Cliona amplicavata Rutzler 1974

Cliona amplicavata Rützler, 1974

(Figs. 5 A–B, 13B)

Selected synonymy: Cliona amplicavata Rützler, 1974:26; Carballo et al. 2004:370.

Material examined. CNPGG –1223 Alacranes reef (22°23'1.68”N 89°40'22.8”W), depth 8 m, 03/VIII/2009.

Description. Burrowing sponge, growing in alpha stage inside the conch Lobatus gigas (Fig. 13 B), excavating to a depth of 12 mm into the substratum. It is of bright yellow color in vivo, which turns to yellowish brown in alcohol.

Excavations. Circular papillae are 0.5–3 mm in diameter, the burrowed cavities are irregular, circular or elongated with “tissue” adhering to walls of the cavity, measuring 5–13 mm, separated by septa, 1–5 mm in thickness. The papillar spicules are oriented perpendicularly to the surface. There is no particular skeletal arrangement towards the interior. Papillae are not observed out of water.

Spicules. Megascleres are slightly curved tylostyles 140–291 × 2.8–5.2 µm, with typically mucronate and spherical tyles (Fig. 5 A), a dark spot in the centre of the tyle corresponding to the axial canal, can be seen when viewed under LM (Fig. 5 B). The diameter of the tyles is 7.8–13 µm. In a lesser amount styles are also present, 165–192 × 1.3–3.9 µm. Microscleres are thin raphids 70–124.8 × 0.8 µm.

Distribution and ecology. Bermuda (Rützler 1974) and Cuba (Buznego & Alcolado 1987). This sponge inhabits reef environments burrowing dead corals, and other thick structures made of calcium carbonate such as the large shells of Lobatus gigas and other gastropod or bivalve mollusks. The present specimen is the first record for the southeastern Gulf of Mexico.

Remarks. Apparently Cliona amplicavata goes unnoticed to the viewer due to alpha growth with small papillae of up to 3 mm. The studied material agrees in all descriptive and morphometric characteristics with the original description except that the Bermuda material has thicker tylostyles (190–290 × 4.5–8 µm) and larger raphids (117.5–150 µm). C. amplicavata has been recorded in the Mediterranean (Rosell & Uriz 2002) although these specimens showed substantial differences from the original description, such as tylostyles 230–490 × 6–12 µm and raphids 120–250 µm, which is nearly double the size of those reported in the original description, and they have a lobed tyles which is not a trait of C. amplicavata. In addition, the Mediterranean specimen inhabits deeper environments (60–100 m), and it burrows huge galleries (1.5–3 cm) compared with the original description (0.5 × 0.3–2.2 × 1.2 cm). In our view, the Mediterranean specimens need to be revised.

On the other hand, the identity of specimens collected in both Atlantic and eastern Tropical Mexican Pacific (Carballo et al. 2004), should be confirmed by molecular studies to either validate the presence of an amphiamerican distribution for this species, or the presence of two cryptic allopatric species.