Form: The sponge consists of a basal reticulation of thin-walled tubes which creep and anastomose over the substrate, from which arise numerous, long, free-standing, closely-set oscular tubes which are always provided with lateral diverticula, which may subdivide even further. "It occurs as a bushy form and as an arborescent form."

Colour: Off-white to grey.

Smell: None.

Consistency: Very delicate and soft; "very fragile".

Surface: That of the tubes is soft and smooth; "minutely hispid".

Apertures:

• The oscules are terminal on erect tubes. "The oscular rim is short."

Contraction:

• The tubes cling together by surface tension when out of the water. Otherwise no noticeable contraction occurs.

Synonyms: None in common use. Treated by Burton (1963:159) as one of several 'Named Forms' comprising Leucosolenia botryoides (Ellis and Solander, 1786:190), the name which he regarded as valid for the whole complex.

Internal characters

Skeleton: The skeleton of the chamber layer consists of triradiates. The endosomal skeleton is of quadriradiates, which also line the atrial cavity. Oxea are also present.

Spicules: Triradiates have paired rays 75-90 x ca. 7 μm thick and basal ray 100-200 μm long x ca. 6 μm thick. Quadriradiates have basal ray 100-200 μm long x ca. 6 μm thick, the other rays are 70-90 x ca.7 μm. The oxea are of two sizes; the larger, 190-280 x 9-10 μm thick, usually have lanceolate distal ends and curved shafts; the smaller are usually abundant, without lanceolate endings, 70-140 x ca. 3 μm thick.

Identity: Superficially this species can be confused with several other 'Named Forms' of Leucosolenia, including L. botryoides, L. variabilis and L. contorta. Can field characters be established to separate them?

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

iNaturalist: Leucosolenia complicata at iNaturalist World Species Observations database.

WoRMS: Leucosolenia complicata at World Register of Marine Species. Accepted name: Leucosolenia complicata (Montagu, 1814). AphiaID: 132219.

Classification: Biota; Animalia; Porifera; Calcarea; Calcaronea; Leucosolenida; Leucosoleniidae; Leucosolenia

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