Corbitella cf. elegans (Marshall, 1875)

Tabachnick, Konstantin R. & Menschenina, Dorte Janussen And Larisa L., 2008, New Australian Hexactinellida (Porifera) with a revision of Euplectella aspergillum *, Zootaxa 1866 (1), pp. 7-68 : 58-61

Corbitella cf. elegans (Marshall, 1875) ( Fig. 28 , Tab. 26)

Material. WAM Z 266 (4 specimens) — RV Soela , sta. SO 1/84/122, W of Broom, 17 o 59’–54’ S 118 o 23’ –29’E, depth 389–390 m. Corbitella speciosa , holotype — MNHN – RV Astrolabe , off the Molukkas Islands .

Description. Body: At least two sponges are represented by fragments of the walls and the basal parts. The biggest basal part is 110 mm in length and oval in section 120x 170 mm, the walls are 2–4 mm in thickness with lateral oscula 2–5 mm in diameter.

Spicules: Choanosomal spicules are large diactins, the largest ones fused; they are several mm in length and up to 0.15 mm in diameter. The smaller diactins, 0.7–1.4/ 0.003 ­0.015 mm, are loose spicules with clavate rough outer ends and show a widening in the middle. Dermalia are hexactins with rounded, smooth, rarely rough, outer ends and rays 0.005 –0.009 mm in diameter. Atrialia are pentactins with rays similar to those of the dermal spicules.

Microscleres are discohexactins, oxyhexactins (usually spiny) and some discohexasters. Some discohexactins show abnormal rays with tyloidal or onychoidal outer ends. Discohexasters have very short principalia.

Remarks. The genus Corbitella comprises 4 species. The investigated fragments are very similar to C. elegans (Marshall, 1875) except for the dimensions of discohexactins (diameter of discohexactins in the holotype 0.22–0.264 mm) as reported by Ijima (1903) in his re­description of this species. The diameter of these spicules is more similar to that of C. speciosa (Quoy and Gaimard, 1833) ; diameter of discohexasters and rare discohexactins in this species is 0.1–0.145 mm ( Ijima 1903). Unfortunately both species are known from single representatives, which contain only a few loose spicules; both species were found off the Molucca. It is very likely that C. speciosa and C. elegans are complete synonyms, but it is also possible that the Australian specimens described here should be regarded as a new subspecies of C. elegans . In any case the settlement of this question requires analysis of additional material of these two species.

Regadrella Schmidt, 1880

Regadrella okinoseana Ijima, 1896 ( Tab. 28)

Material. NTM Z 0002581 (three specimens)—sta. NWS­0043, off Rowley Shoals, Northwest Shelf, 17 o 18’S 119 o 4’E, 426 m.

Description. Body: This species is represented by three fragments; they probably belong to three different specimens. These sponges are at least 250 mm long with walls about 5 mm in thickness. One sponge contains several dense spherical aggregations 4–12 mm in diameter composed of sponge tissue with spicules. Inside each such sphere a specimen of Solenogastres Genus sp. (Mollusca) was found.

Spicules: The spicules of these Australian specimens do not differ in shape from other specimens of R. okinoseana . Occasionally it is possible to find among the dermal hexactins some diactins with rays very similar to those of the hexactins; the length of these diactins corresponds to axial length of the hexactins.

Remarks. R. okinoseana is widely distributed in the Indo­West Pacific; the last revision was done by Tabachnick and Lévi (2004), and the Australian specimens have very similar spicule dimensions to those of both well­investigated locations (off Japan and off New Caledonia). The only notable differences are the dimensions of dermal pentactins: the distal rays of the ‘Australian’ specimens are longer than those from off Japan and shorter than those from off New Caledonia; and the other rays of dermal hexactins are smaller in the sponges from off Australia. The microscleres are very similar in their shape and dimensions. Unlike the specimens of R. okinoseana described from the Great Australian Bight (off South Australia) ( Reiswig 1992), the investigated specimens have very few oxypentasters and no oxyhexasters at all; the rays of dermal hexactins correspond to the smallest ones of those described from off South Australia.

Rossellidae Schulze, 1885

Rossellinae Schulze, 1885

Scyphidium Schulze, 1900

Figures

FIGURE 28. Corbitella c.f. elegans (Marshall, 1875), spicules, WAM Z 266. A, hexactin with clavate outer ends. B, hexactin with abnormal discoidal outer ends. C, outer end of onychoidal type of hexactin. D, choanosomal diactin.