Clathria (Microciona) normani (Burton, 1930a) is one of the many thinly encrusting Clathria species which can be only reliably identified by microscopic examination. It lacks chelae. It has been recorded only once from Norwegian waters.
Colour: Light brown in alcohol.
Shape, size, surface and consistency: Thinly encrusting, pores and oscules not apparent.
Spicules: Megascleres: Ectosomal subtylostyles, smooth: 210 x 2 µm; long styles, smooth except for a few irregular tuberculations at the base: 330 x 9 µm; small entirely spined acanthostyles: 90 x 3 µm.
Microscleres: Toxas with a shallow curve, in a single but variable size category: 45-90 µm.
Skeleton: Leptoclathriid/ hymedesmioid: long styles and acanthostyles with their bases embedded in a basal plate of spongin; ectosomal subtylostyles form an irregular tangential layer at the surface.
Ecology: No data.
Etymology: Named after the Rev. A.M. Norman, pincipal collector for Bowerbank, and editor of Volume IV of Bowerbank's Monographs of the British Spongiadae.
Type specimen information: The type is in the Natural History Museum, London.
The species is the type species 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. In fact Burton (1930) mentions the finding of a single palmate isochela (9 µm) in a slide made of this species, but he considered this foreign. Several other species of Clathria lacking chelae exist; one other from Scandinavia is C. bitoxa Burton, 1930a, but this has styles 3 times as long as those of C. normani.
Source: Burton, 1930a.