Eptatretus mccoskeri McMillan, 1999: 115 Eptatretus mccoskeri Mok et al. , 2001: 1026 McMillan & Wisner, 2004: 55 Mincarone & McCosker, 2004: 166 Møller & Jones, 2007: 64 McCosker & Rosenblatt, 2010: 172 Mincarone & Fernholm, 2010: 797 Knapp et al. , 2011: 404 Ruiz et al. , 2011: 30 Mincarone & McCosker, 2014: 347 Cruz-Mena & Angulo, 2015: 325 Angulo & Del Moral-Flores, 2016: 105 Eptatretus Eptatretus mccoskeri Møller & Jones, 2007: 64 Review of the hagfishes (Myxinidae) from the Galapagos Islands, with descriptions of four new species and their phylogenetic relationships Mincarone, M. M. Plachetzki, D. McCORD, C. L. Winegard, T. M. Fernholm, B. Gonzalez, C. J. Fudge, D. S. Zoological Journal of the Linnean Society 2021 192 453 474 6FYS6 MCMILLAN, 1999 McMillan 1999 [226,715,1146,1171] Myxini Myxinidae Eptatretus Animalia Myxiniformes 9 462 Chordata species mccoskeri  ( FIGS 1, 2D, 3C, 5, 6C; TABLES1–3)      Eptatretus mccoskeri  McMillan, 1999: 115, fig. 2d–g [type locality: Galapagos Islands, 01°06.3’S, 89°06.9’W, depth  704 ft(correct depth  660 ft/  201 m); type series: holotype, CAS 86431; paratypes, SIO 97-75(2), USNM 344905(1)].    Eptatretus mccoskeri. – Mok, 2001: 356. –  Mok et al., 2001: 1026. –  McMillan & Wisner, 2004: 55. –  Mincarone & McCosker, 2004: 166. –  Møller & Jones, 2007: 64. –  McCosker & Rosenblatt, 2010: 172. –  Mincarone & Fernholm, 2010: 797. –  Knapp et al., 2011: 404. –  Ruiz et al., 2011: 30. –  Mincarone & McCosker, 2014: 347. –  Cruz-Mena & Angulo, 2015: 325. –  Angulo & Del Moral-Flores, 2016: 105.    Eptatretus Eptatretus mccoskeri.–  Møller & Jones, 2007: 64.   Material examined:  CAS86431, holotype( 310 mm), off SE San Cristobal Island, 01°06’19”S, 89°06’56”W,  201 mdepth, submersible  Johnson Sea Link, baited minnow trap, JohnE. McCosker,  16 November 1995.  SIO 97–75, paratype( 290 mm), and  USNM 344905, paratype( 284 mm), taken with the holotype.  MCCDRS 9397  COI,16S, 2( 303–304 mm) and  SIO 19-81  COI,16S, 2 (310– 310 mm), between Santa Cruzand Santa Fé islands, 00°48’00”S, 90°10’12”W,  155 mdepth,  Valeska Yamile, sta. G1, baited trap, Douglas Fudge et al.,  26 May 2019, 08:01–10:06 h.  Diagnosis: Eptatretus mccoskeridiffers from all congeners, except  Eptatretus poicilus Zintzen & Roberts, 2015from New Zealand, by having eight pairs (seven pairs in one specimenof  E. mccoskeri) of gill apertures well-spaced and arranged in a near straight line, and a 3/3 multicusp pattern of teeth.  Eptatretus mccoskeridiffers from  E. poicilusby its number of trunk pores (38–43 vs. 45–50), number of total pores (69–75 vs. 78–86) and by its colour pattern (body purple to purplish brown vs. body strongly mottled with pale brown, dark brown and white-beige) ( McMillan, 1999; Zintzen et al., 2015).  Description:Body elongated, subcylindrical at prebranchial and branchial regions, laterally compressed at trunk and strongly compressed at tail. Rostrum bluntly rounded. Two bilaterally symmetrical nasal-sinus papillae in the dorsal surface of the nasal sinus. Eyespots conspicuous. Three pairs of barbels on head: first two about equal in size (1.5–2.2% TL) and adjacent to opening of nasopharyngeal duct; third pair longer (1.9–2.9% TL) and immediately adjacent to mouth. Ventral finfold absent (occasionally represented by a white line) or low ( 1–2 mmhigh), beginning within anterior 1/3 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 holotypefollowed by range of paratypesin brackets): preocular length 7.1 (5.6–6.3); prebranchial length 25.8 (22.6–26.1); branchial length 10.0 (8.8– 13.5); preventral length 51.6 (38.7–53.4); trunk length 49.7 (49.3–56.1); tail length 15.8 (10.6–16.9); body width at PCD 7.3 (6.9–8.6); body depth at PCD (6.6–8.4); body depth including VFF 8.2 (7.7–9.3); body depth excluding VFF 8.2 (7.4–9.1); body depth at cloaca 7.3 (6.8–14.5); tail depth 8.9 (7.1–9.8). Counts (description of the holotypefollowed by range of paratypesin brackets): multicusp pattern 3/3; anterior unicusps 10 (8–10); posterior unicusps 9 (8–10); total cusps 51 (44–51). Prebranchial pores 13 (13–16); branchial pores 7 (6–7); trunk pores 43 (38– 43); tail pores 10 (10–12); total pores 73 (69–75). Eight pairs of gill pouches corresponding to eight pairs of gill apertures ( one specimenwith seven pairs of gill pouches and 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 5–6. Ventral aorta branches at gill pouches 6–7. Colour (in life): body purple to purplish brown; mouth with white margin; barbels white; eyespots visible, but not prominent; gill apertures with white margins; ventral finfold occasionally lighter than body; caudal finfold with white margin ( Fig. 3). Colour in alcohol darker than that described for live specimens.  Distribution and habitat:Galapagos Islands: known from seven specimenscollected in two localities: off south-eastern San Cristobal Island, on the top of a seamount at about 201 mdepth; and between Santa Cruz and Santa Fé islands, at 155 mdepth ( Fig. 1). CAS 86431 [420,664,1274,1296] CAS 215 -1.105 Galapagos Islands 130 -89.115 9 462 SIO 97-75, USNM 344905 2 Galapagos holotype CAS 86431 1995-11-16 CAS John & McCosker San Cristobal Island 201 -1.1052778 San Cristobal Island 21 -89.115555 9 462 1 holotype [827,1253,197,219] SIO San Cristobal Island 9 462 SIO 97-75 1 paratype USNM San Cristobal Island 9 462 USNM 344905 2 paratype MCCDRS San Cristobal Island 9 462 MCCDRS 9397 1 paratype 2019-05-26 SIO Valeska Yamile & Douglas Fudge San Cristobal Island 155 -0.8 Santa Cruz 21 -90.17 Santa Fe islands 9 462 SIO 19-81 1 paratype