Xenia Lamarck, 1816

Halász, Anna, Mcfadden, Catherine S., Toonen, Robert & Benayahu, Yehuda, 2019, Re-description of type material of Xenia Lamarck, 1816 (Octocorallia: Xeniidae), Zootaxa 4652 (2), pp. 201-239 : 204

Genus Xenia Lamarck, 1816

Type species: Xenia umbellata Lamarck, 1816

Diagnosis. Colonies are small and soft with cylindrical stalk, undivided or branched, terminating in one or more domed polyp-bearing regions. Polyps are not retractile and are always monomorphic. Sclerites are ellipsoid platelets, usually abundant in all parts of the colony. They are mostly up to 0.025 mm in maximal diameter, and are composed of calcite rods, often dendritic or sinuous, mostly radially arranged, at least at the periphery of the sclerites. Tips of rods can be observed on the surface of the platelet, commonly providing it with a granular appearance; in a few cases, distal parts of rods are arranged parallel to the sclerite surface. The rods are mostly uniform in width (0.1–0.2 µm), but in some species their distal ends are wider. The sclerites often tend to fracture during dehydration for SEM purposes, thus also enabling examination of their inner parts and the morphology and arrangement of rods.