Amphimedon hamadai, 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 : 12

Amphimedon hamadai sp.nov. ( Figs. 1 F, 5A–C)

Material examined. Holotype ZMA Por. 17343, El Gharkana, 10m, coll. T. Helmy, 30­07­2000.

Description. Colour: Brown with purple shades. Shape: Irregularly lobate ( Figure 5A ), sometimes with finger­like projections 3–4 cm in diameter, with some randomly distributed clearly raised oscula, rims 1 mm high, and 2–3 mm in diameter. The sponge is solidly attached to the substratum with its whole underside. Surface: Bumpy, more or less smooth, non­punctate on the flattened parts. Texture: Compressible and difficult to tear.

Skeleton. Ectosomal skeleton ( Figure 5 B) composed of thin spicule tracts 28­33­42 µm in thickness, with inconspicuous spongin sheath enveloping 7–12 spicules, forming isotropic meshes 140­180­250 µm in diameter. Choanosomal skeleton ( Figure 5 C) anisotropic with quadrangular meshes 90­115­130 µm in diameter formed by spicule tracts in a ladder­ like construction. The primary tracts are 40­45­50 µm in diameter and are cored by approximately 10 spicules in cross section. They are interconnected by secondary fibres of 20­25­30 µm diameter cored by fewer spicules. Spicules: Oxeas ( Figure 1 F), short straight, 48­55­ 60 x 2–3 µm.

Etymology. The species is named after Mohamed Helmy for his help during the collection of the species.

Ecology. Always attached to dead corals or rocks in the coral reef community.

Distribution. Found in Ras Nusrani, Shark Observatory and Hurgada (pers. obs. T.H.).

Remarks. The new species differs from A. dinae sp.nov. and A. jalae sp.nov. as well as from A. chloros and Indian Ocean A. brevispiculifera ( Dendy, 1905) and A. delicatula (Dendy, 1889) in having unusually short and at the same time relatively thick oxeas. From A. dinae sp.nov. and A. jalae sp.nov. it differs furthermore in lacking a punctate surface. From A. chloros it differs in being more irregular in shape and having a different live colour.

Figures

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

FIGURE 5. A. Amphimedon hamadai sp. nov., habit (scale bar = 1 cm); B. Amphimedon hamadai sp. nov., peripheral skeleton (scale bar = 500 µm); C. Amphimedon hamadai sp. nov., choanosomal skeleton showing the anisotropic arrangement of the fibres (scale bar = 100 µm).