Bigelow, 1911
Description
Nectophore [Rosacea plicata ]: the small, globular larval nectophore resembles that of the hippopodiids except that its somatocyst is kinked and a central organ usually is present. This nectophore is replaced by two elongated definitive nectophores, which contain large quantities of mesogloea. The hydroecium extends along approximately 3/4 of the ventral surface reaching neither apex nor base, and the simple somatocyst runs the mid-line of the dorsal surface. The nectosac is basal.
Eudoxid [R.plicata-eudox ]: bract kidney-shaped and compact. The longitudinal bracteal canals are reduced to spurs, and the dorsal canal arises distal to the spur on the left hydroecial canal. The gonophores are simple and bell-shaped.
Size
Nectophore of adults up to 30 mm in length.
Depth range
Mesopelagic, 200-500 m.
Remarks
There has been much confusion in the past regarding the taxonomy of prayine siphonophores. Totton (1965) is followed in using the generic name Rosacea in the sense Bigelow (1911) applied to it.
Distribution in the North Sea
It is not known whether the species have penetrated into the English Channel or the North Sea, but there are many records of its presence in the western British waters.
World distribution
A well-known and common species throughout the World’s oceans, but most commonly found in temperate waters. It is present in the western British waters.
[After Kirkpatrick and Pugh, 1984]