Artemisina transiens Topsent, 1892a is a globular pedunculate sponge with an apical, slightly raised oscule. The surface is even but hispid. The species is known only from a few records off the north west coast of Spain, and its status is questionable.
Shape, size surface and consistency: Globular sponge on a short stalk, with an apical fistular oscule. It reminds of Suberites carnosus. Surface even, but finely hispid.
Spicules: Styles in two size categories, palmate isochelae, toxas.
Megascleres: The ectosomal styles are smaller but not clearly differentiated in size from those of the choanosome, they are provided with microspined heads: 150-250 µm; choanosomal styles likewise provided with microspined heads: up to 600 µm in length.
Microscleres: Palmate isochelae: 20 µm; toxas thin, shallowly curved, with smooth apices: up to 100 µm long.
Skeleton: Styles are arranged perpendicular to the surface, but become confused towards the interior.
Ecology: No data.
Distribution: Asturias, Santander (NW coast of Spain).
Etymology: The name refers to the fact that according to Topsent characters of this species link two species formerly thought to be unrelated (i.c. Artemisina suberitoides Vosmaer and Amphilectus apollinis Ridley and Dendy).
Type specimen information: The type is in the Monaco Museum.
The specific distinctness from A. arcigera of this species rests on the absence of spined ends of the toxas and the presence of spines on the style heads. If these features would be demonstrated to be variable, then synonymization under A. arciger is necessary.
Ferrer-Hernandez (1917) described a third Artemisina, viz. A. hispanica from Santander, slightly to the east of Topsent's locality. From his descriptions it is clear that it is conspecific with the present species.
Source: Lévi, 1960