Eustomias quadrifilis Gomon & Gibbs 1985

View data on Catalog of Fishes here.

The following description is based on the holotype and only known specimen, a male, 105.0 mm SL.

D 22. A 34. P1 2. P2 7. IP 7. PV 33. VAV 16. OV 34. VAL 16. AC 17. IA 56. IC 73. OA 50. OC 67. VAV photophores over anal–fin base 5. Branchiostegal photophores 10. Vertebrae 64.

Premaxillary teeth 11 left, 13 right: from anterior to posterior, a moderate fixed tooth followed by a long space, a fixed fang followed by a moderate space, a short fixed tooth, 5 moderate depressible teeth (only 2 right), 2 short fixed teeth (1 right), and a short depressible tooth (7 on right). Maxilla with about 20 small, slanting, serra–like teeth. Mandibular teeth 17 left, 13 right: from anterior to posterior, a short depressible symphysial tooth with replacement followed by a moderate space, a fixed fang followed by a moderate space, 2 moderate depressible teeth (1right) followed by a short space, 2 short depressible teeth followed by a short space (a short fixed, a moderate depressible, and another short fixed tooth on right), a long depressible tooth, 2 short depressible teeth (6 right), 5 moderate–toshort depressible teeth (none right), and 3 short fixed teeth (none right).

Opaque barbel bulb elongate, about 5 times longer than wide, rounded proximally, narrowing almost to a point distally. Wide, clear sheath around bulb, with 2 well separated pairs of filaments arising from its distal end. One filament apparently simple; others branching and with several fine branches distally that are tangled together.

The darkness of the skin prevented counting of paired dorsal spots.

A single, elongate terminal bulb 2.6% SL, about 5 times longer than wide. Two pairs of complex terminal filaments about 2.2% SL arising separately from end of clear sheath of bulb. Barbel length 35.9% SL. Stem axis darkly pigmented. External chevron-shaped or roundish striated areas on stem not pigmented. Serial photophores: PV 33, OV 34, IA 56, IC 73. Vertebrae 64.

The only known specimen was taken in a warm–core eddy surrounded by Slope Water east of New Jersey, USA.

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 quadrifilis 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.

East of New Jersey, U.S.A., 38°58'N, 71°16'W, depth 250-500 meters.

Holotype: USNM 266296.

Eustomias quadrifilis

DIAGNOSIS.—A single, elongate terminal bulb 2.6% SL, about 5 times longer than wide. Two pairs of complex terminal filaments about 2.2% SL arising separately from end of clear sheath of bulb. Barbel length 35.9% SL. Stem axis darkly pigmented. External chevron-shaped or roundish striated areas on stem not pigmented. Serial photophores: PV 33, OV 34, IA 56, IC 73. Vertebrae 64.

DESCRIPTION OF HOLOTYPE.—Male, 105.0 mm SL. D 22. A 34. P1 2. P2 7. IP 7. PV 33. VAV 16. OV 34 (first on left side paired, count could be 35). VAL 16. AC 17. IA 56. IC 73. OA 50. OC 67. VAV photophores over anal-fin base 5. Branchiostegal photophores 10. Vertebrae 64. Premaxillary teeth 11 left, 13 right: from anterior to posterior, a moderate fixed tooth followed by a long space, a fixed fang followed by a moderate space, a short fixed tooth, 5 moderate depressible teeth (only 2 right), 2 short fixed teeth (1 right), and a short depressible tooth (7 on right). Maxilla with about 20 small, slanting, serra-like teeth. Mandibular teeth 17 left, 13 right: from anterior to posterior, a short depressible symphysial tooth with replacement followed by a moderate space, a fixed fang followed by a moderate space, 2 moderate depressible teeth (1 right) followed by a short space, 2 short depressible teeth followed by a short space (a short fixed, a moderate depressible, and another short fixed tooth on right), a long depressible tooth, 2 short depressible teeth (6 right), 5 moderate-to-short depressible teeth (none right), and 3 short fixed teeth (none right).

Measurements (in mm): Predorsal length 88.8, preanal length 77.2, prepelvic length 60.4, head length 11.7, barbel length 39.7, opaque-bulb length 2.7, filament length ∼2.3 (distal ends tangled), fleshy orbit length 2.8, postorbital-organ length 0.9, lower-jaw length 11.3, upper-jaw length 10.5, depth behind head (greatest depth) 7.7, caudal-peduncle depth 2.0, pectoral-fin length 13.6, pelvic-fin length 14.5, dorsal-base length 13.2, anal-base length 25.3, longest premaxillary tooth 2.0, longest mandibular tooth 1.8.

Opaque barbel bulb elongate, about 5 times longer than wide, rounded proximally, narrowing almost to a point distally. Wide, clear sheath around bulb, with 2 well separated pairs of filaments arising from its distal end. One filament apparently simple; others branching and with several fine branches distally that are tangled together.

The darkness of the skin prevented counting of paired dorsal spots.

SIMILAR SPECIES.—The structure of the terminal filaments is unlike that of any other species of Biradiostomias. The elongate bulb of quadrifilis resembles those of leptobolus and macrophthalmus; its length is similar to that of leptobolus, shorter than in macrophthalmus. Barbel length is similar to leptobolus, shorter that in macrophthalmus. Photophore counts are within the range of macrophthalmus and lower than in leptobolus. Neither leptobolus (with one questionable exception) nor macrophthalmus has more that a short, simple filament (the three filaments of the exceptional leptobolus are less than half as long as those of quadrifilis).

DISTRIBUTION.—The only known specimen was taken in a warm-core eddy surrounded by Slope Water east of New Jersey, USA.

ETYMOLOGY.—The name quadrifilis is a Latin adjective meaning four-threaded, in allusion to the two pairs of terminal filaments.

MATERIAL EXAMINED.—Holotype: USNM 266296 (, 105.0), 38°58′N, 71°16′W, 250–500 m, 0307–0327, 22 Apr 1982.

Eustomias xenobolus Regan and Trewavas, 1930

Eustomias xenobolus Regan and Trewavas, 1930:92 [barbel of holotype fig. 75].—Morrow and Gibbs, 1964:428–429 [part; barbel fig. 110K; no additional material; E. pyrifer placed in synonymy].—Rass, 1971:512 [listed in Caribbean Sea].—Nielsen, 1974:19 [holotype in ZMUC].

DIAGNOSIS.—A single terminal bulb 0.5%–1.4% SL, in 2 distinct parts: proximal part a slender stalk about stem-axis width (almost a separate small bulb); distal part globular and much wider. One to 3 terminal filaments, simple or with side branches, 0.4–2.1 times bulb length. Filaments with few or no bulblets. Barbel length 22%–57% SL. Axis of stem darkly pigmented; a second cylinder of pigment around axis in swollen stem near bulb. External chevron-shaped or roundish striated areas pigmented in distal part of stem. Serial photophores: PV 34, OV 34. Vertebrae 65. Paired dorsal spots between occiput and dorsal-fin origin 8.

DESCRIPTION.—Of the two known specimens (100 and 171 mm SL) the smaller has a longer barbel (56.6 mm vs. 37.2 mm), larger bulb (1.4 mm vs. 0.9 mm), and longer terminal filament (∼3.0 mm vs. ∼0.5 mm). Thus, a decrease with growth is indicated for all three characters.

Stem pigmentation is described in the diagnosis.

The terminal bulb is in two distinct parts. A proximal, stalk-like part of the bulb could be interpreted as a separate small bulb, contiguous with the larger globoid distal part.

The smaller specimen has a single terminal filament 3.0% SL, 2.1 times bulb length bearing side branches. The larger specimen had three short terminal filaments arising from a single point, the longest ∼0.2% SL, ∼40% of bulb length, but these are now missing.

Both specimens are females with well-developed ova (up to 0.6 mm diameter) and have small postorbital organs (0.7%–1.0% SL, 20%–22% of fleshy orbit length.

Both specimens have nine pairs of subcutaneous spots along the dorsum, the last one under the dorsal fin.

No color observations have been recorded.

SIMILAR SPECIES.—Eustomias xenobolus is unique among the species of Biradiostomias in having a single, non-bilobate terminal bulb with two distinct parts: a slender, stalk-like proximal swelling and a globular and much wider distal part. It resembles E. hulleyi in having a darkly pigmented stem axis and a second cylinder of pigment around the axis proximal to the bulb, but hulleyi differs in bulb shape and has a longer barbel (75%–87% SL vs. 22%–57%). Both pyrifer and precarius, like hulleyi, have single, relatively simple bulbs, but the stem axis of pyrifer is lightly pigmented, that of precarius has almost no pigment, and precarius has a longer barbel (64% SL) than xenobolus.

DISTRIBUTION.—The holotype was taken off St. Croix, Virgin Islands, the second specimen from the southwestern Gulf of Mexico, the questionable specimen from the northeastern Gulf (Figure 20).

MATERIAL EXAMINED (3).—Holotype: ZMUC P201913 (, 171), 17°43′N, 64°56′W, 0–∼500 m (1000 mw), 2100, 30 Mar 1922.

Non-type: MCZ 56608 (, 99.7) 23°13′N, 94°50′W, 0–128 m, 2355–0413, 18–19 Jun 1966.

Questionable: USNM 266588 (, 104.3), 27°N, 86°W, 360–530 m, 0738–1058, 6 Jun 1972.

DOUBTFUL SPECIES

Two nominal species cannot be associated with any of the species that we recognize. Each is known only from its holotype, and both holotypes are young specimens that appear to have damaged barbels.

Eustomias globulifer Regan and Trewavas, 1930

Eustomias globulifer Regan and Trewavas, 1930:93 [holotype only; barbel fig. 76A].—Morrow and Gibbs, 1964:411 [no additional specimens].—Rass, 1971:511 [listed in Caribbean Sea].—Nielsen, 1974:16 [holotype in ZMUC].

The holotype is 70.4 mm SL and is incompletely metamorphosed. Its two developed pectoral rays are preceded by a short projection that may be a rudimentary ray of the sort that is commonly seen in small Eustomias and later disappears. Its barbel is short, 9.5% SL, with a pigmented stem, a single ovoid terminal bulb, and a short, pigmented terminal projection (Figure 14d). The projection could be a portion of stem that has been broken off between two bulbs, so that barbel length may well have been longer. At 70 mm SL, the barbels of most Biradiostomias species for which developmental series are available are increasing rapidly in relative length, and the short barbel of globulifer could associate it with many or all the species that we recognize here. If the end of the barbel is not broken, the shape of the single bulb is vaguely reminiscent of pyrifer, hulleyi, or precarius, but the terminal appendage is unlike any of these. If the barbel is broken, its remaining bulb resembles the proximal bulb of polyaster, dubius, variabilis, hypopsilus, metamelas, or dispar. Of these six species, metamelas and dispar are known only from south of 10°N; the other four have been taken in the Bahamas area, as was globulifer, and any of these might be conspecific with globulifer. At this time we cannot associate globulifer with any one of the known species of Biradiostomias.

DISTRIBUTION.—The holotype, and only known specimen, was taken east of Martinique in the Lesser Antilles.

MATERIAL EXAMINED.—Holotype: ZMUC P201899 (?, 70.4), 14°38′N, 61 ° 16′W, 0–∼300 m (600 mw), 0315, 7 Apr 1922.

Eustomias quadrifilis és una espècie de peix de la família dels estòmids i de l'ordre dels estomiformes.

Eustomias quadrifilis, especie de pez, de la familia Stomiidae, en el orden de los Stomiiformes.

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Eustomias quadrifilis Eustomias generoko animalia da. Arrainen barruko Stomiidae familian sailkatzen da.