Species Card of Copepod
Calanoida ( Order )
    Clausocalanoidea ( Superfamily )
        Aetideidae ( Family )
            Aetideus ( Genus )
Aetideus divergens  Bradford, 1971   (F,M)
Syn.: Aetideus armatus : Campbell, 1929 (p.311); ? A. armatus : Tanaka, 1957 a (p.31, figs.F,M)
Bradford, 1971 (p.24,figs.F,M); Gardner & Szabo, 1982 (p.200, figs.F, M); Markhaseva, 1996 (p.17, figs.F,M, Rem.)
Species Aetideus divergens - Plate 1 of morphological figuresissued from : J.M. Bradford in N.Z. Jl Mar. Freshw. Res., 1971, 5 (1). [p.25, Fig.9]; From off British Columbia: 52°02'N, 132°53'W).
Female: a, habitus (dorsal); b, idem (lateral right side); c, genital segment and posterior thoracic points (lateral right side); d, e, rostrum (from two specimens).
Nota: Seminal receptacle with a moderately long thick tube, about 4 times as long as wide, connecting the dorsal and ventral sacs. Mouth parts and swimming legs identical with those of A. armatus

Male: f, habitus (ventral); g, idem (lateral right side); h, P5.
Nota: Rostrum absent. All appendages as in A. australis.

Species Aetideus divergens - Plate 2 of morphological figuresissued from : O. Tanaka in Publ. Seto Mar. Biol. Lab., 1957, VI (1). [p.32, Fig.23]. As Aetideus armatus.
Female (from Sagami Bay, Japan): a, habitus (dorsal); b, forehead (lateral); c, last thoracic segment and urosome (lateral left side); d, rostrum; e, P1 (right leg is of abnormal structure); f, P2.
Nota: Rostrum with a knob at the middle of the base. Proportional lengths of urosomites and furca 35:16:14:12:23 = 100. A1 (23-segmented) extends to distal end of furca. Mx1 has 9 setae on outer lobe, 11 setae on exopod, 6+3+4 setae on endopod, 5 setae on 2nd basal segment. Terminal spine of exopod of P2 has 17 teeth.

Male (from Sagami Bay, Japan): g, forehead (lateral); h, last thoracic segment and urosome (lateral left side); i, P5.
Nota: Rostrum reduced, represented by only a small knob. Proportional lengths of urosomites and furca 16:23:23:21:2:15 = 100. Anal segment almost concealed beneath the preceding. A1 reaches back to middle of third urosomal segment. End-spine of P2 has 26 teeth.

Species Aetideus divergens - Plate 3 of morphological figuresissued from : E.L. Markhaseva in Trudy Zool. Inst. RAN, St. Petersburg, 1996, 268. [p.18, Fig.6].
Female (from 29°17'N, 142°47'E) & Male from Bradford (1971)

Species Aetideus divergens - Plate 4 of morphological figuresissued from : J.M. Bradford in N.Z. Jl Mar. Freshw. Res., 1971, 5 (1). [p.18, Fig.4, b]. [modified C.R]
Rostrum width : depth plotted against rostrum depth (c) for Aetideus divergens. SA: South Africa.
Compare with A. australis, A. truncatus, A. armatus and A. pseudarmatus.

Species Aetideus divergens - Plate 5 of morphological figuresAetideus divergens female:
1 - Posterior corners not prolonged into wing-like lobes; points of last thoracic segment not reaching the middle of urosomal segment 2. Anterior part of cephalon without crest.
2 - Right P1 basipodite with an external tooth-like projection distally. Coxopodite of P4 without spinules near the base of internal seta.
3 - Posterior corners of last thoracic segment divergent, always exceeding posterior border of genital segment. Rostral excavation 0.8-1.2 times as wide as deep.

Species Aetideus divergens - Plate 6 of morphological figuresAetideus divergensMale:
1 - Last thoracic segment with points.
2 - Points of posterior last thoracic segment exceeding posterior border of urosomal segment 1 (in dorsal view).
3 - Caudal rami 2.35-2.55 times as long as wide. 2nd segment of P5 less than 4 times as long as wide.

Compl. Ref.:
Robertson & Frost, 1977 (p.231, feeding); Mackas & Anderson, 1986 (p.115, Table 2); Shih & Marhue, 1991 (tab.2, 3); Mauchline, 1998 (tab.20, 21); Rebstock, 2002 (p.71, Table 3, Fig.5, climatic variability); Humphrey, 2008 (p.83: Appendix A); Galbraith, 2009 (pers. comm.); DiBacco & al., 2012 (p.483, Table S1, ballast water transport); in CalCOFI regional list (MDO, Nov. 2013; M. Ohman, pers. comm.)
NZ: 1 + 1 doubtful

Distribution map of Aetideus divergens by geographical zones
Species Aetideus divergens - 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.
NE Pacif. (off British Columbia), British Columbia, Fjord system (Alice Arm & Hastings Arm), Portland Inlet, Puget Sound (near Seattle), CalCOFI refion, ? Japan (Sagami, Suruga, Izu-Bonin trench.

Type locality: 52°02'N, 132°53'W.
N: 9
(37) F: 1,9-1,69; M: 1,43-1,25; ? (39) F: 1,82; M: 1,8; {F: 1,69-1,90; M: 1,25-1,43}
Rem.: epi-mesopelagic.
A doubt subsists concerning the identity of the Tanaka's (1957) form.
After Robertson & Frost (1977) the feeding behavior of this species, usually occur at subsurface depths seem to be adapted for feeding on large particles, possibly large phytoplanctonic organisms and fecal pellets, which sink out of the mixed layer.
Last update : 19/06/2023
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Razouls C., Desreumaux N., Kouwenberg J. and de Bovée F., 2005-2024. - Biodiversity of Marine Planktonic Copepods (morphology, geographical distribution and biological data). Sorbonne University, CNRS. Available at http://copepodes.obs-banyuls.fr/en [Accessed May 25, 2024]

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