Review of the Australian hagfishes with description of two new species of Eptatretus (Myxinidae)

A new species of the hagfish genus Eptatretus (Myxinidae) from the Bahamas, western North Atlantic

A new species of the hagfish genus Eptatretus (Myxinidae) is described based on two specimens (407-433 mm total length) collected off the northern Bahamas, between depths of 910 and 1153 m. The new species is distinguished from its congeners by having seven pairs of gill apertures well-spaced and arranged in a near straight line, a 3/2 multicusp pattern of teeth, 10-11 anterior unicusps, 50-51 total cusps, 12-14 prebranchial pores, 48-52 trunk pores, 79-84 total pores, and no nasal-sinus papillae. An identification key for the species of Eptatretus from the western Atlantic Ocean is also provided.

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

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.

A new species of hagfish, Eptatretus wandoensis sp. nov. (Agnatha, Myxinidae), from the southwestern Sea of Korea

Four specimens of the five-gilled white mid-dorsal line hagfish, Eptatretuswandoensissp. nov. were recently collected from the southwestern Sea of Korea (Wando). This new species has five pairs of gill apertures, 14–18 prebranchial slime pores, 4 branchial slime pores, a dark brown back with a white mid-dorsal line and a white belly. These hagfish are similar to Eptatretusburgeri and Eptatretusminor in having a white mid-dorsal line, but can be readily distinguished by the numbers of gill apertures (5 vs. 6–7), gill pouches (5 vs. 6), and prebranchial slime pores (14–18 vs. > 18), as well as the body color (dark brown back vs. gray or brown pale). In terms of genetic differences, Eptatretuswandoensis could be clearly distinguished from E.burgeri (0.9% in 16S rRNA and 8.5% in cytochrome c oxidase subunit I sequences) and E.minor (4.5% and 13.9%).

Evolution of Vertebrate Phototransduction: Cascade Activation

We applied high-throughput sequencing to eye tissue from several species of basal vertebrates (a hagfish, two species of lamprey, and five species of gnathostome fish), and we analyzed the mRNA sequences for the proteins underlying activation of the phototransduction cascade. The molecular phylogenies that we constructed from these sequences are consistent with the 2R WGD model of two rounds of whole genome duplication. Our analysis suggests that agnathans retain an additional representative (that has been lost in gnathostomes) in each of the gene families we studied; the evidence is strong for the G-protein α subunit (GNAT) and the cGMP phosphodiesterase (PDE6), and indicative for the cyclic nucleotide-gated channels (CNGA and CNGB). Two of the species (the hagfish Eptatretus cirrhatus and the lamprey Mordacia mordax) possess only a single class of photoreceptor, simplifying deductions about the composition of cascade protein isoforms utilized in their photoreceptors. For the other lamprey, Geotria australis, analysis of the ratios of transcript levels in downstream and upstream migrant animals permits tentative conclusions to be drawn about the isoforms used in four of the five spectral classes of photoreceptor. Overall, our results suggest that agnathan rod-like photoreceptors utilize the same GNAT1 as gnathostomes, together with a homodimeric PDE6 that may be agnathan-specific, whereas agnathan cone-like photoreceptors utilize a GNAT that may be agnathan-specific, together with the same PDE6C as gnathostomes. These findings help elucidate the evolution of the vertebrate phototransduction cascade from an ancestral chordate phototransduction cascade that existed prior to the vertebrate radiation.

Morphometics and gonadal development of the hagfish Eptatretus cirrhatus in New Zealand

Hagfishes have been the target of commercial fisheries in many areas of the world, with the catch processed for leather and for human consumption. A fishery has been operating in New Zealand waters for the last six years, harvesting the bearded hagfish, Eptatretus cirrhatus. The fishery has thus far been unregulated. Based on samples collected dockside over a two-year period, this report expands the morphometric database for this species, provides information on the size and weight of the harvested animals, determines the sizes at the onset of gonadal development and the minimum sizes at sexual maturation for males and females, and indicates that E. cirrhatus, like most other hagfish species, has no specific breeding season. Although females appear in the population at smaller sizes, the sex ratio for mature animals is 1:1 and the sizes of the largest males and females are comparable. The changes observed in sex ratio as a function of TL suggest differences in the timing and rates of gonadal development in females versus males rather than protogyny. Based on the size of the eggs, the number of eggs per female, the proportion of the population that contains large eggs, and the number of postovulatory females, it is clear that E. cirrhatus, like other hagfish species, are potentially vulnerable to overexploitation.

First record and further description of the Cape hagfish Myxine capensis(Myxinidae) off Mozambique, western Indian Ocean

The first record of the Cape hagfish Myxine capensis in Mozambican waters is reported based on a single 356 mm total length specimen taken by bottom trawl off Maputo, 25° 52·9' S; 34° 42·7' E - 25° 54·1' S; 34° 41·0' E, at depths from 557 to 564 m. This account also represents the northernmost record of a hagfish in the western Indian Ocean. Morphometric and meristic data are provided and compared with those of 27 specimens (including the holotype) caught off Namibia and South Africa.

A new species of hagfish (Myxinidae: Eptatretus) from Papua New Guinea

A new species of seven-gilled hagfish Eptatretus astrolabium (Myxinidae) is described from a 400 mm total length female trapped 1 km east from Planet Rock, Astrolabe Bay, Papua New Guinea, at c. 500 m depth. This is the first hagfish species reported from the waters around New Guinea. It can be distinguished from other hagfishes by a combination of characters including seven pairs of gill apertures, three-cusp multicusps on the anterior and posterior rows of cusps, 10 posterior unicusps, 52 total cusps, 18-19 prebranchial pores, five branchial pores, 48-49 trunk pores, 83-84 total pores and no nasal-sinus papillae.