(Kramp, 1930)
Description
Umbrella usually flatter than a hemisphere, with uniformly thin jelly. Velum broad, 1/3 bell radius or more [Mitrocomella brownei ].
Stomach short, four-sided, with very small base. Mouth with four simple slightly recurved lips. Radial canals four, these and ring canal very narrow but funnelling out into stomach.
Gonads oval in males, somewhat elongate in females, situated near ends of radial canals. Marginal tentacles [M.brownei-margin detail ] 11-24, typically 16; when extended longer than diameter of bell, with broad rounded bases. 6-8 marginal cirri between adjacent tentacles, coiling spirally. Marginal vesicles 8(-11), open, each with five to seven concretions.
Size
Diameter of umbrella 4-7 mm at maturity.
Colour
Stomach, gonads and marginal tentacles bright pinkish or ochreous yellow [M.brownei-female-habitus ]; large specimens with streaks of bluish-black pigment on either side of tentacle bases.
Ecology
Medusa recorded around the British Isles April-May, August-November (Russell, 1953a); and off Roscoff in 'spring' (Teissier, 1965); presumably the polyp stage starts releasing medusae some weeks before that and continues through to early autumn.
Depth range
— Medusa in coastal plankton.
— Hydroid only known from primary polyps on the sea fan Eunicella (Rees and Russell, 1937).
Distribution around the British Isles
Medusa recorded the southern North Sea (Kramp, 1930) and from the eastern North Sea off Norfolk (Hamond, 1963) and Scotland (Fraser, 1972).
World distribution
Medusa recorded in the NE Atlantic off Roscoff, Brittany (Teissier, 1965), Villefranche, Mediterranean (Kramp, 1958), and British Isles (Fraser, 1972; Russell, 1953a; Kramp, 1961); E and W South Atlantic; circum-Antarctic (Bouillon, 1999).
Remark
The polyp is only known from cultures.
[Description after Cornelius, 1995a]