Taxonomic research on Deania calcea and Deania profundorum (Family: Centrophoridae) in the Cantabrian Sea (Northeast Atlantic) with comments on Deania hystricosa

Abstract

Three elasmobranch species of the genus Deania are currently reported in NE Atlantic waters: D. calcea, D. hystricosa and D. profundorum; however, in north Spanish waters (NE Atlantic), only D. calcea and D. profundorum have been caught. Among the criteria used to discriminate Deania species one is dermal denticle length and body colour. In this study the authors explore the feasibility of these criteria and examine other morphological characters to investigate if sexual or ontogenic features had relevance for the distinction of the species particularly those sampled in this study, D. calcea and D. profundorum. Molecular analyses were conducted to validate these results.In D. calcea, dermal denticle length ranged from 340μm to 1400μm (763.2μm± 180.4 s.d.); in D. profundorum, dermal denticle length ranged from 195μm to 650μm (372.3μm± 111.7 s.d.). In both Deania species, a significant positive correlation was found between shark total length and dermal denticle length. Dermal denticles varied in size and shape along the shark body. These differences were significant both intra- and inter-specifically.A multivariate analysis based on morphological characters was used to test differences between D. calcea and D. profundorum. The hierarchical analysis clearly identified three groups; two groups corresponded to each species, and a third group discriminated between small and large individuals of D. profundorum. The morphometric characters that contributed most to the divergence between both species were mainly related to the size of the dorsal fins, the inter-dorsal distance and the distances from the snout to the origin of each dorsal fin. Based on morphological characters, no sexual dimorphism was observed.The phylogenetic tree was reconstructed with molecular COI sequences available on BOLD and those obtained in this study. The output tree discriminate D. calcea from D. profundorum, however could not separate molecularly D. calcea and D. hystricosa.