Eustomias orientalis Gibbs, Clarke & Gomon 1983

View data on Catalog of Fishes here.

Based on 2 specimens, 78 and 118 mm; proportions listed for small specimen followed by large specimen. In percent of SL: barbel length 50–53; filament length 4.2–5.3; proximal bulb 0.8–1.3; distal bulb 1.4–0.9; distance between bulbs 0.8–0.6. In percent of proximal bulb: distal bulb 183–73; distance between bulbs 100–47. In percent of distal bulb: distance between bulbs 55–64.

The stem axis is well pigmented proximally, becoming lighter or unpigmented distally. The axis between the bulbs and in the filament is unpigmented. The external chevron-shaped or roundish striated areas on the stem are unpigmented. The proximal bulb is ovoid, the distal spheroidal in both specimens. Tiny bulblets were present in the proximal part of the filament in the smaller specimen, but were not discerned in the larger.

No large males were available to Gibbs et al (1983) for measurement of the postorbital organ.

Two terminal bulbs separated by a very short interspace (0.6%–0.7% SL, 0.5–0.6 of distal-bulb length. Barbel 50%–53% SL. Terminal filament short, 4. l%–5.3% SL, without branches. Distal bulb 1.8 times length of proximal bulb in the small specimen, 0.7 in the larger specimen. Proximal bulb in larger specimen large for its size, 1.5 mm (1.3% SL) at 118 mm SL. Barbel without pigment in smaller specimen; larger specimen with fairly dense pigment in proximal part of axis, little or none in distal part. External chevron–shaped or roundish striated areas on stem not pigmented. Middorsal paired spots between occiput and dorsal-fin origin 8.

Known only from the westernmost Pacific from north of New Guinea to Suruga bay, Japan.

Gibbs RH, Jr, Clarke TA, Gomon JR. 1983. Taxonomy and distribution of the stomioid fish genus Eustomias (Melanostomiidae), I: Subgenus Nominostomias. Smithsonian Contributions to Zoology 380:1–139.

To at least 118 mm SL.

Northwestern Pacific, 25°13'N, 128°32'W, depth 0-100 meters.

Holotype: IOM uncat.

Two terminal bulbs separated by a very short interspace (0.5-0.6 times length of distal bulb). Barbel 50-53% SL. Terminal filament short, 4.1-5.3% SL without branches. Distal bulb 1.8 times length of proximal bulb in small specimens, 0.7 in larger ones. Proximal bulb in larger specimens large for its size, 1.5 mm at 118 mm SL. Barbel without pigment in smaller specimens; larger ones with fairly dense pigment in proximal part of axis, little or none in distal part. External chevron-shaped or roundish striated area on stem not pigmented. Middorsal paired spots between occiput and dorsal-fin origin 8 (Ref. 11333).

Dorsal soft rays (total): 24; Analsoft rays: 36; Vertebrae: 68

Mesopelagic species (Ref. 559).

Eustomias orientalis

Eustomias bibulbosus.—Imai, 1957:559 [2 specimens from Suruga Bay, Japan; barbels fig. 9; not examined by us].—Parin et al., 1977:101, 102 [part; Vityaz sta 7171, examined by us].

DIAGNOSIS.—Two terminal bulbs separated by a very short interspace (0.6%–0.7% SL, 0.5–0.6 of distal-bulb length. Barbel 50%–53% SL. Terminal filament short, 4.1%–5.3% SL, without branches. Distal bulb 1.8 times length of proximal bulb in the small specimen, 0.7 in the larger specimen. Proximal bulb in larger specimen large for its size, 1.5 mm (1.3% SL) at 118 mm SL. Barbel without pigment in smaller specimen; larger specimen with fairly dense pigment in proximal part of axis, little or none in distal part. External chevron-shaped or roundish striated areas on stem not pigmented. Middorsal paired spots between occiput and dorsal-fin origin 8.

DESCRIPTION.—Based on 2 specimens, 78 and 118 mm; proportions listed for small specimen followed by large specimen. In percent of SL: barbel length 50–53; filament length 4.2–5.3; proximal bulb 0.8–1.3; distal bulb 1.4–0.9; distance between bulbs 0.8–0.6. In percent of proximal bulb: distal bulb 183–73; distance between bulbs 100–47. In percent of distal bulb: distance between bulbs 55–64.

The stem axis is well pigmented proximally, becoming lighter or unpigmented distally. The axis between the bulbs and in the filament is unpigmented. The external chevron-shaped or roundish striated areas on the stem are unpigmented. The proximal bulb is ovoid, the distal spheroidal in both specimens. Tiny bulblets were present in the proximal part of the filament in the smaller specimen, but were not discerned in the larger.

No large males were available for measurement of the postorbital organ.

DESCRIPTION OF HOLOTYPE.—Female, 118.0 mm. D ~24. A 36. P1 3. P2 7. IP 7. PV 34. VAV 18. OV 35. VAL 17. AC 19. IA 59. IC 78. OA 52. OC 71. VAV photophores over anal-fin base 7. Branchiostegal photophores 11. Premaxillae missing. Maxilla with about 5 erect teeth and about 14 short, slanted, serra-like teeth. Mandibular teeth 15 left, 16 right: from anterior to posterior, a short fixed symphysial tooth followed by a moderate space, a fixed fang followed by a longer space, a long depressible tooth, a short fixed tooth (2 on right), a long depressible tooth, a short-to-long series of 1 fixed and 2 depressible teeth, a short-to-long series of 4 smaller depressible teeth, and a short-to-long series of 3 small depressible teeth. Vertebrae 68.

Measurements (in mm): Predorsal length ~91.4, preanal length 76.3, prepelvic length 64.4, head length ~11.9, barbel length 62.0, proximal bulb length 1.5, distal-bulb length 1.1, distance between bulbs 0.7, filament length 6.2, fleshy orbit length 2.5, postorbital length 0.3, lower-jaw length 11.4, depth behind head (greatest depth) 6.2, caudal-peduncle depth 1.4, pectoral fin broken, pelvic-fin length 14.6, dorsal-base length 14.0, anal-base length 28.6, longest mandibular tooth 1.4.

Barbel with ovoid proximal bulb narrowing distally, spheroidal distal bulb wider than proximal bulb.

SIMILAR SPECIES.—Eustomias bibulboides most closely resembles orientalis, but has a smaller proximal bulb in large specimens (maximum 0.9% SL, vs. 1.3% in the larger orientalis) and a smaller distal bulb (maximum 1.0% SL in specimens smaller than 100 mm, 0.7% in larger specimens vs. 1.4% in the smaller orientalis, 0.9% in the larger).

In australensis the distance between bulbs is longer (1.8% SL vs. 0.6%–0.8% in orientalis) and the distal bulb is longer (1.8% SL vs. 0.9%–1.4% in orientalis).

All other species with simple filaments have either longer barbels, a longer interspace between the bulbs, or contiguous bulbs.

DISTRIBUTION.—Known only from the westernmost Pacific from north of New Guinea to Suruga bay, Japan (Figure 40).

ETYMOLOGY.—From the Latin adjective orientalis (of the east), referring to the distribution of this species in the part of the world known as the Orient.

MATERIAL EXAMINED (1 female, 1 unsexed).—Holotype: IOAN uncat. (, 118), 25°13′N, 128°32′W, 0–100 m, 8 Feb 1975.

Paratype: ZMUC P202703 (?, 78.0), 02°10′N, 138°20′E, 0–~150 m (300 mw), 0320, 13 Jul 1929.