Crella (Pytheas) digitifera (Lévi, 1959) has erect branches issuing from a thick basal mass. Its colour is greenish. It is a southern species originally described from West Africa but also cited from Roscoff.
Colour: Greyish green.
Shape, size, surface and consistency: Massive basis of 2 cm thick, with fairly weak prolongations of 3 cm long and 1.5 cm diameter sticking up from it. Surface even and smooth; "skin" stretched over subdermal canals. Consistency soft.
Spicules: (Crella digitifera spics) Megascleres: Tornotes are fusiform oxeotes, straight, often faintly polytylote, with irregular mucronate or lanceolate points: 250-270 x 6-9 µm; ectosomal acanthostyles curved regularly, entirely spined: 130-135 x 5-6 µm; basal acanthostyles, straight, finely spined: 130-150 x 8-10 µm.
Microscleres: Arcuate chelae of normal shape: 20 µm.
Skeleton: Ectosomal: a feltwork of tangential acanthostyles. Choanosomal: irregular columns of tornotes, mixed with acanthostyles; these same acanthostyles are distributed everywhere in the choanosome.
Ecology: On pebbles in deeper water, 60-75 m.
Distribution: Gulf of Guinea (W Africa), Mediterranean, Roscoff.
Etymology: The name refers to the surface prolongations.
Type specimen information: The type is in the Muséum National d'Histoire Naturelle, Paris.
This species is closely related to C. (Yvesia) rosea, which is also a rather elaborate Crella and has similar spiculation. The colour of that species is more orangeish and prolonged digitations are not known. Since the record of C. (P.) digitifera from Roscoff was not accompanied by a description it needs to be confirmed by re-examination of the specimen in the collections of the Station Biologique.
Source: Lévi, 1959.