(Van Koolwijk, 1982)
Species Overview
Sycon scaldiense (Van Koolwijk, 1982) is a whitish tubular sponge resembling the closely related S . ciliatum , but differing from it in being "hairy" due to protruding long spicules. So far it is only known from SW Netherlands and it is suspected to have been introduced with imported oyster sprat.
Taxonomic Description
Colour: Grey or brownish white.
Shape, size, surface and consistency: (Sycon scaldiense holotype) (Sycon scaldiense draw) Tubular, erect, cylindrical, syconoid. Length up to 5 cm. Surface hispid, scarcely papillate. Oscule apical, always with large stiff crown of spicules. Consistency fragile, compressible.
Spicules: (Sycon scaldiense spics) Calcareous. Triactines of distal cones: 30-60 x 5-10 µm; tubar triactines: regular to sagittal, rays 80-150 x 9-11 µm; subchoanosomal triactines: sagittal, paired rays 80-200 x 5-10 µm, basal ray 180-350 x 5-10 µm; choanosomal triactines: sagittal or subregular, paired rays 100-280 x 5-10 µm. Choanosomal tetractines: similar to choanosomal triactines, with apical ray 80-350 x 5-10 µm.
Ectosomal oxeas: 500-7000 x 5-10 µm.
Skeleton: (Sycon scaldiense cross) Distal chambers grouped around central atrial cavity, Tubar skeleton of basal rays of subendosomal sagittal triactines. Distal cones ornamented with large oxeas giving the sponge a very "hairy" look. Choanosomal skeleton of paired rays of subchoanosomal sagittal triactines and choanosomal triactines and tetractines.
Reproduction: The breeding period is from June to early February. This period is divided into two by a sexually non-active period in the month of September. A large part of the population disintegrates during early fall but the remaining part of the population and the fast growing young individuals continue to live throughout the winter. This group is forming oocytes in late spring. The winter breeding period of this species might indicate that it originates from the southern hemisphere though imported oyster sprat.
Ecology: Occurs on weeds attached to pontoons and harbour piles.
Distribution: So far known only from the Oosterschelde sea arm in the SW of the Netherlands.
Etymology: Scaldiensis (Latin) = from the Schelde, referring to the type locality.
Type material: The types are in the Amsterdam Museum: holotype ZMA POR. 4650, from Kats, SW Netherlands; paratypes ZMA POR. 4651 (8 specimens) and 4652 (20 specimens) from Schelphoek and Wemeldinge, SW Netherlands.
Remarks
This species is easily distinguished from the closely related and sympatric S . ciliatum in the extreme length of the ectosomal oxeas which give the tubes a very hairy aspect. The length of the apical ray of the choanosomal tetractines is also clearly larger than that of S . ciliatum . Colour and general aspect of the two are also clearly different.
Source: Van Koolwijk, 1982