(Cabioch, 1968)
Species Overview
Axinyssa digitata (Cabioch, 1968) is a digitate cushion-shaped sponge with a conulose surface. It has a superficial resemblance with Ciocalypta , but that has transparent fistules and a surface crust of tangentially arranged spicules. It has been recorded only twice, occurring in deeper water (40-80 m) off the coasts of France and Spain.
Taxonomic Description
Colour: Lemon-yellow.
Shape, size, surface and consistency: Massive base of 0.8-3 cm in thickness from which rise irregular often coalescing conical digitations of 0.3-2.2 cm high and 0.2-1.5 cm diameter at their base. The surface is conulose and hispid, and along the digitations the conules are aligned to form longitudinal ridges with intervals of 0.5-1.5 mm. Consistency not recorded.
Spicules: (Axinyssa digitata spics) Oxeas only, of a single but very variable category. They frequently have stairstepped ends, and strongyloxea-like modifications are common. Most are curved and some have a median swelling. Size 315-890 x 6-22 µm.
Skeleton: Spicules are arranged in longitudinal tracts, which are frequent at the base, becoming more rare at the surface, where they lift the organic skin into conules. Many spicules are singly and confusedly arranged. There is no tangential or perpendicular ectosomal skeleton.
Ecology: Deeper water, 40-80 m, in soft sediment overlying hard bottom.
Distribution: Known only from the type locality north of Ile de Batz, Roscoff, Bretagne, and from the Straits of Gibraltar.
Etymology: The name refers to the shape.
Type specimen information: The type (Axinyssa digitata Cabioch) is in the collection of the Station Biologique, Roscoff.
Remarks
The erect conulose digitations distinguish this species from other Halichondrids as Halichondria spp. Hymeniacidon perlevis may have long digitations, but that species has exclusively styles which are also considerably shorter than the oxeas of A . digitata . Another species with long erect fistules/digitations is Ciocalypta penicillus . This has transparent white fistules with a tangential crust of intercrossing spicules and predominantly styles, in two distinct size classes.
Cabioch (1968) assigned his species to the genus Pseudaxinyssa , but that was recently synonymized with Axinyssa . The species clearly conforms to the expanded definition of Axinyssa given by Van Soest et al. (1990).
Source: Cabioch, 1968.