Prosuberites longispinus Topsent (1893) is a cream-yellow encrustation with a very hispid punctiform surface. It is a southern species, recorded a few times from the Roscoff area.
Shape, size, surface and consistency: Thin encrustation, lateral expansion several cms, less than a mm in thickness, with very hispid surface. Punctiform openings evenly distributed. Consistency soft.
Spicules: Tylostyles, long, strong, straight or lightly curved, with well-developed ellipitcal heads, with gradually tapering and sharply pointed ends: up to 2000 x 17 µm (heads up to 25 µm).
Skeleton: Spicules are arranged singly erect, heads down, perpendicular to and penetrating the surface.
Ecology: Rocks and pebble bottoms, from 60 m downwards.
Distribution: Roscoff; Mediterranean.
Etymology: The name refers to the hispid nature of the surface.
Type specimen information: The type is in the Paris Museum.
This species is similar in most aspects to Protosuberites denhartogi, but that has much shorter and thinner tylostyles (less than 600 x 11 µm), and is consequently less obviously hispid.
Source: Topsent, 1900.