View data on Catalog of Fishes here.
This species is based on two specimens, 89 and 92 mm SL. Proportions, bulb shape, and filament are as in "diagnostic description." The illustration of the bulb of the holotype (Regan and Trewavas, 1930; fig. 77A) shows the proximal part being about as wide as the distal part. We found the bulb of the holotype to be similar to Gomon and Gibbs (1985:fig. 14b), with a more slender proximal part. The axis of the stem is darkly peppered with melanophores in the 92-mm holotype.
The second specimen has no stem pigment, but the body is also faded. Both specimens are females with small postorbital organs, 0.6%–0.8% SL, 28%–29% of fleshy orbit length.
Nine pairs of subcutaneous spots along the dorsum, the last under the dorsal–fin base, were counted in one specimen. The bulb of the 89-mm immature female, after being in preservative for some weeks, was an overall light purple.
A single large, elongate terminal bulb 3.3%–3.5% SL, approximately 6 times longer than wide, with constriction before tip. Proximal portion of bulb longer and somewhat more slender than part distal to constriction. Terminal filament minute and simple. Barbel length 46%–49% SL. Stem axis darkly pigmented. External chevron–shaped roundish striated areas on stem not pigmented. Serial photophores: PV 33–34, OV 33, IA 57–59, IC 75– 77. Vertebrae 65–67. Paired dorsal spots between occiput and dorsal–fin origin 8.
The holotype was taken in the Straits of Florida, the second specimen from the northern Gulf of Mexico.
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 leptobolus 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.
Regan CT, Trewavas E. 1930. The fishes of the families Stomiatidae and Malacosteidae. Danish Dana Expedition 1920−22 6:1−143.
To at least 92 mm SL.
View original type description here.
23°13'N, 82°21'W, 0—400 m (800 mw), 1900, 5 Feb 1922.
Holotype: ZMUC P201900
