Amphimedon jalae, Helmy, Tamer, Van, Rob W. M. & Soest, 2005

Helmy, Tamer, Van, Rob W. M. & Soest, 2005, Amphimedon species (Porifera: Niphatidae) from the Gulf of Aqaba, Northern Red Sea: Filling the gaps in the distribution of a common pantropical genus, Zootaxa 859, pp. 1-18 : 9

Amphimedon jalae sp.nov. ( Figs. 1 E, 4 A–C)

Material examined. Holotype ZMA Por. 17342, Ras Um El Seed, 15m, coll. T. Helmy, 25­07­ 2000.

Description. Colour: Dark brown alive and preserved. Shape: Cushion­shaped ( Figure 4A ), 3 cm high and 7 cm wide, with several large oscula of 5 mm diameter. Surface: Optically smooth, but uneven bumpy surface, microconulose, with distinct coarsely punctate surface. Texture: Easy to compress but difficult to tear.

Skeleton. Ectosomal skeleton ( Figure 4 B) a paratangential (three­dimensional) network of spicule tracts, spongin inconspicuous, forming polygonal meshes of 150­250­350 µm. Choanosomal skeleton ( Figure 4 C) anisotropic, consisting of pauci­multispicular tracts. Primary tracts 100–150 µm and secondary tracts 30–50 µm in diameter, forming rounded meshes of 600–800 µm. Spongin cannot be observed clearly in the spicule tracts. Spicules: Oxeas ( Figure 1 E) 100­140­170 x 4–6 µm, sometimes curved, with abrupt thin sharp endings.

Etymology. Named after Jala Helmy, Canal and Sinai Developing Agency, Ismailia, Egypt for her continuous help during the work.

Ecology. On hard substrata, both on rocks and dead corals in coral reef communities.

Distribution. Frequently found in the Gulf of Aqaba (pers.obs. T.H.).

Remarks. The new species is similar to Amphimedon dinae sp.nov., described above, in shape, colour and punctate surface, but the two differ sharply in skeletal features. A. dinae has predominantly a spongin fibre skeleton with few and thin coring spicules, whereas A. jalae sp.nov. has scarce spongin and robust spicules and spicule tracts. Although variability of coring (number of coring spicules, thickness of coring spicules) has been reported as considerable in isolated haplosclerid taxa (e.g. the chalinid Chalinula molitba , cf. De Weerdt, 2000), the difference in length of the spicules of A. dinae sp.nov. (50–60 µm) and A.jalae sp.nov. (100–170 µm) is too great to allow assignment of both to a single species. A. jalae sp.nov. also is notably coarser of texture than A. dinae sp.nov., due to the larger skeletal meshes.

The new species differs from A. chloros in its cushion­shape, not globular with fingerlike projections (cf. above) and live colour of A. chloros . Among the many Indian Ocean species assignable to Amphimedon and related genera, A. jalae sp.nov. appears similar in shape and surface characters to A. navalis Pulitzer­Finali, 1993 , but this species is blueviolet in colour and has much more robust and longer spicules (160–210 x 11–15 µm). It is also similar to A. rubiginosa Pulitzer­Finali, 1993 , which is red­brown in colour, has the oscules with raised rims, and its spicules are clearly in excess (180–210 x 5–12 µm) of those of A. jalae sp.nov.

Figures

FIGURE 1. Map of the Northern Red Sea showing the localities where the described sponges were observed and collected.

FIGURE 4. A. Amphimedon jalae sp. nov. habit (scale bar = 1 cm); B. Amphimedon jalae sp. nov., ectosomal skeleton showing the three­dimensional network of spicule tracts (scale bar = 100 µm); C. Amphimedon jalae sp. nov., cross section of choanosomal skeleton, (scale bar = 100 µm).