Psilocalyx wilsoni, IJIMA, 1927

Dohrmann, Martin, Göcke, Christian, Janussen, Dorte, Reitner, Joachim, Lüter, Carsten & Wörheide, Gert, 2011, Systematics and spicule evolution in dictyonal sponges (Hexactinellida: Sceptrulophora) with description of two new species, Zoological Journal of the Linnean Society 163 (4), pp. 1003-1025 : 1014-1015

PSILOCALYX WILSONI IJIMA, 1927

Material examined: One specimen ( QM G331821 , SMF 11033) collected 12.xii.2009 during DDU from Osprey Reef, ROV Dive #6, 13°48′S, 146°32′E, depth 508 m.

Additional material examined: Psilocalyx wilsoni Ijima 1927 , syntype, Zoological Museum of Amsterdam (ZMA Por. 3402) .

Description: Small thick-walled cup or short tube attached by broad base to hard substrate, superior round osculum ( Fig. 12 , supporting movie M3, available at Open Data LMU http://dx.doi.org/10.5282/ ubm/data.36). Specimens observed by video were colonized by small actinians. Colour of the living sponge and in ethanol fixation is white. Specimen examined measures about 100 mm high and 50 mm in diameter, wall 10–14 mm thick and permeated by 5–10 mm wide ovoid to irregular apertures, which open into a labyrinthic schizorhysial channel system.

Skeleton ( Figs 13–14 , Table 6): Dictyonal skeleton with regular rectangular and triangular meshes, mesh width of the inner skeleton 170–343 Mm, dictyonal beams are spiny and 21–86 Mm in diameter. The external dictyonal surface layer is thickened into a hard crust, hypersilicified surface is tuberculate with beam length 166–500 Mm and ray thickness 111– 200 Mm. Loose dermal spicules are strongyloscopules, 560–860 Mm total length, with four to six rough tines, 80–120 Mm long, and uncinates, 450–670 Mm length, with very small barbs. Dermal and atrial hexactins or pentactins are absent. Microscleres are lophodiscohexasters, 50–66 Mm total diameter, with primary rays, 10–15 Mm long, and five to ten microspined secondary rays, 15–18 Mm long.

All measurements in Mm.

D, diameter; L, length.

Remarks: Together with a few specimens recently collected off New Zealand ( Reiswig & Kelly, 2011), this is one of the first findings of this species since the description of the type material ( Ijima, 1927), collected from Arafura and Banda Seas, Indonesia, during the Dutch Siboga expedition (1899–1900). The collection depth (508 m) is well within the range of 424–1045 m reported by Reiswig & Kelly (2011) for their specimens of this species. The heredescribed material confirms the true absence of dermalia and atriala in Psilocalyx (see Reiswig, 2002e). The Australian specimen differs from the holotype by having generally smaller scopules and hexasters as described by Reiswig (2002e). Furthermore, the hexasters of the holotype show longer primary rays relative to the secondary rays and they have generally more secondary rays than the hexasters of our specimen. However, according to spicule composition, skeletal architecture, and body shape, we consider the attribution to P. wilsoni as justified.

The thickening of the dermal dictyonal layers of Psilocalyx into a hard surface crust is very similar to the extreme hypersilicification of the dictyonal outer layers found in many Mesozoic hexactinosidan and lychniscosidan genera (e.g. Schrammen, 1912).

Figures

Figure 12. Psilocalyx wilsoni, live photograph taken by the remotely operated vehicle ‘Cherokee’ (http://www.marum. de). Approximate size of specimen in the middle: 100 mm.

Figure 13. Psilocalyx wilsoni, skeleton. A, lophodiscohexaster (scale bar = 10 Mm). B, scopule head (scale bar = 15 Mm). C, hexasters and scopule within the dictyonal skeleton. D, dictyonal framework, transition to the thickened dermal layer (scale bar = 300 Mm). E, dermal dictyonal (hypersilicified) cortex layer (scale bar = 100 Mm).

Figure 14. Psilocalyx wilsoni, spicules. A, uncinate. B, scopule. C, lophodiscohexaster.