View data on Catalog of Fishes here.
Body moderately elongate; eyes tubular, directed dorsally; mouth small; premaxillary teeth uniserial, dentary teeth biserial anteriorly; gillrakers on first arch 20–25, very short; branchiostegal rays 10, 4 on epihyal. Dorsal finrays 11–12, followed by a dorsal adipose fin long based, over entire anal fin; pectoral finrays 8; pelvic finrays (6) 7, its base behind dorsal fin origin; anal finrays 15–17, its origin well behind end of dorsal fin base; anal fin base about equal to or slightly shorter than dorsal fin base; last dorsal and anal finrays split to base; small pre-anal ventral adipose fin present. Vertebrae 40–42. Photophores (adult): ORB 2; BR 11 (12); OP 3; IV 25 (24–26); VAV + AC 21–24; OA 24–25 (23-26).
Colour: back dark, scale pockets edged dark, finrays speckled basally; flanks silvery-translucent, peritoneum silvery.
For a key to photophore terminology, click here.
Ichthyococcus ovatus is reliably distinguished from other species of the genus by the lack of the SO photophore, very narrow interorbital distance and low values of some meristic characters.
Widely distributed through subtropical and tropical seas worldwide.
Pre-metamorphic post-larvae in upper 150 m; metamorphic postlarvae in the mesopelagic at 400–750 m; juveniles and adults centred in 200–500 m; no diel vertical migrations.
Mukhacheva V. 1980. A review of the genus Ichthyococcus Bonaparte (Photichthyidae). Voprosy Ikhtiologii 20(6):771–786.
The following description from Mukhacheva (1980) applies to all species of Ichthyococcus.
Eye large, telescopic, directed obliquely or dorsally. Interorbital distance less than snout length and eye diameter, thin supraorbital crest above each orbit. Snout short, blunt. Mouth small, straight or slightly oblique; anterior part of lower jaw contained in upper jaw with mouth closed. Teeth on both jaws very small, closely set, of uniform size, in a single row. Vomer lacking teeth, or with few, barely perceptible teeth; palatine, pterygoid and tongue lacking teeth. Gill rakers short, smooth, 19–37 on first arch. Pseudobranchia absent. Body covered with large deciduous scales. Origin of dorsal fin equidistant from end of snout and base of caudal fin or nearer former. Origin of anal fin far beyond vertical through end of dorsal fin. Origin of dorsal adipose fin on vertical through anus. Bases of pelvic fins above middle of dorsal fin. Ventral adipose fin small or absent. Anus immediately in front of anal fin.
Dorsal-fin rays 10–16; Anal-fin rays 12–17; Pectoral-fin rays 7–8; V 6–8; lateral line scales 32–44; vertebrae 38–42 . Photophores. SO 0-1, ORB 2, in front of eyes and beneath center of orbit: OP 3, upper on same level as center of eye or slightly higher, lower anterior approximately on same level as end of maxillary, lower posterior behind it, nearer margin of operculum, BR 11-13. Body with 2 rows of photophores: IV 23-28, 1–7 in straight row, 8th displaced upward and outward, others in straight row, or partly on broken line from 8th to 14th, others in straight row; VAV 9–16; AC 11–15, in unbroken row or with hiatus above last few anal-fin rays. OA 23–34, not reaching anal fin.
Badcock J. 1984. Photichthyidae. pp. 318–324. In: P.J.P. Whitehead MLB, J.-C. Hureau, J. Nielsen, and E. Tortonese editor. Fishes of the Northeastern Atlantic and the Mediterranean. Paris: UNESCO. p 1473 pp.
Mukhacheva V. 1980. A review of the genus Ichthyococcus Bonaparte (Photichthyidae). Voprosy Ikhtiologii 20(6):771–786.
To about 50 mm SL.
Messina, Sicily, Italy, Mediterranean Sea.
No types known.
Ichthyococcus ovatus is a lightfish of the genus Ichthyococcus.[1]
Ichthyococcus ovatus is a lightfish of the genus Ichthyococcus.
