Stelletta lactea Carter, 1871


Family : Ancorinidae

Form: Massive, spreading, insinuating in crevices and small holes in shells and rocks. Surface contours follow that of the substrate.

Colour: Grey, white interior.

Consistency: Consistency hard outside, soft and crumbly inside.

Surface: Rough to the touch.

Apertures: Large, gaping, flush oscules. Pores concentrated in rounded fields.

Internal characters

Skeleton: Cortex thin, charged at the surface with an abundant layer of asters carried by the cladi of the triaenes. Cortical skeleton traversed by bundles of oxeas, which become irregular towards the interior.

Spicules: Huge oxeas, fusiform, slightly curved, 1250 μm; orthotriaenes: 825 μm; dichotriaenes: 825 μm. Microscleres : Oxyasters, small, with numerous rather blunt rays, but rather variable: 12 μm; trichodragmas: 25 μm long.

Habitat: Shallow-water, in crevices and small holes, in rock pools; elsewhere down to 500 m. Although Stephens (1912) reports this species as fairly common it is ill-known. Reliable descriptions date back from the previous century, although its occurrence is mentioned in later faunal lists. Its distinction from sympatric Stelletta species such as the common S . grubii is rather easily made when spicules are examined microscopically: a single category of euasters and the trichodragmas are distinctive. The trichodragmas are shared with Dragmastra normani Sollas, but that has pro-and anatriaenes, and much longer oxeas.

Distribution: Ireland, SW England, Normandy, Bretagne, Galicia; Azores.

Distribution Map: NBN map : National Biodiversity Network mapping facility, data for UK.

Identity: Stelletta lactea is a white massive crust with rough surface, provided with pore fields. It is apparently quite rare, having been recorded only a few times from the south coast of Britain and the west coasts of France and Spain.

Editors: Christine Morrow, Bernard Picton & Rob van Soest.

 Picton, B.E., Morrow, C.C. & van Soest, R.W.B., 2011. [In] Sponges of Britain and Ireland