, D.J. & Didier, D.A. (2009) A new species of chimaera, Hydrolagus melanophasma sp. nov. (Chondrichthyes: Chimaeriformes: Chimaeridae), from the eastern North Pacific. Zootaxa, 2218, 59–68.
Kemper, J.M., Ebert, D.A., Compagno, L.V.J. & Didier, D.A. (2010) Chimaera notafricana sp. nov. (Chondrichthyes: Chimaeriformes: Chimaeridae), a new species of chimaera from southern Africa. Zootaxa, 2532, 55–63.
Kemper, J.M., Ebert, D.A., Naylor, G.J.P. & Didier, DA. (2015) Chimaera carophila (Chondrichthyes: Chimaeriformes: Chimaeridae), a new species of chimaera from New Zealand. Bulletin of Marine Science, 91 (1), 1–18.
Moura, T., Figueiredo, I., Bordalo-Machado, P., Almeida, C. & Gordo, L.S. (2005) A new deep-water chimaeroid species, Hydrolagus lusitanicus n. sp., from off mainland Portugal with a proposal of a new identification key for the genus Hydrolagus (Holocephali: Chimaeridae) in the north-east Atlantic. Journal of Fish Biology, 67, 742–751.
https://doi.org/10.1111/j.0022-1112.2005.00774.xNaylor, G.J.P., Ryburn, J.A., Fedrigo, O. & Lopez, J.A. (2005) Phylogenetic relationships among the major lineages of modern elasmobranchs. In: Hamlett, W.C. (Ed.), Reproductive biology and phylogeny of Chondrichthyes: sharks, batoids and chimaeras. Enfield NH: Science Publishers, Inc. pp. 1–25.
Quaranta, K.L., Didier, D.A., Long, D.J. & Ebert, D.A. (2006) A new species of chimaeroid, Hydrolagus alphus sp. nov. (Chimaeriformes:Chimaeridae) from the Galapagos Islands. Zootaxa, 1377, 33–45.
Sabaj Pérez, M.H. (Ed.) (2016) Standard symbolic codes for institutional resource collections in herpetology and ichthyology: an Online Reference. Version 6.5 (16 August 2016). Electronically accessible at http://www.asih.org/, American Society of Ichthyologists and Herpetologists, Washington, DC
Stamatakis, A. (2014) RAxML version 8: a tool for phylogenetic analysis and post-analysis of large phylogenies. Bioinformatics, 30 (9), 1312–3.
https://doi.org/10.1093/bioinformatics/btu033Walovich, K.A., Ebert, D.A., Long, D.J. & Didier, D.A. (2015) Redescription of Hydrolagus africanus (Gilchrist, 1922) (Chimaeriformes: Chimaeridae), with a review of southern African chimaeroids and a key to their identification. African Journal of Marine Science, 37 (2), 157–165.
https://doi.org/10.2989/1814232X.2015.1033012Weigmann, S. (2016) Annotated checklist of the living sharks, batoids and chimaeras (Chondrichthyans) of the world, with a focus on biogeographical diversity. Journal of Fish Biology, 88 (3), 837–1037.
https://doi.org/10.1111/jfb.12874