Psammocinia alba Calcinai, Bastari, Bertolino & Pansini

Calcinai, Barbara, Bastari, Azzurra, Bavestrello, Giorgio, Bertolino, Marco, Horcajadas, Santiago Bueno, Pansini, Maurizio, Makapedua, Daisy M. & Cerrano, Carlo, 2017, Demosponge diversity from North Sulawesi, with the description of six new species, ZooKeys 680, pp. 105-150 : 116-117

Psammocinia alba Calcinai, Bastari, Bertolino & Pansini sp. n. Figure 9

Material examined.

Holotype: MSNG 60140, PH-41, 14/01/2005, Timur (Bunaken Island), 22 m depth.

Diagnosis.

Lobate, white sponge with oscular cavities at the top of the lobes. Thin armoured surface with sand and foreign spicules. Slightly fasciculated fibres, not very dense.

Description.

Massive, lobate sponge with flush, roundish oscular cavities (about 1.5 cm) where the excurrent canals converge, located at the top of the lobes (Fig. 9A). The deposited holotype consists of fragments 3 × 1.5 cm, coming from a larger specimen approximately 15 cm across (Fig. 9A).

The colour in life is white outside (Fig. 9A) and cerulean inside; it becomes light cerulean after collection and beige after preservation in alcohol. Surface characterised by numerous small conules, 0.5-1 mm high and 2 mm apart, united by ridges (Fig. 9A, B). Consistence soft, but elastic, difficult to tear apart.

Skeleton. The surface is covered by a thin reticulation of sand and foreign spicules, forming regular, more or less circular, meshes 100 µm in diameter (Fig. 9C), well visible in the stereo-microscope. The density of the fibres is moderate. The primary fibres of the choanosome are slightly fasciculated (Fig. 9D), about 80 µm thick and cored with foreign debris and a few foreign spicules. The secondary fibres are thinner (20 µm in diameter) and free from inclusions (Fig. 9D). The size of the ovoid meshes ranges from 50 × 80 to 57.5 × 115 µm; a few smaller meshes, 30 × 55 µm, are also present. Filaments, 2.5 µm thick, are numerous and dense.

Etymology.

Referring to the white colour in life.

Remarks.

Our species is attributed to Psammocinia due to the presence of a surface armoured by sand and foreign spicules and to the reticular skeleton of primary and secondary fibres.

According to van Soest et al. (2016), 25 species of Psammocinia are known in total. Most of them have been described from New Zealand and South Korea and only one from Brazil.

Psammocinia bulbosa Bergquist, 1995 from New Caledonia and P. lobatus Sim & Lim, 2002 from Korea are the most similar species to Psammocinia alba sp. n. Psammocinia bulbosa is a massive, repent sponge with quite long oscular fistules. Its surface is covered by small conules 0.5-1 mm high and has a sandy crust up to 1 mm thick. The skeleton is formed by primary fibres giving rise to columns up to 700 µm long and secondary fibres 30-50 µm in diameter. The main differences to our species are the presence of fistules, a distinctive characteristic of P. bulbosa , and thicker fibres. Psammocinia lobatus , lobate in shape, has a surface covered by conules 1-2 mm high and 2-5 mm apart. Both primary and secondary fibres (60-10 µm thick) are comparable in size with our species. The main differences to P. alba sp. n. are the colour (dark brown, black), the presence of sharp conules and the small amount of foreign material present in the fibres. From New Zealand, the following species have been described: P. beresfordae Cook & Bergquist, 1996, formed by a compact base with broad-based fistules with an apical osculum 3-7 mm in diameter and primary fibres 120 µm thick; P. verrucosa Cook & Bergquist, 1996, a small, massive sponge with a very characteristic surface with rounded lamellae supported by skeletal fibres and a reticulate pattern; P. hirsuta Cook & Bergquist, 1998, formed by a coalescent group of digitate structures or lobes, with long, cylindrical fistules and a thick (400 µm) superficial sand layer; P. charadrodes Cook & Bergquist, 1998, a massive sponge with very long, rounded conules and very thick (till 1086 µm) primary fibres; P. papillata Cook & Bergquist, 1998, a massive, compact sponge with a coarsely conulose surface and both primary and secondary fibres thicker than in Psammocinia alba sp. n.; P. perforodosa Cook & Bergquist, 1998, a massive, compact sponge without conules, with a folded surface (800 µm thick) armoured by sand, foreign spicules and rocky fragments; P. maorimotu Cook & Bergquist, 1998, a lobate sponge with oscula on top, a surface with grooves and ridges and primary fibres with a thickness of 349 µm. From South Korea and China, the following species have been described: P. conulosa Lee & Sim, 2004, a massive sponge with ectosomal membrane covered by sand but devoid of circular meshes, oscula scattered and sharp conules 2-4 mm high; P. ulleungensis Lee & Sim, 2004, dark grey in colour, with a smooth surface and thick, slightly fasciculated, primary fibres (100-300 µm); P. mammiformis Sim, 1998, a massive, grey or purple coloured sponge, covered with mammiform protuberances and with very thick choanosomal fibres 550-900 µm; P. mosulpia Sim, 1998 mainly differs from P. alba sp. n. for its crust of sand and foreign spicules not organised in circular meshes; P. jejuensis Sim, 1998, characterised by tick fibres (up to 470 µm) and by filaments with large terminal knobs (12-20 µm in diameter); P. gageoensis Sim & Lee, 2001, has no detritus in the fasciculated primary fibres. Both P. samyangensis Sim & Lee, 1998 and P. wandoensis Sim & Lee, 1998 differ from P. alba sp. n. mainly in the thickness of the secondary fibres. Finally, P. rubra Sim & Lee, 2002 differs from P. alba sp. n. for its red colour and the larger size (up to 320 µm) and colour (reddish-brown) of the fibres.

The other species of Psammocinia have a particular morphology, very different respect to Psammocinia alba sp. n.; P. arenosa (Lendenfeld, 1888) and P. hawere Cook & Bergquist, 1996 are cup-shaped sponges. Psammocinia halmiformis (Lendenfeld, 1888) is irregularly lamellate and P. vesiculifera ( Poléjaeff, 1884) is a tube sponge. Psammocinia amodes Cook & Bergquist, 1998 is a spatulate sponge with a thin, semi-cylindrical basal portion for anchoring to the substrate, while P. bergquistae Sim & Lee, 2001 has a thumb shape and secondary fibres, forming a secondary web.

Due to the difficulties to differentiate, in some cases, species of the genus Psammocinia from other taxa of the family Irciniidae , we also examined the species belonging to Ircinia and Sarcotragus from the Indo-Pacific area. All these species are different from Psammocinia alba sp. n. in morphology, fibre thickness, and structure (see below).

The incorporation of foreign material can play several roles in sponge growth. Usually, this behaviour is explained just as strengthening of the sponge tissue, but other roles could be considered, e.g. the enhancement of sponging fibre production ( Cerrano et al. 2007).