Picton & Goodwin, 2007
Axinella parva Picton & Goodwin, 2007 is a small and inconspicuous lobate-lumpy sponge, with a grooved and rugose surface. The skeleton is built like most Axinella species by styles and oxeas, but the small size precludes the usuall Axinella structure of axial and extra-axial parts, in stead of which there is a basal mass of oxeas upon which bundles of styles are erected. It is so far known only from the type locality at Rathlin Island, Northern Ireland.
Colour: Pale brown.
Shape, size, surface and consistency:
In shape this species consists of rounded lobes with a slightly narrower base, 1–2 cm in width and height. With a grooved or sulcate appearance to the surface. The oscules are inconspicuous, at the tip of small transparent chimneys of tissue.
Spicules: Styles mostly 600–900 µm by 16–23 µm (but with a few extremes to 250–1070 µm). Usually smoothly bent about 1/4 of the way down the shaft. Some styles have rounded ends and many have telescoped ends, the rest taper smoothly to sharp points. Oxeas 300–500 µm (with a few to 710 µm) by 10–16 µm, typically half the diameter of the styles. Usually bent twice, often in different directions and at different angles, somewhat contorted in appearance. The ends taper smoothly and are frequently telescoped. Occasional oxeas are centrotylote or appear to be formed by fusion of two styles, with rounded swellings on opposite sides of the spicule.
Skeleton: There is a basal skeleton of oxeas, with ascending plumose columns of styles, oriented with their points towards the surface. There is no axial column, just a condensation of spicules at the centre of the base of the sponge. At the surfacea few styles penetrate a short distance, but the surface does not appear hispid. Oxeas occur within the plumose columns, typically oriented across the columns.
Ecology: Cliffs in deeper water.
Etymology: From the latin parv meaning small. Named for its diminutive size.
Type material: Holotype: [Mc2819], section and spicule preparation, Damicornis Bay (55°17.446'N 006°15.200'W; water depth: 30–35 m); 17 August 2005.
Many Axinella species have a spicule complement of only oxeas and styles, this species differs from others in the northeast Atlantic area in the sizes of these spicules. It is small and inconspicuous and occurs with Axinella pyramidata on Rathlin Island. This is also a small species, but has abundant trichodragmata and smaller, thinner styles. It is easy to recognize in situ by its shape and colour and the sulcate grooves in the surface. It may need to be compared with the deep-water species Bubaris vermiculata var. erecta Carter (1876), now assigned to Acanthella.
Source: Picton & Goodwin, 2007