Form: Encrusting sheets to cushions with lobes and ridges.

Colour: White, pale grey.

Smell: None.

Consistency: Firm, crisp, friable.

Surface: Smooth.

Apertures:

• Small, distributed along the tops of lobes or ridges, "naked" (i.e. without collar of spicules).

Contraction:

• None.

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Synonyms: Leucandra nivea (Grant, 1826) Haeckel, 1872:211. Treated by Burton (1963:273) as being one of several 'Named Forms' comprising Leuconia barbata (Duchassaing & Michelotti, 1864:111), the name which he regarded as valid for this whole complex.

Internal characters

Skeleton: The ectosomal skeleton consists of several tangential layers of triradiates; the skeleton of chamber layer is of triradiates and microxea, irregularly arranged. The endosomal skeleton, and linings of exhalant canals, are tangential layers of quadriradiates.

Spicules: The ectosomal triradiates (a) have rays ca. 120 μm long, those of the chamber layer (b) 50-1200 μm; microxea (c) are 40-60 μm long. The endosomal quadriradiates (d) are sagittal and have paired rays ca. 20 μm long and basal ray ca. 60 μm.

Identity: Superficially this species can be confused with Leuconia johnstoni (see Burton, 1963:266) and Leuconia gossei (see Burton, 1963:505). It would be useful to see if the three species occupy different ecological niches.

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

iNaturalist: Leuconia nivea at iNaturalist World Species Observations database.

WoRMS: Leuconia nivea at World Register of Marine Species. Accepted name: Leuconia nivea (Grant, 1826). AphiaID: 132201.

Classification: Biota; Animalia; Porifera; Calcarea; Calcaronea; Baeriida; Baeriidae; Leuconia

Voucher: BELUM : Mc1778. St. Kilda, W. Scotland.

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