Eustomias micraster Parr 1927

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The barbel apparently grows little or not at all after about 100 mm SL, decreasing relative to SL from 44%–68% in specimens smaller than 75 mm to 37%–48% in the largest (142–149 mm). All specimens have black pigment in the axis of the stem, between the bulbs, and usually in the proximal part of the filament. The intensity of the pigment varies, and it may be uneven, uniform, or speckled. In all except 2 small specimens (68 and 70 mm) there is a dark spot or cap at the proximal end of the distal bulb. The external chevron–shaped or roundish striated areas on the stem are usually pigmented, but may be unpigmented in the distal stem or throughout.

The proximal bulb is oblate-spheroidal to longovoid, the distal bulb spheroidal to ovoid. Neither terminal bulb appears to grow after 70 mm SL is attained. The proximal bulb decreases relative to SL from 1.0%–1.8% in specimens smaller than 75 mm to 0.7%–0.9% in the largest (142–149 mm). The distal bulb also decreases, from 1.0%–1.4% to 0.3%–0.6%. In some small specimens, the length of the proximal bulb equals or slightly exceeds that of the distal bulb. In most, including all over 100 mm SL, the distal bulb is smaller than the proximal.

The distance between the bulbs, relative to other species, is long in all specimens but decreases relative to SL from 2.9%–4.5% in specimens smaller than 75 mm to 2.2%–2.7% in the largest (142–149 mm). The relationship of the interspace to bulb length is quite variable, but no growth changes are apparent. The interspace is 2.3–4.0 times the proximal-bulb length, 2.6–7.8 times the distal–bulb length.

In 2 small specimens and 1 large one with unbroken terminal filaments, these filaments are long, 16%–21% of SL. The filament has 4–11 short branches, usually with internal bulblets and swollen tips, arising near the bulb. One or more single, short branches may be present distad from the basal group. Tiny bulblets are present along the filament axis; they may be few or difficult to discern in smaller specimens, but they are closely spaced and form 2–3 rows in larger ones.

The postorbital organ of the 3 largest males (112–128 mm) is 0.7%–0.9% SL, 21%–27% of fleshy orbit length, barely larger than those of female micraster.

wo terminal bulbs separated by a long interspace (2.2%–4.5% SL, 2.6–7.8 times length of distal bulb, 2.3–4.0 times length of proximal bulb). Barbel length less than 60% SL (68% in one small specimen). Terminal filament long (16%–21% SL), with 4 or more short, bulbletbearing branches near the bulb, the branches usually with expanded tips. Distal bulb shorter than proximal bulb in specimens over 90 mm SL, not more than 1.25 times the proximal bulb in smaller specimens, never longer than 1.0 mm. Stem axis and external chevron–shaped or roundish striated areas moderately to darkly pigmented. Number of middorsal paired spots between occiput and dorsal–fin origin not determined.

The vicinity of islands from the northern Bahamas to the Lesser Antilles and offshore in the southwestern Sargasso Sea.

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.

Eustomias micraster is a member of the subgenus Nominostomias Reagan and Trewavas (1930). The following description applies to all member of Nominostomias.

Three 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 the terminal bulbs (E. multifilis may have a few short filaments on the stem near the bulb). One or 2 relatively small terminal bulbs, the distalmost with a projection or filament of variable complexity (the projection almost indiscernible in a few species). No wide ventral body groove posterior to pectoral–fin base (a narrow, shallow groove observed in some specimens). Photophore and vertebral counts high. Photophores in ventral series (IC) 69–80 (seldom fewer than 72, species modes mostly 75–78), in lateral series (OC) 63–73 (seldom fewer than 66, species modes mostly 69–72), VAV and VAL 15–21 (seldom fewer than 16, species modes 17–18 and 18–19, respectively). Vertebrae in continuous series 64–71 (seldom fewer than 65, species modes mostly 67–69). No paired photophores in lateral series. Number of teeth high: premaxillary 11–20, mandibular 14–29 in large specimens (fewer in many specimens less than 100 mm SL).

Counts of fin-rays, photophores, vertebrae, and teeth are of little use in distinguishing most species of Nominostomias, for even those species that show modal differences overlap the ranges of most other species.

None of the body proportions examined by Gibbs et al. (1983) showed convincing differences among species of Nominostomias. Differences in size or relative–growth patterns appeared to characterize a number of species for which few specimens were measured, but these are believed to be artifacts of sampling. The cloud of points of species with abundant measurements usually encompassed those of species with few measurements, and in those abundant species, isometric growth is indicated for almost every body part once metamorphosis is complete. The only body measurement to indicate allometric growth is the least caudal-peduncle depth, which decreases relative to 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.

Regan CT, Trewavas E. 1930. The fishes of the families Stomiatidae and Malacosteidae. Danish Dana Expedition 1920−22 6:1−143.

To at least 128 mm SL.

Off Eleuthera Island, Bahamas, 24°51'N, 76°38'W, 8000 feet wire out.

Holotype: YPM 2040.

Two terminal bulbs separated by a long interspace (usually 2.6-7.8 times length of distal bulb; 2.3-4 times of proximal bulb length). Barbel less than 60% SL. Terminal filament long, 16-21% SL with 4 or more short, bulblet-bearing branches near the bulb, the branches usually with expanded tips. Distal bulb shorter than proximal bulb in specimens over 9 cm SL; not more than 1.25 times the proximal bulb in smaller specimens, never longer than 1 mm. Axis of stem and external chevron-shaped or roundish striated areas moderately to darkly pigmented. Middorsal paired spots between occiput and dorsal-fin origin undetermined (Ref. 11333).

Eustomias micraster Parr, 1927

Eustomias bibulbosus micraster Parr, 1927:72 [24°51′N, 76°38′W].

Eustomias micraster.—Regan and Trewavas, 1930:84 [6 additional specimens, all from northern Lesser Antilles region].—Beebe and Crane, 1939:211 [E. bituberatus possibly in synonymy].

Eustomias bibulbosus.—Morrow and Gibbs, 1964:391 [part; no additional specimens; E. micraster in synonymy, wrongly attributed to Beebe and Crane, 1939].—Bekker et al., 1975:305 [part, sta 1177; examined by us].

DIAGNOSIS.—Two terminal bulbs separated by a long interspace (2.2%–4.5% SL, 2.6–7.8 times length of distal bulb, 2.3–4.0 times length of proximal bulb). Barbel length less than 60% SL (68% in one small specimen). Terminal filament long (16%–21% SL), with 4 or more short, bulblet-bearing branches near the bulb, the branches usually with expanded tips. Distal bulb shorter than proximal bulb in specimens over 90 mm SL, not more than 1.25 times the proximal bulb in smaller specimens, never longer than 1.0 mm. Stem axis and external chevron-shaped or roundish striated areas moderately to darkly pigmented. Number of middorsal paired spots between occiput and dorsal-fin origin not determined.

DESCRIPTION.—The barbel apparently grows little or not at all after about 100 mm SL, decreasing relative to SL from 44%–68% in specimens smaller than 75 mm to 37%–48% in the largest (142–149 mm). All specimens have black pigment in the axis of the stem, between the bulbs, and usually in the proximal part of the filament. The intensity of the pigment varies, and it may be uneven, uniform, or speckled. In all except 2 small specimens (68 and 70 mm) there is a dark spot or cap at the proximal end of the distal bulb. The external chevron-shaped or roundish striated areas on the stem are usually pigmented, but may be unpigmented in the distal stem or throughout.

The proximal bulb is oblate-spheroidal to long-ovoid, the distal bulb spheroidal to ovoid. Neither terminal bulb appears to grow after 70 mm SL is attained. The proximal bulb decreases relative to SL from 1.0%–1.8% in specimens smaller than 75 mm to 0.7%–0.9% in the largest (142–149 mm). The distal bulb also decreases, from 1.0%–1.4% to 0.3%–0.6%. In some small specimens, the length of the proximal bulb equals or slightly exceeds that of the distal bulb. In most, including all over 100 mm SL, the distal bulb is smaller than the proximal.

The distance between the bulbs, relative to other species, is long in all specimens but decreases relative to SL from 2.9%–4.5% in specimens smaller than 75 mm to 2.2%–2.7% in the largest (142–149 mm). The relationship of the interspace to bulb length is quite variable, but no growth changes are apparent. The interspace is 2.3–4.0 times the proximal-bulb length, 2.6–7.8 times the distal-bulb length.

In 2 small specimens and 1 large one with unbroken terminal filaments, these filaments are long, 16%–21% of SL. The filament has 4–11 short branches, usually with internal bulblets and swollen tips, arising near the bulb. One or more single, short branches may be present distad from the basal group. Tiny bulblets are present along the filament axis; they may be few or difficult to discern in smaller specimens, but they are closely spaced and form 2–3 rows in larger ones.

The postorbital organ of the 3 largest males (112–128 mm) is 0.7%–0.9% SL, 21%–27% of fleshy orbit length, barely larger than those of female micraster.

A 110 mm male (ISH 1074/79) when fresh had a white proximal bulb and a pale blue distal bulb; the swollen branch tips were white, and the rest of the barbel lacked color; the postorbital organ was white.

SIMILAR SPECIES.—None of the other species with a single terminal filament has a group of 4 or more short branches near the distal bulb. In arborifer, small bimargaritatus, small bimargaritoides, grandibulbus, and crossotus, 2 branches arise near the bulb, but these branches are approximately as long as the main filament. In E. kreffti there are 2 long filaments, as well as several short filaments with swollen tips, but all of these arise from the bulb.

DISTRIBUTION.—The vicinity of islands from the northern Bahamas to the Lesser Antilles and offshore in the southwestern Sargasso Sea (Figure 40).

MATERIAL EXAMINED (4 males, 8 females, 2 unsexed).—Holotype: BOC 2040 (, 223.5), 24°51′N, 76°38′W, 0–~1200 m (8000 ft wire), 17 Mar 1930.

Non-types: ZMUC P202728 (?, 68.2, identity uncertain), 17°59′N, 64°41′W, 0–~150 m (300 mw), 2355, 12 Aug 1921. ZMUC P202729–30 (?, 67; , 73.4), 19°01′N, 65°23′W, 0–~150 m (300 mw), 0050, 3 Jan 1922. ZMUC P202731 (, 92.2), 17°43′N, 64°56′W, 0–~500 m (1000 mw), 0010, 6 Mar 1922. BMNH 1929.7.6.101 (, 70.0), 15°08′N, 61°31′W, 0–~150 m (300 mw), 2215, 25 Nov 1921. BMNH 1929.7.6.102 (, 71.6), 17°59′N, 64°41′W, 0–~500 m (1000 mw), 1815, 30 Nov 1921. USNM 223964 (, 148.3), 20°10′N, 71°30′W, 0–250 m, 13 Oct 1963. USNM 229981 (, 128.0), 24°24′N, 77°20′W, 0–1526 m, 1758–2300, 20 Apr 1975. UMML 33542 (, 149.0), 24°39′N, 76°31′W, 0–1628 m, 1535–1920, 15 Apr 1975. UMML 33543 (, 118.0), 23°55′N, 77°18′W, 0–1390 m, 0710–1117, 2 Mar 1976. ISH 1074/79 (, 110.3), 25°14′N, 67°45′W, 0–1800 m, 1410–1820, 12 Apr 1979. IOAN uncat. (, 112.2), 20°14′N, 65°09′W, 0–500 m, 31 Jan 1973. VIMS 05738 (, 142), 23°47′N, 75°49′W, 0–1807 m, 1051–1153, 3 Sep 1980.

Eustomias bituberatus Regan and Trewavas, 1930

Eustomias bituberatus Regan and Trewavas, 1930:83 [6 syntypes, the smallest with juvenile characters and considered herein to be E. kreffti].—Beebe and Crane, 1939:211 [no additional specimens].

Eustomias bibulbosus.—Morrow and Gibbs, 1964:391 [part, no additional specimens; E. bituberatus in synonymy].—Blache et al., 1970:171 [part, fig. 459b only].

DIAGNOSIS.—Two terminal bulbs separated by an interspace 1.6%–3.1% SL (1.0–1.9 times length of distal bulb). Barbel very long, 95%–152% SL in specimens over 80 mm SL, 78% at 70 mm. Terminal filament long, up to 25% SL, with 1–3 (usually 2) short branches near the base, these branches with tiny bulblets but without swollen tips. Distal bulb 1.1%–2.0% SL, 1.0–1.7 times length of proximal bulb. Stem axis and external chevron-shaped or roundish striated markings lightly to moderately pigmented. Middorsal paired spots between occiput and dorsal-fin origin 8 or 9.

DESCRIPTION.—The barbel is 78% SL in the smallest specimen (70 mm), increasing continuously to a maximum of 152% SL. All specimens have black pigment in the axis of the stem, between the bulbs, and in at least the proximal part of the filament. The external chevron-shaped or roundish striated areas on the stem are sometimes pigmented, sometimes unpigmented. The proximal and distal bulbs are both ovoid in shape. Both bulbs appear to increase in length only slightly with growth, and to decrease slightly relative to SL. The proximal bulb is 1.6% SL at 70 mm, 0.9%–1.4% in the largest specimens. The distal bulb is 1.6%–2.0% SL in specimens smaller than 90 mm SL, 1.1% in the largest specimen.

The 2 bulbs are equally long in 1 specimen. In all others, the distal bulb is 1.2–1.7 times the proximal-bulb length.

The distance between the bulbs also appears to increase slightly with growth, but to decrease relative to SL, from 3.1% at 70 mm to 1.9% in the largest specimen (133 mm). The distance is 1.0–1.9 times the distal-bulb length.

The terminal filament is 18%–25% SL in 4 specimens 85–117 mm SL. In 3 others, 111–133 mm, the filaments are 11%–15% SL; we did not record whether they appeared broken, but suspect that they were. The filament has 1–3 short branches, with small internal bulblets but without swollen tips, arising not far from the bulb. Tiny bulblets appear to form 2 rows along the filament axis; these bulblets were not observed in all specimens, but they are difficult to discern except under high power and good lighting.

The only 2 identified males, 106 and 117 mm, have very small postorbital organs (0.7% and 0.8% SL, 23% of fleshy orbit in the larger). It is possible that enlargement of their postorbital organs had not yet begun, although males of E. bibulbosus and other species at this size have distinctly enlarged postorbitals.

There are no reports of colors in fresh specimens.

LECTOTYPE DESIGNATION.—We select as lectotype ZMUC P201953, a female, 111.0 mm SL. D 24. A 38. P1 3. P2 7. IP 7. PV 33. VAV 18. OV 32. VAL 19. AC 19. IA 58. IC 77. OA 51. OC 70. VAV photophores over anal-fin base 7. Branchiostegal photophores 11. Premaxillary teeth 12. Mandibular teeth 19. Vertebrae 69.

Measurements (in mm): Predorsal length 95.8; preanal length 81.2, prepelvic length 65.4, head length 14.2, barbel length 139.0, proximal-bulb length 1.4, distal-bulb length 1.4, distance between bulbs 2.2, filament length 12.3 (probably broken), snout length 6.4, fleshy orbit length 4.3, postorbital-organ length 0.6, lower-jaw length 13.5, upper-jaw length 12.0, dorsal-base length 14.5, anal-base length 30.6, longest premaxillary tooth 2.3, longest mandibular tooth 1.2.

SIMILAR SPECIES.—The only other species in which the barbel exceeds SL is bituberoides from the Pacific. In that species the barbel apparently does not increase in length after 100 mm SL, and the range of relative barbel lengths (78%–135% SL) characterizes all sizes; in bituberatus, there appears to be a continuous increase in relative length, and all specimens over 100 mm have barbels exceeding SL. In bituberoides both terminal bulbs and their interspace are smaller than in bituberatus at any size (Figures 7 and 8). Both species apparently have a long terminal filament, but that of bituberoides lacks short proximal branches.

Three similar species occur in the Atlantic. Large (over 100 mm) specimens of bibulbosus and austratlanticus may attain barbel lengths up to 85% SL and may have short branches on the terminal filament. The proximal bulb is smaller in austratlanticus than in bituberatus (0.6%–0.7% SL vs. 0.9%–1.6%), and in the smaller austratlanticus (74 mm) the distal bulb is about half as long as that of similar-sized bituberatus (Figure 7); the distance between the bulbs in the larger austratlanticus (156 mm) is much longer than in any bituberatus (3.4% SL vs. a maximum of 3.1%); and the terminal filament of austratlanticus is shorter in the larger specimen (9% SL) than in intact ones of bituberatus (18%–25%).

It is more difficult to differentiate bibulbosus except by barbel length and the fact that very few bibulbosus have branches on the terminal filament. Both terminal bulbs appear to be smaller in bibulbosus less than 100 mm SL, but there is considerable overlap at larger sizes (Figure 8). The distance between the bulbs tends to be greater in bibulbosus, but there is overlap. The relationship of bulb size to interspace provides a separation; in bituberatus the interspace is 1.5–2.6 times the length of the proximal bulb and 1.0–1.9 times the length of the distal bulb, while in bibulbosus these ratios are 2.3–8.5 and 2.0–7.5, respectively. The postorbital organ of large male bibulbosus and austratlanticus is larger than in the only large males of bituberatus.

The terminal filament of E. micraster has 4 or more short branches near the bulb, and some of these have swollen tips. Its barbel is shorter (maximum 68% SL) than in bituberatus, the distal bulb is smaller at any given size (Figure 7), and the proximal bulb is longer than the distal bulb in specimens over 90 mm SL.

DISTRIBUTION.—Known from the Straits of Florida, the Lesser Antilles, and the oceanic area just east of the southernmost Antilles (Figure 40). A paralectotype from the southern Sargasso Sea may not be this species; it is discussed below.