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(Montagu, 1818)

Species Overview

Leucosolenia complicata (Montagu, 1818) is a mass of whitish tubes which rise up or hang down from the substrate to form arborescent bushes. The tubes always have side-branches (diverticula). It is similar to Leucosolenia variabilis but that species normally does not become arborescent (it is just a thick mass of interwoven tubes) and has no or few diverticula. It is a fairly common species occurring in the shallow sublittoral along most rocky coasts of Europe.

Taxonomic Description

Colour: Off-white to grey.
Shape, size, surface and consistency: The sponge consists of a basal reticulation of thin-walled tubes which creep and anastomose over the substrate, from which arise numerous, long, free-standing, closely-set oscular tubes which are always provided with lateral diverticula, which may subdivide even further. It occurs as a bushy form and as an arborescent form. Surface of the tubes is soft and smooth; minutely hispid. The oscules are terminal on erect tubes. The oscular rim is short. Consistency very delicate and soft; very fragile. Contraction: The tubes cling together by surface tension when out of the water. Otherwise no noticeable contraction occurs.
Spicules: (Leucosolenia complicata spics) Calcareous. Triactines have paired rays 75-90 x ca. 7 µm thick and basal ray 100-200 µm long x ca. 6 µm thick. Tetractines have basal ray 100-200 µm long x ca. 6 µm thick, the other rays are 70-90 x ca.7 µm. The oxeas are of two sizes; the larger, 190-280 x 9-10 µm thick, usually have lanceolate distal ends and curved shafts; the smaller are usually abundant, without lanceolate ending, 70-140 x ca. 3 µm thick.
Skeleton: The skeleton of the chamber layer consists of triactines. The choanosomal skeleton is of tetractines, which also line the atrial cavity. Oxeas are also present.
Ecology: This sponge reaches its optimal development under overhangs on the shore, growing as compact, hanging 'bunches', often associated with the red alga Plumaria elegans. Rarely found in situations in which it is liable to be left dry at low tide. The 'bushy form' may be more typical of muddy estuarine conditions; the 'arborescent form' of clear water, free of mud and sediment? Observations would be welcome on this feature. Littoral to 93 m.
Distribution: Arctic; Atlantic coasts of Europe; Mediterranean.
Etymology: The name refers to the habit.
Type specimen information: BMNH: 1910.1.1.435Aa (2 slides), Norman Collection. "From Minchin Coll. Type".


Superficially this species can be confused with several other species of Leucosolenia including L. botryoides, L. variabilis and Clathrina contorta.
Source: Ackers et al., 1992

Leucosolenia complicata