Genus Batzella Topsent, 1893

Batzella aurantiaca (Lévi, 1958)

(Fig. 5 A–C)

Examined material. Sample SC1: Hawai’i, O’ahu Island, Shark’s Cove, depths between 9–15 m, 11 June 2007.

Description. Encrusting sponges <1mm thick, covering two small portions of a colony of Carijoa riisei of about 2 cm in length. The anthocodiae are free to expand and retract (Fig. 5 A). Yellow in situ (Fig. 5 A) and whitish in formalin.

Skeleton. No ectosomal skeleton. Choanosomal skeleton of small bundles of strongyles, not bound by spongin (Fig. 5 B).

Spicules. Straight and very thin strongyles, sometimes with slightly different extremities (Fig. 5 C) and with a black axial canal evident microscopically, 180 – (194.5 ± 2.3) – 205 x 2.5 µm.

Distribution and remarks. Red Sea. This is a new record for Hawai’i. Like B. aurantiaca (Lévi, 1958), the congeneric species B. frutex Pulitzer-Finali, 1982 and B. melanos (de Laubenfels, 1954) were also described from the Indo-Pacific. Batzella frutex is an erect sponge, composed of numerous branches, with a minutely spined surface. The skeleton consists of spongin fibres of 35 µm in diameter and strongyles of two kinds (regular strongyles 230 – 280 x 3 μm, strongyles with a blunt or mucronate extremity 125 – 175 x 3 µm). Batzella melanos from Marshall Islands is a black, encrusting species, with skeleton confusedly arranged and straight strongyles (227 µm).

Lévi described B. arauntiaca (as Prianos) from the Red Sea as encrusting, orange-brownish in colour, with irregular tracts of straight strongyles (180 – 190 x 1.5 µm) often characterised by an evident central canal. Later, Vacelet & Vasseur (1971) found other specimens of B. aurantiaca encrusting massive corals in Tulear (South West of Madagascar), with larger strongyles (230 – 290 x 2.5 – 4 µm). The specimens from Tulear vary in colour from orange to mauve.

The specimen growing on C. riisei fits well with these previous descriptions of B. aurantiaca; in particular, strongyles have the same shape and comparable size, and the skeletal organisation is similar. Several hypotheses may explain this record from Hawai’i, geographically distant from the type locality of the species. Batzella aurantiaca may be a new introduction to Hawai’i much like many other recent records in the archipelago (Carlton & Eldredge 2009). Alternatively, it may have been overlooked by previous surveys (de Laubenfels 1950a; 1951; 1957; Bergquist 1967; 1977). Great help in clarifying the cryptogenic nature of species with such a wide geographical distribution could come from molecular studies, as already happened for Cliona celata (Xavier et al. 2010; Paula et al. 2012) and Chondrilla nucula (Usher et al. 2004) .