Genus Biemna Gray, 1867

Biemna lutea Bertolino, Costa & Pansini sp. nov.

(Figure 2, Table 3)

Type material. Holotype: MSNG 60890 (CILE 16), Seno Magdalena A (44.763254°S 72.891581°W), Puerto Cisnes (Chile), depth 20 m, on a rocky slope, 2014.

Other material examined. CILE 77, Seno Magdalena D (44.614863°S 72.958312°W), Puerto Cisnes (Chile), depth 15 m, on a rocky slope, 2014.

Description. Massive sponge, rather irregular, about 5 cm long and 3 cm thick, with a conulose, very hispid surface. The colour in life is dull yellow. The sponge is not very dense, characterized by the presence of columns of spicule tracts with more or less conical extremities. Oscules are round, small, on top of some of these columns. Consistence is soft due to the flaky texture (Fig. 2A).

Skeleton. The skeleton has the typical biemnidae structure, plumose and with variable development of spongin fibres (Fig. 2B). Plumoreticulate choanosomal skeleton, with spongin fibres cored by bundles of spicules (styles) and oxeote spicules that pierce the sponge surface and render it hispid. Ectosomal skeleton formed by brushes of megascleres at the end of the ascending choanosomal skeletal columns (Fig. 2B).

Spicules. Megascleres: Styles, smooth, straight or slightly curved, with regular, round heads. Their thickness shows a wide range of variation, but they cannot be divided into size categories. (Fig. 2C), 530 (627.5) 660 x 5 (18.5) 32.5 µm. Microscleres: raphides with microspines at their extremities, 112.5 (130.6) 142.5 x 1 µm (Fig. 2D); short and thick microxeas, 35 (37) 40 x 2.5 µm, with small scattered spines (Fig. 2E); C-shaped sigmas with microspined extremities clearly divided into two size categories, I (Fig. 2F) 140 (159.5) 180 x 5 (5.7) 7.5 µm, and II 10 (14.5) 17.5 µm (Fig. 2G).

Etymology. The new species is named after its yellow colour.

Ecology. It lives between 15-20 m depth, on rocky slopes covered by coralline algae.

, Remarks. In Chile and in geographically related areas, there are four species of Biemna: B. chilensis Thiele, 1905, B. macrorhaphis Hentschel, 1914, B. polyphylla Lévi, 1963 and B. strongylota Rios & Cristobo, 2006 . These species differ from the new one in the size of spicules (Table 3). The closest species, B. polyphylla, is separated from the new species by its much thicker styles and the absence of thin styles. In addition, in B. polyphylla there are three categories of sigmas. Other important differences concern the sponge shape that is pedunculate and lamellar in B. polyphylla and irregularly massive in the new species. B. polyphylla was recorded only once from South Africa. Consequently, we consider Biemna lutea sp. nov. new to science.