Clathrina repens sp.nov.

Figures 26a–d

Material examined. Holotype, RMNH Por. 10161a, Maldives, Faafu Atoll, Wallstreet, 3.119°N 72.979556°E, depth 10 m, scuba, coll. N.J. de Voogd, field nr. MAD10 /MAS122, 20 February 2015.

Description. Open network of creeping and upright tubuli, covering the surface of a keratose sponge ( Hyrtios sp.) (Fig. 26a), size several cm2. A second specimen (Fig. 26a 1, not collected) encrusted an ascidian. Individual tubuli approximately 2 mm high and 1 mm diameter. Upright tubuli often open-ended, presumed to be oscules. Color shades of dull orange, pink-orange and beige; pale beige in preservation (Fig. 26b).

Aquiferous system. Asconoid.

Skeleton. (Fig. 26c) Walls of tubuli with a single layer of spicules.

Spicules. (Fig. 26d) Triactines with conical actines, variable in length, 66– 97 –129 x 6 – 7.4 –9 µm.

Distribution and ecology. Maldives, coral reef, 10 m.

Etymology. Repens (L.) means creeping, referring to the reticulation of small tubuli closely adhering to the substratum.

Remarks. Morphologically, this appears a unique species. Its habitus and spicule sizes show similarity to Indonesian Arturia tubuloreticulata Van Soest & De Voogd, 2015, but this has a minority of tetractines. We examined the present specimen exhaustively, but could find no tetractines.

Unfortunately, no sequences were obtained from it.