Hymedesmia (Stylopus) perlucida Calcinai, Bavestrello, Bertolino, Pica, Wagner & Cerrano, 2013, n. sp.
Creators: name: Calcinai, Barbara
name: Bavestrello, Giorgio
name: Bertolino, Marco
name: Pica, Daniela
name: Wagner, Daniel
name: Cerrano, Carlo
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Porifera
Demospongiae
Poecilosclerida
Hymedesmiidae
Hymedesmia
Hymedesmia perlucida

description: Hymedesmia (Stylopus) perlucida n. sp.
(Fig. 15 A–G)
Holotype material. MSNG 56264: sample Bugor 511: Indonesia, North Sulawesi, Nain Island, Jalan Masuk, 17 m, 9 September 2007.
Diagnosis. Hymedesmia (Stylopus) perlucida n. sp. is characterised by a single category of acanthostyles and by fusiform isotornotes.
Description. Very thin encrusting sponge (about <1 mm thick) growing on Paratelesto rosea (Fig. 15 A–C); only the anthocodiae are free from sponge cover (Fig. 15 C). The holotype covers a portion of a Paratelesto colony that is about 8 cm long (Fig. 15 B). Surface is macroscopically smooth. The consistency is gelatinous. Transparent in situ (Fig. 15 A) and in ethanol (Fig. 15 B), so that the red colour of the octocoral is visible through the sponge tissue; white in dried state (Fig. 15 C).
Skeleton. The ectosomal skeleton consists of confused plurispicular tracts and scattered tornotes. The choanosomal skeleton consists of single acanthostyles erect on the coral surface and paucispicular tracts of tornotes (Fig. 15 D, E).
Spicules. Isotornotes straight, fusiform, gradually thinner towards the extremities (Fig. 15 F), 147.5 – (156.5 ± 7.8) – 170 x 2.5 μm. Acanthostyles with small spines concentrated on the head and scarce along the shaft (Fig. 15 G), 110 – (131.7 ± 14.7) – 155 x 2.5 – (3.3 ± 1) – 5 μm.
Remarks. Among the nine species of Hymedesmia (Stylopus) of the Indo-Pacific area (van Soest et al. 2011), those closest to this new species are H. (S.) parvispicula Burton & Rao, 1932 and H. (S.) australiensis (Hentschel, 1911), both of which also have tornotes and acanthostyles in a single category. The other known species differ in the larger size of the spicules: H. (S.) acerata (Topsent, 1904) has tornotes of 460–480 μm, and acanthostyles of 140–380 μm; H. (S.) dendy Burton, 1930 has tornotes of 700 x 16 μm and tylostyles of 2 mm and acanthostyles of 120–240 μm; H. (S.) indivisa Topsent, 1928 has tylotes of 420–540 μm and acanthostyles of 210–595 μm; H. (S.) obtusa Topsent, 1904 has acanthostyles of 130–230 μm and polytylote tylotes of 280 μm. H. (S.) australis (Bergquist & Fromont, 1988), H. (S.) lissostyla (Bergquist & Fromont, 1988) and H (S.) oculifera (Hentshel, 1911) have two categories of acanthostyles.
In H. (S.) parvispicula tornotes vary in shape from strongylote to amphytylotes; their size is also bigger (210 x 3 μm). Hymedesmia (S.) australiensis differs from the new species especially in the shape of the tornotes, which are characterised by swollen extremities, and in their size (176 – 192 x 2 μm).
Etymology. Named after the transparent colour of living tissues.
description: Published as part of Calcinai, Barbara, Bavestrello, Giorgio, Bertolino, Marco, Pica, Daniela, Wagner, Daniel & Cerrano, Carlo, 2013, Sponges associated with octocorals in the Indo-Pacific, with the description of four new species, pp. 1-61 in Zootaxa 3617 (1) on page 25, DOI: 10.11646/zootaxa.3617.1.1, http://zenodo.org/record/248150