Genus Hamigera Gray, 1867

Emended diagnosis: Hymedesmiidae without acanthostyles; with strongyles or tylotes as tornotes; with coring and echinating smooth styles or subtylostyles. The styles can also be polytylote with two size categories; arcuate chelae or cleistochelae.

Hamigera cleistochela Bertolino, Costa & Pansini sp. nov.

(Fig. 5)

Type material. Holotype: MSNG 60892 (CILE 67), Seno Magdalena F (44.631235°S 72.904239°W), Puerto Cisnes (Chile), 25 m depth, on a rocky slope, 2014

Description. Small, massive globose sponge (covering an area of about 5 cm 2) (Fig. 5A). Surface regularly areolate with inhalant and exhalant parts clearly distinguishable from one another (Fig. 5A). The colour in life is ochre (Fig. 5A). Consistence is soft and compressible.

Skeleton. Plumose skeleton with multispicular tracts of polytylote styles that form bouquets near the sponge surface. Microscleres scattered in the skeleton, but they are mainly concentrated in the sponge surface.

Spicules. Megascleres: Two size categories of polytylote styles: (I), larger styles, straight with acerate tips, 440 (482.5) 580 x 5 (8.6) 10 µm (Fig. 5B); (II), very thin, smaller polytylote styles, straight, 105 (188.2) 252.5 x 2 (2.3) 2.5 µm (Fig. 5C). Microscleres: Cleistochelae with frontal teeth more or less fused together (Fig. 5D). Arcuate isochelae with short, inward teeth (Fig. 5E). Both measure 25 (30.1) 35 x 5 (5.3) 7.5 µm.

Etymology. The new species in named after its characteristic chelae (cleistochelae).

Ecology. Our specimen was found on rocky walls at 25 m depth.

Remarks. The species is assigned to Hamigera Gray, 1867 due to the presence of an areolate surface, according to the structure skeleton and the absence of acanthostyles. Four species of the genus are known in total. None has polytylote styles and cleistochelae, therefore they are all different from the new species. Hamigera hamigera (Schmidt, 1862), collected in Mediterranean Sea down to 23 m, has tornotes in the form of strongyles to tylotes (230–320 x 3–7 µm), styles to subtylostyles (240–320 x 5–9 µm), and arcuate isochelae (15–22 µm). Hamigera macrostrongyla Bergquist &Fromont, 1988, from New Zaland, has styles (360–490 x 5–10 µm), strongyles (370– 460 x 7–10 µm), and arcuate isochelae (49–56 µm). Hamigera strongylata Burton, 1934, from East Australia, has strongyles (280–400 x 8 µm) and isochelae (30 µm). Hamigera tarangaensis Bergquist & Fromont, 1988, from New Zealand, has strongyles (210–440 x 3.5–7 µm), and arcuate isochelae with short alae (23–60 µm).

Hamigera cleistochela sp. nov., according to its unusual spicular set, with two size categories of polytylote styles, and chelae including cleistochelae, is here considered as new to science.