Review of Nine Species of North Atlantic Eustomias, Subgenus Dinematochirus (Pisces: Stomiidae), with the Description of Two New Species
Abstract
Fourteen species of Eustomias with two pectoral fin rays and short, branched barbels have been described from the North Atlantic, most of them based on single specimens. All but six of these nomimal species have at one time or another been placed in the synonymy of one of the others. Examination of many more specimens indicates that 11 of the 14 are valid species. Two of these have been reviewed previously. Of the nine considered here, Eustomias bigelowi, E. fissibarbis, E. macronema, E. satterleei, and E. schmidti are each represented by numerous specimens from throughout much of the Atlantic and Indo-Pacific. Eustomias binghami, E. paucifilis, E. silvescens, and E. triramis, some still represented by only one or a few specimens, are apparently confined to restricted areas of the North Atlantic. Two new species are described: E. borealis from the North Atlantic and E. curtifilis from the South Atlantic.
Species of the pelagic fish genus Eustomias (Stomiidae) are distinguished primarily by differences in the chin barbel. Regan and Trewavas (1930) erected 10 subgenera based on differences in general barbel features and pectoral and pelvic fin ray counts. Within these subgenera, specific differences were based almost exclusively on details of barbel structure. The subgenus Dinematochirus included species with two pectoral fin rays and relatively short, branched barbels. Between 1914 and 1933, 14 species or subspecies with these characters were described from the North Atlantic; 10 of these were based on single specimens. Pappenheim (1914) described E. fissibarbis, and Welsh (1923) described E. bigelowi. Parr (1927) characterized E. bigelowi as E. b. bigelowi and described E. bigelowi paucifilis, E. bigelowi parvibulbus, E. binghami, and E. nigrifilis. Regan and Trewavas (1930) described E. dendriticus, E. frondosus, E. macronema, E. monoclonus, E. silvescens, E. schmidti, and E. triramis. They raised E. bigelowi paucifilis and E. b. parvibulbus to species rank and relegated E. nigrifilis to the synonymy of E. fissibarbis. Beebe (1933) described E. satterleei.
Beebe and Crane (1939) found that the types of E. bigelowi and E. parvibulbus and a similar specimen from their collections were females and the type of E. paucifilis and a similar specimen from their collections were males. They relegated E. paucifilis to the synonymy of E. bigelowi on the basis of sexual dimorphism. They also relegated E. parvibulbus to the synonymy of E. bigelowi on the basis of barbel similarity. Without examining the type or additional specimens, they further decided that E. triramis was a “growth stage” of E. bigelowi and relegated it also to the synonymy of the latter species. They relegated E. satterleei to the synonymy of E. silvescens on the assumption that the former was the female and the latter the male of the same species. Their basis for matching the pairs of species assumed to be sexual morphs was not given—in spite of rather prominent differences between barbels of the presumed males and females of the same species. Based on reexamination of the holotype of E. binghami, they also relegated E. frondosus to the synonymy of E. binghami. Morrow and Gibbs (1964) restored E. parvibulbus but accepted the remainder of Beebe and Crane's actions and further relegated E. macronema to the synonymy of E. binghami and E. monoclonus to the synonymy of E. dendriticus on the assumption that the differences were sexual or ontogenetic. Most of these actions were taken with few or no new specimens and in some cases without reexamination of the types.
After examination of many more specimens of many species of Eustomias, Gibbs et al. (1983) concluded that sexual and ontogenetic differences in barbels were minor and that most described forms of Eustomias as well as numerous undescribed forms were valid species. In addition to revising the subgenus Nominostomias and describing many new species, they modified the subgeneric scheme of Regan and Trewavas (1930). The subgenus Dinematochirus was expanded to also include species of Eustomias lacking pectoral fin rays. They recognized three species previously relegated to synonymies (E. macronema, E. paucifilis, E. satterleei) as valid but without supporting evidence.
Clarke (1999) concluded that two of the North Atlantic species mentioned above, E. dendriticus and E. monoclonus, were both valid and described several new species that all shared a single barbel character with them. Here, I report on examination of numerous specimens, including most of the holotypes, of the remaining species mentioned above. I conclude that all of these except E. frondosus, E. nigrifilis, and E. parvibulbus are valid and that E. bigelowi, E. fissibarbis, E. macronema, E. satterleei, and E. schmidti occur throughout much of the the Atlantic and Indo-Pacific. I also describe two new Atlantic species, E. borealis and E. curtifilis, which are similar to E. paucifilis. I hope resolution of the ranks of these forms as well as more complete diagnoses and descriptions will eliminate the confusion concerning Dinematochirus species in the Atlantic. A subsequent report will deal with Indo-Pacific Dinematochirus.
Materials and Methods
Methods, definitions, and abbreviations follow those of Gibbs et al. (1983) except for some specific to Dinematochirus given in Clarke (1998). As in Clarke (1998), abbreviations used are SL, standard length (to the nearest millimeter); BL, barbel length from the origin to the distal tip of the terminal bulb exclusive of branches or terminal filaments; “distal barbel,” distance from the origin of branch(es) off the stem to the tip of the terminal bulb; PO, maximum dimension of the postorbital organ; “eye,” diameter of the fleshy orbit (all to the nearest 0.1 mm). All measurements and particularly those of barbel parts require some degree of stretching or straightening, and differences in ratios based upon them must be interpreted conservatively. I assume the barbel is normally carried trailing caudad and that the side closest to the fish is dorsal.
In the Material examined sections, institutional abbreviations are as listed in Leviton et al. (1985). Full collection data are given only for type specimens. For the large numbers of specimens taken southwest of the island of Oahu, Hawaii (21°10–30′N, 158°10–30′W), location is given as “near Hawaii.” For geographical distributions, I have supplemented material examined and literature records with location data for unexamined specimens of E. bigelowi, E. fissibarbis, E. macronema, E. satterleei, and E. schmidti cataloged at USNM, MCZ, and ISH.
Results
All specimens examined share the characters given for Dinematochirus by Gibbs et al. (1983). Furthermore, all have two pectoral fin rays (a third rudimentary ray is often present), seven pelvic fin rays, and barbels with a prominent branch or branches arising dorsally from the main barbel stem well proximal to the terminal bulb (Figs. 1–3). These characters are assumed in the diagnoses and descriptions below. Morphometric and, with few exceptions, meristic characters do not appear to differ among the species included here. The ranges of predorsal, preanal, and mandible lengths (as percentages of SL) are very similar for all species and, overall, fall within the ranges reported for other subgenera of Eustomias (Gibbs et al., 1983; Gomon and Gibbs, 1985). The ranges of dorsal and anal fin ray counts are 20–27 and 37–45, respectively. Ranges of photophore counts for most species are (values representing only one or two individuals in parentheses): BR 10–14, IP 7, PV (26)27–31, VAV 12–17, OV 27–31(32), VAL 13–17, and AC 19–23. Anal fin ray counts for E. fissibarbis, 37–39, are at the lower end of the overall range but still overlap with those of several other species. PV and OV photophores for E. binghami (both 24–26) are below the ranges of the other species. Eustomias schmidti occasionally has eight IP photophores, and the posteriormost pair are much more closely spaced than the anterior five or six. Otherwise, the ranges of both morphometric and meristic characters for individual species represented by more than four individuals were similar to or only slightly narrower than the overall figures. The ventral groove extends from the isthmus to PV photophore 3–10 overall. The individual species' ranges differ somewhat (see accounts below) but usually overlap those of several other species.
Citation: Ichthyology & Herpetology 2000, 1; 10.1643/0045-8511(2000)2000[0096:RONSON]2.0.CO;2
The following artificial key, based on barbel characters, distinguishes all described Atlantic species of Dinematochirus with two pectoral fin rays except those of the E. dendriticus species group (Clarke, 1999). Particularly in the relatively poorly sampled South Atlantic, undescribed forms may well be present. (Species with branched barbels but lacking pectoral fin rays are reported in Clarke, 1998. Otherwise, Eustomias lacking pectoral fin rays are currently recognized as E. lipochirus.)
- 1A.
Terminal bulb with a single pair of laterally based terminal filaments (tiny and inconspicuous in some species) . . . E. dendriticus species group (Clarke, 1999)
- 1B.
Terminal bulb either without filaments or with at least one medially based filament (paired lateral filaments may also be present . . . 2
- 2A.
Terminal bulb pigmented only on ventral surface, pigment reaching to or almost to bulb tip (not clear in some large females with very small bulbs); lateral branches relatively simple, uniramous . . . E. bigelowi Welsh
- 2B.
Terminal bulb either lacking external pigment or at least some of its dorsal surface pigmented; lateral branches variable, relatively simple only in combination with pigment on dorsal surface of terminal bulb . . . 3
- 3A.
Lateral branches arising from medial branch well distal to origin of latter from barbel stem . . . E. fissibarbis (Pappenheim)
- 3B.
Lateral branches arising from stem together medial branch or arising from medial branch immediately distal to the medial origin . . . 4
- 4A.
Terminal bulb occupying most of distal barbel, unpigmented externally, tightly constricted distally . . . E. schmidti Regan and Trewavas
- 4B.
Terminal bulb length less than half distal barbel or, if greater, with pigment on dorsal surface, not tightly constricted distally . . . 5
- 5A.
Terminal bulb more or less spheroidal, its length less than twice its thickness . . . 6
- 5B.
Terminal bulb elongate, its length greater than twice its thickness . . . 11
- 6A.
Distal barbel unpigmented except for small internal dots in stem or small patches or lines on terminal bulb . . . 7
- 6B.
Distal barbel stem and dorsal surface of terminal bulb pigmented externally . . . 10
- 7A.
Terminal bulb unpigmented; terminal filament single . . . E. silvescens Regan and Trewavas
- 7B.
Terminal bulb with small streaks or patches of pigment on dorsal surface; a pair of laterally based terminal filaments and one or more medial terminal filaments present . . . 8
- 8A.
Pigment on terminal bulb limited to irregular streaks more or less outlining internal ovoid bodies . . . E. borealis new species
- 8B.
A pair of solid patches of pigment on proximo-dorsal surface of terminal bulb . . . 9
- 9A.
Terminal filaments longer than bulb; bulb pigment patches separated by a row of protruding ovoid bodies . . . E. paucifilis Parr
- 9B.
Terminal filaments shorter than or barely longer than bulb; bulb pigment patches not separated by a row of ovoid bodies . . . E. curtifilis new species
- 10A.
Distal boundary of bulb pigment jagged, typically forked dorsally; branches typically longer than distal barbel; terminal filament conspicuous, simple to complex . . . E. satterleei Beebe
- 10B.
Distal boundary of bulb pigment smooth; branches shorter than distal barbel; terminal filament absent or simple, inconspicuous . . . E. triramis Regan and Trewavas
- 11A.
Three branches off stem; medial branch much shorter than lateral branches, not reaching barbel tip; bulb with several terminal filaments . . . E. binghami Parr
- 11B.
Five branches off stem; medial branch nearly equal to or longer than lateral branches; bulb with a single terminal filament . . . E. macronema Regan and Trewavas
Eustomias bigelowi Welsh, 1923 Figures 1, 4
Citation: Ichthyology & Herpetology 2000, 1; 10.1643/0045-8511(2000)2000[0096:RONSON]2.0.CO;2
Eustomias bigelowi Welsh, 1923:6–7, figures 5–6 (holotype and paratype; North Atlantic). Regan and Trewavas, 1930:98, figure 85 (North Atlantic). Beebe, 1937:199 (Bermuda). Beebe and Crane, 1939:213 (synon.), 225, figure 74A (Bermuda). Morrow and Gibbs, 1964:396 (in part, type specimens only). Gibbs et al., 1983:11 (inclusion in Dinematochirus). Clarke, 1987:64 (central Pacific).
Eustomias bigelowi bigelowi Parr, 1927:77–79.
Eustomias bigelowi parvibulbus Parr, 1927:77–79, figure 46 (type, North Atlantic). Beebe and Crane, 1939:213,225 (synon. of E. bigelowi).
Eustomias parvibulbus Regan and Trewavas, 1930:98 (elevation to species rank). Morrow and Gibbs, 1964:421, figure 126 (restor. from synon. of E. bigelowi).
Eustomias sp. 2 Parin and Pokhilskaya, 1974:336, figure 10b (in part, Vitiaz 6493/617 and Tamango 27 only, North Pacific).
Diagnosis
Barbel with a medial branch arising from stem and a pair of lateral branches arising either together with medial (Atlantic) or from medial distal to its origin (Pacific); medial branch terminating in a bulblet or rounded tip with tiny filaments; lateral branches tapering, ending in filamentous tips (little more than short filaments in some Pacific specimens); barbel stem pigment extending onto ventral surface of terminal bulb; terminal bulb protruding mostly dorsad, three to five medial terminal filaments on distal end of bulb; smaller paired lateral filaments, simple to lanceolate, on either side of medial filaments and proximally on both pigmented and unpigmented sections of bulb.
Description
BL 9.2–15.7% of SL, branches arising at 33–50% of BL. Medial branch slender to almost as thick as stem; its length 39–105% of distal barbel. Lateral branch lengths 75–200% of distal barbel in Atlantic specimens, 10–65% in Pacific specimens, approximately 70% in the single, slightly damaged Indian Ocean specimen. Lateral branches arising at 6–47% of length of medial branch in Pacific specimens. Entire stem, proximal portions of branches, and ventral surface of terminal bulb solidly pigmented. Terminal bulb protruding mostly dorsad; its dorsal edge rounded to conical in lateral profile; its length 1.1–1.7 times its thickness and 35–50% of distal barbel (12–20% in three large females); thickness ranging from only slightly larger than to about four times diameter of distal portion of stem. Bulb with a distal row of three to five medial filaments; the longest 40–150% of distal barbel (about 200% in large females); shorter, simple to lanceolate paired filaments on either side of medials and proximally on the bulb.
Premaxillary teeth 8–13; mandibular teeth 12–17 (8–11 in seven specimens < 71 mm SL). Ventral groove extending to PV 4–6 in most specimens (3 in two and 7 in one). PO/eye 66–113% in eight apparently mature males 96–135 mm SL; 60% in a 79 mm nearly mature male; 20–35% in females and unsexed juveniles. A 198 mm female with vitellogenic oocytes 0.7 mm in diameter; three females 138–158 mm with vitellogenic oocytes 0.2–0.3 mm in diameter; six females 100–147 mm SL with only small previtellogenic oocytes.
Comments
As noted by Parr (1927), the holotype of E. bigelowi has been dried. Initially, its barbel does not appear to resemble the original illustration (Welsh, 1923). All three branches are twisted and stuck together as are the terminal filaments, which are also stuck to the bulb; the pigment on the distal section of the stem has faded; and the bulb shape has distorted.
The terminal bulb of E. bigelowi varies in size and shape, but for the most part, variation is unrelated to size or geography. For example, differences between the two Atlantic specimens illustrated by Regan and Trewavas (1930, fig. 85) are seen also among specimens from near Hawaii. The bulbs of three large Atlantic females (139 mm, 158 mm, and the 198 mm SL type of E. bigelowi parvibulbus) are, however, distinctly relatively shorter (bulb lengths are 12–20% of distal barbel vs 35–50% in all other specimens) and barely thicker than the distal stem. The small bulb was the original basis for recognizing E. parvibulbus as a separate species, but, since no small specimens of either sex have similarly reduced bulbs, it appears that relative size of the bulb decreases with growth above approximately 125–150 mm SL—sizes reached only by females.
For two of the above females and another (144 mm SL) with a “normal” bulb, the lateral branches are about twice the length of the distal barbel (vs a maximum of 1.5 times in other specimens), and the medial terminal filaments are also much longer (relatively) and much more ornate than in the other specimens. These differences also apparently result from allometry in barbel growth that becomes apparent only at lengths of over approximately 125–150 mm.
All Atlantic E. bigelowi have lateral branches that arise from the stem with the medial branch and reach almost to or beyond the barbel tip. There are usually only three prominent medial terminal filaments with one or two more medial filaments and a few pairs of much less prominent lateral filaments. In Pacific specimens, the lateral branches arise from the medial branch at varying distances from the stem and their relative lengths vary from nearly as long as in the Atlantic specimens to much shorter filaments. The medial branch also tends to be relatively shorter and often stouter than in Atlantic specimens. The medial terminal filaments of the Pacific specimens tend to be less prominent than in those from the Atlantic and the paired lateral filaments more numerous and often nearly as prominent as the medial filaments.
The significance of many of these differences is equivocal because of the difference in size composition of available specimens from the Atlantic and Pacific Oceans and the near absence of material from the Indian Ocean. Two-thirds of the Pacific specimens are less than 100 mm SL, and about a third of the Atlantic specimens are larger than the largest one from the Pacific. Furthermore, some of the large Pacific specimens, for example Parin and Pokhilskaya (1974, fig. 10b), more closely resemble Atlantic specimens than do most of the smaller Pacific specimens. Thus some of the differences in branch and terminal filament development could be due to slight differences in ontogenetic pattern of barbel development. The differences in origin of the lateral branches and in terminal filament arrangement are, however, more qualitative. The single specimen from the Indian Ocean is small and possibly incompletely developed, but it appears to be intermediate between Atlantic and Pacific forms in that the lateral branches are relatively long and arise from the medial branch only a very short distance distal to the stem and that the terminal filaments appear to be more like those of Atlantic specimens.
Distribution
Known from the western North Atlantic within roughly 20–35°N and 35–90°W, the South Atlantic within 0–25°S and 0–30°W, near Hawaii and south of the equator in the eastern Pacific, a few scattered records in the western Pacific, and one from the western Indian Ocean.
Material examined
Nine males, 79–135 mm; 12 females, 88–198 mm; 24 sex undet., 52–134 mm: Holotype: USNM 84284, sex undet., 102 mm, “170 miles southeast from Cape Hatteras.” Paratype: USNM 103767, sex undet., 82 mm, “120 miles east-southeast from Cape Hatteras.” Nontypes: (Atlantic) BOC 2096 (type of E. bigelowi parvibulbus), female, 198 mm, 22°31′N, 74°26′W; USNM 230067, male, 101 mm, 24°28′N, 76°57′W; USNM 261291, male 96 mm, female 138 mm, 32°22′N, 64°04′W; USNM 261292, male, 135 mm, 31°50′N, 64°08′W; USNM 261293, male, 110 mm, 32°14′N, 64°20′W; USNM 261296, female, 144 mm, 32°26′N, 64°10′W; AMNH 44222, female, 101 mm, 32°12′N, 64°36′W; FMNH 76660, sex undet., 68 mm, 28°58′N, 88°18′W; ISH 23-1979, sex undet., 60 mm, 25°37′N, 64°56′W; ISH 676-1966, female, 139 mm, 13°31′S, 28°09′W; ISH 755-1966, male, 109 mm, female, approximately 100 mm, sex undet., 88 mm, 21°00′S, 30°00′W; ISH 889-1968, female, 129 mm, 3°00′S, 26°16′W; ISH 1192-1968, sex undet., 70 mm, 21°02′S, 30°05′W; ISH 1268-1968, sex undet., 68 mm, 23°26′S, 33°30′W; ISH 1676-1971, male, 119 mm, 21°35′S, 2°00′W; ISH 2162-1971, female, 147 mm, 2°29′S, 18°58′W. (Pacific, near Hawaii) USNM 317495, male, 103 mm; USNM 322659, male, 125 mm; USNM 322660, sex undet., 63 mm; USNM 322661, sex undet., 66 mm; USNM 322662, sex undet., 64 mm; USNM 322666, 2 sex undet., 60–66 mm. USNM 322668, sex undet., 71 mm; USNM 322670, sex undet., 58 mm; Univ. Hawaii, uncataloged, Kana Keoki St. 78-3-4, sex undet., 78 mm. (Other Pacific) USNM 256880, male, 79 mm, 17°25′N, 157°25′W; USNM 321963, female, 96 mm, 4°56′S, 129°41′E; USNM 321964, sex undet., 68 mm, 5°00′S, 129°48′E; USNM 322091, sex undet., 52 mm, 4°57′S, 129°51′E; USNM 322092, female, 88 mm, 4°39′S, 129°54′E; USNM 322093, sex undet., 65 mm, 4°56′S, 129°36′E; USNM 322096, sex undet., 67 mm, 24°31′N, 157°50′W; SIO69-342, sex undet., 62 mm, 17°42′S, 110°20′W; SIO73-169, female, 122 mm, 0°07′S, 155°4′W; BPBM 26299, sex undet., 76 mm, 8°45′S, 150°,59′W; IOAN, uncataloged, Vitiaz St. 6493/617, sex undet., 123 mm, 13°03′N, 139°58′E; IOAN, uncataloged, Tamango St. 27, sex undet., 134 mm, 16°17′N, 129°06′E. (Indian) SIO69-24, sex undet., 71 mm, 17°04′S, 67°08′E.
Eustomias fissibarbis (Pappenheim), 1914
Neostomias fissibarbis Pappenheim, 1914:175–176, figures 4, 5 (type, North Atlantic).
Citation: Ichthyology & Herpetology 2000, 1; 10.1643/0045-8511(2000)2000[0096:RONSON]2.0.CO;2
Eustomias fissibarbis Parr, 1927:81. Regan and Trewavas, 1930:73 (type species of Dinematochirus), 103–104, figure 94 (North Atlantic, Caribbean, Gulf of Mexico, Florida Straits). Beebe, 1937:199 (Bermuda). Beebe and Crane, 1939:213, 232. Morrow and Gibbs, 1964:409 (Bermuda). Parin et al., 1974:90 (South Atlantic). Parin and Pokhilskaya, 1974:334–336, figure 10a (New Guinea). Bekker et al., 1975:304 (Caribbean). Parin, 1976:198 (same spec. as Parin and Pokhilskaya, 1974). Parin et al., 1977:98 (western Pacific). Gibbs et al., 1983:11 (inclusion in Dinematochirus).
Eustomias nigrifilis Parr, 1927:81–83, figure 49 (type, North Atlantic). Regan and Trewavas, 1930:103 (synon. of E. fissibarbis). Beebe and Crane, 1939:213 (reexam. type).
Diagnosis
Barbel with a single-based branch arising from the stem; a pair of bifurcate lateral branches arising from medial branch well distal to its origin; medial branch prominent and extending well beyond origin of laterals, with a small bulblet at distal end; terminal bulb with both medial and laterally paired, relatively simple terminal filaments, their lengths less than 50% of distal barbel.
Description
BL 15–21% of SL, branch arising at 48–64% of BL. Medial branch with terminal bulblet bearing a group of filaments which themselves may have terminal ovoid bodies; its length (from stem, exclusive of distal filaments) 14–28% of distal barbel, distal filaments 20–64% of medial branch length. Lateral branches bifurcate, bearing smaller side filaments and often small ovoid bodies, arising at 15–28% of length of the medial branch, their lengths 86–113% of distal barbel. Barbel stem solidly pigmented, pigment extending up to proximal half of terminal bulblet of medial branch, and over proximal third to half of the terminal bulb. Terminal bulb length 2.0–2.5 times its thickness and about 30–50% of distal barbel. Longest terminal filament 18–47% of distal barbel. (Barbel, branch, and filament lengths relatively less in individuals less than 60–65 mm SL.)
Premaxillary teeth 7–12; mandibular teeth 9–13. Ventral groove extending to PV 6–7 (rarely 8 or 9). PO/eye 24% and 43% in two females 144 and 145 mm SL; 83% in apparently mature males 101 and 117 mm, and ≤ 30% in specimens ≤ 100 mm. The two large females with vitellogenic oocytes about 0.15 and 0.50 mm in diameter, respectively.
Distribution
Known from most of the Atlantic between roughly 35°N and 27°S, near Hawaii and just south of the equator in the eastern Pacific, several stations in the western Pacific north of the equator, and the southwestern Indian Ocean.
Material examined
Two males, 101–117 mm; five females, 78–145 mm; 14 sex undet., 46–100 mm: Nontypes: (Atlantic) ISH 1875–1979, sex undet., ca. 100 mm, 30°45′N, 46°08′W. (Pacific, near Hawaii) USNM 257256, 2 sex undet., 60–63 mm; USNM 317507, sex undet., 62 mm; USNM 322779, sex undet., 68 mm; USNM 322781, male, 117 mm; USNM 322784, female, 89 mm; USNM 322787, female, 145 mm; USNM 322788, sex undet., 63 mm; USNM 322815, female, 78 mm; USNM 322816, female, 79 mm; USNM 322857, sex undet., 63 mm; USNM 322858, sex undet., 71 mm; USNM 323525, female, 144 mm; BPBM 37777, male, 101 mm. (Other Pacific) USNM 322094, sex undet., 75 mm, 3°18′N, 124°10′E; USNM 322782, sex undet., 63 mm, 3°16′S, 145°02′W; ZUMC P202720, sex undet., 79 mm, 1°42′N, 124°29′E; NSMT P49519, sex undet., 70 mm, 12°N, 140°E; NSMT P49528, sex undet., 61 mm, 23°N, 150°E. (Indian) USNM 201010, sex undet., 46 mm, 10°01′S, 64°19′E.
Eustomias schmidti Regan and Trewavas, 1930
Eustomias schmidti Regan and Trewavas, 1930:100–101, figures 89, 90 (3 syntypes, North Atlantic). Beebe, 1937:199 (Bermuda). Beebe and Crane, 1939:230–232 (no additional specimens). Grey, 1955:282 (Bermuda). King and Iversen, 1962:319 (central Pacific). Morrow and Gibbs 1964:424–425 (no additional specimens). Gibbs, 1971:241 (Bermuda). Parin et al., 1973:20 (southeastern Pacific). Parin and Pokhilskaya, 1974:332–333 (New Guinea, southeast of Japan). Bekker et al., 1975:304 (Caribbean). Parin, 1976:198 (western Pacific). Parin et al., 1977:98 (western Pacific). Parin, 1978:159 (New Guinea). Gibbs et al., 1983:11 (inclusion in Dinematochirus). Swinney, 1990:3 (Madeira).
Diagnosis
Barbel with three branches arising from stem; medial branch stout, bulbous and with distal filaments, barely reaching to barbel tip; lateral branches tapering, extending well beyond end of barbel (except in small specimens); terminal bulb unpigmented and elongate, occupying most of distal barbel, tightly constricted distally into spheroidal terminal section; terminal filament or single-based group of filaments arising ventrally from constriction.
Description
BL 13.5–18.1% of SL; branches arising at 45–64% of BL. Medial branch length (exclusive of distal filaments) 25–37% of distal barbel; distal filaments roughly twice the branch's length and often reaching slightly beyond barbel tip. Lateral branch lengths 133–230% of distal barbel (less than distal barbel in some specimens less than 70 mm SL and 540% in a 186 mm female). Stem solidly pigmented up to terminal bulb, branches unpigmented except near junction with stem. Bulb length 3.2–4.3 times its thickness and 68–76% of distal barbel; constriction at approximately 75–80% of its length. Terminal filament single or a single based group, often with small side filaments; its length 50–100% of distal barbel except in some individuals less than 75 mm SL.
Premaxillary teeth 8–13; mandibular teeth 9–14. Ventral groove extending to PV 4–6. PO/eye 22–30% in four females (111–186 mm SL) and 50–78% in five males (85–113 mm SL), 47% in an unsexed specimen 74 mm SL, and 17–33% in the remaining unsexed specimens (66–82 mm SL). The three largest females (144–186 mm SL) with vitellogenic oocytes 0.2–0.5 mm in diameter; a 111 mm female with previtellogenic oocytes. The largest male (113 mm) apparently mature; four others 85–103 mm nearly mature.
Distribution
Known from the Atlantic and Pacific between 35–40°N and 30–35°S, primarily in boundary currents or equatorial waters; generally absent from central gyres.
Material examined
Five males, 85–113 mm; six females, 111–186 mm; 19 sex undet., 60–89 mm: Syntype: ZMUC P201973, sex undet., 68 mm, Dana St. 1010, 31°06′N, 41°45′W, 150 m wire out. Non-types: (Atlantic) FMNH 66626, sex undet., 82 mm, 28°33′N, 88°48′W; ARC 8600353, female, 132 mm, 37°39′N, 72°19′W; ARC 8704159, sex undet., 86 mm, 39°44′N, 56°59′W; ARC 8706466, female, 137 mm, 39°41′N, 56°30′W; ARC 8706881, sex undet., 89 mm, 39°7′N, 55°16′W. (Pacific) USNM 201702, sex undet., 69 mm, 31°06′N, 135°13′W; USNM 292248, sex undet., 80 mm, 17°33′S, 148°47′E; USNM 292831, 2 females, 164–186 mm, 31°N, 135°W; USNM 292832, 2 sex undet., 61–66 mm, 11°50′N, 144°48′W; USNM 292833, sex undet., 66 mm, 3°16′S, 145°02′W; USNM 292865, sex undet., 74 mm, near Hawaii; USNM 292901, 2 sex undet., 63 mm, 11°49′N, 144°51′W; USNM 292902, male, 99 mm, 2 sex undet., 74 mm, 11°53′N, 144°48′W; AMS I20315-019, female, 144 mm, 33°53′S, 152°02′E; AMS I20872-004, male, 113 mm, 36°31′S, 151°23′E; AMS I21365-011, 2 males, 99–103 mm, 33°09′S, 153°05′E; AMS I27168-002, sex undet., 86 mm, 32°06′S, 169°21′E; NSMT P49520, sex undet., 71 mm, 23°N, 150°E; NSMT P49524, sex undet., 60 mm, 23°N, 150°E; NSMT P49525, sex undet., 62 mm; 23°N, 150°E; BPBM 37778, male, 85 mm, 8°45′N, 158°01′W; NMFSH, uncataloged, Townsend Cromwell St. 88-050145, female, 111 mm, 31°01′N, 175°53′E; Univ. Hawaii, uncataloged, sex undet., 71 mm, Kana Keoki St. 780104, 9°29′N, 150°W.
Eustomias silvescens Regan and Trewavas, 1930 Figure 5
Eustomias silvescens Regan and Trewavas, 1930:100, figure 88 (type, eastern Caribbean). Beebe and Crane, 1939:213,228–230, fig. 75C (in part, type of E. silvescens only). Morrow and Gibbs, 1964:425–426 (in part, type of E. silvescens only). Gibbs et al., 1983:11 (inclusion in Dinematochirus).
Diagnosis
Barbel with three branches arising together from stem; barbel stem pigmented only up to origin of branches; distal stem pigmented only on axis; terminal bulb spheroidal, without pigment or internal structures, bearing a single, simple terminal filament.
Description
BL 11.2% of SL, branches arising at 40% of BL. Medial branch length 3.5 times distal barbel; proximal section as thick as stem, packed with large internal ovoid bodies and bearing prominent bulblets some of whose diameters are equal to that of the branch; distal section tapering and with numerous beaded side filaments. Lateral branch lengths 2.3 times distal barbel; bifurcate just distal to origin, both rami stout proximally and bearing bulblets, distal portion of longer ramus tapering and with many beaded side filaments. Barbel stem pigmented up to origin of branches, only axis of distal portion pigmented. Terminal bulb spheroidal with small indentation distally, no pigment or internal structures visible; bulb length 1.2 times its thickness and 31% of distal barbel. Terminal filament with internal ovoid bodies; its length 20% of distal barbel.
Premaxillary teeth 11; mandibular teeth 15. Ventral groove extending to PV 7. PO/eye 80% in the only known specimen, an apparently mature male 110 mm SL.
Comments
The illustration of the holotype by Regan and Trewavas (1930) is accurate except that the spheroidal bulblets arising from the proximal end of the medial branch are equal in diameter to the branch rather than smaller as illustrated.
Distribution
Known only from the eastern Caribbean.
Material examined
Holotype: ZMUC P201910, male, 110 mm, Dana St. 1266, 17°45′N, 64°55′W, 800 m wire out.
Eustomias borealis new species Figures 2B, 5
Citation: Ichthyology & Herpetology 2000, 1; 10.1643/0045-8511(2000)2000[0096:RONSON]2.0.CO;2
Eustomias bigelowi Beebe and Crane, 1939:213, 225, figure 74A (in part, male from Bermuda only). Grey, 1955:282, figure 49 (Bermuda). Morrow and Gibbs, 1964:396 (in part, above two specimens only).
Eustomias paucifilis Beebe, 1937:199 (Bermuda). Beebe and Crane, 1939:213, 225 (in part, male from Bermuda only, synon. of E. bigelowi).
Diagnosis
Barbel with three branches arising together from stem; barbel stem pigmented only up to origin of branches; distal stem pigmented only in axis and small internal spots; terminal bulb roughly spheroidal with short streaks of pigment on the dorsal surface roughly outlining numerous unpigmented ovoids visible internally; ovoids not protruding above bulb surface; a single pair of laterally based terminal filaments on the dorsal tip of bulb and two or three medial filaments ventral to them; the dorsal pair longer, usually thicker, and with more side filaments than the medial filaments.
Description
BL 12.1–14.7% of SL (9.8% in a 51 mm specimen), branches arising at 27.5–34.0% of BL. Medial branch length 33–73% of distal barbel in specimens 51–143 mm SL and 174% in a 165 mm female; pigment present only in axis of proximal portion, stout side filaments arising from proximal section, slender beaded filaments from distal. Lateral branch lengths 38–61% of distal barbel (139% in the largest specimen); bifurcate and simpler in structure than medial, but with several side filaments distally. External pigment on stem extending only to the origin of the branches, internal small dots and axis pigmented in distal portion. Bulb length 90–125% its thickness and 19–27% of distal barbel. A pair of bifurcate terminal filaments dorsally and two or three medial filaments ventrally; the paired lateral filaments longest; their lengths 38–61% of distal barbel.
Premaxillary teeth 11–14 (9 in one specimen); mandibular teeth 13–19. Ventral groove extending to PV 5–7 (6 in most). PO/eye 71–86% in three males 133–143 mm SL; 21–30% in females, smaller males, and undetermined juveniles. The largest female, 165 mm, with small previtellogenic oocytes; two other females, 102 and 128 mm immature; four males 113–143 mm apparently mature.
Etymology
An adjective from Latin referring to the northerly distribution pattern of this species.
Distribution
Known from the western North Atlantic north of 30°N.
Material examined
Five males, 95–143 mm; three females, 102–165 mm; two sex undet., 51–75 mm: Holotype: USNM 261281, male, 138 mm, Acre St. 12-83N, 32°13′N, 64°16′W, 0–950 m. Paratypes: USNM 322914, female, 165 mm, Anton Dohrn St. 256/79, 30°27′N, 66°08′W, 0-1800 m; USNM 322917, male, 143 mm, Anton Dohrn St. 323/79, 31°55′N, 42°46′W, 0–300 m; AMNH 44217, male, 133 mm, 32°12′N, 64°36′W; FMNH 49859, female, 102 mm, Caryn St. 39, 32°10′N, 64°38′W, 200 m; MCZ 96093, female 128 mm, Knorr-58 St. JEC7632, 38°55′N, 72°28′W, 0–750 m; MCZ 96112, sex undet., 75 mm, Knorr-65 St. MOC10-34.2, 36°37′N, 66°41′W; ARC 8704341, male, 95 mm, 39°52′N, 63°47′W. Nontypes: USNM 261289, male, 113 mm, 32°14′N, 64°14′W; MCZ 56682, sex undet., 51 mm, 35°43′N, 67°21′W.
Eustomias paucifilis Parr, 1927 Figures 2A, 5
Eustomias bigelowi Morrow and Gibbs, 1964:396 (in part, type of E. paucifilis only).
Eustomias bigelowi paucifilis Parr, 1927:77–79, figure 45 (type, Bahamas).
Eustomias paucifilis Regan and Trewavas, 1930:99, figure 87 (North Atlantic). Beebe and Crane, 1939:213 (in part, type of E. paucifilis only, synon. of E. bigelowi). Gibbs et al., 1983:11 (inclusion in Dinematochirus).
Diagnosis
Barbel with three branches arising together from stem; barbel stem pigmented only up to origin of branches; distal stem pigmented only on axis and small internal spots; terminal bulb roughly spheroidal with a pair of prominent irregularly shaped patches of pigment on proximal dorsal surface; two to six unpigmented ovoids or “beads” medially between pigment patches, often protruding above pigmented surface; a single pair of laterally based terminal filaments on dorsal tip of bulb; two medial filaments ventral to lateral filaments; ventralmost medial filament usually longer or more ornate than lateral filaments.
Description
BL 9.3–13.6% of SL; branches arising at 25–31% of BL. Medial branch with many side filaments along most of its length; pigment present only on axis of proximal portion; its length 71–114% of distal barbel in specimens 66–124 mm SL, 56% in a 58 mm specimen, and 230–300% in three females 139–169 mm. Lateral branches bifurcate but otherwise simpler in structure than medial branch with only a few side filaments distally; their lengths 54–150% of distal barbel; relatively longest in large specimens. Barbel stem pigmented up to origin of branches, only small internal dots and axis of distal portion pigmented. Bulb length 75–125% its thickness and 16–32% of distal barbel. The dorsal pair of terminal filaments bifurcate but otherwise simpler in structure than medial filaments which bear several side filaments; ventralmost medial filament usually longest and stoutest; its length 50–85% of distal barbel.
Premaxillary teeth 9–14; mandibular teeth 10–17. Ventral groove extending to PV 5–6. PO/eye 88% in 124 mm SL male; 26–42% in 10 females and undetermined juveniles. Two females, 168 and 169 mm SL, with vitellogenic ooctyes 0.4 and 0.2 mm in diameter, respectively; four females 96–139 mm with only small previtellogenic oocytes; the sole male apparently mature.
Distribution
Known from the western and central Atlantic from about 12–32°N and 36–86°W.
Material examined
One male, 124 mm; six females, 96–169 mm; four sex undet., 58–82 mm: Holotype: BOC 2095, male, 124 mm, Pawnee St. 11, 23°58′N, 77°26′W, “7000 feet wire.” Nontypes: USNM 216280, female, 139 mm, 32°32′N, 64°04′W; USNM 270602, sex undet., 82 mm, “Bahamas”; USNM 278266, female, 169 mm, 27°N, 86°W; USNM 278267, female, 100 mm, 27°N, 86°W; USNM 322913, female, 116 mm, 23°46′N, 58°59′W; USNM 337550, 2 females, 96 and 168 mm, 25°08′N, 67°34′W; MCZ 96113, sex undet., 58 mm, 23°02′N, 45°08′W; ZMUC P201874, sex undet., 68 mm, and P201875, sex undet., 66 mm, 12°11′N, 35°49′W.
Eustomias curtifilis new species Figures 2C, 4
Diagnosis
Barbel with three branches arising together from stem; barbel stem pigmented only up to origin of branches; distal stem pigment only in axis and small internal spots; terminal bulb roughly spheroidal with a bilobed, reticulated patch of pigment on proximal dorsal surface; no unpigmented ovoids associated with bulb pigment; terminal filaments short and simple, a single laterally based pair on the dorsal tip of bulb and one or two medial filaments ventrad of these.
Description,
BL 10.3–12.0% of SL (7.5% in a metamorphoric 56 mm specimen), branches arising at 31.0–37.7% of BL. Medial branch length 210–260% of distal barbel; pigment present only in axis of proximal portion of branch, a prominent bulblet at the end of pigmented section with two or three stout side branches arising from the branch; distal section of medial branch relatively simple, beaded internally and with a few slender beaded side filaments. Lateral branch lengths 72–89% of distal barbel; branches simple with small bifurcation and only a few small side filaments distally. Bulb length 1.45–1.7 times its thickness and 24–35% of distal barbel. Terminal filament lengths 20–35% of distal barbel, with few or no side filaments. (Relative lengths of branches and filaments are much less in a 56 mm specimen.)
Premaxillary teeth (8)10–11; mandibular teeth (8)15–16. Ventral groove extending to PV 4–5. PO/eye 27–36% in two females and two unsexed juveniles. The largest female, 166 mm SL, with vitellogenic oocytes 0.5 mm in diameter; the 97 mm female with only small previtellogenic oocytes.
Etymology
A compound adjective from Latin referring to the short terminal filaments of this species.
Distribution
Known from the South Atlantic between 17–21°S and 28–30°W.
Material examined
Two females, 97–166 mm; two sex undet., 56–84 mm: Holotype: ISH 714–1966, female, 166 mm, Walther Herwig St. 190/66, 17°36′S, 28°53′W, 160–660 m. Paratypes: USNM 355575, female, 97 mm and ISH 756–1966, sex undet., 84 mm, both Walther Herwig St. 191/66, 21°00′S, 30°00′W, 120–200 m. Nontype: ISH 2186–1968, sex undet., 56 mm, 21°04′S, 30°08′W.
Eustomias satterleei Beebe, 1933 Figures 3A–B, 4
Citation: Ichthyology & Herpetology 2000, 1; 10.1643/0045-8511(2000)2000[0096:RONSON]2.0.CO;2
Eustomias satterleei Beebe, 1933:164–166, fig. 3 (type, Bermuda). Beebe, 1937:199 (listing of type). Beebe and Crane, 1939: 213, 228–230 (synon. of E. silvescens). Gibbs et al., 1983:11 (inclusion in Dinematochirus). Clarke, 1987:64 (central Pacific).
Eustomias silvescens Beebe and Crane, 1939:213,228–230, figure 75A,B (in part, type of E. satterleei only). Morrow and Gibbs, 1964:425–426 (in part, type of E. satterleei only). Clarke, 1982:297 (Hawaii).
Eustomias bigelowi? Parin et al., 1977:100 (North Pacific).
Diagnosis
Barbel with three branches arising from stem; medial branch shorter than lateral branches but all similar in structure; external pigment present on barbel stem and dorsal surface of terminal bulb except for unpigmented tip; distal boundary of pigment irregular and forked dorsally; terminal bulb with a single or a single-based group of three to six terminal filaments near distal tip.
Description
BL 9.2–16.1% of SL, (most values 11–14%); branches arising at 32–48% of BL. Medial branch length 55%–150% of distal barbel (most values over 75%); lateral branch lengths 90–275% of distal barbel (most values over 150%). (Relative barbel or branch lengths less in some specimens less than 70 mm SL.) Branches pigmented only in proximal part of axis or externally near junction with main stem, internal ovoid bodies and side filaments present, usually numerous and prominent, occasionally few and barely visible. Terminal bulb ovoid to spheroidal, often irregular in shape, its length about twice its thickness and usually slightly less than half distal barbel, occasionally shorter and barely thicker than distal stem. Longest terminal filament 10–50% of distal barbel, most values 10–30%.
Premaxillary teeth 9–14, mandibular teeth 12–18. Ventral groove extending to PV 5–9 (6–7 in most). PO/eye 75–103% in six apparently mature males 132–152 mm SL; 46% in an immature male 118 mm; 26–42% in 11 females 119–170 mm; 17–37% in unsexed juveniles ≤ 110 mm. Seven females 133–177 mm with vitellogenic oocytes 0.2–0.7 mm in diameter; four females 119–166 mm with smaller, previtellogenic oocytes.
Comments
Barbels of Eustomias satterleei vary in branch length and complexity; size, shape, and pigmentation of the terminal bulb; and number of terminal filaments. Branches range from almost simple with a single, barely visible internal ovoid body in each to complex with many, often ornate, side filaments and rows of prominent internal ovoid bodies. The thickness of the terminal bulb ranges from only slightly greater than that of the stem to over two times greater. Although external pigment usually extends almost to the tip dorsally, the dorsal boundary is occasionally closer to the proximal end of the bulb. Ventrally the pigment typically extends about to the point where the bulb diameter exceeds that of the stem, but in some specimens it terminates on the stem a few millimeters proximal to the bulb.
The variability in branch length, bulb shape and pigmentation and number of terminal filaments is not obviously related to size, sex, or geography and may simply reflect the large number and broad size range of specimens available from this wide-ranging species. In most cases, only one of the above features deviated strongly from the norm. Six Indo-Pacific specimens (two unsexed 70–79 mm SL and four females 118–166 mm), however, have very small bulbs, very simple branches, and relatively short lateral branches. One of these lacks a terminal filament; the other five have 4–6 single-based terminal filaments. Four of the six (USNM 256869, 322459, 341943, and 341946) are from near Hawaii; one (ZMUC P202706), from the western equatorial Pacific; one (ZMUC P201822), from the eastern Indian Ocean.
I tentatively include under E. satterleei an Atlantic specimen from near the Cape Verde Islands (USNM 321571) which lacks a terminal filament. Medial and lateral branch lengths are approximately 35% of distal barbel—much shorter than in either any other E. satterleei or any specimens of E. triramis, a similar Atlantic species (see below). I include it under E. satterleei because the bases of the branches are pigmented further distally than in E. triramis and more like E. satterleei; the tiny ovoids in the branches are more proximal than in E. triramis; the bulb shape is more typical of E. satterleei; and the distal boundary of the pigment is jagged rather than smooth as in E. triramis.
Distribution
Known from 20–40°N and 30–80°W in the North Atlantic, near 20°S, 30°W in the South Atlantic, near Hawaii and scattered locations in the western and southern Pacific, and two stations in the southern Indian Ocean.
Material examined
Eight males, 112–149 mm; 15 females, 97–177 mm; 34 sex undet., 58–144 mm: Holotype: USNM 170927, female, 139 mm, 32°12′N, 64°36′W, “1000 fathoms.” Nontypes (Atlantic): USNM 261286, 1 female, 2 males, 133–141 mm, 32°22′N, 64°4′W; USNM 261287, female, 149 mm, 32°14′N, 64°2′W; USNM 261290, male, 139 mm, 32°14′N, 64°00′W; ARC 8704333, sex undet., 62 mm, 39°30′N, 65°5′W; USNM 321571(tentative), male, 112 mm, 18°29′N, 29°13′W; ISH 1800–1966, female, 109 mm, sex undet., 78 mm, 21°00′S, 30°00′W. (Pacific, near Hawaii) USNM 317496, sex undet., 69 mm; USNM 317498, sex undet., 104 mm; USNM 322170, female, 177 mm; USNM 322458, female, 97 mm; USNM 322459, sex undet., 79 mm; USNM 322460, sex undet., 83 mm; USNM 322461, 2 females, 113–161 mm, 1 sex undet., 85 mm; USNM 322463, male, 138 mm; USNM 322464, sex undet., 76 mm; USNM 322465, 2 sex undet., 89–94 mm; USNM 322466, sex undet., 95 mm; USNM 322467, sex undet., 58 mm; USNM 322468, sex undet., 82 mm; USNM 322474, male, 149 mm; USNM 322475, 2 sex undet., 91–92 mm; USNM 322480, sex undet., 61 mm; USNM 322481, sex undet., 72 mm. USNM 322482, sex undet., 66 mm; USNM 322483, sex undet., 70 mm; USNM 322484, 7 sex undet., 64–104 mm; USNM 322485, sex undet., 114 mm; USNM 322487, sex undet., 105 mm; USNM 341943, 2 females, 166–170 mm; USNM 341946, female, 119 mm; USNM 322488, sex undet., 62 mm; Univ. Hawaii, uncataloged: “Tsuji IV-47A,” female, 122 mm; Kana Keoki St. 771008, sex undet., 76 mm; Kana Keoki St. 780302, male, 118 mm; Kana Keoki St. 780802, sex undet., 67 mm. (Other Pacific) USNM 256879, sex undet., 70 mm, 17°24′N, 157°25′W; USNM 317497, sex undet., 77 mm, 15°44′S, 143°00′W; SIO60-251, female, 110 mm, 19°50′N, 156°15′W; SIO71-309, sex undet., 73 mm, 27°27′N, 155°40′W; AMS I20315-021, male, 132 mm, 33°53′S, 152°02′E; ZMUC P201818, sex undet., 90 mm, 1°13′S, 138°42′E; ZMUC P202706, female, 151 mm, 4°03′N, 123°26′E; NSMT P49530, sex undet., 74 mm, 23°N, 150°E; IOAN, uncataloged, Vitiaz 7374, sex undet., 144 mm, 17°48′N, 143°46′E; BPBM 37779, sex undet., 65 mm, 3°44′S, 155°57′W. (Indian) USNM 201025, sex undet., 98 mm, 19°24′S, 65°04′E; ZMUC P201822, female, 141 mm, 11°24′S, 50°05′E.
Eustomias triramis Regan and Trewavas, 1930 Figures 3C, 5
Eustomias triramis Regan and Trewavas, 1930:99, figure 86 (type, central N. Atlantic). Beebe and Crane, 1939:213,228 (synon. of E. bigelowi). Gibbs et al., 1983:11 (inclusion in Dinematochirus).
Eustomias bigelowi Beebe and Crane, 1939:213,228 (in part, type of E. triramis only). Morrow and Gibbs, 1964:398 (in part, type of E. triramis only).
Diagnosis
Barbel with three relatively simple branches arising from stem; none reaching bulb tip; external pigment present on barbel stem and dorsal surface of terminal bulb except for unpigmented tip; distal boundary of pigment smooth; terminal filament absent or small and simple.
Description
(data from holotype in parentheses) BL 11.2–13.3 (14.7)% of SL; branches arising at 38–41 (42)% of BL. Medial branch length 55–73 (44)% of distal barbel; lateral branch lengths 61–73 (41)%. Medial branch and occasionally laterals with a few small side filaments, often with small ovoids near their tips; pigment variably present proximally in axes of branches, usually the laterals, small smudges of external pigment occasionally present. Terminal bulb length 1.8–2.0 times (1.8) its thickness and 30–39% (44%) of distal barbel. Terminal filament absent in holotype and one other specimen, simple and its length 5–6% of distal barbel in two others.
Premaxillary teeth 11–13 (11); mandibular teeth 14–16 (15). Ventral groove extending to PV 5–6 (6). PO/eye 27–35% in three immature females 93–108 mm SL (25% in unsexed 72 mm holotype).
Comments
The bulb of the holotype has darkened, but the pigmentation pattern appears to be as illustrated by Regan and Trewavas (1930, fig. 86). Otherwise, the barbel differs from the illustration only in having a smoother contour ventrally at the juncture of the distal stem and bulb and in that the ovoids in the branches are less prominent than illustrated.
The other three specimens assigned to E. triramis, all from the Gulf of Mexico and well west of the central Atlantic type locality, have relatively longer branches, and the medial branches have one or more small side filaments proximal to the side filament near the tip also present in the type. In all three, the only unpigmented portion of the stem is a saddle-shaped area on the dorsal surface just distal to the branches; whereas, in the type the stem lacks pigment only on the ventral surface of the distal section. Two of the three Gulf of Mexico specimens have small terminal filaments on the terminal bulb. These differences may be ontogenetic since, although the type appears fully metamorphosed, all three additional specimens are larger. Until more specimens are available it seems best to treat the latter as E. triramis.
Eustomias triramis resembles E. satterleei—especially certain specimens of the latter with short and simple branches. The medial branch lengths of some E. satterleei are less than 70% of distal barbel and similar to those of E. triramis. The shortest lateral branches seen in E. satterleei (90 and 93% of distal barbel) are, however, longer than those of any E. triramis. In E. satterleei, external pigment extends from the stem a short distance onto the proximal parts of the branches (especially the medial) but not in E. triramis. Furthermore, internal beads and side filaments in even the simplest branches observed in E. satterleei are relatively closer to the origin of the branches than in E. triramis. In E. satterleei, the dorsal pigment on the bulb is forked and irregular at its margins but is solid and smooth-margined in E. triramis. Terminal filaments of E. satterleei are quite variable, but except for two specimens which lacked any filament (see above), they were longer, more obvious and usually not simple as in two specimens with filaments assigned to E. triramis.
Distribution
The type was taken in the tropical central North Atlantic; the other three specimens are from the northern Gulf of Mexico.
Material examined
Three females, 93–108 mm; one sex undet., 72 mm: Holotype: ZMUC P201912, sex undet., 72 mm, Margrethe St. 1063, 21°47′N, 47°11′W, 110 m wire out. Nontypes: USNM 278268, female, 101 mm, 27°00′N, 86°00′W; USNM 278269, female, 93 mm, 27°00′N, 86°00′W; MCZ 60361, female, 108 mm, 27°40′N, 90°50′W.
Eustomias binghami Parr, 1927 Figure 5
Eustomias binghami Parr, 1927:80–81, figures 47, 48 (type, North Atlantic). Regan and Trewavas, 1930:103, figure 93. Beebe and Crane, 1939:213 (reexam. type). Morrow and Gibbs, 1964:398, figure 106G (reexam. type). Gibbs, 1971:239 (Bermuda). Gibbs et al., 1983:11 (inclusion in Dinematochirus).
Eustomias frondosus Regan and Trewavas, 1930:103, figure 92 (six syntypes, North Atlantic). Beebe and Crane, 1939:213 (synon. of E. binghami). Morrow and Gibbs, 1964:398 (synon. of E. binghami).
Diagnosis
Barbel with three branches arising together from stem; medial branch simple, much shorter than distal barbel; lateral branches bifurcate, reaching to or well beyond barbel tip; stem solidly pigmented externally, pigment extending onto dorsal surface of elongate terminal bulb; several terminal filaments, the longest arising medially from dorsal tip of bulb, shorter medial and laterally paired filaments arising ventrally.
Description
BL 14–20% of SL, branches arising at 45–50% of BL. Medial branch length 68% of distal barbel in a 101 mm specimen, 10–27% in three smaller individuals; occasionally bearing small side filaments. Lateral branch lengths 85% of distal barbel in a 51 mm individual and 145–165% in larger specimens; bearing small side filaments and, in some specimens, small bulblets at the tips. Terminal bulb often directed slightly ventrad; its length 2.5 times its thickness and about half distal barbel. Dorsal terminal filament often branched; its length 38–51% of distal barbel; other terminal filaments simpler and less than half the length of the dorsal filament.
Premaxillary teeth 9–14; mandibular teeth 11–15. Ventral groove extending to PV 7–9. PO/eye 64% in a 101 mm SL male, 30% in 80 mm female and unsexed specimens; PO of type (99 mm SL) “nearly as large as the eye.” (Parr, 1927). No examined specimens mature.
Distribution
Known from the North Atlantic, roughly 22°–34°N, 45°–80°W.
Material examined
One male, 101 mm; one female, 80 mm; two sex undet., 51–84 mm: USNM 261294, male, 101 mm, 33°32′N, 64°04′W; USNM 261295, female, 80 mm, 32°31′N, 63°41′W; ZMUC P201967 (syntype of E. frondosus), sex undet., 84 mm, 25°50′N, 76°55′W; ZMUC P201969 (syntype of E. frondosus), sex undet., 51 mm, 26°56′N, 53°09′W.
Eustomias macronema Regan and Trewavas, 1930 Figures 3D, 4
Eustomias macronema Regan and Trewavas, 1930:101–102, figure 91 (type, North Atlantic). Morrow and Gibbs, 1964:399 (synon. of E. binghami). Gibbs et al., 1983:11 (inclusion in Dinematochirus). Swinney, 1990:3 (Madeira).
Eustomias binghami Morrow and Gibbs, 1964:399 (in part, type of E. macronema only).
Diagnosis
BL less than 20% of SL; barbel with five branches apparently arising together from stem; lateralmost pair of branches, which actually arise from bases of the medio-lateral pair, usually shortest; medio-lateral pair usually longest; diameter of stem distal to branches greater than that proximal to branches; stem solidly pigmented, pigment extending onto dorsal surface of terminal bulb; terminal bulb elongate and with an unpigmented tip usually directed dorsad; swollen ventrally, its length 2.0–2.5 times its thickness; a single terminal filament arising ventral to bulb tip, usually about as long as distal barbel, but occasionally minute.
Description
BL 15.5–19.5 % of SL (11.5–14.6% in four small specimens 61–63 mm), branches arising at 43.4–57.6% of BL. Medial branch length 60–130% of distal barbel in all but two specimens (28% and 219%). Medio-lateral pair of branches 70–196% of distal barbel (251% in a 82 mm specimen). Lateral pair of branches 51–125% of distal barbel in most specimens (20%, 28%, and 143% in three small specimens). Out of 23 undamaged and clearly postmetamorphic specimens, medio-lateral branches longest in 11, medial branch longest in nine and lateral branches longest in three. All branches pigmented exteriorly in proximal sections, the medial usually unpigmented in its distal section, the two lateral pairs variably pigmented distally; branches bearing short side filaments often with tiny bulblets; medial branch often with numerous complex filaments in its distal, unpigmented section; prominent bulblets on distal portion in five specimens (63–140 mm). Terminal bulb length 2.0–2.5 times its thickness and 40–50% of distal barbel. Terminal filament simple or with small side filaments; its length 10–162% of distal barbel in most specimens; minute, pressed against bulb, and very difficult to see in two specimens 82 and 163 mm SL. Pigmented portion of bulb and distal section of stem with small beaded filaments in several specimens.
Premaxillary teeth 7–11 (7–9 in most); mandibular teeth 6–14 (8–10 in most). Ventral groove extending to PV 8–10 (7 in three specimens). PO/eye 96–112% in five apparently mature males 115–135 mm SL; 59% and 69% in immature males 98 and 111 mm; 52% in a 163 mm female with vitellogenic oocytes 0.5–.6 mm in diameter, 36–38% in 140 and 147 mm females with early vitellogenic oocytes 0.15–0.20 mm in diameter, and 17–37% in smaller females and juveniles 61–104 mm.
Comments
The holotype of E. macronema is small (67 mm SL) and the branches not yet fully developed. The barbel stem is also twisted between the branches and the terminal bulb, and in the illustration by Regan and Trewavas (1930, fig. 91) the bulb is upside-down.
Distribution
Known from roughly 20–32°N in the North Atlantic and Gulf of Mexico, two stations at 20–23°S, 22–33°W in the South Atlantic, widely scattered locations thoughout the Pacific, and west of Australia and near the equator south of India in the Indian Ocean.
Material examined
Seven males, 90–135 mm; eight females; 81–163 mm; 19 sex undet., 49–85 mm: Holotype: ZMUC P201902, sex undet., 67 mm, Dana St. 1152, 30°17′N, 20°44′W, 600 m wire out. Nontypes: (Atlantic) USNM 261282, male, 135 mm, 31°29′N, 64°49′W; USNM 261283, male, 115 mm; 2 sex undet., 62–78 mm, 32°22′N, 64°04′W; USNM 261284, sex undet., 63 mm, 32°22′N, 64°11′W; USNM 261285, 2 sex undet., 61–63 mm, 32°05′N, 64°03′W; USNM 261300, female, 140 mm, 31°51′N, 63°35′W; ISH 419-1968, female, 108 mm, 20°4′S, 21°46′W; ISH 1210-1968, female, 115 mm, sex undet., 69 mm, 21°4′S, 30°8′W; ISH 2185-1968, sex undet., 68 mm, 23°26′S, 33°30′W. (Pacific, near Hawaii) USNM 322571, female, 82 mm; USNM 322629, male, 129 mm; USNM 322630, female, 104 mm; USNM 322631, female, 163 mm; 2 males 98–111 mm; USNM 322566, sex undet., 61 mm; USNM 322289, 2 sex undet., 73–80 mm; USNM 322627, 2 sex undet., 74–76 mm; ZMUC P206122, male, 90 mm; ZMUC P206121, sex undet., 68 mm. (Other Pacific) USNM 292263, sex undet., 49 mm, 13°50′S, 148°18′E; USNM 322570, sex undet., 61 mm, 5°57′S, 160°04′W; SIO 68-482, sex undet., 85 mm, 22°10′N, 171°57′E; ZMUC P201824, sex undet., 85 mm, 3°40′N, 137°53′E; HUMZ 74923, female, 147 mm, 26°14′N, 135°46′E. (Indian) ZMUC P201826, female, 81 mm, 1°45′N, 71°05′E; AMS I22818012, sex undet., 82 mm, 18°27′S, 116°33′E; AMS I31141006, male, 132 mm, 20°17′S, 113°13′E.
Discussion
Seven of the 11 species covered here (E. bigelowi, E. borealis, E. fissibarbis, E. macronema, E. paucifilis, E. satterleei, and E. schmidti) are represented by more than 10 individuals including both mature females and males. (Though I examined only four specimens of E. binghami including one of each sex, it also is known from over 10 other specimens.) In all seven, the largest females are considerably larger than the largest males, and in most, the size at maturity appears to be greater for females. PO/eye is greater than 75% in mature males of these species but only 20–40% in females and juveniles. Similar sexual difference in size and in relative size of the postorbital organ have been reported for other species of Dinematochirus (Clarke, 1998).
In four species (E. bigelowi, E. borealis, E. paucifilis, and E. schmidti) lateral branches of the barbels of some females over 125 mm were relatively longer than in other specimens of the same species. Some large females of E. bigelowi also had relatively smaller terminal bulbs and relatively longer terminal filaments as well. These differences probably do not represent sexual dimorphism in barbel features that is associated with maturity in females but rather are consequences of changes in allometry of barbel growth at sizes greater than 125–150 mm SL. To ascertain this would, of course, require examination of males considerably larger than the largest observed. Whatever the cause, large females of other species of Dinematochirus may be expected to exhibit differences in relative size of some barbel features.
Five species appear to be distributed worldwide, assuming that absence of some from the Indian Ocean is due to lack of sampling effort there. Their distribution patterns within the Atlantic and Pacific are broad as well. Eustomias schmidti occurs in all tropical and subtropical areas but is absent or rare in central water masses at latitudes between approximately 20°–30°N or S. Eustomias bigelowi, E. fissibarbis, E. macronema, and E. satterleei are absent from eastern boundary currents but otherwise appear to occur throughout subtropical and at least western tropical regions of both oceans.
Among these widely distributed (and frequently captured) species, neither E. fissibarbis nor E. schmidti appear to vary much in barbel characters. In contrast, E. macronema and E. satterleei exhibit considerable variability in certain barbel characters. In E. macronema, the relative lengths of the branches and their complexity are quite variable and a few individuals have either markedly more complex medial branches, small filaments on the distal portion of the stem as well as the bulb, or a reduced terminal filament. In E. satterleei, bulb shape, number of terminal filaments, and complexity of the branches vary greatly, and a few individuals have both markedly smaller bulbs and relatively short, simple branches. In neither of these species are such variations clearly related to size or geography.
In E. bigelowi, however, Pacific specimens differ to varying degrees from Atlantic specimens in several barbel characters. The significance of these differences is confounded by differences in size composition between available Atlantic and Pacific specimens and the near absence of material from the Indian Ocean. Future collections of larger Pacific specimens and more specimens from the Indian Ocean may well indicate that the Pacific specimens represent a distinct species.
In contrast to the above species, E. binghami, E. borealis, and E. paucifilis appear limited to restricted areas of the North Atlantic. Eustomias borealis occurs in the North Sargasso Sea, and E. paucifilis in the Gulf of Mexico and South Sargasso Sea faunal provinces of Backus et al. (1977). Both E. borealis and E. paucifilis have been taken near Bermuda at the sharp boundary between the two provinces (Backus et al., 1969) but not on the same cruise. Eustomias binghami occurs in both the North and South Sargasso Sea provinces but appears limited to the western half of the North Atlantic Subtropical faunal region. Two other species with barbels similar to those of E. borealis and E. paucifilis are known from few specimens. Eustomias silvescens is known only from one station in the Caribbean—outside the ranges of both the above species—and E. curtifilis from only three closely spaced stations in the South Atlantic Subtropical region. These two may also eventually prove to have relatively restricted ranges.
The range of E. triramis, as construed herein, appears to be similar to that of E. paucifilis, but the holotype was collected far away from the three other (and larger) known specimens. More and larger specimens from the South Sargasso Sea region would be necessary to confirm my inclusion of the Gulf of Mexico specimens and better define the range of this species.
Lateral views of barbels of Eustomias bigelowi. (A) USNM 261306, 158 mm SL, female with relatively small terminal bulb and long lateral branches and terminal filaments, from near Bermuda. (B) USNM 322659, 125 mm SL, male with slender branches and well-developed medial terminal filaments, from near Hawaii. (C) USNM 317495, 103 mm SL, male with stout medial branch and less developed medial terminal filaments, from near Hawaii. Scale bars equal 5 mm
Locations of capture of Eustomias bigelowi, E. curtifilis, E. macronema, and E. satterleei in the Atlantic Ocean. Large star at 21°S, 30°W indicates capture of all four species. Large triangle at 32°30′N, 64°W indicates capture of all except E. curtifilis near Bermuda
Locations of capture of Eustomias binghami, E. borealis, E. paucifilis, E. silvescens, and E. triramis in the North Atlantic Ocean. Large triangle at 32°30′N, 64°W indicates capture of E. binghami, E. borealis, and E. paucifilis near Bermuda
Lateral views of barbels, with dorsal views of terminal bulbs, of (A) Eustomias paucifilis, USNM 261280, 139 mm SL, female; (B) E. borealis, holotype, USNM 261281, 138 mm SL, male; and (C) E. curtifilis, holotype, ISH 714-1966, 166 mm SL, female. Scale bars equal 5 mm
Lateral views of barbels of (A) Eustomias satterleei, USNM 322170, 177 mm SL, female from near Hawaii with relatively “normal” branches and a single terminal filament; (B) E. satterleei, USNM 317495, 69 mm SL, unsexed juvenile from near Hawaii with very simple branches, a reduced bulb and multiple terminal filaments; (C) E. triramis, MCZ 60361, 108 mm SL, female; (D) E. macronema, USNM 322629, 129 mm SL, male. Scale bars equal 5 mm