Scyphidium australiensis, Tabachnick & Menschenina, 2008

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 : 61-63

Scyphidium australiensis sp.nov. ( Fig. 29 , 30 ; Tab. 28)

Etymology. The name refers to the type locality of this species.

Material. Holotype: WAM (p14)— RV Soela, sta. SO 17­ 80, 43 o 33.10’–33.05’ S 179 o 27.25’ –27.08’E, depth unknown

Description. Body: The sponge is represented by a single fragment of the wall, 200x 300 mm and about 15 mm in thickness.

Spicules: Choanosomal spicules are diactins 0.4–7/ 0.004 –0.017 mm, usually stout and sometimes with a widening or four rudimental tubercles in the middle, their outer ends are rough, conically pointed or rounded. Fragments of large choanosomal hexactins with distally directed rays 0.1–0.22 mm, tangential rays, about 0.3 mm, and long proximal rays were found in very restricted numbers. Dermalia are pentactins with rays covered by short spines and conically pointed outer ends, and have tangential rays 0.056 –0.122 mm long and the proximal ray is 0.051 –0.117 mm, their diameter is 0.002 –0.006 mm. Atrialia are hexactins with rays similar to those of the dermal spicules and of nearly equal length, their proximal ray is 0.051 –0.316 mm, tangentials are 0.041 –0.347 mm, the distal ray is 0.056 –0.332 mm, their diameter is 0.002 ­0.008 mm.

Microscleres: Microscleres are discoidal (large and small spicules), oxyoidal and abnormal derivatives of large discoidal spicules, and all oxyoidal forms. The large discoidal spicules are spherical discohexasters, hemidiscohexasters, discohexactins. Small discoidal spicules are the microdiscohexasters. Oxyoidal spicules are oxyhexasters, hemioxyhexasters and oxyhexactins. The large discohexasters (with 2–3, rarely 4–5 secondary rays) and large hemihexasters are 0.046 –0.084 mm in diameter with a primary rosette 0.004 –0.015 mm in diameter, the large discohexactins are similar in size to hexaster­like forms, but sometimes bigger, 0.050 – 0.097 mm long. The small discohexasters are rare; they are 0.034 –0.055 mm in diameter with a primary rosette 0.006 –0.013 mm in diameter. The oxyoidal spicules have 1–3 rough secondary rays, their diameter is 0.038 –0.097 mm, the primary rosette in oxyhexasters and oxyhemihexasters is 0.006 –0.013 mm in diameter.

Remarks. The unique features of this new species of Scyphidium are the presence of large discoidal spicules and their abnormal forms, as well as the diameter of large discohexasters and their derivatives, which are too small for the other species of the genus. Only the type species of S. septentrionale Schulze, 1900 , from off Greenland, has similar size large discohexasters 0.05–0.094 mm in diameter ( Tabachnick 2002c). S. australiensis is the third species of the genus collected in the Southern Hemisphere. The two other species are S. chilense Ijima, 1927 (former Rossella sp. ( Schulze 1899)) off Chile and S. hodgsoni (Kirkpatrick, 1907) —the latter was described as Holascus hodgsoni but definitely belongs to Scyphidium by having two types of discohexasters – from the Antarctic Ocean (Mount Erebus). Another species of the genus, which was described without hypodermal pentactins, may be S. tuberculata (formerly Aulosaccus tuberculatus Okada, 1932 ).

Lanuginellinae Schulze, 1897

Sympagella Schmidt, 1870

Figures

FIGURE 29. Scyphidium australiensis, sp. n., external shape, holotype, scale 20 mm.

FIGURE 30. Scyphidium australiensis, sp.n., spicules, holotype. A, dermal pentactin. B­C, atrial hexactin. D­F, choanosomal diactin. G­H, abnormal oxyoidal microscleres. I, oxyhemihexaster. J, oxyhexactin. K, large discohexaster. L, large hemidiscohexaster. M, large discohexactin. N, small discohexaster.