Lanternfish

14-17 AO photophores; 8-10.5 tooth patches on the lower limb of the second gill arch; 37-44 lateral line organs (Ref. 36121). Pectoral fin rays rather weak, flexible (Ref. 36121).

Oceanodromous. Migrating within oceans typically between spawning and different feeding areas, as tunas do. Migrations should be cyclical and predictable and cover more than 100 km.

Dorsal spines (total): 0; Dorsal soft rays (total): 16 - 18; Analspines: 0; Analsoft rays: 20 - 23; Vertebrae: 37 - 44

Oceanic (Ref. 4066), found between 650-1,000 m during the day; between 60-225 m at night (maximum abundance (mainly juveniles) at 100 m) (Ref. 4479). Uncommon species (Ref. 36121).

Oceanic (Ref. 4066), found between 650-1,000 m during the day; between 60-225 m at night (maximum abundance (mainly juveniles) at 100 m) (Ref. 4479). Mesopelagic (Ref. 58302). Uncommon species (Ref. 36121).

Lampanyctus lineatus

This is a large lanternfish, attaining a size of 221 mm (Hulley, 1981); the largest specimen taken in the study area was 165 mm. Lampanyctus lineatus is either a bipolar subtropical species or a tropical-subtropical species (Backus et al., 1977). It is uncommon in the study area, never being among the 20 most abundant species (Table 131). The Ocean Acre collections contain 84 specimens; 35 were caught during the paired seasonal cruises, 19 of these in discrete-depth samples, of which 18 were in noncrepuscular tows (Table 23).

DEVELOPMENTAL STAGES.—Postlarvae were 7–24 mm, juveniles 25–92 mm, subadults 93–165 mm, and adults 140–165 mm. Fish larger than 99 mm amounted to 10 females 116–165 mm and 5 males 100–140 mm.

REPRODUCTIVE CYCLE AND SEASONAL ABUNDANCE.— Spawning apparently takes place at low levels for about half of the year. It cannot be established whether the population near Bermuda is self-sustaining or is dependent upon an influx of recruits from elsewhere to maintain its numbers. Judging from the large size, the life span probably is three or more years, but the collections provide little information concerning this due to the paucity of specimens taken at any season (Table 95).

Large fish were taken over most of the year and presumably were permanent residents of the area. Adults were taken only in late spring (a female) and in August (one of each sex). A 152 mm female taken in July, categorized as a subadult, may have been a spent adult. Postlarvae, including transformation stages, were taken only in late summer. Juveniles smaller than 30 mm were taken in September, October, and February. Taken together these data indicate that spawning occurs at least from late spring to winter.

The entire catch in late spring consisted of nine fish 44–165 mm, with only fish 44–92 mm taken in discrete-depth tows. Only postlarvae were caught during the paired late summer cruises. However, the Engel trawl fished at that season took 19 fish 37–165 mm. Four fish 25–85 mm were taken in winter, all in February.

VERTICAL DISTRIBUTION.—No more than six specimens were taken during the day or night at any of the three seasons. Day captures in winter were at 701–750 m and 801–850 m, in late spring 751–800 m and 1101–1150 m, and in late summer 901–950 m and 1001–1050 m. Night captures in winter were at 151–200 m and 301–350 m, in late spring 251–300 m and 951–1000 m, and in late summer the upper 50 m (Table 95).

Postlarvae may be stratified by size. Those taken in the upper 50 m were 9–12 mm and those from 901–1050 m were 20–24 mm. However, the shallow captures were at night and the deep ones during daytime.

Nannobrachium lineatum (Tåning, 1928)

Lampanyctus lineatus Tåning, 1928:68 [original description, North Atlantic].—Parr, 1928:88, 108–110 [key, western Atlantic, description, figure].—Bolin, 1959:34 [discussion, distribution],—Backus et al, 1965:144 [western Atlantic].—Bekker 1967a: 117 [equatorial Atlantic],—Backus et al, 1969:95 [western Sargasso Sea],—Nafpaktitis and Nafpaktitis, 1969:41–42 [tropical Indian, description, figure].—Badcock, 1970:1039 [off Canary Islands],—Gibbs et al, 1971:43, 107 [key, vertical distribution near Bermuda, figure],—Krefft and Bekker, 1973:188–189 [biology, synonymy].—Nafpaktitis, 1973: 40 [redescription, figure and designation of lectotype],—Nielson, 1974:38 [listing of lectotype],—Bekker et al, 1975:314 [distribution, Caribbean Sea and Gulf of Mexico].—Badcock and Merrett, 1976:42 [30°N, 23°W].—Brooks, 1976:570, 575, 581 [swimbladder size].—Parin and Golovan, 1976:262 [off West Africa].—Backus et al, 1977:267, 275, 277 [zoogeography].—Nafpaktitis et al, 1977:199–201 [description, distribution, figure].—Parin et al, 1977:122, 123 [tropical Pacific] [in part?].—Parin et al, 1978:175 [eastern tropical Atlantic].—Paxton, 1979:14 [lectotype].—Hulley, 1981:206–208 [description, Atlantic distribution]; 1984b:464 [description, northeast Atlantic distribution]; 1986b:236, 242, 245 [zoogeography, Benguela region]; 1986c:308, fig. 86.80 [description, South Africa, figure].—Gloerfelt-Tarp and Kailola, 1984:77 [illustration from Nafpaktitis and Nafpaktitis].—Moser et al, 1984:239 [relationships, larval description].—Hulley and Krefft, 1985:35, 43–46 [North Atlantic zoogeography].—Rubies, 1985:578, 584 [Valdivia Bank off Namibia; gill raker count].—Clarke, 1987:66–67 [biogeography in central Pacific, listed as c.f. lineatus].—Gartner et al, 1987:86, 88, 91, 95 [eastern Gulf of Mexico].—Karnella, 1987:52, 112 [ecology and biology near Bermuda].

Lampanyctus (Lampanyctus) lineatus.—Fraser-Brunner, 1949:1086 [illustrated key].—Bekker, 1983:87, 89, 201, 202 [key, description, distribution].

Lampanyctus niger.—Parin et al., 1977:122, 123 [?in part] [western Pacific].—[Not Günther, 1887.]

COMPARATIVE DIAGNOSIS.—Nannobrachium lineatum (Figure 17) can be distinguished from N. cuprarium by its higher number of AO photophores, lateral line organs, and vertebrae (Table A10). In addition, its caudal peduncle is longer than the upper-jaw length (shorter than the upper jaw in N. cuprarium), and the Prc3 lies below a line connecting Prc2 and Prc4 (on that line in N. cuprarium). Nannobrachium lineatum can be separated from all other species of Nannobrachium by the combination of characters in Table 1.

DESCRIPTION.—Counts are based on up to 29 specimens from the Atlantic and up to 22 specimens from the Indo-Pacific and are given in Tables A2–A8, A10.

Proportions: Given in Table 14, for Atlantic material only.

Fins: Origin of anal fin under middle of base of dorsal fin. Pectoral fin not reaching vertical from PO4, its rays rather weak, flexible. Adipose fin above end of anal-fin base.

Luminous Organs: PLO –2 photophore diameters below lateral line. PO4 slightly higher than level of PVO2 and approximately above PO3 or slightly behind vertical from PO3. VLO not more than one photophore diameter below, frequently touching, lateral line. SAO2 slightly before vertical from AOa1-AOa1 slightly depressed; AOa1–2 interspace sometimes enlarged. AOp1 above end of anal-fin base. Pol2 well before vertical from origin of adipose fin. Prc1–3 forming gentle curve; Prc4 at lateral line with Prc3 midway between Prc2 and Prc4 but below line connecting them. Supracaudal and infracaudal luminous scales well developed; frequently one, rarely two, separate scales before infracaudal gland; rather inconspicuous covering of black pigment on posterior tips of infracaudal and supracaudal glands, resembling hood or cap; black pigment least developed in some Indo-Pacific specimens. Rows of minute photophores between rays of caudal fin.

Size: Nannobrachium lineatum appears to be the largest bodied species of Nannobrachium, reaching a maximum size well in excess of 200 mm in the Atlantic but apparently not so large in the Indo-Pacific. The largest specimen examined in this study was 237 mm. Nafpaktitis et al. (1977) reported a size of over 235 mm, with three gravid females 171–237 mm. Hulley (pers. comm., 1980) reported a maximum size of 221 mm for 157 specimens from the North and South Atlantic. Gibbs et al. (1971) found the maximum size in the Bermuda Ocean Acre material to be 161 mm. From those few specimens available, it appears that Indo-Pacific forms referable to this species do not reach such a large size. The largest specimens reported by Nafpaktitis and Nafpaktitis (1969) among their material from the Indian Ocean was 97 mm. The largest specimen from the Indo-Pacific examined in this study was 122 mm.

Material: 203 (26–237 mm) specimens were examined, including the lectotype, a male, 121.5 mm, ZMUC P2330212, Dana sta 1186 I, 17°54′N. 65°54′W. 30 November 1921 (Nafpaktitis, 1973).

DISTRIBUTION AND GEOGRAPHIC VARIATION.—Nannobrachium lineatum is an uncommon species (Nafpaktitis et al., 1977), never particularly abundant. Most collections examined contained only one or a few specimens. It appears to have a tropical to subtropical distribution (Figure 16). In analyzing the Walther Herwig collections, Hulley (1981) found that N. lineatum was much more abundant in the collections between 9°N and 10°S, indicating a tropical distribution. It occurs at reported daytime depths of 700–1150 m (Nafpaktitis et al., 1977). Nighttime depths appear bimodal, as shallow as 65–350 m and as deep as 900–1000 m, indicating both migrants and non-migrants. Karnella (1987) reported similar ranges for Ocean Acre material from near Bermuda.

No consistent variation was apparent between North and South Atlantic specimens of N. lineatum, but there are considerable differences between Atlantic and Indo-Pacific material. These are manifested largely in a greater range of lateral line organ and vertebral counts, and to a lesser extent, gill raker counts (Table A10), suggesting that more than one species may be present. An attempt was made to analyze the differences between the Atlantic and Indo-Pacific specimens but was inhibited by the lack of adequate material. Until material of adequate quantity and quality becomes available, it seems best at this time to treat all forms as N. lineatum. (See also discussion of Fujii's two specimens of “Lampanyctus nigrum” from near the Ogasawara Islands in the western Pacific under N. nigrum).

Western Atlantic: disjunct distribution between 42°N and 10°S

oceanic and mesopelagic, found between 650-1,000 m during the day; between 60-225 m at night (maximum abundance (mainly juveniles) at 100 m)

nektonic