Euplectella aspergillum subsp. indonesicum, Tabachnick, Janussen & 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 : 53-54

E. aspergillum indonesicum ssp. nov. ( Fig. 26; Tab. 22)

Synonymy. E. aspergillum Owen (in part) in Tabachnick, 2002b: 1391.

Etymology. Subspecies name refers to the region where the holotype was found.

Material. Holotype: IORAS 5 /2/1324—Indonesian Archipelago, RV Vityaz —50, sta. 6482, 4 o 31’2” – 30’8” N 112 o 55’7” –56’3”E, depth 85–88 m.

Description. Body: The single specimen has the typical body form for E. aspergillum . The length is 190 mm, its diameter about 40 mm, the sieve­plate is oval 38x 48 mm, anchorate basalia protrude about 60 mm, the walls are about 2.5 mm thick. Lateral ridges both circular and oblique are not very prominent, they are 2– 3 mm high and rather short (usually 30–40 mm long), the last ridge situated close to the sieve­plate, often known as the cuff, is higher 4–5 mm. The lateral oscula are 0.8–1.5 mm in diameter, they are situated partly in regular rows and partly in alternating position, the sieve­plate shows colander structure with meshes triangular and rectangular 1–3.5 mm. This specimen was already figured in Tabachnick (2002b: Fig. 1 A, B ).

Spicules: The spicules are very similar to E. aspergillum aspergillum and their important measurements are given in the Tab. 22. The proportions of the oscularia are following: hexactins – 3 %, pentactins – 69 %, stauractins – 7 %, paratetractins – 4 %, triactins and diactins – 9 % (n=112) (their rays are 0.014 –0.034 mm in diameter).

Remarks. The new subspecies is very similar to E. aspergillum aspergillum in sizes and shapes of most spicules. The proportion of microscleres which are located in the vicinity of the lateral oscula is also similar between these two sponges: pentactins predominate in E. aspergillum indonesicum (69 %); these are also common for E. aspergillum aspergillum where their proportion varies between 20 and 96 % (usually closer to the latter). The only difference between the two subspecies is the ray length of oscularia, which measure 0.061–0.19/ 0.008 –0.023 mm; length average is 0.124 mm. In E. aspergillum aspergillum the corresponding spicule rays are 0.076 –0.684 mm long (their average length varies in different specimens between 0.23–0.349 mm, which is significantly longer than that of E. aspergillum indonesicum ). In any investigated specimen of E. aspergillum aspergillum the maximal length of oscularia is much longer then 0.19 mm in length (maximal length of that in the new subspecies). Since these spicules (oscularia) are becoming important for the recognition of the subspecies of E. aspergillum , as it is stated in this publication, we suppose that such difference in the ray length variation is also important and may be considered as a character of lower then species level too.

Figures

FIGURE 1. Hyalonema (Hyalonema) proximum. A, dermal pinule, NTM Z 0002594, scale 30 µm. B, macramphidisc, NTM Z 0002573, scale 100 µm. C, mesamphidisc, NTM Z 0002594, scale 10µm. D, hexactin with micramphidiscs, NTM Z 0002594, scale 30µm.