Review of the hagfishes (Myxinidae) from the Galapagos Islands, with descriptions of four new species and their phylogenetic relationships

Abstract

Hagfishes are an ancient group of benthic marine craniates that are found in deep or cold waters around the world. Among the 83 valid species, four are described from the Galapagos Islands: Eptatretus bobwisneri, E. grouseri, E. mccoskeri and Rubicundus lakeside. During a recent expedition to the archipelago, six species of hagfishes were collected, including four undescribed species of the genera Eptatretus (Eptatretus goslinei sp. nov.) and Myxine (Myxine greggi sp. nov., M. martinii sp. nov. and M. phantasma sp. nov.). In this paper, we provide a review of the eight species of hagfishes from the Galapagos Islands, including new diagnoses and an identification key for all species. Myxine phantasma is remarkable in that it is the only species of Myxine known to completely lack melanin-based pigments. Our species delineations were based on both morphological and molecular analyses. A phylogenetic hypothesis based on molecular data suggests that Galapagos hagfishes arose from multiple independent colonisations of the islands from as many as five different ancestral lineages. The large number of endemic hagfishes in the geologically young Galapagos Islands suggests that there is much global hagfish diversity yet to be discovered.

Comparison of vertebrate skin structure at class level: A review

“…The skin of Myxine is almost devoid of pigment and quite transparent, which may be related to its deep-sea habitat and burrowing habits, while in shallow-water species of the genus Eptatretus, the skin is less transparent (Fernholm & Holmberg, 1975;Hardisty, 1979). Recently, M. phantasma was reported to have transparent skin due to a complete lack of melaninbased pigmentation (Mincarone et al, 2021).…”

Epidermal threads reveal the origin of hagfish slime

“…To reduce heterozygosity, comparative transcriptome analyses were conducted using data from a single E. goslinei individual (Mincarone et al 2021). In addition, we filtered our phylogenetic analyses of transcripts to include only approximately full-length sequences that had expression levels above TPM > 10 for replicate RNAseq datasets.…”

Evolution of a remarkable intracellular polymer and extreme cell allometry in hagfishes

“…Vertical lines represent genus-specific means (black) and medians (gray). (D) Mapping of L max for all sampled species on a recent phylogeny 15 shows that body size is not phylogenetically conserved (see also Figure S1B and Data S1). Report been examined (Figure 2B).…”

“…Correlational tests were conducted using R. 32 For phylogenetically justified analyses, we used the latest molecular phylogeny 15 (Figure S1B), which included 11 of 19 sampled species in this study. This phylogeny is non-ultrametric given the lack of hagfish fossils that can be used for calibrating the age of nodes.…”