Ircinia dendroides

(Schmidt, 1862)

Species Overview

Ircinia dendroides (Schmidt, 1862) is a greyish repent-ramose sponge with conulose branches of 1-2 cm diameter creeping over the substrate. It is a Mediterranean species recorded from Portugal and NW Spain.

Taxonomic Description

Colour: Grey to greyish white.
Shape, size, surface and consistency: (Ircinia dendroides PF) Creeping cylindrical or flattened branches of 1-2 cm in diameter. Surface conulose with conules 1 mm high. No apparent oscules. Consistency firm, very solid.
Spicules: Absent.
Skeleton: The ectosome consists of a tough epidermis charged with small uniformly shape sand grains, here and there forming a reticulation. The choanosomal skeleton is made up of spongin fibres of which the primary fibres are filled with foreign material (sand grains, broken spicules); their diameter is 120-200 µm. Secondary fibres are 30-90 µm in diameter, stratified but free from sand grains; they often anastomes tightly t form perforated (fenestrated) spongin sheets. Filaments , thin threads of clear-transparent spongin, are numerous and relatively thick: 3.5-5 µm; they end in globular swellings of 8-10 µm in diameter.
Ecology: On rocks and coralline algae in Laminaria zone.
Distribution: Portugal, NW Spain, Mediterranean.
Etymology: Dendroides = tree-like, referring to the shape.
Type specimen information: The type specimens are in the Graz Museum: LMJG 15497, 15498, 15442.

Remarks

Ircinia species are best identified by their growth form; this is the only Ircinia species in the area having a repent-ramose habit.
Source: Vacelet, 1959.