Chelonaplysilla noevus (Carter, 1876)


Family : Darwinellidae

Form: Encrusting, conulose, several mm in thickness and of indefinite lateral expansion. Conules coarse, sharp, several mm apart.

Colour: Dark purple-violet, in life as well as in alcohol.

Consistency: Soft, thin crust.

Surface: Surface bears a characteristic reticulation of sand grains visible to the naked eye.

Apertures: Oscules conspicuous, wide, slightly raised.

Contraction: Slight.

Internal characters

Skeleton: Dendritic fibres rise from a basal spongin plate adhering the substrate, similar to the condition found in Aplysilla species. They are 75-80 Ám diameter at the base, 20-30 Ám near the surface. Spongin purple coloured, layered, with a wide darker area in the centre (pith). Fibres may divide a few times but seldom anastomose. Surface reticulation of sand grains with meshes of 160-170 Ám diameter.

Spicules: Absent.

Habitat: On rocks in the shallow sublittoral, 15-115 m. Usually on vertical or overhanging bedrock surfaces in offshore, exposed sites.

Distribution: Ireland, Roscoff, Naples, Monaco, Azores, Cape Verde Islands; a rare species in Western Europe.

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

Identity: Along the coasts of Western Europe this is the only representative of the genus Chelonaplysilla, and through its surface reticulation of sand grains is easily recognizable. In deeper waters off the Azores, C. psammophila, occurs which may be distinguished by having a much paler colour. In the Eastern Mediterranean, a third species, C. erecta, occurs which is very similar to the present species, but it forms creeping or erect branches.

Voucher: BELUM : Mc1866: Ruecallan, Rathlin Island, Antrim, Northern Ireland

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