Aetideus divergens - Species Card - Marine Planktonic Copepods

Aetideus divergens Bradford, 1971 (F,M)

Taxonomy

Order Calanoida

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Superfamily Clausocalanoidea

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Family Aetideidae

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Genus Aetideus

details list species for this Genus

Abbreviations or symbols

Synonymy

Aetideus armatus : Campbell, 1929 (p.311); ? A. armatus : Tanaka, 1957 a (p.31, figs.F,M)

References

List of the studied authors

Bradford, 1971 (p.24,figs.F,M); Gardner & Szabo, 1982 (p.200, figs.F, M); Markhaseva, 1996 (p.17, figs.F,M, Rem.)

Figures

Plate 1 issued 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 figures

Plate 2 issued 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 figures

Plate 3 issued 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)

Plate 4 issued 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.

Plate 5 Aetideus 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.

Plate 6 Aetideus 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.

Complementary References

List of the studied authors

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.)

Distribution

NZ: 1 + 1 doubtful

Distribution map of Aetideus divergens by geographical zones

Additional Maps & Charts

Map 2 issued 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.

Localisations

Geographical glossary

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.

Quotations

N: 9

Dimensions (mm)

References of the authors concerning dimensions

(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}

Remarks

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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