Species Card of Copepod
Calanoida ( Order )
    Clausocalanoidea ( Superfamily )
        Aetideidae ( Family )
            Aetideus ( Genus )
Aetideus pacificus  Brodsky, 1950   (F,M)
Syn.: no ? Aetideus armatus : Esterly, 1905 (p.145, figs.F)
Brodsky, 1950 (1967) (p.145, Descr.F, figs.F); Vinogradov, 1968 (1970) (p.257); Park, 1968 (p.542, Redescr.F, figs.F); Shih & al., 1971 (p.142); Minoda, 1971 (p.23, Rem.); Bradford, 1971 (p.18, Rem.); Bradford & Jillett, 1980 (p.14); Gardner & Szabo, 1982 (p.202, figs.F); Markhaseva, 1996 (p.21, figs.F,M)
Species Aetideus pacificus - Plate 1 of morphological figuresissued from : E.L. Markhaseva in Proc. Zool. Inst. RAN, St. Petersburg, 1996, 268. [p.22, Fig.9].
Female (from 45°11'N, 152°28'E).
R: rostrum (anterior); CP4: coxopodite of fourth leg.

Species Aetideus pacificus - Plate 2 of morphological figuresissued from : E.L. Markhaseva in Proc. Zool. Inst. RAN, St. Petersburg, 1996, 268. [p.23, Fig.10].
Male (specimen from Kurile-Kamchatka Trench region). P.md: palp of Md.

Species Aetideus pacificus - Plate 3 of morphological figuresIssued from : T.S. Park in Fishery Bull. Fish Wild. Serv. U.S., 1968, 66 (3). [p.539, Pl.4, Figs.16-24].
Female: 16, habitus (dorsal); 17, idem (right lateral side); 18, rostrum ( (frontal view); 19, last thoracic segment and urosome (dorsal); 20, idem (right lateral side); 21, urosome (ventral); 22, A2; 23, Md; 24, masticatory edge of Md.

Nota: The processes of the last thoracic segment does not extend beyond the distal end of the genital somite.

Species Aetideus pacificus - Plate 4 of morphological figuresIssued from : T.S. Park in Fishery Bull. Fish Wild. Serv. U.S., 1968, 66 (3). [p.543, Pl.5, Figs.1-7].
Female: 1, Mx1; 2, Mx2; 3, Mxp; 4, P1; 5, P2; 6, P3; 7, P4.

Species Aetideus pacificus - Plate 5 of morphological figuresIssued from : K.A. Brodskii in Calanoida of the Far Eastern Seas and Polar Basin of the USSR. Opred. Fauna SSSR, 1950, 35 (Israel Program for Scientific Translations, Jerusalem, 1967) [p.146, Fig.60].
Female (from NW Pacif.): habitus (dorsal and lateral left side); R, rostrum; M, Md; S1, P1.

Species Aetideus pacificus - Plate 6 of morphological figuresissued from : C.O. Esterly in Univ. Calif. Publs Zool., 1905, 2 (4). [p.145, Fig.14]. As Aetideus armatus. With doubt.
Female (from San Diego Region): a, habitus (lateral); b, P2 (St = terminal bristle of exopod).

Species Aetideus pacificus - Plate 7 of morphological figuresAetideus pacificus female:
1 - Posterior corners of last thoracic segment prolonged into points.
2 - Posterior corners not prolonged into wing-like lobes. Points not reaching the middle of urosomal segment 2. Anterior part of cephalon without crest.
3 - basipodite of right P1 without external tooth-like projection distally. Coxopodite of P4 usually with spinules near the base of internal seta.
4 - Posterior corners of last thoracic segment with points not reaching posterior border of genital segment.
5 - Rostrum long, rami long.

Species Aetideus pacificus - Plate 8 of morphological figuresAetideus pacificus male:
1 - Last thoracic segment with points.
2 - Points exceeding posterior border of urosomal segment 1 (in dorsal and lateral view).
3 - Caudal rami 3.5-3.7 times as long as wide. 2nd segment of P5 more than 4 times as long as wide.

Compl. Ref.:
Peterson & Miller, 1975 (p.642, 650, Table 3, interannual abundance); 1976 (p.14, Table 1, 2, abundance vs interannual variations); Peterson & Miller, 1977 (p.717, Table 1, seasonal occurrence); Chen Y.-Q., 1986 (p.205, Table 1: abundance %, Table 2: vertical distribution, as pacifica); Cervantes-Duarte & Hernandez-Trujillo, 1989 (tab.3); Hattori, 1991 (tab.1, Appendix); Yamaguchi & al., 2002 (p.1007, tab.1); Sedova & Grigoriev, 2005 (p.112); Hooff & Peterson 2006 (p.2610); Galbraith, 2009 (pers. comm.); Homma & Yamaguchi, 2010 (p.965, Table 2); Homma & al., 2011 (p.29, Table 2, 3, abundance, feeding pattern: suspension feeders); Palomares-Garcia & al., 2013 (p.1009, Table I, abundance vs environmental factors); Ohashi & al., 2013 (p.44, Table 1, Rem.)
NZ: 4

Distribution map of Aetideus pacificus by geographical zones
Species Aetideus pacificus - Distribution map 2issued from : J.M. Bradford in N.Z. Jl Mar. Freshw. Res., 1971, 5 (1). [p.35, Fig.14].

North Pacific Ocean showing distribution of four Aetideus species.
Japan (off Sanriku), Pacif. (NW), Kuril-Kamchatka, Okhotsk Sea, Bering Sea, S Aleutian Basin, S Aleutian Is., Station "P", Pacif. (N central), British Columbia, Oregon (Yaquina, off Newport), W Baja California, G. of California (rare).

Type locality: 43°30'N, 147°30'E.
N: 22
(22) F: 3-2,2; (37) F: 2,5-2,2; M: 2,1-1,9; (72) F: 2,3-2,21; (208) F: 2,25-2; M: 1,9-1,87; {F: 2,00-3,00; M: 1,87-2,10}
Rem.: Epi and mesopelagic.
This species is very comparable to Aetideus armatus.
Y.-Q. Chen (1986) during the Krill Expedition from 23°N to 3°S in the Pacific East tropical (May-June 1974), this species shows a mean percentage of the total copepods: 0.9 % (day: 0.5, night: 1.4). This species occurred mainly below 100 m. In general, it ranged from 100 to 350 m at abundances varying from 200 to 500 individuals/1000 m3. The maximum female concentration was 8160 individuals/1000 m3. Female numbers were higher than those of males and juveniles.
In night samples A. pacificus was found in the uppermost 100 m. A maximum of 13,600 individuals/m3 was observed between 0 and 100 m at station 14; the species also occurred at 600 m.
It was not found in the oxygen-deficient area. (see in Subeucalanus subtenuis Chart Fig.1, hydographic conditions Figs.12, 13).
Last update : 16/03/2021
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Razouls C., Desreumaux N., Kouwenberg J. and de Bovée F., 2005-2023. - Biodiversity of Marine Planktonic Copepods (morphology, geographical distribution and biological data). Sorbonne University, CNRS. Available at http://copepodes.obs-banyuls.fr/en [Accessed November 28, 2023]

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