Microciona bitoxa Burton, 1930

Order : POECILOSCLERIDA

Family : Microcionidae

Form: A thin encrusting species with obvious surface channels.

Colour: Grey when alive, pale brown in alcohol

Surface: Thinly encrusting, pores, exhalant canals and oscules apparent.

Internal characters

Skeleton: Hymedesmoid: long styles and acanthostyles with their bases embedded in a basal plate of spongin; ectosomal subtylostyles form an irregular tangential layer at the surface. Small toxas scattered irregularly throughout the sponge; hair-like toxas forming wisp-like bundles.

Spicules: Megascleres : Ectosomal subtylostyles, smooth, with a crown of small spines at the base: 600 x 5 μm; long styles, smooth: 900-1200 x 15 μm; small entirely spined acanthostyles: 60 x 5 μm. Microscleres : Toxas of two kinds, short stout, variable in size: 30-105 x 4 μm, and long hair-like forms: 150 μm.

Distribution: Type locality is Norway, reported also from the West coast of Sweden and Western Scotland.

Identity: The species was erected as member of a genus Hymantho Burton (1930) based on the absence of chelae. In view of the variability of the presence of chelae in the order Poecilosclerida, this genus is considered artificial. A second species of Clathria lacking chelae is Clathria normani Burton, 1930, differing in having much smaller styles and only a single toxa category.

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