Eurypon gracilis Bertolino, Calcinai & Pansini

Bertolino, Marco, Cerrano, Carlo, Bavestrello, Giorgio, Carella, Mirco, Pansini, Maurizio & Calcinai, Barbara, 2013, Diversity of Porifera in the Mediterranean coralligenous accretions, with description of a new species, ZooKeys 336, pp. 1-37 : 10-11

Eurypon gracilis Bertolino, Calcinai & Pansini sp. n. Figs 9 A–G

Material examined.

Type specimen: Holotype MSNG 57017. Specimen PdF-S-BL4-sp18-sciaf., on a coralligenous concretion, depth 40 m, Stat. 4, 27-07-2009. leg. M. Bertolino, alcohol preserved.

Type locality.

Italy, Ligurian Sea, Portofino Promontory (Punta del Faro) 44°17'54.20"N, 9°13'06.93"E.

Other examined material.

Specimen IG-F-BL1-sp4-fot.; specimen IG-F-BL1-sp15-fot.; alcohol preserved, Gallinara Island (station 2, Falconara) 44°01'22"N, 8°13'34"E, depth 35 m, collected 17-06-2009; specimen IG-S-BL3-sp6-fot.; alcohol preserved, Gallinara Island (station 3, Sciusciaù) 44°01'34"N, 8°13'45"E, depth 30 m, collected 17-06-2009; specimen PM-BL1-sp9-sciaf.; alcohol preserved, Punta Manara (station 6) 44°15'05.61"N, 9°24'09.33"E, depth 35 m, collected 13-06-2009.

Description.

All the specimens were encrusting on the surface of coralligenous blocks, covering surfaces up to 2 cm2. The sponge surface is corrugated, hispid. The colour in life is brick red (Fig. 9A).

Skeleton. The skeleton consists of a basal layer of spongin in which the spicules are vertically positioned, perpendicular to the substrate. Both the categories of acanthostyles are close one another (Fig. 9C) with the heads embedded in the basal spongin layer. Styles and oxeas–with the same vertical arrangement–are grouped in bundles which are faintly echinated, in their lower part, by the smaller acanthostyles (Fig. 9B). Oxeas are positioned in the basal part of the bundles. The styles protrude trough the sponge surface making it hispid.

Spicules. Long styles to tylostyles, curved or flexuous (Fig. 9D), 788 (1101) 1280 × 5 (6.8) 10 µm; oxeas thin, almost straight or with a slight curvature (Fig. 9E), 365 (483) 650 × 2.5 µm; acanthostyles without head and uniformly spined, in two sizes categories: I) large acanthostyles, straight or slightly curved with rather small spines (Fig. 9F), 200 (253) 320 × 5 (6) 7.7 µm; II) small acanthostyles straight, with spines more robust than in the previous category (Fig. 9G), 90 (119.5) 160 × 2.5 (3.8) 5 µm.

Etymology.

The species is named after the slenderness of all the spicule types.

Distribution.

So far known only from the Ligurian Sea.

Ecology.

It lives at 30-40 m depth on coralligenous concretion, characterized by the presence of a Paramuricea clavata facies.

Discussion.

This species, characterized by a microcionid skeleton with a basal layer of spongin, extra-axial spicules and echinating achantostyles embedded in spongin fibres, clearly belongs to the genus Eurypon .

Only five, out of the numerous species of the genus Eurypon found in the temperate Western Atlantic have oxeas or tornotes as structural megascleres together with styles or tylostyles. All of them ( Eurypon cinctum Sarà, 1960, Eurypon denisae Vacelet, 1969, Eurypon obtusum Vacelet, 1969, Eurypon major Sarà & Siribelli, 1960 and Eurypon lacazei (Topsent, 1891) occur in the Mediterranean Sea. Eurypon cinctum showing a lilac colour, achantostyles with discrete heads and different size in the other megascleres is not close to the new species. Eurypon denisae is also different according to the description given above. Eurypon obtusum is grey in colour and has smaller oxeas and acanthostyles than those of the present species, but the maximum length of its tylostyles is unknown. Eurypon lacazei remarkably differs from the present species for the green colour and spicule shape and size. The closest species to the new one is Eurypon major but its tylostyles are longer and stouter (1445-2210 × 10-17 µm) and differ in the shape of the heads, while the acanthostyles, in a single size category, have well formed heads. Only two other species from the temperate Atlantic: Eurypon lictor (Topsent, 1904) and Eurypon (Acantheurypon) mucronale (Topsent, 1928) present oxeas. However, they are both deep species (recorded deeper than 1500 m from the Azores) and they differ also in the spicule characters from Eurypon gracilis sp. n. There are two other species of Eurypon with oxeas reported in the literature: Eurypon calypsoi Lévi, 1958 from the Red Sea which is blue in colour and Eurypon fulvum Lévi, 1969 from South Africa which is yellow. Both have a single size category of acanthostyles and differ in the spicule morphology. Eurypon gracilis therefore has to be considered as new for science.