Hagfish phylogeny and taxonomy, with description of the new genusRubicundus(Craniata, Myxinidae)

Abstract

A recent phylogenetic analysis of the Myxinidae based on the 16S rRNA gene resulted in synonymization of Paramyxine with Eptatretus. This created homonymy of Paramyxine fernholmi with Eptatretus fernholmi and Paramyxine wisneri with Eptatretus wisneri. In order to resolve this nomenclatural dilemma, we made a more extensive phylogenetic assessment of the Myxinidae and examined the nomenclature of the family. We used 75 sequences (37 of which new for this study) of a 561 bp fragment of the 16S rRNA gene, representing 33 species, and 72 sequences (37 of which new for this study) of a 687 bp fragment of the cytochrome c oxidase subunit I (COI) gene, representing 23 species, to reconstruct the phylogeny of Myxinidae. The monophyly of the subfamily Myxininae, traditionally characterized by having a single pair of external gill openings, was rejected (0.50 Bayesian posterior probability) by the 16S analysis, but supported by the COI and combined COI+16S analyses (0.99 and 0.81 Bpp, respectively). The monophyly of the subfamily Eptatretinae, characterized by having several pairs of external gill openings, was not supported by the 16S analysis and rejected by the COI and combined COI+16S analysis due to the placement of Eptatretus lopheliae as the earliest branch of Myxinidae (0.71 and 0.57 Bpp, respectively). Eptatretus lopheliae and Eptatretus rubicundus formed a monophyletic group and were allocated to a new genus, Rubicundus, characterized by the presence of an elongated tubular nostril and reddish coloration. A new monotypic subfamily, Rubicundinae, was proposed for Rubicundus. The synonymy of the genera Paramyxine and Quadratus with Eptatretus was confirmed. E. fernholmi is renamed Eptatretus luzonicus. Eptatretus wisneri was renamed Eptatretus bobwisneri. Petromyzon cirrhatus Forster, 1801, Homea banksii Fleming, 1822, and Bdellostoma forsteri Müller, 1836 are synonyms, but no type specimens are known to exist. Petromyzon cirrhatus was designated as type species of Eptatretus, conserving present usage. Gastrobranchus dombeyi Shaw, 1804 has priority over other names for Chilean myxinids. Bdellostoma stoutii was designated as type species of Polistotrema Gill. The validity of the Western Atlantic Myxine limosa as distinct from the Eastern Atlantic Myxine glutinosa was confirmed.

New records of hagfishes (Myxini: Myxiniformes: Myxinidae) from the Pacific coast of Costa Rica

“…These fi shes occur in all oceans at depths between 15 and 5000 m (Nelson 2006, Fernholm and Mincarone 2010, Fernholm et al 2013). …”

“…The taxonomy of hagfi shes is based mainly on the variation in the teeth and gill structures, as well as a limited set of meristic, morphological, and colour characteristics, with the latest review of the family by Fernholm (1998) and Fernholm et al (2013). Currently, members of the family are divided into three subfamilies: Myxininae, Eptatretinae, and Rubicundinae (see Fernholm et al 2013).…”

“…Currently, members of the family are divided into three subfamilies: Myxininae, Eptatretinae, and Rubicundinae (see Fernholm et al 2013). Myxininae includes four genera (Myxine Linnaeus, 1758;Nemamyxine Richardson, 1958;Neomyxine Richardson, 1954;and Notomyxine Nani et Gneri, 1951) and about 27 valid species (Rubio et al 2005, Kuo et al 2010, Fernholm et al 2013, Eschmeyer and Fong 2015.…”

“…Currently, members of the family are divided into three subfamilies: Myxininae, Eptatretinae, and Rubicundinae (see Fernholm et al 2013). Myxininae includes four genera (Myxine Linnaeus, 1758;Nemamyxine Richardson, 1958;Neomyxine Richardson, 1954;and Notomyxine Nani et Gneri, 1951) and about 27 valid species (Rubio et al 2005, Kuo et al 2010, Fernholm et al 2013, Eschmeyer and Fong 2015. Eptatretinae and Rubicundinae are represented each one by a single genus (Eptatretus Cloquet, 1819;and Rubicundus Fernholm, Norén, Kullander, Quattrini, Zintzen, Roberts, Mok et Kuo, 2013, respectively) and a total combined of about 51 valid species (Eschmeyer and Fong 2015).…”

“…The genus Myxine is the most diverse within the subfamily Myxininae (see Fernholm 1998, Fernholm et al 2013 and is characterized by the following combination of characters:…”