Williamsium, Moore & Alderslade & Miller, 2017

Moore, Kirrily M., Alderslade, Philip & Miller, Karen J., 2017, A taxonomic revision of Anthothela (Octocorallia: Scleraxonia: Anthothelidae) and related genera, with the addition of new taxa, using morphological and molecular data, Zootaxa 4304 (1), pp. 1-212 : 120

Williamsium gen. nov. Moore, Alderslade & Miller

http://zoobank.org/2540CBA5-F386-4C40-B302-92EE309C0385

Diagnosis: Monomorphic scleraxonians which form arborescent colonies with a single, short main stem; simple, sparse branching basically in one plane; anastomoses absent; medulla without large, well-defined coelenteric canals, separated from the cortex by a ring of boundary canals; polyps sparse, retractile into tall calyces on all sides of branches but restricted to the distal half of the branches; sclerites predominately short, flat rods arranged transversely in the tentacle rachis, transverse scales in pinnules, small tuberculate rods in the neck and pharynx, and tuberculate sticks and spindles in the points, calyx, cortex and medulla.

Type species: Anthothela parviflora Thomson, 1916 here designated.

= Williamsium parviflorum new combination

Remarks: The genus is placed tentatively in the family Anthothelidae with the knowledge that the family as currently recognised ( Williams & Cairns 2015) is polyphyletic ( Cairns & Wirshing 2015). Of the recognised scleraxonian families with an unconsolidated axis, the lack of well-defined coelenteric canals in the medulla and the presence of pharynx sclerites excludes it from Victorgorgiidae n. fam.; the lack of radiate capstans among the cortex sclerites excludes it from Spongiodermidae ; the lack of fused spindles in the medulla excludes it from Subergorgiidae ; monomorphic polyps exclude it from Paragorgiidae ; and the distinct ring of boundary canals excludes it from Briareidae . The boundary canals, prominent calyces and sclerites, and mainly tuberculate sticks and spindles in a collaret and point arrangement place it within the current diagnosis for Anthothelidae . However, given that the arrangement and shape of the sclerites in the tentacles differ significantly from those found in Anthothela specimens it is likely that this genus will need reassignment in the future.

Etymology: This genus is named in honour of Dr Gary Williams in recognition of the extensive research conducted by him on octocorals from the waters around South Africa, including a redescription of the type species of the genus.