Form: Very variable. Thin sheets may have thin tassel-like outgrowths reminiscent of Halichondria bowerbanki, but are thinner. Encrusting forms resemble Haliclona viscosa or Halichondria cinerea, with lobate growths each with oscules. Tassel-like forms similar to Iophon nigricans have been observed in sheltered conditions.

Colour: Greyish beige, with a tinge of pink or purple.

Smell: None.

Consistency: Very soft, compressible.

Surface: Smooth or rugose, or smoothly lobate, with a porous appearance similar to that of Haliclona viscosa.

Apertures:

• These may be the most constant feature of the external appearance of this species. The oscules have a raised transparent rim with a few converging transparent excurrent canals. The oscular rims may develop short tassels reminiscent of Amphilectus fucorum (q.v.). However, in thinly encrusting specimens the oscules may not be apparent.

Contraction:

• Oscules become inconspicuous on collection.

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Internal characters

Skeleton: Slender styles often forming wisp-like bundles running towards the surface; otherwise somewhat irregularly arranged.

Spicules: Slender styles, often flexuous, typically ca. 220 μm x 3-6 μm. According to Burton, distal ends narrow to a point in semi-discrete steps - this feature is not visible in all specimens, and occurs in only about 10% of spicules in most specimens.

Identity: Very thin styles (with distinctive narrowing to the point), together with soft texture, lack of microscleres or other types of megascleres, and halichondroid skeleton, are the best distinguishing features.

Distribution Map from NBN: Rhaphidostyla kitchingi at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Rhaphidostyla kitchingi at iNaturalist World Species Observations database.

WoRMS: Rhaphidostyla kitchingi at World Register of Marine Species. Accepted name: Rhaphidostyla kitchingi Burton, 1935. AphiaID: 132715.

Classification: Biota; Animalia; Porifera; Demospongiae; Heteroscleromorpha; Suberitida; Halichondriidae; Rhaphidostyla

Voucher: BELUM : Mc617. Ard Bay, Galway.

Editors: D. Moss, B.E. Picton.