Crella (Pytheas) basispinosa Burton, 1931 is a papillate subspherical sponge recorded only once from a fjord in northern Norway. It differs from other Crella species of the area in microscopical detail.
Colour: Ash-grey in alcohol.
Shape, size, surface and consistency: Sponge subspherical to massive, papillate. Surface smooth, easily detachable. Papillae are up to 5 or 6 mm long. Consistency fragile.
Spicules: (Crella basispinosa spics) Megascleres: Choanosomal tornotes smooth, with ends usually slightly unequal and varying from tylote to strongylote, or even mucronate: 560 x 7 µm; large acanthostyles, with base densely spined, but with remainder of their length sparingly spined: 630 x 8 µm; small acanthostyles, densely spined throughout: 250 x 7 µm.
Microscleres: Arcuate (?, Burton says: spatulate) isochelae: 25 µm.
Skeleton: Ectosomal: a dense tangential layer, one spicule thick, of small acanthostyles. Choanosomal: a coarse irregular reticulation of tornotes, with acanthostyles of both sizes associated with it and scattered in its interstices.
Ecology: In fjords, 50-200 m.
Distribution: Northern Norway.
Etymology: The name refers to the acanthostyles.
Type specimen information: The holotype is in the Tromsø Museum.
Neither of the acanthostyle types appears to be echinating, and where they are associated with the bundles of tornotes, their association is very loose and haphazard. The form of the species and the sizes of the spicules appear to be distinctive.
Source: Burton, 1931.