Species Card of Copepod
Calanoida ( Order )
    Clausocalanoidea ( Superfamily )
        Scolecitrichidae ( Family )
            Undinothrix ( Genus )
Undinothrix spinosa  Tanaka, 1961   (F)
Tanaka, 1961 a (p.154, Descr.F, figs.F); Bradford & al., 1983 (p.122)
Species Undinothrix spinosa - Plate 1 of morphological figuresissued from : O. Tzanaka in Publ. Seto Mar. Biol. Lab., 1961, IX (1). [p.155, Fig.112].
Female (from Japan: Sagami Bay): a, habitus (dorsal); b, forehead (lateral); c, rostrum (frontal view); d, last thoracic segment (lateral, left side); e, idem (right side); f, distal segments of A1; g, Mx1; h, Mx2; i, Mxp; j, P1; k, P2; l, P3; m, P4 (3rd segment); n, endopod of P4; o, P5.

Nota Female:
- Cephalothorax and abdomen ratio 1.16 : 0.98.
- Head and 1st pedigerous segment fused, 4th and 5th pedigers incompletely separated.
- Posterior lateral corners of the last thoracic segment asymmetrical; distal margin more produced on left side; lateral distal margins are outwardly curved (in dorsal view).
- Urosome 4-segmented; segments and caudal rami in proportional lengths 43 : 18 : 18 : 7 : 17 = 100.
- Genital segment swollen laterally about the middle; slightly concave ventrally at genital area; dorsal surface convex.
- Caudal rami longer than wide; appendicular seta small.
- A1 23-segmented, extends to yje distal end of the 2nd abdominal segment.
- A2 exopod about as long as endopod.
- Md with a slender endopod.
- Mx1 with 9 setae on outer lobe; 5 setae on exdopod; 9 setae on endopod; 5 setae on the 2nd basal segment.
- Mx2 with 3 worm-like and 5 small bud-like sensory filaments on endopod..
- Mxp characteristic; 2nd basal segment coarsely dentate on the proximal margin ; outer marginal setae on the 4th and 5th endopodal segments well developed.
- P1 exopod 3-segmented, endopod 1-segmented; 1st exopodal segment without outer marginal spine; outer marginal spines on the 2nd and 3rd exopodal segments slender and long.
- P2 exopod 3-segmented, endopod 2-segmented; outer edge spine of the 1st exopodal segment long and furnished with fuine spinules on inner margin; 2nd and 3rd exopodal segments and the 1st and 2nd endopodal segments furnished with rows of spinules on posterior surface; terminal spineof exopod with a characteristic arrangement of teeth (fig.k).
- P3 and P4 with endopod and exopod 3-segmented each; posterior surface of exopod and endopod of P4 more finely furnished with spinules.
- P5 symmetrical, 3-segmented; segments about equal length; terminal segment with 3 spines, of which the apical two are very strong and furnished with denticles on outer distal margin; Outer marginal spine short and furnished with small denticles on either side of the spine

Species Undinothrix spinosa - Plate 2 of morphological figuresissued from : O. Tzanaka in Publ. Seto Mar. Biol. Lab., 1961, IX (1). [p.154].
Female: Proportional lengths of the segments of A1.

Compl. Ref.:
Furuhashi, 1966 a (p.295, vertical distribution in Kuroshio region, Table 10); Kuriyama & Nishida, 2006 (p.293, 300: Tab.II; fig.7, 10, vertical distribution)
NZ: 1

Distribution map of Undinothrix spinosa by geographical zones
Japan (Sagami Bay, SW Bösö))
N: 3
(108) F: 2,14; (1000) F: 2,1 ± 0,1; {F: 2,0-2,20}
Rem.: meso-bathypelagic. 298-526 m at Station N-1 (SW Bösö, E middle Japan) from Furuhashi (1966 a).
See diagnosis in the Genus Undinothrix.
After Tanaka (1961 a, p.156) this species has a general resemblance with the genus Lophothrix Giesbrecht in the structure of the appendages but can be distinguished from them by the rostrum, by the strong terminal spines of P5, and the distal 2 segments of A1 completely fused.
Last update : 18/01/2021
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Razouls C., Desreumaux N., Kouwenberg J. and de Bovée F., 2005-2022. - Biodiversity of Marine Planktonic Copepods (morphology, geographical distribution and biological data). Sorbonne University, CNRS. Available at http://copepodes.obs-banyuls.fr/en [Accessed May 21, 2022]

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