Species Card of Copepod
Calanoida ( Order )
    Clausocalanoidea ( Superfamily )
        Aetideidae ( Family )
            Gaetanus ( Genus )
Gaetanus sp.  Tanaka & Omori, 1970   (M)
Syn.: Gaidius sp. Tanaka & Omori, 1970 (p.130, Descr.M, figs.M)
Species Gaetanus sp. - Plate 1 of morphological figuresIssued from : O. Tanaka & M. Omori in Publ. Seto Mar. Biol. Lab., 1970, XVIII, 2. [p.131, Fig.7]. As Gaidius species.
Male (from Izu region): a, habitus (dorsal); b, forehead (lateral); c, A2; d, P1; e, P2; f, P5.

Nota: Cephalothorax and abdomen in the proportional lengths 73 : 27.
Cephalothorax 2.3 times as long as wide.
Lateral spines of the last thoracic segment extend a little beyond the middle of the 1st abdominal segment.
Rostrum one-pointed, and bifid at the apex; directed downward.
Abdominal segments and caudal rami in the proportional lengths 16 : 29 : 24 : 15 : 3 : 13 = 100.
A1 extends about to the distal margin of the thorax.
A2 exopod nearly as long as the endopod; endopod with 6 setae on the outer lobe and 7 setae on the inner lobe.
Md robust; 2nd basal segment with 1 small marginal seta; endopod with 9 setae on the distal margin.
Mx1 similar to that of G. tenuispinus.
Mx2 considerably reduced.
Mxp similar to that of G. tenuispinus; endopod with 4, 4, 3, 3+1, and 4 setae on the 1st to 5th segments.
In P1 the 1st and 2nd segments of the exopod fused; there is a minute distal spine on the outer margin of the 2nd segment of the exopod. In P2 the endopod 2-segmented; terminal spine of the exopod with 25 teeth. The P3 and P4 each with 20 teeth on the terminal spine of the exopod.G. tenuispinus, but differs from that of the latter in the structure of the endopod of the left leg; the 3rd segment of the exopod has no outer marginal spine.

Species Gaetanus sp. - Plate 2 of morphological figuresIssued from : O. Tanaka & M. Omori in Publ. Seto Mar. Biol. Lab., 1970, XVIII, 2. [p.130]. As Gaidius species.
Male: Proportional lengths of segments of the left A1.

Nota: The proximal 6 segments are each fringed with scattered spinules on the posterior margin.

NZ: 1

Distribution map of Gaetanus sp. by geographical zones
Japan (Izu region)
N: 1
(113) M: 3,65; {M: 3,65}
Last update : 05/01/2015
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 Any use of this site for a publication will be mentioned with the following reference :

Razouls C., Desreumaux N., Kouwenberg J. and de Bovée F., 2005-2021. - Biodiversity of Marine Planktonic Copepods (morphology, geographical distribution and biological data). Sorbonne University, CNRS. Available at http://copepodes.obs-banyuls.fr/en [Accessed February 28, 2021]

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Marine Planktonic Copepods

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