De Weerdt, 1986
Haliclona (Soestella) xena De Weerdt, 1986 forms a mass of purple tubes characteristically growing on oyster beds. The surface is somewhat irregular and the consistency is soft and fragile. So far it has been found only in shallow waters, even intertidally, in the SW of Holland and in the harbour of Le Havre, and very probably has been imported along with young oysters.
Colour: Soft purple.
Shape, size, surface and consistency: Basically the sponge consists of a massively encrusting base, from which rise osculiferous, hollow tubes (Haliclona xena De Weerdt) and solid digitations. The tubes coalesce in various degrees; they are l-ca. 5 cm long and 2-6 mm thick. The oscules at the end of the tubes are wide, circular or with an irregular outline, 1-6 mm in diameter (Haliclona xena Ates). The species may develop a considerable size; it may grow out to thick masses of tubes and digitations up to 15-40 cm in diameter (Haliclona xena France). Surface rather irregular caused by the numerous digitations which branch off from the main body and the tubes; fairly to strongly hispid; very slightly crispy. Consistency soft, very fragile.
Spicules: Evenly but rather strongly curved, slender oxeas, which are gradually tapering towards a sharp point: 110-160 x 3-8 µm.
Skeleton: The ectosomal skeleton (Haliclona xena skeldraw1) consists of a discontinuous, but coherent, tangential reticulation of single spicules. The choanosomal skeleton (Haliclona xena skeldraw2) is a somewhat confused reticulation of paucispicular primary lines which are interconnected by rather irregularly scattered secondary spicules. In places the skeleton is more regularly ladder-like. There are many subdermal and choanosomal spaces. Spongin moderate, mostly confined to the nodes of the spicules; occasionally enclosing an individual spicule.
Reproduction: Larval release in August. They are small (140-190 µm) and white with a brown posterior ring (Wapstra and Van Soest, 1987) (Haliclona xena larva).
Ecology: The species occurs in high abundance on oysters.
Distribution: The species was originally described from the SW parts of the Netherlands: Oosterschelde and from two places in the Grevelingen, a closed-off sea-arm, to the north of the Oosterschelde. It is now one of the more common species in SW Netherlands. Most probably the species has been introduced in the Netherlands through the import of oysters. Subsequently it was found also in the harbour of Le Havre (NW France).
Etymology: xenos (Greek) = allochthonous, outlandish, referring to the unknown origin of the species.
Type specimen information: Holotype. ZMA POR. 5000, NE of Yerseke, Oosterschelde, the Netherlands, LLWS, O m, on oysterbeds, 6-XI-1982, coll. W. H. de Weerdt.
Paratypes. ZMA POR. 6032, NE of Yerseke, Oosterschelde, the Netherlands, LLWS, O m, on oysterbeds, 22-X-1983, coll. W. H. de Weerdt; ZMA POR. 6033, NE of Yerseke, Oosterschelde, the Netherlands, LLWS, O m, on oysterbeds, 8-X1-1983, coll. W. H. de Weerdt; ZMA POR. 6034, NE of Yerseke, Oosterschelde, the Netherlands, LLWS, O m, on oysterbeds, I5-X-1984, coll. M. Wapstra and J. Vermeulen; BMNH 1986:7: 31: 1, NE of Yerseke, Oosterschelde, the Netherlands, LLWS, O m, on oysterbeds, 8-XI-1983, coll. W. H. de Weerdt; BMNH 1986:7:31:2, NE of Yerseke, Oosterschelde, the Netherlands, LLWS, O m, on oysterbeds, 15-X-1984, coll. M. Wapstra and J. Vermeulen.
Haliclona (Soestella) xena is characterized by the tubular/massive form, the large size, the fragility, and the curved, slender oxea. In the north-eastern Atlantic area there are no species with which it could be confused, but outside the area there are several species which seem closely related. These are the Mediterranean species Haliclona (Soestella) flavescens (Topsent, 1893), Haliclona (S.) arenata (Griessinger, 1971), Haliclona (S.) mamillata (Griessinger, 1971), Haliclona (S.) mucosa (Griessinger, 1971), Haliclona (S.) valliculata (Griessinger, 1971), the North American species Haliclona (S.) tubifera (George and Wilson, 1919), and the West Indian species Haliclona (S.) caerulea (Hechtel, 1965). All these share the skeletal architecture which consists of ill-defined paucispicular primary lines, irregularly connected by unispicular secondaries. There is a strong tendency to form rounded meshes, but these reach never the sturdiness of, for instance, Petrosia. In all the species the skeleton is very delicate. The ectosomal skeleton, present in all the species which belong to this group, is a discontinuous, but still coherent reticulation of spicules which are at the nodes connected by spongin.
H. (S.) xena differs from H. (S.) arenata especially by the verrucose surface, the greyish colour and slimy consistency of the latter species. H. (S.) flavescens is massive and light yellow. H. (S.) mamillata has a very regular and smooth surface and gives off a considerable amount of mucus when it is teared. H. (S.) mucosa is extremely slimy and cream-yellow. H. (S.) valliculata is massive, beige, and it has a conspicuous irregular surface. All Griessinger's type-material, which is present in the MNHN has been studied; H. (S.) flavescens is in the MNHN represented by a microcopical slide (MNHN D.T. 278). The differences between the new species and the Mediterranean species are obvious enough, and it is quite certain that neither of them is conspecific.
Source: De Weerdt, 1986