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(Bowerbank, 1866)

Species Overview

Haliclona (Rhizoniera) rosea (Bowerbank, 1866) is a rose-pink or light-brown, thinly encrusting or irregularly cushion-shaped sponge with scattered, slightly elevated, rarely tubular oscules. Fistular outgrowths are not uncommon. Surface is even and slightly hispid. A good way to tell it apart from the similar species Haliclona (Reniera) cinerea is the absence of slime-strands when a piece is broken off. In microscopical preparations they differ in the scarcity of spongin and the absence of a surface skeleton in the present species. It has an Arctic-Boreal distribution. Common under intertidal boulders.

Taxonomic Description

Colour: Varying from light brown to lavender-purple. The colour disappears completely in alcohol.
Shape, size, surface and consistency: The form varies from thinly encrusting patches, not exceeding 3 cm in diameter (Haliclona rosea MCS), to thickly encrusting cushion shaped masses, up to 15 cm in diameter. Surface: slightly hispid from projecting spicules. The oscules vary from 0.5-2 mm in the thinly encrusting growth form to 0.5 to 1.0 cm in the more massive and larger forms. They may be flush with the surface or be situated at the summits of chimney-shaped elevations (Haliclona rosea BandW). In the larger specimens there are commonly a few thin, solid digitations branching off from the main body. Consistency soft and fragile.
Spicules: Rather long oxeas, with long points: 150-220 x 4-11.5 µm.
Skeleton: Of the ectosome absent (Haliclona rosea SEM). The choanosomal skeleton (Haliclona rosea skel) consists of paucispicular primary lines, which are connected by irregularly scattered, single secondary spicules. The primary lines are often somewhat wavy. Spongin: absent, or scarce, and confined to the nodes of the spicules.
Reproduction: Larvae are described as having a ring of longer cilia and an orange (Topsent, 1888a) or whitish pink (Wapstra and Van Soest, 1987) bare posterior pole.
Ecology: Under intertidal stones and in the infralittoral, to ca. 100 m.
Distribution: Davis Strait, south-west and east coast Greenland, Iceland, Spitsbergen, Murmansk, Norway, Denmark, Swedish west coast, the Netherlands, British Isles, France.
Type specimen information: Lectotype BMNH 1932:1:5:3 (dry + slide) (Isodictya rosea), Tenby, England.


Like Haliclona (Reniera) cinerea, Haliclona (Rhizoniera) rosea is difficult to characterize morphologically. It is rather polymorphous, but to a lesser degree than H. (R.) cinerea. Most distinguishing is its skeletal architecture. It differs from H. cinerea in the absence of an ectosomal skeleton, and in the pauci-multispicular primary lines.
H. (R.) rosea is closely related to Haliclona (Rhizoniera) indistincta (Bowerbank: north-eastern Atlantic,?Amphi-Atlantic), Haliclona (Rhizoniera) viscosa (Topsent: north-eastern Atlantic) and Haliclona (Rhizoniera) curacaoensis (Van Soest, 1980: West Indies). They share the architecture of the choanosomal skeleton, viz. pauci-multispicular primary lines, which are connected by single secondary spicules, and with scarce spongin. The differences in skeletal architecture between H. (R.) rosea, H. (R.) indistincta and H. (R.) viscosa are so small that they are hardly distinguishable on the basis of this character. In H. (R.) indistincta (which is probably conspecific with Haliclona canaliculata Hartman, 1958a) and H. (R.) viscosa the skeleton is more close-meshed than in H. (R.) rosea. The primary lines are built up by more spicules, and the secondary spicules are more confused. The oxeas of H. (R.) indistincta andH. (R.) viscosa are completely similar in shape and size, and measure 110-150 x 3-7.5 µm, thus slightly smaller than in H. (R.) rosea. The three species are, however, well distinguished by their external features and also by their habitat preference.
H. (R.) rosea has been frequently misinterpreted in the past; it has been confused with several species, especially H. (R.) cinerea. The synonymy given here is restricted. For a comprehensive treatment you are referred to the paper of De Weerdt and Stone, 1987.
Source: De Weerdt, 1986

Haliclona rosea