Hymedesmia lenta

Descatoire, 1966

Species Overview

Hymedesmia lenta Descatoire, 1966 is a thinly encrusting bright orange to yellow sponge. The surface is provided with numerous rounded pore fields and it is slightly sticky. So far it has been recorded only once from the west coast of France.

Taxonomic Description

Colour: Bright orange to yellow.
Shape, size, surface and consistency: Thinly encrusting and filling interstices between rock and barnacles. Size extensive, up to 20 cm in lateral expansion. Surface provided with numerous small pore fields. Sticky to the touch, thready when damaged.
Spicules: Megascleres : Ectosomal tornotes shaped as tylostrongyles, with mucronate ends, flexuous: 210-220 x 2-10 µm; a single category of acanthostyles, not always present, spines few in number, with conical pointed end: 170-180 x 10 µm. Microscleres : Arcuate isochelas, elongate, may be rare: 25-35 µm; sigmas, numerous: 35 µm.
Skeleton: In the ectosome the tornotes are arranged irregularly and singly; in the choanosome bundles of 5-10 tornotes are formed which are arranged in an anastomosing system; rare acanthostyles are erect on the substrate.
Ecology: Sublittoral, on rocks, Laminaria holdfasts and in crevices, 0-18 m.
Distribution: Iles de Glénan, S Bretagne. No further records.
Etymology: Lentus (Latin) = flexuous, referring to the condition of the tornotes.
Type specimen information: No data.

Remarks

This is not a typical Hymedesmia because there is only a single acanthostyle category of acanthostyles which is also rare, whereas the tornotes form a well developed skeleton. Possibly the species is better assigned to Phorbas .
Source: Descatoire, 1966.