Picton & Goodwin, 2007
Antho (Antho) granditoxa Picton & Goodwin (2007) is one of the many thin orange-red crusts, that can only be distinguished by microscopic examination of the spicules. Its distinctive characters are very large toxas in combination with a basal reticulation of acanthostyles, with in addition the usual ectosomal subtylostyles, choanosomal larger styles and palmate isochelae of the Microcionidae.
Shape, size and consistency: Forms bright orange/red patches with no excurrent channels visible and very inconspicuous osculae. Surface has hispid appearance and is sometimes lightly silted. Patches very variable in size, from 3–20 cm maximum diameter.
Spicules: Megascleres: Choanosomal smooth styles: vary widely in size, 240–850 by 6–14 µm. Choanosomal acanthostyles: 150–180 by 10–12 µm, entirely spined with small gritty spines, which are denser on the head. Ectosomal styles: 410–500 by 2–3 µm. Head very slightly tylote and microspined. Microscleres: Toxas: two categories, 30–100 by 0.5–2 µm. Very abundant in the choanosome. The second, larger category is much scarcer, these measure 210–540 by 8–12 µm. Palmate isochelae: 16–18 µm.
Skeleton: Choanosome has ascending fibres of bundles of three or four smooth styles with a reticulation of acanthostyles. Splayed bundles of thin subtylostyles form the ectosome, these echinate the surface.
Ecology: Deeper water, 20-35 m, on cliffs.
Distribution: So far only known from Rathlin Island, Northern Ireland.
Type specimen information: Holotype: [Mc2538]; White Cliffs, Rathlin Island, 55°17.539'N 006°14.549'W; water depth: 28–33 m; 4 July 2005.
This species is most similar in spiculation to A. (Antho) involvens. It is distinguished by the presence of very large thick toxas (>500 by 12 µm), the ectosomal and choanosomal styles also reach much greater lengths than those found in A. (A.) involvens. The only species with similar giant toxas (termed toxiform oxeas by Lévi (1960)) is Antho paradoxa, orginally described by Babic (1922) from Croatia as Artemisina paradoxa. However, this species is described as branching and 5.5 cm in height, there is a much larger range in the size of the chelae and acanthostyles, and the choanosomal and ectosomal styles are much shorter. A further encrusting specimen from Roscoff was attributed by Lévi (1960) to Antho paradoxa. The spicule sizes given for this and the encrusting habit described are much more similar to the Rathlin specimens and it may be that they are the same species. Unfortunately the slides of Lévi’s material cannot currently be located, and Lévi (1960) states that the specimen was lost.
Source: Picton & Goodwin, 2007.