Iophon hyndmani (Bowerbank, 1858)


Family : Acarnidae

Form: Thin sheet or cushion, developing into branching-repent form with anastomosing branches, 3 - 4mm diameter.

Colour: Pale yellow, purple only when preserved. The colour change on preservation in alcohol to brown is distinctive, paper labels are stained brown.

Smell: ? None, not strong?

Consistency: Moderately soft, branches have no axial skeletal structure and apparently only develop fully in fairly sheltered conditions. Friable and not easy to section.

Surface: "Wrinkled or thrown into prominent folds." Initially smooth sheets, developing into fistular outgrowths, and eventually anastomosing branches.

Apertures: Oscules "small, scattered", not obvious.

Contraction: None.

Internal characters

Skeleton: A plumo-reticulation of loose, multispicular fibres, with echinating spicules. There is a surface layer of strongyles (lying tangentially or in vertical brushes). Spongin is scarce.

Spicules: Megascleres of the main skeleton are acanthostyles (a), which are smooth in the distal (i.e. further from the base) half, 200-(225)-250Ám. The echinating acanthostyles are entirely spined and are 130-(155)-175Ám "110Ám" long. The ectosomal spicules are very thin tornotes (b), with strongylote ends which bear crowns of a few spines, ca. 135-(170)-195Ám. Microscleres are palmate anisochelae (c), 13-20Ám long, and bipocilles with saucer shaped ends (d), 9-15Ám long.

Habitat: On shells such as Modiolus modiolus, Chlamys varia, and Aequipecten opercularis; on rocks, in localities sheltered from wave action, with no or slight tidal action. "On hydroids, other sponges, coralline algae, nullipores, fucoids, etc."

Distribution: "Norway; British Isles; France; Mediterranean." Recent voucher specimens from Strangford Lough (the original type specimen was collected from Strangford Lough by Hyndman). Also Mulroy Bay; Lough Hyne; Rathlin Is.; Kilkieran Bay; Skomer; Loch Sunart, Loch Fyne. Common.

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

Identity: Difficult to identify with confidence when encrusting, but when well developed the characteristic branching combined with the colour are fairly distinctive. It belongs to a very difficult group taxonomically, so all identifications must be treated as provisional - see also Iophon ingalli, Iophon pattersoni (Bwk., 1866:255), etc. This description is based partly on voucher material collected from the type locality, Strangford Lough, in 1980.

Voucher: BELUM : Mc138. Strangford Lough, Down.

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

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