Halichondria (Halichondria) bowerbanki Burton, 1930

(Figure 12)

Halichondria bowerbanki Burton 1930: 489 .

Material examined: ESFM-POR/2017-616, T3, 40–50 m, on stone, 2 specimens.

Description: Specimens have a very polymorphic morphology with long, string-like projections (0.5–1 mm in diameter) from a thin, encrusting base (Figure 12a). Color is light yellow. The consistency is rather firm and compressible. The osculum is inconspicuous and irregular (1–5 mm). The ectosomal skeleton has a halichondroid skeletal structure, with spicules arranged randomly or in tight bundles (Figure 12b). The choanosomal skeleton is disordered, with dendritic bundles terminating at the surface on different sides. Spicules consist only of oxeas (145–400 × 3.6–10.1 µm) (Figure 12c–d). No microscleres.

Habitat and distribution: This Atlanto-Mediterranean species was reported from different hard and muddy substrata in the Adriatic Sea (Cardone et al. 2014), Alboran Sea (Carballo & Garcia-Gómez 1994), Tyrrhenian Sea (Marra et al. 2016), Celtic Sea (Morrow et al. 2012) and the northern Atlantic Ocean (Montagu [1814] 1818). It was also found in cave habitats (0–7 m) in the Black Sea (Ereskovsky et al. 2018) and on Mytilus galloprovincialis (Evcen et al. 2023a) This species is a new record for the marine fauna of the Aegean Sea.