Euplectella aspergillum australicum, 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 : 55-58

Euplectella aspergillum australicum ssp. nov. ( Fig. 27 ; Tab. 23, 24)

Etymology. Subspecies name reflects the region of type locality.

Material. Holotype: WAM Z 545 — RV Soela , sta. SO 2/82/ 44, 124 miles NW of Port Headland 18 o 54’– 55’ S 117 o 2’ –0’E, depth 300–306 m.

Paratypes: WAM Z 546 (4 specimens)—together with the holotype . WAM Z 551 (3 specimens) — RV Soela , sta. SO 4/82/08 C, N of Port Headland, 18 o 43’S 117 o 12’E, depth 368 m. WAM Z 643 — RV Soela , sta. SO 2/82/18, 56 miles of Imperieuse Reef, 18 o 8’–9’ S 118 o 6’ –4.60’E, depth 404 m. WAM Z 552 — RV Soela , sta. SO 2/82/ 37, 124 miles NNW of Port Headland, 18 o 26’–19’ S 118 o 0’ –1’E . WAM Z 592 — RV Soela , sta. SO 2/82/ 42, 119 miles NW of Port Headland, 18 o 44’S 117 o 20’–19’E, depth 326– 360 m. WAM Z 653 —sta. 008, SW of Imperieuse Reef Rowley Shoals , 17 o 42’S 118 o 38’E . WAM Z 553 —SW of Imperieuse Reef Rowley Shoals , 17 o 37’S 118 o 46’E . WAM 72­91 — RV Courageous , sta. 013, NE of Mermaid Reef, Rowley Shoals, 16 o 49’S 119 o 59’E . NTM Z 0001154 (2 specimens) — RV Soela , sta. NWS­0005, W off port Headland, Northweste Shelf, 18 o 42’S 117 o 18’E, depth 360 m. NTM Z 0002568 —sta. NWS­0040, off Rowley Shoals , Northwest Shelf, Scampi trawl Grounds, 17 o 23’S 118 o 57’E, depth 430 m. NTM Z 0002575 (2 specimens)—sta. NWS­0042, off Rowley Shoals , Northwest Shelf, Scampi trawl Grounds, 17 o 24’S 118 o 52’E, depth 445 m.

Other materials ( Euplectella aff. aspergillum australicum ): WAM Z 569 — RV Soela, SO 1/84/067, NW of Bathurst Island , 14 o 21.50–22.30’ S 122 o 2.40 –1’E, depth 348–350 m. NTM Z 0002586 —location unknown .

Description. Body: The body shape is similar to that of E. aspergillum aspergillum , parietal ledges are found in both spiral and circular arrangements. The holotype is 150 mm in length, oval in section 23x 27 mm, the tuft of basalia is about 50 mm in length. The other complete sponge is WAM Z 546, it is 110 mm in length, 23 mm in diameter with basalia up to 50 mm in length, the other numerous paratypes are mostly fragments of the upper part of the body, one fragment reaches 260 mm in length, the diameter of these fragments is 22–35 mm. The parietal ledges of these sponges are up to 1–2 mm high, the rigid walls are 2–3 mm in thickness, the lateral osula are 0.5–1.5 mm in diameter, the sieve­plate is colander­like with meshes mostly triangular, 1–2 mm in diameter.

Spicules: Principalia are stauractins with rays about 12/ 0.11–0.16 mm. Other choanosomal spicules are tauactins with rays several mm in length and 0.01–0.06 mm in diameter. Basalia are anchors with spiny shafts 0.1–0.13 mm in diameter and 6 teeth. Spicules of the sieve­plate are diactins, some tauactins, small hexactins and pentactins. The diactins are 0.46–several mm long and 0.004–0.05 mm in diameter, they are usually slightly curved and have a widening in the middle, their outer ends are conically pointed or rounded, smooth or rarely rough. The small and rare hexactins and pentactins have conically pointed outer ends, usually rough. All these spicules show notable fusions, which makes their measurements rather difficult. Dermalia are hexactins with distal ray rough, other rays are smooth, conically pointed with rough distal ends. The distal ray of dermal hexactins is 0.066 –0.179 mm long, tangential rays are 0.087 –0.204 mm, the proximal ray is 0.194 – 0.944 mm, their diameter is about 0.007 mm. Atrialia are pentactins with rounded and rough outer ends, the tangential rays of atrial pentactins are 0.112–0.27 mm long, the distal ray is 0.306 –1.352 mm long; their diameter is about 0.01 mm.

The oscularia are mainly diactins, some triactins, rarely tetractins and other rarely found spicules, ranging from monactins to hexactins. Only one specimen, WAM Z 546, has a larger proportion of the triactins (see Tab. 24), but this may be a result of its poor condition. The rays of these spicules are smooth with conically pointed or sometimes rounded outer ends, they measure 0.076–0.608/ 0.002–0.046 mm.

Microscleres: floricomes, oxyhexasters, hemioxyhexasters and other oxyoidal abnormal forms, in some specimens oxyhexactins, graphiocomes and sigmatocomes. The floricomes are 0.067 –0.092 mm in diameter with the primary rosette 0.008 –0.019 mm in diameter. The oxyhexasters, oxyhemihexastrs and abnormal spicules with several primary rays reduced (observed in the specimenWAM Z 546) are 0.065 –0.113 mm in diameter with the primary rosette 0.006 –0.013 mm in diameter. The sigmatocomes (probably young floricomes) are very rare ( WAM Z 545 and WAM Z 546 ); they are 0.061 –0.063 mm in diameter with the primary rosette 0.013 –0.014 mm in diameter. Graphiocomes are equally rare and only represented by a few primary rosettes, 0.019 –0.021 mm in diameter .

Remarks. E. aspergillum australicum has several peculiar features in comparison with the typical subspecies: it shows notable skeleton fusions and oscularia are mainly diactins (or diactins and triactins). Oxyhexasters have thin secondary rays (about 0.001 mm in diameter), they are often curved and many specimens have hemioxyhexasters, and sometimes even oxyhexactins are derived from the oxyhexasters.

Placopegma Schulze, 1895

Placopegma plumicomum Tabachnick and Levi, 2004 ( Tab. 25)

Material. MNHN (p13; fr871)— Cidaris I , RV Franklin, sta. 13­ 1, 17 o 58.59’ S 148 o 38.40’ E, depth 1040–1059 m .

Description. Body: The specimen (or specimens?) is represented by small fragments.

Spicules: Choanosomal spicules are diactins and hexactins. The diactins are several mm in length and 0.006–0.05 mm in diameter with conically pointed outer ends, stout or rarely with a widening in the middle. The rare hexactins have rays about 2/ 0.05 mm. A unique anchorate spicule shows four short teeth and spiny shaft about 0.04 mm in diameter. Dermal spicules are hexactins with distal ray almost spiny and other rays rough, they are 0.01–0.025 mm in diameter and have conically pointed or rounded outer ends. The atrialia, and probably also a portion of the dermalia, are pentactins with rough rays, their outer ends similar to those of dermal spicules, the diameter of their rays is 0.008 mm.

Microsleres are spherical discohexasters with 4 (rarely 2) secondary rays, plumicomes and a unique hemidiscohexaster (0.084 mm in diameter).

Remarks. The sponge is attributed to P. plumicomum described from off New Caledonia ( Tabachnick and Lévi 2004) with very large probability. The only notable differences are not significant and are considered to be intraspecific variation: Length of distal ray of dermal hexactins and diameter of plumicomes ( Tab. 25); the latter is a result of different lengths of the sigma­like secondary rays, while the primary rosettes are nearly equal.

Corbitellinae Gray, 1872

Corbitella Gray, 1867

Figures

FIGURE 27. Euplectella aspergillum australicum, ssp.n., spicules. A­B, dermal hexactin. C­D, choanosomal pentactins. E, anchorate spicule. F, oscularia. G, hexactin of the sieve­plate. H, floricome. I, graphiocome. J, sigmatocome. K, oxyhexaster. L, oxyhemihexaster. M, oxyhexactin. N, oxypentactin. A­E; G­I; K­M, holotype. F, J, N, WAM Z 546.