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Schulze, 1880

Species Overview

Plakortis simplex Schulze (1880) is a thinly encrusting, smooth, brownish crust with regularly distributed tiny holes on the surface. Its spiculation is unique. It is a Mediterranean species with several records from Western Europe (Roscoff and SW Ireland).

Taxonomic Description

Colour: Tan outside, whitish inside.
Shape, size, surface and consistency: Thinly encrusting, generally 2-5 mm in thickness. Surface smooth and regularly pierced by small punctiform inhalant openings. Oscules about 1 mm in diameter and low in frequency. Consistency compressible.
Spicules: (Plakortis simplex spics) Centrotylote diods, somewhat sinuous: 60-150 x 3-6 µm; rare triods with rays 25-50 x 3-6 µm.
Skeleton: Spicules are packed throughout the sponge, around small choanocyte chambers.
Ecology: On and under rocks and boulders from the littoral to at least 15 m.
Distribution: Mediterranean, West Africa, Roscoff, SW Ireland, Norway; reported from all over the world, but these are probably closely related species.
Etymology: The name refers to the simple shape of the spicules as compared to those of Plakina and Plakinastrella species, which were described in the same publication.
Type specimen information: No type material in BMNH.


The thin smooth crusts with regularly distributed holes is fairly distinctive, but microscopic examination is necessary. The spicules are unique, although Plakina monolopha is close; however that species has lophotriaenes.
Sources: Topsent, 1895; Díaz and Van Soest, 1994.

Plakortis simplex