Ophthalmolycus andersoni, Matallanas, Jesús, 2009

Matallanas, Jesús, 2009, Description of Ophthalmolycus andersoni sp. nov. (Pisces, Zoarcidae) from the Antarctic Ocean, Zootaxa 2027, pp. 55-62 : 56-58

Ophthalmolycus andersoni sp. nov.

( Figs. 1 –2; Table 1)

Holotype. UAB:B03BSZ 25, 263 mm SL male, Paradise Bay, Antarctic Peninsula, cruise BENTART-03, R/V “Hespérides” stn 22A, 64º 50’ 37’’S, 62º 58’ 09’’W, collected with an Agassiz trawl at 286 m depth, 24 February 2003.

Paratypes. UAB:B03BSZ 9, 255 mm SL male, same collection data as holotype; and UAB:B03BSZ 99, 212 mm SL female, same collection data as holotype.

Diagnosis. A species of Ophthalmolycus as defined by Anderson (1992, 1994) with the following combination of characters: 6 branchiostegal rays; pectoral fin origin well below midbody, pectoral base extending ventrally to abdomen; lateral line double with ventral and medio-lateral branches; oral valve not reaching anterior edge of vomer; gill slit extending ventrally well below ventral end of pectoral fin base; vertebrae asymmetrical 22+70–74=92–96; dorsal fin origin associated with vertebrae 4 or 5 with no supraneurals; pectoral fin rays 16 or 17; postorbital pores two (positions one and four); 2 well developed pyloric caeca and 0–3 pseudobranch filaments.

Description. Body laterally compressed and relatively short; tail laterally compressed, especially posteriorly ( Fig. 1 ). Head nearly triangular in cross section; eye ellipsoid, not entering dorsal profile of head. Scales small, sparse, present only on tail and un-paried fin bases. Gill slit extending ventrally well below lower edge of pectoral fin base ( Fig. 1 c). Triangular opercular flap at upper end of gill slit. Pectoral-fin origin well below midbody, pectoral-fin base with its lower end on abdomen, pectoral-fin margin rounded; ventralmost 5–7 rays thickened, tips exserted ( Fig. 1 c).

Upper jaw protruding, end of maxilla extending to posterior margin of eye; upper jaw length apparently dimorphic, longer in the two males than in the female. Head wider in the adult male (holotype) than in paratypes (immature male and female). Mouth inferior; lower lip with a small lobe. Nasal tube long, unpigmented, overhanging upper lip. Oral valve not reaching anterior margin of vomer. Teeth in jaws, vomer and palate conical. Upper jaw with 2 or 3 rows anteriorly merging into single posterior row; lower jaw with 3 rows of teeth anteriorly and single row posteriorly. Vomerine teeth in a patch. A single row of palatine teeth. Two well-developed pyloric caeca present, their length about 66 % of eye diameter. Gill rakers 3+ 8–9, triangular. Pseudobranch filaments 0–3.

Cephalic lateralis pore system with pores enlarged except the seventh and eighth preoperculomandibular, and the two postorbital pores ( Figs. 1 a & b). Two nasal pore, first pore located anteromesial to nasal tube, the other dorsoposterior to it. Two postorbital pores (positions 1 and 4). Six suborbital pores all on the ventral ramus. Eight preoperculomandibular pores. Interorbital and occipital pores absent. Body lateral line configuration with 2 rows of neuromasts ( Fig. 1 a): lower lateral-line beginning just behind the fourth postorbital pore, steeply sloping above pectoral fin and extending ventrolaterally to the end of the tail; middle lateral line, originated behind the anal-fin origin and coursing to tail tip.

Suspensorium and preopercle of Ophthalmolycus andersoni , paratype (UAB:B03BSZ99); external view of the right side: EC, ectopterygoid; HY, hyomandibula; MS, mesopterygoid; MT, metapterygoid; PAL, palatine; QD, quadrate; SY, symplectic; 5–8, preopercular pores.

Palatopterygoid series well developed, with ectopterygoid broadly articulating with quadrate and mesopterygoid overlapping half or more dorsal margin of quadrate (Fig. 2). Metapterygoid large, thickened. Posterior ramus of hyomandibula not elongate. Hyoid bar with ceratohyal-epyhial juncture smooth. Six branchiostegal rays articulating with the hyoid arch according to the pattern of 2 on the epihyal and 4 on the ceratohyal.

Vertebrae asymmetrical, 22+70–74. Last precaudal vertebra associated with dorsal fin rays 18 or 19. First dorsal fin pterygiophore associated with vertebra 4 or 5, with no free supraneurals. Terminal dorsal-fin ray associated with second preural vertebra. Anal-fin origin associated with first caudal vertebra, with 2 preanal pterygiophores and 2 anal fin rays. Second caudal vertebra with 2 pterygiophores and 2 anal fin rays. Terminal anal-fin ray associated with second preural vertebra. One epural. First pleural centrum, ural centrum, parhypural and hypurals fused into one element. Caudal fin rays 10 or 11, with 2 epural, 4 upper hypural and 4 or 5 lower hypural rays.

Color in alcohol light brown not uniform; vertical fins greyish; belly, pelvic and pectoral fins ashcoloured; contour of pectoral fin dark; lips, nasal tube and cephalic pores light; lining of mouth dark grey; branchial chamber and peritoneum black.

Counts and proportions. Holotype first, followed in parentheses by range of paratypes. Vertebrae 22+74=96 (22+70–73=92–95); dorsal-fin rays 91 (87–91); anal-fin rays 77 (72–74); caudal-fin rays 10 (10 or 11); pectoral-fin rays 17 (16); pelvic-fin rays 3 (3); gill rakers 3+9 (3+8–9); pseudobranch filaments 0 (2–3). Following proportions as percent SL: head length 22.1 (20.1–22.7); head width 11.7 (8.7–9.1); head depth 10.0 (9.2–9.9); pectoral-fin length 11.4 (9.9–10.4); predorsal length 24.3 (20.7–25.1); preanal length 41.8 (40.5–43.3); body depth 8.7 (7.6–8.3); gill slit length 7.9 (7.5–8.2); isthmus width 3.2 (2.7–3.1); dorsal-fin height above anal-fin origin 3.8 (3.4–3.8). Following proportions as percent HL: head width 53.0 (43.1–43.6); head depth 45.5 (43.6–46.0); upper jaw length 51.5 (34.7–48.4); pectoral-fin length 51.5 (45.9–49.3); pelvicfin length 11.5 (10.2–12.9); caudal-fin length 37.1 (29.8–35.2); snout length 27.4 (26.6–27.4); eye diameter 14.4 (13.4–15.4); nostril tube length 10.8 (9.2–10.4); gill slit length 35.7 (36.1–37.3); interorobital width 6.0 (5.1–5.6); pectoral base/length ratio 44.3 (42.3–46.3).

Etymology. The new species is named after Dr. M. Eric Anderson, in honour of his many contributions to knowledge of zoarcids.

Figures

FIGURE 1. Ophthalmolycus andersoni sp. nov., holotype (UAB: B 03 BSZ 25). a: left lateral view; b: left lateral view of head showing pore pattern; c: ventral view showing insertion of pectoral and pelvic fins, and ventral extension of gill slit. Scale bars = 10 mm. Drawing: J. Corbera.