Tessaradoma Norman, 1869

Arakawa, Shinji, 2024, Descriptions of Three Cheilostomatid Bryozoan Species from the Continental Shelf off Boso Peninsula, Japan, Species Diversity 29 (1), pp. 99-110 : 100

Genus Tessaradoma Norman, 1869

Diagnosis. Colony erect, unjointed, attached by encrusting base. Frontal shield striated, granular, or smooth, with an umbonuloid component and marginal pores. Tubiform spiramen present. Primary orifice semicircular, concealed by projecting peristome. Adventitious avicularia present or absent. Ovicell peristomial, imperforate.

Type species. Pustulipora gracilis Sars, 1851 .

Remarks. The type species is now regarded as a synonym of Tessaradoma boreale ( Busk, 1860) (originally Onchopora borealis ) (e.g., Hayward and Ryland 1979, 1999; Winston 2005; Denisenko 2014), but I believe that T. boreale from the Atlantic and Arctic Oceans may include two or more species as discussed by Winston (2005) and Souto et al. (2016), although Sars (1863) also considered Busk’s species as the synonym of T. gracile . Illustrations of the Arctic species ( Smitt 1868; Kluge 1962) show smaller marginal pores and avicularia, and a more highly projecting peristome than the European species from Britain ( Busk 1860; Alder 1864; Hincks 1880; Hayward and Ryland 1979, 1999), Denmark ( Marcus 1940), southern Spain ( Zabala and Maluquer 1988) and the Azores ( Jullien and Calvet 1903). However, as Souto et al. (2016) pointed out, ontogenetic changes in zooids have not been sufficiently compared, and thus no consensus on the synonymy has been reached.