L. Agassiz, 1862

Description
Umbrella hemispherical or somewhat flatter [G.vertens-habitus ]; jelly moderately thick; velum very broad. Four radial canals and ring canal moderately broad; centripetal canals absent.
Manubrium fusiform, slightly shorter than bell cavity, on slight gastric peduncle; mouth with four perradial lips with slightly crenulated margins.
The four gonads in form of folded pendant sac, along greater part of radial canals [G.vertens-habitus ].
Marginal tentacles 60-80, long and rather stiff, each with many spiral or annular nematocyst clusters and an adhesive pad near the sharply bent distal end; statocysts imbedded in mesogloea near ring canal, about as numerous as tentacles.

Size
Umbrella 15-20 mm wide.

Colour
Umbrella yellowish green, gonads deep red, radial canals dark brown [G.vertens-habitus ].

Ecology and depth range
Brackish coastal waters.

Distribution in the North Sea
North Sea from southern Norway (Oslofjorden) to the English Channel, though scarcer in northern parts.

World distribution
Circumglobal in northern temperate coastal waters.

[After Russell, 1953a; Kramp, 1959; Kramp, 1961]

Kingdom Animalia
Phylum Cnidaria
Superclass Hydrozoa
Class Leptolida
Subclass Limnomedusae
Family Olindiasidae
Genus Gonionemus
Species Gonionemus vertens

Status in World Register of Marine Species

Accepted name: Gonionemus vertens A. Agassiz, 1862

Scientific synonyms and common names

Gonynema vertens | Haeckel, 1879
Gonionemus vindobonensis | Joseph, 1918 Considered as a probable synonym, see Kramp, 1959.

Fraser, J.H., 1972. The distribution of the Medusae in the Scottish area. Proceedings of the Royal Society of Edinburgh (B) 74(1): 1-25.

Kramp, P.L., 1959. The hydromedusae of the Atlantic Ocean and adjacent waters. Dana Report 46: 1-283; 2 plates, 335 text figures.

Kramp, P.L., 1961. Synopsis of the medusae of the world. Journal of the Marine Biological Association of the United Kingdom 40: 1-469.

Russell, F.S., 1953a. The medusae of the British Isles. Anthomedusae, Leptomedusae, Limnomedusae, Trachymedusae, and Narcomedusae. Cambridge University Press, 530 pp. 319 figures, 35 plates.

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