Antho (Plocamia) sarasiri, Costa & Pansini & Bertolino, 2019

Costa, Gabriele, Pansini, Maurizio & Bertolino, Marco, 2019, A new sponge species of the genus Antho (Demospongiae, Microcionidae) from the Tyrrhenian deep Sea, Zootaxa 4674 (3), pp. 397-400 : 397

Antho (Plocamia) sarasiri sp. nov.

MATERIAL Holotype: Rete Bruno B, Secca P.ta Fetovaia , Elba Island , North Tyrrhenian Sea , 13.06.2012, 70 m depth [ MSNG 60890 ] . Comparative material: (15), Gaiola , Gulf of Naples , 17.11.1959, detritic bottom, exact depth unknown ; (319), Gaiola , Gulf of Naples , detritic bottom, 40–50 m, Sarà & Siribelli , 1960 . (450:3), Benda Palummo , Gulf of Naples , on rocky fragments, 10.5.1961, 50– 70 m depth ; (567:5), Benda Palummo , Gulf of Naples , on mollusc shell, 19.7.1961, 50– 70 m depth, Sarà & Siribelli , 1962.

DESCRIPTION Holotype ( Figure 1A ) is a small (2 cm across) incrustation on a piece of coralligenous concretion. The surface is rather hispid and the colour brown in the dry state. No oscules are detectable. The comparative material, encrusting on rock and a mollusc shell, looked red in colour and slimy according to Sarà & Siribelli (1960, 1962) who observed it fresh after collection.

Skeleton. No discrete ectosomal skeleton. A damaged dermal membrane is supported by the reticulation below ( Figure 1B ). Ectosomal subtylostyles and structural styles, apparently not forming brushes, rendering the sponge surface slightly hispid ( Figure 1D ). Choanosome with a rather dense reticulation forming irregular meshes of one to three dumbbell spicules at a side ( Figure 1C ), echinated by acanthostyles ( Figure 1D ). Mesh size 143 (218) 285 µm. Ascending tracts are sometimes detectable ( Figure 1E ). Isochelae densely packed ( Figure 1F ) and included in the network.

Spicules (micrometers in Table 1 ). Ectosomal subtylostyles, gently curved, with smooth or finely spined heads. Spines short and often blunt ( Figure 2A ). Ectosomal subtylostyles, straight, with a few spines on the head, and on the proximal third of the shaft ( Fig. 2D ). Dumbbell spicules, slightly curved, generally with well formed heads but also in form of almost straight strongyles. The head spines are sharp or blunt ( Fig. 2B ). Acanthostyles slightly curved with microspines on the heads, and on the proximal third of the shaft ( Figure 2C ). Microscleres toxas with a slight curvature reminding the oxhorn morphotype, or sometimes straight ( Fig. 2E ). Palmate isochelae with a straight regular shaft, often twisted ( Fig. 2F ).

ETYMOLOGY The name “sarasiri” is derived from the union of the names of the authors, Sarà and Siribelli, who first recorded this new species from the Gulf of Naples that confused her with Antho (Acarnia) circonflexa (Lévi, 1960) . ECOLOGY The species has been found on hard substrata in the Thyrrenian Sea (from the Gulf of Naples to Elba Island). The depth range is 40– 70 m.

REMARKS The new species has been ascribed to the genus Antho , subgenus Plocamia Schmidt, 1870 according to the presence of dumbbell spicules that form the reticulation of the basal choanosomal skeleton. Van Soest et al. (2013) reassign to Antho (Plocamia) 14 species in total (11 in WPDB), no one of which is present in the Mediterranean Sea. However three of them: Antho (Plocamia) erecta (Ferrer Hernandez, 1923) , A. (P.) hallezi (Topsent, 1904) and A. (P.) anisotyla (Lévi, 1960) have an East Atlantic distribution. These three are erect species and differ from the new one proposed by their different shape and spicule measurements. Sarà & Siribelli (1960, 1962) firstly recorded A. (P.) sarasiri sp. nov. from two detritic banks of the Gulf of Naples, but attributed it to A. (Acarnia) circonflexa (Lévi, 1960) . Actually, the two species are rather similar, but A. (Plocamia) sarasiri differs from A. (A.) circonflexa in the larger size of megascleres ( Tab. 1 ), in the swollen extremities of the dumbbell spicules, and in the thickness of toxas. As to the subgenus assignment of the new species, we believe it is justified by the swollen dumbbell spicules, whereas the attribution to the same subgenus of A. circonflexa is not considered correct by Van Soest et al. (2013), probably due to the shape of the acanthostrongyles which are faintly tylote (Lévi 1960).

Figures

FIGURE 1. Antho (Plocamia) sarasiri sp. nov. (A) The holotype in life; (B) Damaged dermal membrane; (C) Choanosome; (D) Meshes of 1 to 3 dumbbell spicules at a side echinated by acanthostyles; (E) Choanosome ascending tracts; (F) Isochelae densely packed.

FIGURE 2. (A) Ectosomal styles to subtylostyles; (B) Dumbbell spicules; (C) Acanthostyles slightly curved; (D) Ectosomal subtylostyles; (E) Toxas; (F) Palmate isochelae.