Siphonodictyon coralliphagum Rützler, 1971

Rützler, Klaus, Piantoni, Carla, Van, Rob W. M. & Díaz, Cristina, 2014, Diversity of sponges (Porifera) from cryptic habitats on the Belize barrier reef near Carrie Bow Cay, Zootaxa 3805 (1), pp. 1-129 : 87

Siphonodictyon coralliphagum Rützler, 1971

Synonymy and references. Siphonodictyon coralliphagum Rützler, 1971: 5 ; figs. 4–9, 10c; pls. 3–6, 8: c, d, f, 9a–c, e, f.

Material. USNM 1229123, Carrie Bow Cay back reef, near reef crest, inside and underside of Acropora palmata coral rubble, 0.3 m; K. Ruetzler col. 23 Apr 1974. USNM 1229124, Curlew Bank forereef cave, 20 m; C. Piantoni col. 2 Jul 2007 USNM 1229125, Carrie Bow South reef, lower surface of rock slab, 1 m; K. Ruetzler col. 13 Mar 2009. USNM 1229126, Curlew Bank, forereef cave, ceiling (50-150 cm inside cave), 20 m; C. Piantoni and M. Parrish col. 22 Aug 2012.

External morphology. All specimens are endolithic, ovoid (8– 11 x 5–7 mm), with only one or two tissuelined canals (ca. 1 mm in diameter) leading toward a circular opening at the substratum surface or ending as short tubules or fistules. Consistency soft and slightly mucous. Live color yellowish beige, except for the external tubule or fistule, which may appear whitish from its supporting spicule network.

Skeleton structure. Oxeas in abundance throughout the tissue but without orientation (criss-cross), here and there bundled into a short tract.

Spicules. Oxeas in two size categories, slightly curved, the larger ones with fairly dull points, some with rounded or stepped tips; oxeas I: 140–190 x 5–10 (164 x 8) Μm; oxeas II: 135–155 x 4–7 (144 x 6) Μm.

Ecology. Excavating inside coral rubble and rock on the forereeef, 0.3– 25 m.

Distribution. Caribbean-wide, including the Gulf of Mexico.

Comments. This endolithic growth form was named “forma obruta” in the original description ( Rützler, 1971). We now consider it a mere growth stage that, in cryptic environments, does not develop epilithic tubules, fistules, or crusts.