Amphimedon chloros Ilan et al., 2004

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 : 4-7

Amphimedon chloros Ilan et al., 2004 ( Figs 2A –C)

Synonymy. Dactylochalina viridis Keller, 1889: 391 ;? Pachychalina variabilis ; Row, 1911: 321 (not:Dendy, 1890); Hemihaliclonaviridis; Burton,1937: 18, pl. Ifig.7 (withadditionalsynonyms, but these appear mostly unsustained); Callyspongia viridis ; Burton, 1952: 167; Amphimedon chloro s Ilan et al., 2004: 11, fig. 7.

Material examined. ZMA Por. 17340, Shark Observatory, 3m, coll. T. Helmy, 26­07­ 2000.

Description. Colour: Brown when dried or preserved in alcohol, presumably green in life (not recorded). Shape: Lobate, size 25 cm x 10 cm, attached to hard substrata, with hollow upright, finger­like projections up to 7 cm high. Oscula are distinct, 3–5 mm wide, and scattered over the surface ( Figure 2A ). Surface: Optically smooth, slightly bumpy surface. Punctate due to regularly distributed subdermal spaces. Texture: Compressible, soft, easy to tear.

Skeleton. Ectosomal skeleton composed of a three­dimensional reticulation of uni­, pauci­ or plurispicular spicule tracts of 10–65 µm diameter forming rounded meshes, 90­ 115­ 130 m diameter. Spongin is scarce and forms an indistinct thin layer enveloping and connecting the spicules. Choanosomal skeleton an anisotropic arrangement of plurispicular spicule tracts 10–80µm diameter, ascending towards and protruding slightly from the surface, causing a micro­conulose surface ( Figure 2 B). Meshes similar in size to those of the ectosome, but more squarish in outline, up to 200 µm in diameter. Spicules: Oxeas ( Figure 2 C), curved with sharp endings, 36­120­142 x 1–2 µm.

Ecology. Found on the reef flat, attached to undersides of rocks or sometimes on silt bottoms.

Distribution. Widely distributed in the Gulf of Aqaba (pers. obs. T.H.) and frequently recorded from other areas, such as the coasts of Jeddah and Eilat.

Remarks. We were able to verify the identity of the collected specimen with Dactylochalina viridis Keller, 1889 by the examination of a microscopical slide of the Berlin Museum type specimen ZMB 7654. The genus Dactylochalina Lendenfeld, 1886 to which Keller (1889) assigned this species is a synonym of Callyspongia (Callyspongia) according to Desqueyroux­Faúndez & Valentine, 2002, and thus D. viridis was wrongly assigned. Ilan et al., 2004 made it clear that it belongs to the genus Amphimedon , and consequently they had to give it a new name ( A. chloros ) because the combination Amphimedon viridis is preoccupied by a clearly different species, the Caribbean A. viridis Duchassaing & Michelotti, 1864 . Burton (1937) made Duchassaing & Michelotti's A. viridis the type of a genus Hemihaliclona , which falls into synonymy with Amphimedon according to Desqueyroux­Faúndez & Valentine, 2002. Burton (l.c.) gave a large number of synonyms for D. viridis including the names of several Caribbean and South Australian species. We cannot here decide whether all these synonyms are proper, but grave doubts are in order in view of the implied cosmopolitan nature of such a widespread species. We did check whether the Red Sea species Reniera tabernacula Row, 1911 , allegedly also a synonym according to Burton, conforms to Dactylochalina viridis / Amphimedon chloros by studying slides of the type of Reniera tabernacula , BMNH 1926.2.11.18. Reniera tabernacula is a green, flattened and lamellar mass, with a clear Haliclona (Reniera) type ladder­like skeleton unlike that of A. chloros , with spicules relatively robust, straight and abruptly pointed, unlike the thinner, curved oxeas of A. chloros .

It is likely that the material named Pachychalina variabilis by Row, 1911 is also a specimen of this species, although we did not attempt to verify this. The description of the habit and the skeleton is similar to the one presented above. The original Pachychalina variabilis Dendy, 1887 is Caribbean ( Bahamas) and was assigned to Amphimedon complanata (Duchassaing, 1850) by Wiedenmayer (1977) and to Cribrochalina variabilis by Van Soest (1980); in any case this is a clearly different species not to be confused with the Red Sea species.

A. chloros is not the only green Amphimedon in the Indo­Pacific as there is also A. paraviridis Fromont (1993) from North Australia and Indonesia. This is different in shape, thickly encrusting to ramose, 20 mm in thickness with slightly raised oscules. The skeleton forms a loose reticulation with in addition many interstitial spicules between the fibres, and spicules are longer and thicker: 114–204 x 4 –10.5 µm ( Fromont, 1993).

Figures

FIGURE 2. A. Amphimedon chloros Ilan et al., 2004, habit (scale bar = 1 cm); B. Amphimedon chloros Ilan et al., 2004, structure of the ectosomal skeleton showing the three­dimensional network of spicule tracts (scale bar = 0.5 mm); C – F. SEM­images of oxeas of Amphimedon chloros (C), A. dinae sp. nov. (D), A. jalae sp. nov. (E) and A. hamadai sp. nov. (F) (scale bars = 10 µm).