Special Publication J.L.B. Smith Institute of Ichthyology ISSN: 0075-2088 Num. 61, 1998, pp. 1-8

STUDIES ON THE \par ZOARCIDAE (TELEOSTEI: PERCIFORMES) OF \par THE SOUTHERN HEMISPHERE. VIII. A NEW SPECIES OF THE \par GENUS DIEIDOLYCUS FROM TIERRA DEL \par FUEGO

by \par

M. Eric Anderson

J.L.B. Smith Institute of Ichthyology, Grahamstown 6140, South \par Africa

and

German Pequeno R.

Instituto de Zoologia, Universidad Austral de Chile, Casilla 567, \par Valdivia, Chile

\par Code Number:FS98002
\par Sizes of Files:
\par       Text: 13K
\par       Graphics: Line drawings (gif) - 7K \par

\par

ABSTRACT

A new lower-slope eelpout of the genus Dieidolycus Anderson, 1988 \par (Family Zoarcidae, \par Subfamily Lycodinae), is described from a single juvenile female trawled in 2008-2165 m off \par Tierra del Fuego, Chile. It differs from congeners D. leptodermatus Anderson, \par 1988 and \plain\f3\fs20 \plain\f2\fs20 D. \par adocetus Anderson, 1994 by its head pore pattern, 10 caudal-fin rays, 18 pectoral-fin \par rays and \par longer gill slit.

INTRODUCTION

Gosztonyi (1977) and Anderson and Gosztonyi (1991) reviewed the eelpouts of the \par cold-temperate Magellan Province (sensu Briggs, 1974) of South America. Only two species \par are \par thought to be present in lower continental slope waters there. Lycodonus malvinensis \par has been \par taken to depths of 2044 m (Anderson and Gosztonyi, 1991). Lycenchelys antarctica, \par although \par never captured within the Magellan Province, is known from Antarctic waters and the \par northern \par Peru-Chile Trench in depths of 1976-5320 m (Anderson, 1988a). We consider the distribution \par of L. antarctica to be continuous through Chilean waters and possibly also \par southern Argentina. \par Anderson (1988a) recorded five zoarcid species (Melanostigma bathium, M. \par gelatinosum, \par Lycenchelys antarctica, Lycodapus antarcticus and L. pachysoma) found in both the \par South \par American and Antarctic regions. These deeper-dwelling species compromise the fidelity of \par Briggs' \par (1974) Magellan Province, thus its reference should be confined to shelf/upper slope faunas \par only.

In May 1996 the German research vessel POLARSTERN captured two eelpouts while \par trawling \par east of the entrance to the Beagle Channel, Tierra del Fuego, in Chilean territorial waters. \par These \par specimens were subsequently sent to the authors for identification. One is the rare \par Lycenchelys \par bachmanni Gosztonyi, 1977, and represents a range and depth extension for the species \par (to \par southern Chile in 107 m; see Anderson and Gosztonyi, 1991: 7). The other is a new lower \par slope \par species for southern South America and the third species to be assigned to the genus \par Dieidolycus \par Anderson, 1988.

METHODS

Measurements were made with dial calipers to the nearest 0.1 mm. Definitions of \par characters and \par their reporting follow those established by Gosztonyi (1977) and Anderson (1982), repeated in \par earlier parts of this series (e.g., Anderson, 1988a, b). The abbreviation MNHNC is: Museo \par Nacional de Historia Natural, Santiago, Chile. Other abbreviations are: A, anal-fin rays; C, \par caudal-fin rays; D, dorsal-fin rays; P, pectoral-fin rays; V, pelvic-fin rays; GR, gill-rakers; HL, \par head length; SL, standard length.

Dieidolycus gosztonyii \par sp. nov.

\par

\par Figure 1. \par Dieidolycus gosztonyi sp. n., holotype, MNHNC 7089, 65 mm SL, off Tierra del \par Fuego, Chile.

\par

Holotype: MNHNC 7089, 65 mm SL, female, off Isla Nueva, Chile, \par 5531.6'S, 65 56.8'W to \par 5530.7'S, 6558.8'W, depth 2165-2008 m, FFS POLARSTERN, \par Sta. 40/114, cruise ANT XIII/4, \par 0458-0529 hrs, 18 May 1996.

DIAGNOSIS: A species of Dieidolycus as defined by Anderson (1988a), \par with emendation (see \par REMARKS), with vertebrae 23 + 55; C 10; P 18; gill-slit extending ventrally to opposite \par lower \par margin of pectoral base; suborbital pores 7; occipital pores 3; interorbital pore present; first \par dorsal-fin pterygiophore associated with vertebra 3.

DESCRIPTION: Vertebrae 23 + 55 = 78; D 73; A 57; C 10; P 18; V 2; GR 2 + 7; pyloric \par caeca \par 2; branchiostegal rays 6; vomerine teeth 6; palatine teeth 5-6; pseudobranch absent. \par Measurements \par in percent SL: head length 24; head width 10; head depth 9; predorsal length 25; preanal \par length \par 47; pectoral-fin length 13; body height 7. Measurements in percent HL: head width 41; head \par depth \par 38; upper jaw length 47; snout length 30; eye diameter 21; gill slit length 30; pectoral-fin \par length \par 55; pectoral-base height 24; interorbital width 8; interpupillary width 23; pelvic-fin length 18; \par caudal-fin length 26. Pectoral base/length ratio 43.

Head ovoid, dorsal and ventral profiles parallel behind eyes; snout broad and gently \par inclined \par before eyes. Eye moderately large, rounded, orbit large, ovoid. Single pair of tubular nostrils at \par snout tip, slightly overlapping upper lip when pressed forward. Pectoral fin origin at body \par midline, \par insertion on abdomen. Gill slit extending ventrally to opposite lowermost pectoral-fin ray, slit \par posterodorsally oblique above that, then canted gently anterodorsal from its posteriormost \par corner; \par no fleshy siphonal fold. Body short, ovoid in cross section. Tall gently tapering posteriad both \par laterally and dorsoventrally. Flesh gelatinous around head and abdomen.

Mouth moderately large, terminal. Upper jaw extending to vertical through middle of eye. \par Teeth \par in palate small, barely erupted, blunt. Vomerine teeth in small patch. Palatine teeth in single \par series, \par full complement not present. Anterior jaw teeth largest, in two rows in premaxilla, in four rows \par in dentary; single row in both jaws posteriorly.

Unpaired fins low, anteriormost dorsal and anal-fin rays longest, rays becoming shorter \par posteriad. \par First dorsal-fin pterygiophore associated with third vertebra; last dorsal ray associated with \par fourth \par preural vertebra. No free dorsal-fin pterygiophores. First three anal-fin pterygiophores anterior \par to haemal spine of first caudal vertebra; last anal ray associated with third preural vertebra. \par Caudal \par fin with one epural, four upper hypural and five lower hypural rays. Pectoral fin large, middle \par rays \par longest; lowermost 6-7 rays very slightly thickened, with tips exserted. Pelvic fins about one \par eye \par diameter in length, of two rays each (no spine rudiment). All fin elements segmented soft rays \par except first flexible spine of dorsal fin.

Cephalic lateralis pores enlarged, anteriormost ovoid, dorsoposteriormost rounded. \par Occipital \par pores three. Interorbital pore present. Two pairs of nasal pores (anterior supraorbitals), one \par anteromesial to nasal tube, the other posteromesial. Eight preoperculomandibular pores, four \par emanating from dentary, one from anguloarticular, and three from preopercle. Six suborbital \par pores \par emanating from ventral branch of bone chain and one from ascending ramus behind eye. Three \par postorbital pores ( 1, 3 and 4) on both sides of head. Lateral line mediolateral, not bowed on \par body. Scattered superficial neuromasts on body and head.

Gill rakers minute, blunt, only nine developed in this juvenile. Branchiostegal rays six, four \par articulating with ceratohyal and two with epihyal. Oral valve well developed, reaching anterior \par edge of vomer. No pseudobranch or scales. Pyloric caeca two, greatly reduced.

Color of body uniformly dark brown, head black. Head pores and anus ringed in white. \par Eye and \par coelomic area of abdomen dark blue. All fin membranes dusky but transparent. Lining of \par orobranchial chamber black.

DISTRIBUTION: Known only from lower slope waters east of the southern tip of Tierra \par del \par Fuego. Probably found throughout the Magellan Province and possibly Scotia Sea at lower \par slope \par depths.

ETYMOLOGY: Named in honour of our friend and colleague Dr. Atila Esteban \par Gosztonyi, \par Centro Nacional Patagonico, Puerto Madryn, Argentina, for his contributions to temperate \par South \par American ichthyology, especially his pioneering work on the Zoarcidae.

REMARKS: Anderson (1988a) partially diagnosed Dieidolycus on the basis \par of an absence of a \par lateral line. This was occasioned by observations on the original three very faded types \par (D. \par leptodermatus). A second species, D. adocetus, was based on two \par damaged juveniles in which \par presence or absence of the lateral line (and head pores) could not be verified, as they were \par completely skinned (Anderson, 1994). There is presently some doubt as to the correct generic \par placement of D. adocetus, but that is beyond the scope of the present paper. On \par the basis of D. \par gosztonyii and additional material of D. leptodermatus (see below), the \par diagnosis of the genus is \par here emended to include a single mediolateral lateral line, pending examination of undamaged \par D. \par adocetus. In D. gosztonyii and some D. leptodermatus \par recently observed, often scattered \par superficial neuromasts not forming a defined line run along the bases of the unpaired fins, or \par are \par seen on the body near the lateral line. The new specimens of D. leptodermatus \par and other \par unpublished records of Antarctic zoarcids will be described elsewhere by the senior \par author.

COMPARATIVE MATERIAL: Dieidolycus leptodermatus: USNM uncat. \par (5; 87-170 mm SL); \par South Sandwich Isls.; 5704'S, 26 10. 1'W; 10 ft Blake trawl, \par 2744-2745 m; 22 May 1975; H.H. \par DeWitt, collector.

ACKNOWLEDGEMENTS

For loan of specimens and assistance with data we thank Roberto Melendez, Museu \par Nacional de \par Historia Natural, Santiago, Chile; Jane DeWitt, Orono, Maine, USA; Wolf Arntz, Alfred \par Wegener \par Institute for Marine and Polar Research, Bremerhaven, Germany. Elaine Heemstra, J.L.B. \par Smith \par Institute of Ichthyology rendered the fine illustration.

LITERATURE CITED

ANDERSON, M.E. 1982. Review of the fish genera Gymnelus Reinhardt \par and Gymnelopsis \par Soldatov (Zoarcidae), with two new species and comparative osteology of Gymnelus \par viridis. Natl. \par Mus. Canada, Publ. Zool. 17: 1-76.

-- 1988a. Studies on the Zoarcidae (Teleostei: Perciformes) of \par the southern hemisphere. I. The Antarctic and subantarctic regions. Antarct. Res. Set. \par 47:59-113.

-- 1988b. Studies on the Zoarcidae (Teleostei: Percifonnes) of \par the southern hemisphere. II. Two \par new genera and a new species from temperate South America. Proc. Calif. Acad. ScL \par 45(11): \par 267-276.

-- 1994. Studies on the Zoarcidae (Teleostei: Perciformes) of the southern hemisphere. \par VII. A \par new species of Dieidolycus Anderson, 1988 from the Bismarck Sea. Recs. \par Austral. Mus. 46: \par 121-124.

ANDERSON, M.E. & A.E. GOSZTONYI. 1991. Studies on the Zoarcidae \par (Teleostei: \par Perciformes) of the southern hemisphere. IV. New records and a new species from the \par Magellan \par Province of South America. J. LB. Smith Inst. Ichthyol. Ichthyol. Bull. 55: 1-16. \par BRIGGS, J.C. \par 1974. Marine Zoogeography. McGraw-Hill Book Co., New York, 475 pp.

GOSZTONYI, A.E. 1977. Results of the research cruises of FRV "Walther Herwig" to South America. XLVIII. Revision of the South American Zoarcidae (Osteichthyes, \par Blennioidei) \par with the description of three new genera and five new species. Arch. Fisch Wiss. \par 27(3): 191-249.

Copyright 1998 J.L.B. Smith Institute of Ichthyology \par \par \par \par }

The following images related to this document are available:

Line drawing images