Leucogrammolycus brychios, Mincarone, Michael Maia & Anderson, Eric, 2008

Mincarone, Michael Maia & Anderson, Eric, 2008, A new genus and species of eelpout (Teleostei: Zoarcidae) from Brazil, Zootaxa 1852, pp. 65-68 : 66-68

Leucogrammolycus brychios sp. nov.

White-line eelpout

( Figs. 1 and 2 )

“Espécie indeterminada 1” [unidentified species 1]. — Bernardes et al., 2005: 242 [five specimens, 197–217 mm, off Cabo de Santa

Marta, 490 m].

Holotype: MOVI 39080, male, 198 mm SL, off southeastern Brazil, 23°53.137'S, 42°31.271'W, crab trap, 615 m, FV Royalist, 14:10 h, 12 July 2006.

Paratypes: MOVI 39079, male, 189 mm SL, same collection as holotype. MOVI 39081, male, 172 mm SL and MOVI 39082, female, 167 mm SL, 23°53.553'S, 42°40.910'W, crab trap, 541 m, FV Royalist, 14:50 h, 17 July 2006. MOVI 39083, female, 192 mm SL, MOVI 39085, male, 194 mm SL, and RUSI 80187, female, 205 mm SL, 23°55.522'S, 42°41.257'W, crab trap, 569 m, FV Royalist, 14:45 h, 18 July 2006. MOVI 38816, female, 99 mm SL and MOVI 38817, male, 92 mm SL, 21°48.380'S, 40°01.879'W to 21°47.876'S, 40°04.113'W, GOV demersal trawl, 617–632 m, RV Thalassa , 20:56 h, 22 June 1999.

Diagnosis. As for the genus.

Counts and proportions. Holotype followed parenthetically by the range of the paratypes. Vertebrae 24 + 65 = 89 (23–26 + 62–66 = 85–92); dorsal-fin rays 85 (81–86); anal-fin rays 64 (62–67); caudal-fin rays 9 (9); pectoral-fin rays 17 (16–18); pelvic-fin rays 2 (2); vomerine teeth 11 (6–10); palatine teeth (left/right) 8/7 (6–12/6–12); gill rakers 2 + 14 = 16 (1–3 + 13–14 = 14–17); branchiostegal rays 6 (6); pseudobranchial filaments 5 (4–7). Following proportions as percent SL: head length 19.5 (20.0–23.0); head width 11.4 (7.9–11.5); head depth 11.7 (10.3–13.3); pectoral-fin length 12.3 (11.5–12.8); predorsal length 21.5 (21.2–24.3); preanal length 47.2 (47.5–51.7); body depth 12.8 (10.3–13.0); gill slit length 6.1 (5.6–7.8). Following proportions as percent HL: head width 58.3 (38.3–54.9); head depth 60.1 (49.5–62.8); upper jaw length 57.5 (49.8–57.0); pectoral-fin length 63.2 (52.2–60.7); snout length 21.5 (18.8–28.6); eye diameter 14.8 (6 adults: 12.8–17.0; 2 juveniles: 20.6–21.0); gill slit length 31.1 (26.8–37.0); interorbital width 9.8 (6.8–9.0); interpupillary width 31.1 (25.6–32.2); pelvic-fin length 9.7 (6.1–11.5); caudal-fin length 31.1 (26.6–39.2); pectoral base/length ratio 41.8 (34.5–44.2).

Description. Nine specimens: three adult males, a juvenile male, four adult females and a juvenile female. Head ovoid, deeper across nape in adults than juveniles. No sexual dimorphism of head width detected. Scales and epidermal prickles absent. Eye rounded, not entering dorsal profile of head. Gill slit extending ventrally to opposite second to fourth from lowermost pectoral-fin ray. Gill slit posterodorsally inclined, no opercular flap at upper end. Pectoral-fin origin well below body midline, insertion on abdomen; posterior margin of fin rounded, ventralmost rays slightly exserted, lowermost 5–6 rays slightly thickened.

Mouth subterminal in juveniles, inferior in adults. Upper jaw extending to middle of eye or slightly beyond it. Upper lip broadly adnate to snout tip and coalesced with thickened flesh of cheek, lower lip lobe weak. Nasal tube short, not reaching upper lip when pressed forward. Oral valve weak, not reaching anterior edge of vomer and coalesced with lateral margin of palate before posterior corner of rictus. Jaw teeth small, conical, premaxillae with 2–3 irregular rows of teeth anteriorly, blending into single posterior row; dentaries with 3–5 irregular tooth rows anteriorly, blending into single posterior row. No sexual dimorphism in dentition detected. Vomerine teeth in ovoid patch in adults; palatine teeth in single row.

Cephalic lateralis pores minute, rounded. Two postorbital pores arising from frontal (position 1) and lateral extrascapular (position 4). Two pairs of anterior supraorbital (nasal) pores, one set anteromesial to nasal tube, the other dorsolaterally. Six suborbital pores, all arising from ventral ramus of bone chain below eye. Eight preoperculomandibular pores, four arising from dentary, one from anguloarticular and three from preopercle. Interorbital and occipital pores absent. Body lateral line of superficial neuromasts, with two branches; ventral branch originating about one-third to onefourth pectoral-fin length anterior to pectoral-fin margin, mediolateral branch originating just behind posteriormost postorbital pore; both branches extend to tail tip or very near it. Rows of few neuromasts across snout tip and around nasal tube.

Dorsal-fin origin just behind a vertical through pectoral-fin base, difficult to discern through thickened flesh there, associated with vertebrae 3–4, usually 4, with no free supraneurals. Anal-fin origin associated with second caudal vertebra (except with first caudal vertebra of MOVI 39082). Pterygiophore of last dorsal-fin ray associated with third preural vertebra; pterygiophore of last anal-fin ray associated with second preural vertebra. Caudal fin with one epural, four upper and four lower hypural rays.

One to three short, acute gill rakers on upper limb of first arch, rakers on lower limb also short and acute, all about the same length. Pseudobranchial filaments relatively long. Pyloric caeca one-half to three-fourths eye diameter in length. Female specimen MOVI 39082 with ripe ova averaging 4.6 mm in diameter.

Coloration. Fresh coloration generally chocolate brown except abdomen grayish blue; underside of head and sometimes ventral parts of tail grayish; pectoral fin almost transparent (pale in preserved specimens) with distal margin dark; dorsal, anal and caudal fins black; eye blue; outer edge of gill slit whitish; a variably continuous or interrupted white mid-body stripe forming a chevron on top of snout ( Figs. 1 and 2 ).

Distribution. Upper bathyal zone (490–632 m) off southeastern and southern Brazil ( Fig. 3 ).

Etymology. From the Greek (from the depths [of the sea]).

Discussion. On the basis of its restricted gill slit, two pelvic-fin rays, weak oral valve, lack of scales and submental crests on the dentary and six branchiostegal rays, the new genus keys to Dieidolycus Anderson, 1988 in Anderson (1994a). Dieidolycus , a rare, lower bathyal genus (1957–3040 m) is known from only 12 specimens representing three Southern Ocean species ( Anderson, 1988, 1994b, 2006, Anderson and Pequeño, 1998). Leucogrammolycus differs markedly from Dieidolycus chiefly in its firm flesh with head and body striping (vs. gelatinous, unpigmented flesh in Dieidolycus ), its minute head pores (vs. enlarged pores in Dieidolycus ), its adnate upper lip (vs. free lip in Dieidolycus ), its double lateral line (vs. single lateral line in Dieidolycus ), its greater number of vertebrae (85–92 in Leucogrammolycus vs. 78–81 in Dieidolycus ), the first anal-fin pterygiophore associating with the first or second caudal vertebrae (vs. associating with the last precaudal vertebra in Dieidolycus ), and the presence of a pseudobranch (absent in Dieidolycus ).

Figures

FIGURE 1. Leucogrammolycus brychios. Holotype, MOVI 39080, male, 198 mm SL.

FIGURE 2. Dorsal view of head of Leucogrammolycus brychios, showing the white stripe in its chevron pattern. Holotype, MOVI 39080, male, 198 mm SL.

FIGURE 3. Distribution of Leucogrammolycus brychios. () type locality; () paratypes; () specimens listed by Bernardes et al. (2005: 242).