Cladiella gracilis

Cladiella gracilis (Tixier-Durivault, 1944) (Figs. 15E, 24 & 25) Lobularia gracilis Tixier-Durivault, 1944a: 185–186; Tixier-Durivault 1948: 55-60, Figs. 43–48. Material examined. Syntypes. MNHN-IK-2000-382, Red Sea, 1850, coll. A. B. Clot Bey; MNHN-IK-2000-409 (7 fragments), same details as MNHN-IK-2000-382. Description. Syntype MNHN-IK-2000-382 is a fragment of an encrusting colony with a cross-section of 11 x 80 mm attached to a fragment of a calcareous substrate (Fig. 15E). The laterally compressed lobes and lobules are arranged in groups on the colony surface leaving some empty space between them. The location of the retracted polyps is noted on the lobe surface as dark pits. The sclerome of the polyps includes platelets with a lateral narrowing and an irregular outline, 0.05–0.06 mm long (Fig. 24A). It should be noted that the tubercles of the above-noted sclerites are mostly perforated. Their surface has a tuberculate texture, also in the outer rim, and is in part cristate-like. Some of these platelets feature an elevated circumferential rim around a central depression. The surface of the lobes includes poorly developed dumbbells, 0.06–0.08 mm long, featuring rounded tubercles (Fig. 24B). The sclerites from the interior of the lobes are dumbbells, 0.08–0.09 mm long, mostly with rounded tubercles and occasionally blunt-ended conical ones, separated by a bare waist, 0.02–0.03 mm wide and up to 0.02 mm long (Fig. 24C).. The poorly developed dumbbells of the surface layer of the colony base are 0.06–0.08 mm long, featuring rounded tubercles or blunt-ended conical ones (Fig. 25A). The sclerites from the interior of the colony base are dumbbells, 0.07–0.09 mm long, with blunt-ended conical and some pointed conical tubercles (Figs. 25B). They feature a bare waist, 0.02–0.03 mm wide and 0.01–0.02 mm long. Color. The dry syntype MNHN-IK-2000-382 is beige-brown. Remarks. The initial species assignment of L. gracilis by Tixier-Durivault (1944a: 185-186) did not depict the morphological characters of the syntype colony. Subsequently, they were presented in the revision of the genus (Tixier-Durivault 1948: 55–60, Figs. 43–48). In general, the current morphological examination of MNHN-IK-2000-382 corresponds to its amended description. Notably, in Fig. 48 of the latter reference, the polyp sclerites and those of the surface layer of the lobes seem to be mixed together. This species has remarkable tuberculate polyp sclerites and both the poorly developed dumbbells and dumbbells from the lobe interior are rounded and look perforated which seems diagnostic for this species. The syntype fragments, MNHN-IK-2000-409 (not shown), resemble syntype MNHN-IK-2000-382, except for their size. It should be noted that no details were presented on the precise locality in the Red Sea where the syntypes were collected. Distribution. Red Sea.