Eptatretus bobwisneri, FERNHOLM ET AL., 2013

Mincarone, M. M., Plachetzki, D., McCORD, C. L., Winegard, T. M., Fernholm, B., Gonzalez, C. J. & Fudge, D. S., 2021, Review of the hagfishes (Myxinidae) from the Galapagos Islands, with descriptions of four new species and their phylogenetic relationships, Zoological Journal of the Linnean Society 192, pp. 453-474 : 456-459

EPTATRETUS BOBWISNERI FERNHOLM ET AL., 2013

BOB WISNER’ S HAGFISH

( FIGS 1, 2A, 3A, 5, 6A; TABLES 1–3)

Eptatretus bobwisneri Fernholm et al., 2013: 302 . Replacement for Eptatretus wisneri McMillan, 1999 , preoccupied by Paramyxine wisneri Kuo et al., 1994 . – Cruz-Mena & Angulo, 2015: 325. – Angulo & Del Moral-Flores, 2016: 100.

Eptatretus wisneri McMillan, 1999: 116 [original description; type locality: Galapagos Islands, 00°28.0’S, 91°37.2’W, depth 1848 ft (563 m); typeseries: holotype, CAS 86429; paratype, SIO 97-76 (1)]. – Mok et al. 2001: 1026. – McMillan & Wisner, 2004: 55. – Mincarone & McCosker, 2004: 166. – McCosker & Rosenblatt, 2010: 172. – Mincarone & Fernholm, 2010: 795. – Knapp et al., 2011: 404. – Ruiz et al., 2011: 30. – Mincarone & McCosker, 2014: 347.

Eptatretus Eptatretus wisneri . – Møller & Jones, 2007: 64.

Material examined: CAS 86429, holotype (355 mm), SW Fernandina Island, Cabo Hammond , 00°27’56”S, 91°37’33”W, 563 m depth, submersible Johnson Sea Link , baited minnow trap, John E. McCosker, 14 November 1995 . SIO 97-76 , paratype, 1 (316 mm), NW Fernandina Island, Cabo Douglas , 00°17.5’S, 91°38.9’W, 512 m depth, submersible Johnson Sea Link , baited minnow trap, John E. McCosker, 16 November 1995 . SIO 19-80 COI, 16S, 2 (164–190 mm), NW Fernandina Island, Cabo Douglas , 00°17’37.94”S, 91°39’18.10”W, 557 m depth, Queen Mabel, sta. G20, baited trap, Douglas Fudge et al., 6 June 2019 , 9:51–12:40 h.

Diagnosis: Eptatretus bobwisneri differs from all congeners, except E. gomoni Mincarone & Fernholm, 2010 from Western Australia, E. indrambaryai Wongratana, 1983 from Thailand, E. luzonicus Fernholm et al., 2013 from the Philippines, E. octatrema ( Barnard, 1923) from South Africa and E. okinoseanus ( Dean, 1904) from Japan and Taiwan, by having eight pairs of gill apertures well-spaced and arranged in a near straight line, and a 3/2 multicusp pattern of teeth. Eptatretus bobwisneri differs from these congeners by having: 44–47 total cusps (vs. 50 in E. gomoni and 38–40 in E. octatrema ); 9–11 prebranchial pores (vs. 12–13 in E. gomoni , 22–26 in E. octatrema and 13–17 in E. okinoseanus ); 43–47 trunk pores (vs. 57–58 in E. gomoni , 63–68 in E. octatrema and 54–61 in E. okinoseanus ); 73–76 total pores (vs. 91–93 in E. gomoni , 77–82 in E. indrambaryai , 84–88 in E. luzonicus , 104–117 in E. octatrema and 87–97 in E. okinoseanus ); no nasal-sinus papillae (vs. one single nasal-sinus papilla in E. luzonicus , two bilaterally symmetrical nasal-sinus papillae in E. octatrema ) ( Wongratana, 1983; Mok, 2001; McMillan & Wisner, 2004; Mincarone & Fernholm, 2010; Mincarone & McCosker, 2014; Mincarone, 2017).

Description: Body elongated, subcylindrical at prebranchial and branchial regions, laterally compressed at trunk and strongly compressed at tail. Rostrum bluntly rounded. Nasal-sinus papillae absent. Eyespots conspicuous. Three pairs of barbels on head, first two pairs subequal in size (1.6–2.0% TL) and adjacent to opening of nasopharyngeal duct; third pair longer (2.4–2.7% TL) and immediately adjacent to mouth. Ventral finfold absent or low (1 mm high), beginning within anterior third of trunk, extending backwards to cloaca. Caudal finfold well developed, thin, extending around tail to dorsal surface, ending about over cloaca.

Body proportions (in percentage of TL; description of the holotype followed by the range for paratype and non-type specimens in brackets): preocular length 6.2 (6.3–6.7); prebranchial length 18.9 (19.5–22.8); branchial length 12.1 (8.9–10.4); preventral length 46.5 (45.8–52.2); trunk length 53.5 (48.4–55.3); tail length 17.7 (14.7–16.5); body width at PCD 6.5 (5.3– 7.9); body depth at PCD (6.3–8.2); body depth including VFF 8.0 (5.4–8.7); body depth excluding VFF 7.7 (4.9– 8.7); body depth at cloaca 6.5 (5.8–7.9); tail depth 8.3 (7.8–8.5).

a Left + right side for single specimen.

b One specimen ( SIO 97-77, 138 mm TL) with six gill pouches and apertures.

c One specimen ( MCCDRS 9397, 304 mm TL) with seven gill pouches and apertures.

Counts (description of the holotype followed by the range for paratype and non-type specimens in brackets): multicusp pattern 3/2; anterior unicusps 9 (9–10); posterior unicusps 8 (8–9); total cusps 45 (44–47). Prebranchial pores 9 (9–11); branchial pores 7 (7); trunk pores 43 (45–47); tail pores 14 (12–13); total pores 73 (75–76).

Eight pairs of gill pouches corresponding to eight pairs of gill apertures. Gill apertures well-spaced and linearly arranged. Last branchial duct confluent with pharyngocutaneous duct on left side, forming a larger aperture. Posterior tip of dental muscle reaches gill pouches 4–5. Ventral aorta branches at gill pouch 6.

Colour (in life): body medium to dark brown, head slightly lighter; mouth and surrounding area white; barbels with white tip; very distinct eyespots; gill apertures with white margins; ventral finfold and caudal finfold with white margins ( Fig. 3). Colour in alcohol similar to that described for live specimens.

Distribution and habitat: Galapagos Islands: known only from four specimens collected in two localities off Fernandina Island: Cabo Hammond and Cabo Douglas, at depths from 512 to 577 m ( Fig. 1).