Abstract
The genus Scyliorhinus is part of the family Scyliorhinidae, the most diverse family of sharks and of the subfamily Scyliorhininae along with Cephaloscyllium and Poroderma. This study reviews the phylogenetic relationships of species of Scyliorhinus in the subfamily Scyliorhininae. Specimens of all Scyliorhinus species were examined as well as specimens of four of the 18 species of Cephaloscyllium, two species of Poroderma, representatives of almost all other catshark (scyliorhinid) genera and one proscylliid (Proscyllium habereri). A detailed morphological study, including external and internal morphology, morphometry and meristic data, was performed. From this study, a total of 84 morphological characters were compiled into a data matrix. Parsimony analysis was employed to generate hypotheses of phylogenetic relationships using the TNT 1.1. Proscyllium habereri was used to root the cladogram. The phylogenetic analysis, based on implied weighting (k = 3; 300 replications and 100 trees saved per replication), resulted in three equally most parsimonious cladograms with 233 steps, with a CI of 0.37 and an RI of 0.69. The monophyly of the subfamily Scyliorhininae is supported as well as of the genus Scyliorhinus, which is proposed to be the sister group of Cephaloscyllium. The phylogenetic relationships amongst Scyliorhinus species are presented for the first time.
Highlights
Contrasting hypotheses on the classification of catsharks are widespread in literature and divide opinions of many authors (e.g. White 1936, 1937; Compagno 1973, 1988a; Maisey 1984; Nakaya 1975; Iglésias et al 2005; Human et al 2006; Naylor et al 2005, 2012a; Nelson et al 2016; Weigmann 2016; Weigmann et al 2018)
No cladistic analysis considering morphological data has been performed to elucidate the phylogenetic relationships of catshark species and enlarge
External morphology and internal anatomy of S. cabofriensis, S. haeckelii and S. ugoi were extracted from Soares et al (2015, 2016)
Summary
Contrasting hypotheses on the classification of catsharks are widespread in literature and divide opinions of many authors (e.g. White 1936, 1937; Compagno 1973, 1988a; Maisey 1984; Nakaya 1975; Iglésias et al 2005; Human et al 2006; Naylor et al 2005, 2012a; Nelson et al 2016; Weigmann 2016; Weigmann et al 2018). On the basis of morphological data, Compagno (1988a) proposed that the family Scyliorhinidae is composed of 17 genera, following the traditional arrangement for the group (Nakaya 1975; Springer 1979). Iglésias et al (2005), analysing molecular data, hypothesised that the family Scyliorhinidae is paraphyletic and proposed the re-allocation of 11 catshark genera to the family Pentanchidae, elevated in rank from subfamily (Compagno 1988a). The paraphyly of Scyliorhinidae has been corroborated by later works (Human et al 2006; Naylor et al 2012a, 2012b), recent molecular analysis, including a larger sample of taxa, recovered three different paraphyletic lineages of catsharks instead of two and species of Parmaturus were placed in distinct clades (Naylor et al 2012a, 2012b). No cladistic analysis considering morphological data has been performed to elucidate the phylogenetic relationships of catshark species and enlarge
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