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Barbel length is 13%–30% SL in specimens smaller than 65 mm, 15%–28% in those 65–90 mm, and 23%–33% in those larger than 90 mm. Apparently the increase in relative length occurs at different rates in small specimens, but no further change with growth occurs after about 90 mm SL.
The axis of the stem varies from lightly to darkly peppered with melanophores, or streaked with dark pigment, the variation apparently not size related. The chevron-shaped or roundish striated areas on the stem are unpigmented. The axis between the bulbs is darkly peppered or streaked, especially distad where it extends onto the proximal quarter to third of the distal bulb as a black cap. The filament axis is without melanophores or with a few proximally.
Proximal and distal bulbs vary in shape from spheroidal to ovoid. The proximal bulb is 0.1%– 0.7% SL, distal bulb 0.4%–l.l% SL and 1–5 times proximal–bulb length, neither bulb changing size relative to SL with growth. Several specimens have non–opaque distal bulbs with a reticulate or dendritic network internally. The distance between bulbs is 0.5%–1.5% SL in small specimens, decreasing in relative length to 0.1 %–0.6% in the largest. The distance is 0.3–2.5 times as long as the distal bulb, with no relation to size of fish.
The terminal filament is short, 0.3%–2.5% SL, 0.4–4.0 times distal–bulb length, apparently not changing with growth. It bifurcates or trifurcates near its base, and occasionally branches again further distad. There are no bulblets in the filament.
The postorbital organs of 12 large males (125– 152 mm SL) are 1.4%–2.1% SL, 56%–82% fleshy orbit length. A 134 mm male has a postorbital organ only 1.0% SL, 45% fleshy orbit length, and one 105 mm has an organ 1.2% SL, 43% fleshy orbit length. In one female the organ is 0.9%; in all others it is 0.8% or less.
There are eight paired dorsal spots between occiput and dorsal–fin origin, one beneath the dorsal fin, and one variably present on the caudal peduncle.
In two freshly caught specimens the proximal bulb was yellow, the distal bulb blue.
Two terminal bulbs separated by a short interspace, 0.1%–1.5% SL, about 0.3– 2.5 times distal–bulb length. Proximal bulb small, 0.1%–0.7% SL. Distal bulb 0.4%–1.1% SL, 1–5 times proximal–bulb length, with distinctive black pigment cap on proximal end. Terminal filament short, 0.3%–2.5% SL, without prominent bulblets. Barbel length 13%–33% SL. Stem axis lightly to darkly pigmented. External chevron-shaped or roundish striated areas on stem unpigmented. Paired dorsal spots between occiput and dorsal-fin origin 8..
Eastern Gulf of Mexico, Caribbean Sea, and from 29°N, 80°W (off northern Florida) through the Bahamas, Antilles, and offshore roughly parallel to the coast of South America to about 23°S, extending east to about 30 °W off central Brazil.
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.
Eustomias brevibarbatus is a member of the subgenus Biradiostomias Gomon and Gibbs (1985). Biradiostomias differs from all other subgenera of Eustomias (see Gibbs et al., 1983) in the possession of two long, separate pectoral rays. Dinematochirus, when pectoral fins are present, also has two pectoral rays, but these are closely bound together in black membrane; furthermore, the species of Dinematochirus have a well–developed ventral body groove that extends beyond the pectoral–fin bases, and the barbel is short, usually with a pigmented stem, and usually with branches arising from the stem well before the terminal bulb. Biradiostomias is most similar to the subgenera Nominostomias, Haploclonus, and Eustomias in possessing a relatively long, slender barbel that has little or no external pigment and in lacking a well–developed ventral groove behind the pectoral bases. These three subgenera have three long, separate pectoral rays. Biradiostomias generally is intermediate in photophore, vertebral, anal–ray, and tooth numbers between the higher counts in Nominostomias and Eustomias and the lower counts of Haploclonus. The subgenus Eustomias is unique in having paired photophores in the lateral series. Gibbs et al. (1983, table 1) compare counts of Haploclonus, Biradiostomias (as "2–pectoral–rays"), and Nominostomias.
The following are characters that apply to all species of the subgenus. Two well–developed, free pectoral rays. Seven pelvic rays. Barbel with slender stem having little or no external pigment (axis often pigmented), no row of dark spots, and no branches proximal to terminal bulbs. One to three, rarely four, relatively small terminal bulbs, with or without terminal filaments or projections. No wide ventral body groove posterior to pectoral– fin base. Photophores in ventral series (IC) 69–77 (mostly 71–75), in lateral series (OC) 64– 71 (rarely more than 68, species modes mostly 66–68), VAV and VAL 13–19 (seldom more than 17, species modes 15–17 and 16–17, respectively). Usually 4–6 (rarely 7) VAV photophores located over anal–fin base. No paired photophores in lateral series. Vertebrae in continuous series 63–68 (seldom more than 66, species modes mostly 65–66). Anal rays 31–40, usually 33–38. Premaxillary teeth 7–15; mandibular teeth 9–18 (fewer of each in many specimens less than 100 mm SL).
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.
Parr AE. 1927. The stomiatoid fishes of the suborder Gymnophotodermi (Asthronesthidae, Melanostomiatidae, Idiacanthidae) with a complete review of species. Bulletin of the Bingham Oceanographic Collection 3:1–123.
To 152 mm SL.
Tongue of the Ocean, Bahamas, 23°55'N, 77°09'W, 4000-7000 feet wire out.
Holotype: YPM 2034.
