Antho (Acarnia) circonflexa (Lévi, 1960) is a thinly encrusting red sponge with a slightly hispid surface. The species was recorded only twice from the W coast of France. It is one of the many red encrusting microcionids which can only be identified by careful microscopic study of the spicules and their arrangement.
Shape, size, surface and consistency: Very thin crust with hispid surface. No further information.
Spicules: Megascleres: Ectosomal subtylostyles: 150-400 x 3 µm; principal styles with rugose heads: 150-450 x 10 µm; acanthostyles/strongyles of the basal reticulation, smooth shaft and spined or rugose apices: 80-170 x 6-10 µm; echinating acanthostyles, lightly spined along the shaft, with spined or rugose heads: 80-150 x 8-12 µm. Microscleres: Palmate isochelae, of which part have a twisted shaft (opposite alae align the shaft at different angles): 10-18 µm; toxas, short, with shallow curve and the median part thickened: 25-85 µm.
Skeleton: "Typical for the genus", i.e. presumably with a basal reticulation of short acanthostyles/ acanthostrongyles, echinated at the nodes by short acanthostyles; long styles are erect on the basal reticulation and project beyond the surface; bundles of subtylostyles and loose subtylostyles are found at the surface.
Ecology: Vertical cliffs, 25 m.
Distribution: Bretagne: Rade de Brest (Cormorandière).
Etymology: The name refers to the twisted chelae.
Type specimen information: The type is in the Muséum Nationale d'Histoire Naturelle, Paris.
The twisted chelae and centrally thickened toxas are unique among Antho species of the area.
Source: Lévi, 1960.