Myxine martinii, Mincarone & Plachetzki & McCORD & Winegard & Fernholm & Gonzalez & Fudge, 2021

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 : 464-467

MYXINE MARTINII SP. NOV.

MARTINI’ S HAGFISH

( FIGS 1, 2G, 4B, 5; TABLES 4–6)

Z o o b a n k r e g i s t r a t i o n. u r n: l s i d: z o o b a n k. org:act: 5765A69C-0676-4067-B433-ED64FBDBD684

Holotype: SIO 19-85 COI, 16S, 381 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, 09:51–12:40 h.

Paratypes: SIO 19-80 COI, 16S, 1 (361 mm), taken with the holotype .

Diagnosis: Myxine martinii differs from all congeners, except M. affinis Günther, 1870 and M. australis Jenyns, 1842 from southern South America, M. glutinosa Linnaeus, 1758 from the eastern North Atlantic and Mediterranean, M. limosa Girard, 1859 from the western North Atlantic, M. hubbsi Wisner & McMillan, 1995 from the eastern Pacific, M. hubbsoides Wisner & McMillan, 1995 from Chile, M. jespersenae Møller et al., 2005 from Greenland and Iceland, M. knappi Wisner & McMillan, 1995 from southern Argentina, M. kuoi Mok, 2002 from Taiwan, M. mcmillanae Hensley, 1991 from the Gulf of Mexico and Caribbean Sea, M. paucidens Regan, 1913 from Japan, M. sotoi Mincarone, 2001 from southern Brazil, and M. greggi from the Galapagos, by having six pairs of gill pouches and a 2/2 multicusp pattern of teeth. Myxine martinii differs from these congeners by having: 34 total cusps (vs. 38–46 in M. affinis , 38–44 in M. jespersenae , 30–32 in M. kuoi , 42–48 in M. mcmillanae , 26 in M. paucidens and 34–44 in M. sotoi ); 26–27 prebranchial pores (vs. 30– 31 M. hubbsoides, 28–37 in M. jespersenae , 30–38 in M. knappi and 28–38 in M. sotoi ); 52–54 trunk pores (vs. 57–79 in M. affinis , 57–73 in M. hubbsi , 68–71 in M.hubbsoides , 57–58 in M.kuoi , 60–76 in M.mcmillanae , 61–73 in M. sotoi and 58–66 in M. greggi ); 91 total pores (vs. 94–124 in M. affinis , 111–116 in M. hubbsoides , 107–121 in M. jespersenae , 98–126 in M. knappi , 95–100 in M. kuoi , 101–113 in M. mcmillanae and 101–119 in M. sotoi ); and by having one single conspicuous nasalsinus papilla in the mid-dorsal surface of the nasal sinus (vs. two bilaterally symmetrical nasal-sinus papillae in M. jespersenae ). Myxine martinii can be also distinguished from congeners with six-gill pouches by its colour pattern (body dark brown with white head vs. body entirely pigmented, without white head, in M. affinis , M. australis , M. hubbsoides , M. knappi , M. kuoi and M. paucidens ). Myxine martinii can be further distinguished from M. greggi and M. hubbsi by having a white ventral finfold (vs. same colour or darker than body). In Myxine martinii , the gill aperture on the

a Left + right side for single specimen.

left side is not confluent with the pharyngocutaneous duct aperture, but separated by a very short distance (c. 1 mm). This character is only observed in Myxine paucidens and some specimens of Myxine capensis Regan, 1913 (a species with seven pairs of pouches from southern Africa) ( Hensley, 1991; Wisner & McMillan, 1995; Mincarone, 2001; Mok, 2001, 2002; McMillan & Wisner, 2004; Møller et al., 2005; Mincarone et al., 2011).

Description: Body elongated, subcylindrical at prebranchial and branchial regions, laterally compressed at trunk and strongly compressed at tail. Rostrum triangular with rounded tip. One single conspicuous nasal-sinus papilla in the mid-dorsal surface of the nasal sinus. Eyespots absent. Three pairs of barbels on head: first two about equal in size (1.0–1.2% TL) and adjacent to opening of nasopharyngeal duct; third pair longer (1.6– 1.8% TL) and immediately adjacent to mouth. Ventral finfold low (<1 mm high), beginning within anterior 10% of trunk, extending backward to the cloaca. Caudal finfold thin, rounded, beginning immediately posterior to edge of cloaca, extending around tail to dorsal surface, ending about over cloaca.

Body proportions (in percentage of TL; description of the holotype followed by paratype in brackets): prebranchial length 31.0 (30.2); preventral length 36.2 (33.2); trunk length 56.0 (57.6); tail length 13.0 (12.2); body width at PCD 4.2 (3.9); body depth at PCD 5.0 (5.5); body depth including VFF 4.5 (5.0); body depth excluding VFF 3.9 (4.4); body depth at cloaca 4.2 (3.9); tail depth 5.0 (4.7).

Counts (description of the holotype followed by paratype in brackets): multicusp pattern 2/2; anterior unicusps 6 (6); posterior unicusps 7 (7); total cusps 34 (34). Prebranchial pores 26 (27); trunk pores 54 (52); tail pores 11 (12); total pores 91 (91).

Six pairs of gill pouches, with efferent branchial ducts on either side combined into a single external gill aperture posterior to the gill pouches. Gill aperture on the left side not confluent with the pharyngocutaneous duct aperture, but separated by a very short distance (<1 mm). Dental muscle overlies the first pair of gill pouches. Ventral aorta not branched.

Colour (in life): body dark brown; ventral region between rows of slime pores lighter than body; tip of head, mouth and barbels white; gill apertures with white margin; ventral finfold white; caudal finfold the same colour as body ( Fig. 4). Colour in alcohol similar to that described for live specimens.

Distribution and habitat: Galapagos Islands: known only from two specimens collected off Cabo Douglas, north-western Fernandina, at 557 m depth ( Fig. 1).

Etymology: This species is named for Dr Frederic (Ric) Martini, who for many years taught at the Shoals Marine Laboratory (University of New Hampshire, Cornell University) and introduced many students to

the wonders of hagfish through his lectures and his research publications.