Halichondria Fleming 1828

Subgenus Halichondria Fleming, 1828

Halichondria (Halichondria) cf. melanadocia de Laubenfels, 1936a (Fig. 32 A–C)

Examined material. Sample HK 1: Hawai’i, O’ahu Island, 1 m, 22 June 2005.

Description. Encrusting sponge, about 2 mm thick, covering a small fragment (about 4 cm in length) of a colony of Carijoa riisei (Fig. 32 A). In ethanol the specimen is brownish (Fig. 32 B).

Skeleton. Difficult to study due to the bad condition of the sample. The ectosome consists of uni- or paucispicular tracts of tangential oxeas. The choanosome consists of an irregular reticulation of oxeas; the hispid surface is due to the vague ascending tracts beneath the sponge surface (Fig. 32 B).

Spicules. Oxeas slightly curved, 160 – (404.5 ± 133.6) – 610 x 2.5 – (8.9 ± 5.9) – 20 μm, with gradually pointed tips (Fig. 32 C).

Distribution and remarks. West Indies (de Laubenfels 1936a), North Carolina (Wells et al. 1960), Florida (Little 1963), Jamaica (Hechtel 1965) and Hawai’i (Bergquist 1967). This sample fits the description of the Hawaiian (Bergquist 1967) and Jamaican specimens (Hechtel 1965) in terms of spicule features. Hechtel described oxeas straight to curved, with gradually pointed of 134 – 802 x 3 – 20 μm while, later, Bergquist reported oxeas of 200 – (403) – 512 x 2 – (9) – 13 μm. The main difference with the previous descriptions is in the ectosomal skeleton that was re-described by Hechtel as a tangential reticulation of spicule tracts. Moreover, the peculiar and diagnostic colour of the live specimen, reported by Laubenfels (grey-blackish in the exterior and yellow-green in the interior) does not match that of the Hawaiian specimen here described.

The species was described from the Caribbean, but later Bergquist (1967) reported it from Hawai’i, suggesting that it was probably introduced through fouling.