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.

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Synonyms: In recent literature it is treated as a synonym of Iophon ingalli (Bwk, 1866:258). As it belongs to a taxonomically difficult group, it may be best, at the moment, for us to treat it as I. hyndmani. Also cited as Pocillon hyndmani (Bwk,1858:302) Topsent 1894:8.

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)-250 μm. The echinating acanthostyles are entirely spined and are 130-(155)-175 μm "110 μm" long. The ectosomal spicules are very thin tornotes (b), with strongylote ends which bear crowns of a few spines, ca. 135-(170)-195 μm. Microscleres are palmate anisochelae (c), 13-20 μm long, and bipocilles with saucer shaped ends (d), 9-15 μm long.

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.

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

iNaturalist: Iophon hyndmani at iNaturalist World Species Observations database.

WoRMS: Iophon hyndmani at World Register of Marine Species. Accepted name: Iophon hyndmani (Bowerbank, 1858). AphiaID: 132970.

Classification: Biota; Animalia; Porifera; Demospongiae; Heteroscleromorpha; Poecilosclerida; Acarnidae; Iophon

Voucher: BELUM : Mc138. Strangford Lough, Down.

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