Axinella rugosa

(Bowerbank, 1866)

Species Overview

Axinella rugosa (Bowerbank, 1866) is a pale yellowish irregular bush, with flexible, irregular branches which may partly or wholly fuse. It is not well-known having been recorded only a few times from deeper water along the coasts of Norway, the British Isles and France.

Taxonomic Description

Colour: Light grey with a tinge of yellow (Bowerbank), white-grey (Roscoff), pale yellow (Norway)
Shape, size, surface and consistency: Erect-branching, branches often with irregular outline or flattened, with a tendency to fuse or anastomose into an irregular fan or cup. Height and width up to 15 cm, diameter of branches variably 0.5-2 cm. Surface variably optically smooth (live specimens) or rugose, often provided with ridges or short projections. No obvious oscules or other openings. Consistency flexible.
Spicules: (Dictyocylindrus rugosus) Oxeas and strongyles in very variables sizes and shapes, curved and often slightly flexuous: up to 1750 µm; styles also recorded with similar sizes.
Skeleton: Axial skeleton tight meshed; extra-axial skeleton with often strongly developed bundles, which may end in a long style which protrudes beyond the surface.
Ecology: 24-450 m
Distribution: Roscoff, SW Ireland, Shetlands, Orkney, Faroes, Norway, Sweden, East Greenland.
Etymology: The name refers to the irregular surface.
Type specimen information: The type is in the Natural History Museum, London.

Remarks

This species is not well known and seems an atypical Axinella in many respects. It has been considered a Phakellia by several authors. However, that genus has thin bladed forms only which have a characteristic reticulation of flexuous strongyles and styles, unlike the skeleton found in the present species.
Source: Bowerbank (1866); Arndt (1935).