Haliclona (Halichoclona) fistulosa

Haliclona (Halichoclona) fistulosa (Bowerbank, 1866) Figure 16 Isodictya fistulosa Bowerbank, 1866: 299–300. Haliclona (Halichoclona) fistulosa, de Voogd et al. 2024: 274. Material examined: ESFM-POR/2017-186, S4, 20 m, on stone, 2 specimens; ESFM-POR/2017-375, S19, 24 m, on cave wall, 1 specimen; ESFM-POR/2017-341, S20, 20 m, on coralligenous habitat 1 specimen. Description: Specimens have numerous fistulae and tassel-like projections emerging from the base of the body (Figure 16a). The fistulae (2–4 mm) are slightly directed upwards, and the thicker ones carry the osculum. Its color is pink-white under water and brown in alcohol. Its external surface is smooth and fragile. It does not secrete mucus. Choanosomal and ectosomal skeletons have an isotropic structure. The sponge is quite rare and is found only at the tips of the spicules. Its spicules consist of straight, rarely slightly curved, pointed oxeas (140–235 × 6–13 µm) (Figure 16b, c). Habitat and distribution: This species was previously reported in sheltered, silty areas with moderate tidal currents from the coast to the lower circalittoral zone (Ackers et al. 1992). It is an Atlanto-Mediterranean species (de Voogd et al. 2024), previously reported from the Azores and the Celtic Sea in the eastern Atlantic (Cruz 2002, de Weerdt 1986); from the Adriatic Sea (Griessinger 1971), the Ionian Sea (Pulitzer-Finali 1983) and the Tunisian coast (Ben Mustapha et al. 2003) in the Mediterranean Sea. This is a new record for the eastern Mediterranean. Remarks: Haliclona (Halichoclona) fistulosa is characterised by the growth form of the fistules. A tubular form is rare in the subgenus Halichoclona, whereas a massive or cushion-like form is more common. The forms and dimensions of the skeletons (fibres and spicules) of the our specimens overlap with those reported by de Weerdt (1989) in the Mediterranean Sea.