Microzoanthus Fujii & Reimer, 2011

Swain, Timothy D. & Swain, Laura M., 2014, Molecular parataxonomy as taxon description: examples from recently named Zoanthidea (Cnidaria: Anthozoa) with revision based on serial histology of microanatomy, Zootaxa 3796 (1), pp. 81-107 : 99

Genus Microzoanthus Fujii & Reimer, 2011

Type species. Microzoanthus occultus Fujii & Reimer, 2011 , by original designation.

Diagnosis. Identical to Microzoanthidae (diagnosis of Fujii & Reimer 2011). Colonial Microzoanthidae free-living and lacking a scleroprotein skeleton. Known from temperate and tropical cryptic habitats in the Pacific Ocean at 0– 23 m. Azooxanthellate. Polyps transparent or faintly red, expand to 3 mm wide and 10 mm long. Capitular ridges largely imperceptible because of heavy encrustations. Oral disk calathiform and edged in a distinct zig-zag pattern (diagnosis expanded using data from Fujii & Reimer 2011). Marginal musculature endodermal, 268–331 Μm in length, composed of 10–16 attachment points. Encrustations of column through ectoderm but not penetrating ectodermal surface of the mesoglea; elliptical lacunae just beneath ectodermal surface of mesoglea form an encircling sinus (diagnosis expanded using data presented here).

Remarks. The phylogenetic position of Microzoanthus , as inferred by mitochondrial cytochrome oxidase (COI) and 16s ribosomal (mt 16S rDNA) genes (see Fujii & Reimer 2011; Figs 7 & S1), is near the base of the Zoanthidea and as the sister clade to Isozoanthus (in the COI tree) or all Zoanthidea except Isozoanthus (in the 16S tree). Although these phylogenies are incongruent (with each other and other published hypotheses, e.g., Sinniger et al. 2005, Swain 2010) and poorly supported (both problems may be resolved by multigene analysis applied to comprehensive taxon sampling), they suggest that Microzoanthus may occupy a critical position near the origin of Zoanthidea and could provide insight into the evolution of Isozoanthus and clarify relationships between the genera of Zoanthidea .