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Fishery Bulletin/U S Dept of Commerce National Oceanic Abstract.-Nine new species of hagfishes (Myxinidae, Myxine) from the Review of new world hagfishes of Pacific andAtlantic coasts ofNorth and SouthAmerica are described and a key the genus Myxine is otTered to the new world hagfishes. New data are presented for Myxine (Agnatha, Myxinidae) with circifrons from the eastern Pacific Ocean, M. limosa from the northwest­ descriptions of nine new species ern Atlantic Ocean, and M. a{finis and M. australis from inand neartheStraits ofMagellan. Myxine limosa is removed Robert L. Wisner from. the synonymy ofM. glutinosa. The Charmion B. McMillan nine new species occur as follows: M. hubbsi along the Pacific coastfrom San Marine Biology Research Division, 0202 Francisco, California, to Valparaiso, University of California, San Diego Chile; M. hubbsoides and M. pequenoi La Jolla, California 92093-0202 near Valdivia, Chile; M. mccoskeri and M. robinsi in the southern portion of the Caribbean Sea; M. fernholmi, M. knappi, and M. dorsum near the FalklandIslands, andM. debueni inthe Straits ofMagellan. Myxine mccoskeri and M. pequenoi are regarded as Hagfishes (slime eels) are cartilagi­ Myxine as are the extemal eyespots dwarfed, containingnearlymatureeggs nous, eel-like, abundant bottom­ commoningenusEptatretus (McMil­ ortestes attotallengtbs of230 and 175 dwelling scavengers occurring at lan and Wisner, 1984). Hermaphro­ mm, respectively. Hermaphroditism is depths ranging from a few to at ditism does not occur in our mate­ oftenfound in individuals ofM. hubbsi, M. limosa, and M. affinis. least 2,400 meters. Myxine is one of rial of M. circifrons but is not un­ the six recognized genera in the common inM. limosa, M. affinis, M. "agnathan" family Myxinidae (Nel­ australis, and M. hubbsi and occurs son, 1994). In the new world itcom­ in two ofthe three specimens ofM. prises eight species in the Atlantic hubbsoides. The reItlaining new Ocean and six in the Pacific (refer­ species have too few specimens to ences in this study); species occur­ state with certainty whether or not ring in the Straits ofMagellan also hermaphroditism occurs among may occur in either ocean. The ge­ them. Great variation in develop­ nus Myxine, which presently con­ mental stages ofeggs occurs among tains 19 species including those in specimens of the same length and this study, is characterized princi­ possibly age, which supports a pally by all the efferent gill pouch widely held belief that hagfishes ducts discharging into a single ap­ spawn throughoutthe year. As eggs erture on each side, the left being mature, the polar caps enlarge into confluent with the pharyngocutan­ dome-like structures containing eous duct. This character is shared anchorfilaments thatare connected by the genera Neomyxine Richard­ to the eggs when they are extruded. son, 1953, andNemamyxine Richard­ With one exception (a female M. son, 1958. Neomyxine is furtherchar­ limosa discussed below), eggs ofall acterized by having paired lateral specimens examined here were not finfolds \n the prebranchial region, fully mature; polarcaps were notvis­ as well as the usual ventral finfold ible, norwere they still encapsulated. posterior to the gill apertures. In This study of new world hag­ Nemamyxine, the body is extremely fishes, the latest by us in a series slender and the ventral finfold ex­ on the family Myxinidae begun by tends far forward nearly to the Carl L. Hubbs (deceased), includes anteriormost prebranchial slime all 14 known species ofMyxine from pores. In all othermyxinids the ven­ the Pacific and Atlantic coasts of tral finfold does not extend anterior North and SouthAmerica. We have to the pharyngocutaneous duct. added old world M. glutinosa to all Manuscript accepted 7 December 1994. Head grooves ("lateral lines" ofear­ tablesfor comparisonwiththeclosely Fishery Bulletin 93:530-550 (1995). lier authors) are lacking in genus related M. limosa. Ofthe other four 530 Wisner and McMillan: Review of new world hagfishes of the genus Myxine 531 known species, M. ios from the easternAtlantic andM. anteriormost pairs ofbarbels; head, from tip ofros­ capensis from South Africa are compared briefly with trum to a vertical from wrinkled tissue below the the new world species M. pequenoi. Both M. garmani, mouth;face, ventral aspectofhead; mou~the elon­ and M .. paucidens Regan, 1913 are known only from gate slit in face which opens to permit extrusion of Japan and are not closely related to any new world cusps for feeding (Fig. 2A); multicusp, a unit oftwo species. The number of new species (nine) from near or three cusps (teeth ofother authors), fused together the coasts only, suggests a need for further and more at bases (Fig. 2B); unicusp, a single unfused cusp intensive collecting throughout the world. (Fig. 2C); pores (slime pores), the small openings along the ventral aspect ofbody which emit mucus; gill aperture (GA), the opening through which wa­ Methods ter discharges to the exterior after passing through the gill pouches; PCD, the external opening of the Methods of counting and measuring generally fol­ pharyngocutaneous duct, always on the left side and low those of Fernholm and Hubbs (1981) and usually confluent with the left gill aperture inMyxine McMillan and Wisner (1984). All measurements are (or posteriormost GA inEptatretus); ventralfinfold in mm, and body proportions (Table 1) are in percent (VFF), a band ofthin, fleshy tissue extending along of total length. Features used in measuring and ventral midline of body between PCD and origin of counting are shown in Figures 1 and 2, and geo­ cloaca (Fig. 1); cloaca, the slit-like ventral opening graphic distribution in Figure 3. Counts of slime anterior to tail throughwhich body wastes and sexual pores (Tables 2-5) and unicusps (Table 6) represent products discharge; and caudal finfold (CFF), the the left side only because we have found no signifi­ band ofthin fleshy tissue extending around tail, end­ cant differences between the left and right sides. ing dorsally about over origin ofcloaca (Fig. 1). Occasionally one extra gill pouch occurs, usually on Colors are determined after scraping away the one side only and much smaller than normal; one coating ofcoagulated slime (mucus). Although given less pouch rarely occurs on either side. The one to in the descriptions, color is subjective and may three slime pores which may occur over the change greatly with preservation; therefore~ the use pharyngocutaneous duct are included in the ofcounts is preferred as a more distinguishing char­ prebranchial pore count. In all species ofMyxine only acter; Because eggs are similarin all species, we have two fused cusps (a multicusp) occur on the posterior not used them as a species character. They vary setofcusps (inner row ofFernholm and Hubbs, 1981) widely in length and diameter and in developmental in contrast to either two or three on the anterior set. stages, rangingfrom tiny to nearlymature in females This latter characteris used to group species (Tables of the same length. Accurate measurement ofdiam­ 1-7). Some terms have appeared previously in eter is hindered in eggs deformed because ofcrowd­ myxinid accounts without clear definition. We offer ing in life or during preservation; many are some­ precise definition ofthese and some new terms used what flattened and diameters may vary as much as in this study: rostrum, rounded to pointed, fleshy 1.5 mm in the same specimen. We have not provided extension lying over the nasal orifice between the photographs or drawings ofindividual species since ~ --~ ~ ~ -_.- -_ .. -• • r, ~.... I ~I c:c;;::;;; II ,• I I E F G A B ·c 0 ----t .,.. - a ~ Figure 1 Sketch of a Myxine showing features used in measuring and counting: A-G = total length ITLI; A-B = prebranchiallength; C = opening of the pharyngocutaneous duct (PCD); D = ventral finfold IVFFI, D"= enlarged portion of VFF with dashed line indicating the ap­ proximate difference between a well and a weakly developed VFF; E = origin of cloaca; E-G = tail length; F = caudal finfold (CFFI. The many slime pores along the sides are indicated by a few small circles near PCD and cloaca. 532 Fishery Bulletin 93(3), 1995 there are no distinguishing external features other these materials were obtained follows the Acknowl­ than those characters given in the key. A list of the edgment section. Institutional abbreviations are materials examined and of the collections where listed as in Leviton, et a1. (1985). Key to new world hagfishes (Genus MyxineJ la A 3-cusp multicusp on anterior set, a 2-cusp multicusp on posterior set ofcusps ................ .. 2 Ib A 2-cusp multicusp on both the anterior and posterior sets ofcusps 6 2a Gill pouches 6, rarely 7............................................................... .. 3 2b Gill pouches 5. ...................................................................... .. 4 3a VFF well developed, 3-7 mm high, mounted on thick triangular base extending from the ventral surface; last few prebranchial pores in an uneven line, resembling the letter W; total pores 112-121 ....................................................... .. M. (ern.holmi 3b VFF vestigial, not mounted on triangular fleshy base; last few prebranchial pores in a straight line; total pores 103- 104 M. debueni 4a Anterior unicusps 6-9; total cusps 36-48; total pores 77-92; color light brown, often lighter dorsally than ventrally .............................................. .. M. mccoskeri 4b Anterior unicusps more than 9 each side. ................................................ .. 5 5a Anterior unicusps 11-13; total cusps 56-58; total pores 92-100; VFF usually low (3-6 mm); head and barbels pale M. robinsi 5b Anterior unicusps 7-13; total cusps 43-56; total pores 80-102; VFF usually prominent, averaging 5 mm (1-12 mm); head and barbels usually pale M. circifrons 6a Gill pouches 7; anterior unicusps 4; posterior unicusps 5-6; total cusps 26-28 M. pequenoi 6b Gill pouches 6, rarely 7.. .............................................................. .. 7 7a CFF extending forward dorsally 2-3 times tail length; total pores 108-109; VFF low, (3-5 mm) ................................................................. .. M. dorsum 7b CFF not extending forward dorsally much beyond a vertical above cloacal origin ...
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