A new deep‐water chimaerid 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

Abstract

A new chimaerid species closely related to Hydrolagus pallidus is described from 13 specimens captured on the Portuguese continental slope (north-east Atlantic) by commercial longliners at depths of c. 1600 m. The new species is large-bodied with a rose to light brown body colouration. Hydrolagus lusitanicus n.sp. presents a combination of external morphological characters that allow it to be clearly differentiated from its congeners, in particular, the ratios of pectoral fin length: pectoral fin width and pelvic fin length: pelvic fin width; in having a serrated posterior edge of the dorsal spine; a high number of ridges in the dental plates. Additionally in males, there are differences on the shape and number of hooks in the frontal tenacula, on the number of spines in the prepelvic tenacula and on the length of the pectoral fin margin.

Retinal Morphology and Visual Specializations in Three Species of Chimaeras, the Deep-Sea R. pacifica and C. lignaria, and the Vertical Migrator C. milii (Holocephali)

“…Isolated reports on their diet reveal that Chimaera monstrosa [Bergstad et al, 2003], Hydrolagus spp. [Marques and Porteiro, 2000;Moura et al, 2005;Gonzalez et al, 2007], and Harriota raleighana [Dunn et al, 2010] all feed on benthic invertebrates like crustaceans, ophiurids, polychaete worms, and urchins. However, there is a dietary difference between Harriota spp.…”

Chimaera opalescens n. sp., a new chimaeroid (Chondrichthyes: Holocephali) from the north-eastern Atlantic Ocean

“…obs.). The taxonomy of this group has greatly improved, with 17 new species described since 1990, as a consequence of the increased fishing effort and the survey of deep‐sea biodiversity in the different oceans (Compagno et al , 1990; Hardy & Stehmann, 1990; Didier & Stehmann, 1996; Didier, 1998, 2002, 2008; Didier & Séret, 2002; Soto & Vooren, 2004; Moura et al , 2005; Barnett et al , 2006; Quaranta et al , 2006; Didier et al , 2008; Last et al , 2008). The identification of chimaeroids is often difficult, due to the scarcity of diagnostic morphological features (Didier, 2004).…”

Assessing ecological and molecular divergence between the closely related species Hydrolagus pallidus and H. affinis (Chimaeridae)

“…These two putative species could not be distinguished based on the ABDG analysis. Morphologically, H. lusitanicus has been distinguished from H. pallidus based on the ratio of pectoral‐fin length to pectoral‐fin width (1·5 for H. pallidus and more than 1·9 for H. lusitanicus ; Moura et al, ) but there has been no previous genetic comparison between these two species. Distinguishing between H. lusitanicus and H. pallidus is beyond the scope of this paper, but based on the low mitochondrial substitution rates and long generation times of deep‐water species (Mooers & Harvey, ; Gibbs, ; Galtier et al ., ), we speculate that these morphotypes may represent nascent species with insufficient time for complete lineage sorting at coI .…”