Eustomias digitatus Gomon & Gibbs 1985

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The barbel of E. digitatus apparently increases slightly relative to SL, from 24% to 28% SL between 70 and 122 mm SL. The axis of the stem is darkly streaked with pigment in the two largerspecimens, somewhat more lightly pigmented in the 70-mm specimen.

The external chevron-shaped or rounded striated areas on the stem are not pigmented. The single bilobate bulb is rounded proximally; distally, one lobe is short and ovoid, the second lobe extremely elongate and tapered distally. The elongate lobe bears the filaments, when present. The notch between the lobes is relatively deep, about 75% the length of the ovoid lobe (the lobe is measured from proximal end of bulb to distal tip of lobe). The bulb apparently increases rapidly from 1.0% to 2.3%– 3.8% SL between 70 and 122 mm SL.

Two short, thick, opaque filaments, 0.2% SL, 7% of bulb length, arise from the tip of the elongate lobe of the bulb of the 119 mm specimen. The bulbs of the 70 mm and 122 mm specimens have no filaments, although the tip of the elongate lobe of the larger specimen may be missing.

The two large specimens are females with postorbital organs 0.5%–0.7% SL, 18.2%–30.8% of fleshy orbit. Thus, the size of the male postorbital organ is unknown. There are nine pairs of dorsal spots, the last under the dorsal fin.

No color observations have been recorded.

A single, bilobate terminal bulb, 1.1 %–3.8% SL, 1 lobe short and ovoid, the other (in large specimens) extremely long, 3 to 4 times ovoid lobe, and tapering. Notch in bulb about 75% of ovoid lobe as measured from proximal end of bulb to distal tip of lobe. Two very short filaments (0.2% SL, 7% bulb length) arising from elongate, tapered lobe, or filaments absent. Barbel short, 24%–28% SL. Stem axis lightly to darkly pigmented. External chevron-shaped or roundish striated areas unpigmented. Paired dorsal spots between occiput and dorsal-fin origin 8.

This species is known only from three specimens collected off the Leeward Island.

Gomon JR, Gibbs RH, Jr. 1985. Taxonomy and distribution of the stomioid fish genus Eustomias (Melanostomiidae), II: Biradiostomias, new subgenus. Smithsonian Contributions to Zoology No. 409:1–58.

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.

Gomon JR, Gibbs RH, Jr. 1985. Taxonomy and distribution of the stomioid fish genus Eustomias (Melanostomiidae), II: Biradiostomias, new subgenus. Smithsonian Contributions to Zoology No. 409:1–58.

To at least 122 mm SL.

Off Leeward Islands, 17°43'N, 64°56'W, Lesser Antilles, depth 0 to about 450 meters.

Holotype: ZMUC P201850.

Eustomias digitatus

Eustomias dubius.—Regan and Trewavas, 1930:88 [in part; barbel fig. 68; description based on holotype of dubius and 3 additional specimens that are digitatus],—Beebe and Crane, 1939:222–224 [in part; also includes E. schiffi and E. dubius; no additional digitatus],—Morrow and Gibbs, 1964:404–406 [in part; also includes E. schiffi and E. dubius; barbel p. 394, fig. 110j; no additional digitatus]

DIAGNOSIS.—A single, bilobate terminal bulb, 1.1 %–3.8% SL, I lobe short and ovoid, the other (in large specimens) extremely long, 3 to 4 times ovoid lobe, and tapering. Notch in bulb about 75% of ovoid lobe as measured from proximal end of bulb to distal tip of lobe. Two very short filaments (0.2% SL, 7% bulb length) arising from elongate, tapered lobe, or filaments absent. Barbel short, 24%–28% SL. Stem axis lightly to darkly pigmented. External chevron-shaped or roundish striated areas unpigmented. Paired dorsal spots between occiput and dorsal-fin origin 8.

DESCRIPTION.—The barbel of E. digitatus apparently increases slightly relative to SL, from 24% to 28% SL between 70 and 122 mm SL. The axis of the stem is darkly streaked with pigment in the two larger specimens, somewhat more lightly pigmented in the 70 mm specimen. The external chevron-shaped or rounded striated areas on the stem are not pigmented.

The single bilobate bulb is rounded proximally; distally, one lobe is short and ovoid, the second lobe extremely elongate and tapered distally. The elongate lobe bears the filaments, when present. The notch between the lobes is relatively deep, about 75% the length of the ovoid lobe (the lobe is measured from proximal end of bulb to distal tip of lobe). The bulb apparently increases rapidly from 1.0% to 2.3%–3.8% SL between 70 and 122 mm SL.

Two short, thick, opaque filaments, 0.2% SL, 7% of bulb length, arise from the tip of the elongate lobe of the bulb of the 119 mm specimen. The bulbs of the 70 mm and 122 mm specimens have no filaments, although the tip of the elongate lobe of the larger specimen may be missing.

The two large specimens are females with postorbital organs 0.5%–0.7% SL, 18.2%–30.8% of fleshy orbit. Thus the size of the male postorbital organ is unknown.

There are nine pairs of dorsal spots, the last under the dorsal fin.

No color observations have been recorded.

DESCRIPTION OF HOLOTYPE.—Female, 119.3 mm SL. D 22. A 37. P1 2. P2 7. IP 7. PV 35. VAV 13. OV 34. VAL 15. AC 18. IA 55. IC 73. OA 49. OC 67. VAV photophores over anal-fin base 4. Branchiostegal photophores 10. Premaxillary teeth II left, 9 right: from anterior to posterior, a moderate fixed tooth followed by a long space, a fixed fang followed by a moderate space, a small fixed tooth followed by I long depressible tooth, 2 small fixed teeth (1 on right), and 5 small to moderate depressible teeth (4 on right). Maxilla with about 10 small slanting, serra-like teeth. Mandibular teeth 12 left, 11 right: from anterior to posterior, a short fixed symphysial tooth (replacement tooth also well-developed on left) followed by a moderate space, a fixed fang followed by a moderate space, 1 long depressible tooth, 1 short fixed tooth, 2 long depressible teeth (1 on right), 1 short fixed tooth, and 5 short depressible teeth. Vertebrae 64.

Measurements (in mm): Predorsal length 100.6, preanal length 89.4, prepelvic length 72.2, head length 13.8, barbel length (measured to the ovoid lobe of bulb) 33.7, bulb length 2.8 (short lobe 0.9), filament length 0.2, fleshy orbit length 3.3, postorbital-organ length 0.6, lower-jaw length 13.3, upper-jaw length 11.9, depth behind head (greatest depth) 7.7, caudal-peduncle depth 1.9, pectoral and pelvic fins broken, dorsal-base length 14.5, anal-base length 28.2, longest premaxillary tooth 2.6, longest mandibular tooth 1.8.

The elongate lobe of the bulb of the holotype is now broken and the filaments are missing.

SIMILAR SPECIES.—In E. schiffi and E. dubius, the most similar species, the barbels are longer, 37%–78% SL in specimens 57 mm or longer vs. 24%–28% SL in digitatus; the filaments are more numerous and longer (0.4%–5.2% SL, 38%–213% of bulb length, vs. 0.16% SL, 7% of bulb length in digitatus), and the filament-bearing lobe is shorter (about 0.9–1.7 times the length of the ovoid lobe vs. 3.1–4.4 times in digitatus). In addition, the notch in the terminal bulb of E. schiffi is shallower (about half the length of the ovoid lobe vs. about 75%). In large specimens of E. dubius the notch between the lobes is very deep, almost dividing the lobes completely in two.

DISTRIBUTION.—This species is known only from three specimens collected off the Leeward Islands (Figure 19).