Hymedesmia peachii Bowerbank, 1882


Family : Hymedesmiidae

Form: A very thin encrustation, with oscules surrounded by radiating veins.

Colour: Grey to yellow

Internal characters

Skeleton: Basal layer of acanthostyles, with ascending columns of ectosomal spicules, 38 spicules thick. Chelae are present in the surface layer. A thin sponge typically 500600 μm thick.

Spicules: Acanthostyles: 75320 μm by 814 μm; only one size category is present. The smallest acanthostyles are entirely spined, whereas those at the larger end of the size range may be smooth for up to half of their length. The head is not tylote, and the spicules are sometimes faintly or strongly curved. Extremes of this category are shown; there are intermediates in both size and form. Ectosomal spicules: 165225 μm by 45 μm; tornotes with conical ends. Chelae: two size categories of chelae are present. The largest chelae (2830 μm) have an unusual, broad, flattened shaft, whereas the smaller chelae (2022 μm) are normal arcuate chelae.

Distribution: Hymedesmia peachii was originally described by Bowerbank (1882) from Wick, NW Scotland and has been reported from the North Sea, Sweden, the English Channel and the Mediterranean Sea.

Distribution Map: NBN map : National Biodiversity Network mapping facility, data for UK.

Identity: Can be separated from other Hymedesmia by the unusual form of the large chelae.

Editors: Claire Goodwin & Bernard Picton.

 Picton, B.E., Morrow, C.C. & van Soest, R.W.B., 2011. [In] Sponges of Britain and Ireland