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(Linnaeus, 1759)

Species Overview

Axinella infundibuliformis (Linnaeus, 1759) is a cup-shaped or lamellate creamy yellow coloured sponge with a punctate surface. It occurs in the deep sublittoral or below down to 630 m. It is a northern species with its southerly limit along the west coast of France.

Taxonomic Description

Colour: Buff, creamy white, creamy yellow.
Shape, size, surface and consistency: variably cup-shaped (Axinella infundibuliformis MCS2) or lamellate; basically shaped like an inverted cone, lamellate specimens being incomplete cups. The walls are of regular thickness, 3-4 mm, with the margins of the cup/fan rounded and firm. Stalked or substipitate. Size up to 10 cm across. The outer surface presents moderate friction when rubbed. Oscules are small, scattered evenly over one surface, e.g. in cup-like forms, all the exhalant openings are found on the inner surface. These are larger than the inhalant pores on the outer surface. Neither surface is bristly, both are even. Consistency moderately firm and resilient. Pieces break off if bent through 90°. Overall feel is compact; contraction not noticeable. Smell: none.
Spicules: (Axinella infundibuliformis spic) Megascleres are styles: 212-465 x 13-15 µm and/or oxeas (slightly curved): 225-312 x 13-15 µm, and occasional strongyles. Microscleres: are trichodragmata: 15 µm, longer than those of A. dissimilis.
Skeleton: Plumoreticulate. The contrast between a stiffer axial skeleton and a softer extra-axial skeleton which is characteristic of branched axinellids, is scarcely noticeable in this cup-like species. The megascleres tend to show an axial condensation towards the centre of the choanosome, and a sub-anisotropic reticulation in the extra-axial regions with sub-plumose primary fibres (the amounts of spongin encasing spicules is variable), ending as brushes at the surface. Surface brushes may consist of long or short spicules which pierce the surface (resulting in a rough surface, smooth surfaces being a rarity in axinellids). Dense axial skeleton may be absent; extra-axial reticulation may be completely replaced by plumose fibres.)
Ecology: Shallow sublittoral to 630 m. Usually found on rock in the circa-littoral zone, maybe in presence of sediment. Reported on shells, gravel stones, sand or mud—confirmation of this would be valuable.
Distribution: Norway, Faeroes, British Isles (recently recorded from W. coasts of Scotland and Ireland; Anglesey; Lundy), North and West France. Not found on North Sea coasts of the U.K., although a photographic record exists from off Northumberland (Bamber and Coughlan, 1989).
Etymology: infundibulum (Latin) = funnel, referring to the shape.
Type specimen information: No type material in BMNH; type probably lost. MCS voucher: BELUM Mc1530, Ardnoe Pt., Sound of Jura, Scotland.

Remarks

A well formed cup with rounded edges, attached by a central stalk is unlikely to be anything but A. infundibuliformis. However other species form cups so identification should be confirmed by microscopic examination. Axinella arctica is similar in appearance but lacks trichodragmas; it may turn out to be the same species if it is demonstrated that presence of trichodragmas is variable. Phakellia ventilabrum is also similar, but clearly distinguished by possessing long flexuous (vermiform) strongyles (not straight or slightly curved ones). P. ventilabrum has thinner walls and a sharp edged rim to its cup, and larger specimens have clear venes supporting the cup walls.
NOTE: the variability of the spicule complement and architectural structure is a well-known feature of axinellids. All kinds of combinations can be found e.g. megascleres can be all oxeas (making confusion with Halichondriidae possible), or all styles. If both types are present together, a zonation can often be detected i.e. in a reticulation, the multispicular primary fibres are usually formed by styles and the connective secondary fibres formed of oxeas (often unispicular or up to 3 spicules thick).
Source: Ackers et al., 1985, 1992.

Axinella infundibuliformis