Comprehensive Description
provided by Smithsonian Contributions to Zoology
Nannobrachium ritteri (Gilbert, 1915)
Lampanyctus ritteri Gilbert, 1915:318 [original description, off San Clemente Island].—Parr, 1928:89 [key]; 1929:23–24 [discussion of holotype].—Jordan et al., 1930:167 [original description cited].—Bamhart, 1936:21 [description, San Diego to Monterey, California, figure].—Bolin, 1939:41–143 [description, comparison, figure].—Follett, 1952:412 [off central California].—Böhlke, 1953:20 [2 paratypes originally at Stanford University, now at California Academy of Sciences].—Aron, 1959:414–415 [North Pacific capture depths].—Parin, 1961:268–279 [distribution, gill structure]; 1971:82 [probable misidentification from Peru Current].—Aron, 1962:279, 301, 307 [?inpart] [distribution in northeast Pacific].—Bekker, 1964:474 [boreal and central Pacific]; 1967b:179 [distribution].—Pearcy, 1964:87 [?in part] [off Oregon].—Berry and Perkins, 1966:661–662 [eastern Pacific].—Paxton, 1967a: 429 [vertical distribution off southern California]; 1967b:214–216 [feeding habits, parasites]; 1979:13 [holotype and paratypes].—Rass, 1968:233, 237, 241 [distributional analysis].—Ahlstrom, 1969:42 [California Current larvae].—Fitch, 1969:7 [otoliths].—Ebeling et al., 1970a:5, 7, 14 [off Santa Barbara, California]; 1970b:11-18, 29, 35 [ecology off southern California].—Barham, 1971:109 [swimbladder].—Day, 1971:17 [?in part] [off Canada and Washington].—Butler and Pearcy, 1972:1145–1149 [swimbladder].—Miller and Lea, 1972:70–71 [description, California Current system, figure].—Beklemishev, 1973:294–298 [characteristics of distribution].—Brown, 1974:17, 28 [ecology off southern California].—Chen and Ebeling, 1974:841, 845, fig. 8 [karyotype].—Moser and Ahlstrom, 1974:406–407 [larva figured].—Friedl et al., 1976:611 [deep scattering layer relationships].—Wisner, 1976:170–172 [description, distribution, figure].—McNulty and Nafpaktitis, 1977:510–514 [pineal morphology].—Pearcy et al., 1977: 238–239 [depth distribution off Oregon].—Frost and McCrone, 1978:755, 759 [North Pacific, stations P and Q].—Childress and Somero, 1979:276–277, 281 [enzymic activities].—Lancraft and Robison, 1979:714 [net feeding].—Childress et al., 1980:28–35 [growth and energy relations].—Parin and Bekker, 1981:66 [zoogeographic relations].—Parin and Fedorov, 1981:74–75 [Gulf of Alaska].—Robison and Bailey, 1981:136–138 [sinking rate of feces].—Neighbors and Nafpaktitis, 1982:208–214 [lipid composition].—Eschmeyer and Herald, 1983:94 [family representative].—Sawada, 1983:91, 237 [Japanese], 185, 318 [English] [distinguished from L. regalis].—Moser et al., 1984:238–239, fig. 124A [larva figured, relationships].—Willis, 1984:167 [assemblage membership in northeastern Pacific].—Moser et al., 1987:97 [assemblage relationships] [not seen, fide J. Paxton].—Willis et al., 1988:90 [distribution].—Matarese et al., 1989, unpaginated [not seen, fide, H.G. Moser] [larvae, from northeastern Pacific].—Moser and Smith, 1993:654 [assemblage relationships in California Current].—Moser et al., 1993:44 [distribution and abundance in California Current].—Paxton et al., 1995:1315 [listed; not seen, fide J. Paxton].
Lampanyctus (Lampanyctus) ritteri Fraser-Brunner, 1949:1085 [illustrated key].—Bekker, 1983:85, 86, 193, 198 [in part?] [key, description, distribution].
Nannobrachium ritteri.—Moser and Ahlstrom, 1996:424–425 [early life history and larvae illustrated].
COMPARATIVE DIAGNOSIS.—Nannobrachium ritteri (Figure 11) can be distinguished from all other species in the Regale group, except N. regale, by its lower number of gill rakers and intermediate number of infracaudal luminous gland scales (Table A9). It can be separated from N. regale by the lower position of its VLO (below a line connecting PLO and SAO1 in N. ritteri) and its smaller adipose fin (adipose-fin length more than twice into the caudal peduncle depth in N. ritteri). It can be separated from all other species of Nannobrachium by the combination of characters in Table 1.
DESCRIPTION.—Counts are based on up to 25 specimens from the North Pacific Ocean and are given in Tables A2–A9.
Proportions: Given in Table 9.
Fins: Origin of anal fin under middle of base of dorsal fin. Pectoral fins reaching beyond end of pelvic-fin base; well developed with rather robust, stout rays. Base of adipose fin above end of anal-fin base.
Luminous Organs: PLO 1–3 photophore diameters below lateral line. PO4 usually slightly higher than level of PVO2 and on vertical from PO3. VLO slightly below midway between lateral line and pelvic-fin base. SAO1 above or slightly before vertical from VO3; SAO2 usually above AOa1; and SAO3 above AOa1–2 interspace. Both SAO1 and SAO2 approximately midway between lateral line and level of the VO and AOa series. Line connecting VLO and SAO1 passing through or near lower margin of SAO2 and always much above AOa1. AOa1 often slightly depressed; AOa1–2 interspace often slightly enlarged. AOp1 at end of anal-fin base. Upper Pol before or on vertical from origin of adipose fin. Prc usually continuous with AOp; Prc3 approximately on vertical midway between Prc2 and Prc4 but low and much closer to Prc2. Supracaudal and infracaudal scales well developed, lacking any separated scales preceding infracaudal gland. No secondary photophores found.
Size: Wisner (1976) listed the maximum size to about 120 mm, which is consistent with the maximum-sized specimen of 117 mm examined in this study (the holotype).
Material: 929 (18–117 mm) specimens were examined, including the holotype, 117 mm, USNM 75807, Monterey Bay, California, collected by the Albatross, sta 4513, 23 May 1904.
DISTRIBUTION AND GEOGRAPHIC VARIATION.—Nannobrachium ritteri is restricted to the northeast Pacific Ocean (Figure 10). Bekker, however (1983:198, fig. 91), gave a distribution pattern for N. ritteri that I cannot explain. In addition to the range off California, which corresponds well with my findings, Bekker showed N. ritteri to range off Central and South America, a distribution reminiscent of the southern part of an eastern tropical Pacific pattern, such as that of N. idostigma. I have seen no specimens of N. ritteri from that southern region, however, nor did Wisner (1976). The only supportive references I found were in Russian publications. Parin (1971) listed L. ritteri with a question mark as having been collected in the waters of the Peru Current during the fourth cruise of the R/V Akademik Kurchatov. In that paper, he did not indicate the number of specimens of any of the species, nor the localities at which the purported L. ritteri were taken, presumably because of their rarity. Beklemishev (1973:294–298), in a discussion of what he termed “far-neritic” (or “distant neritic”) species, used the “lampanictine ritteri group” as an example from the eastern Pacific, “which, possibly, belong to a single polymorphic species L. ritteri (Figure 2).” The “ritteri group” distribution map (Beklemishev, 1973, fig. 2) appears to be an approximate composite of the distribution of N. ritteri, N. idostigma, and perhaps the eastern portion of N. regale. Beklemishev attributed the distribution map to information from Andriashev, 1962; Bekker, 1967a; and Bekker, pers. comm., 1977. Then, in dealing with some specific examples of mesopelagic zoogeography in the Pacific, using myctophid distributions, Parin and Bekker (1981:64–70) discussed distributions of “far-neritic groups” in which they estimated that around 20 species show such distribution patterns. After discussing eastern tropical Pacific and western tropical Pacific distributions, they discussed two examples of a transition type of far-neritic distribution: one in the “neutral region between the subtropical and subpolar waters near South America (Hygophum bruuni, 1 species out of the Symbolophorus boops group)” and one “near California (Lampanyctus ritteri and possibly L. ingens).” In this discussion, there is no suggestion that L. ritteri might occur in the far-neritic waters off South America, so it is especially puzzling to see such a distribution pattern in Bekker's (1983) monograph. Bekker not only illustrated the range off Central America and northern South America (1983, fig. 91), he discussed that distribution (1983:198), specifically giving a north-south extent from about 50°N to 30°S, extending westward from the continent to 150°W at the north, to 100°W at the equator and to 80°W in the extreme south. In the absence of specimens, however, or at least the unequivocal identification of specific material of N. ritteri from off Central or South America, I must consider the southern distribution shown by Bekker to be in error.
Wisner (1976) reported the shallowest depth of capture of about 20 m during the night.
- bibliographic citation
- Zahuranec, Bernard J. 2000. "Zoogeography and systematics of the lanternfishes of the genus Nannobrachium (Myctophidae:Lampanyctini)." Smithsonian Contributions to Zoology. 1-69. https://doi.org/10.5479/si.00810282.607
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