Knopia

Diagnosis. Colonies of upright polyps arising from stolons that may coalesce but do not form extensive basal membranes. Polyp bodies and stolons covered with thin cuticle. Polyps retractile. Tentacles lacking free pinnules; instead, the margins of the tentacle are very broad and divided into a series of finger­like caeca as if a single row of closely appressed pinnules had become fused side­to­side along the length of the tentacle. Sclerites, present only on the introvert and tentacles, are minute platelets and small scales that are constructed from sinuous, dendritic, calcite rods that are more or less radially arranged. Zooxanthellate.

Remarks. The specimens of this genus available for examination have not formed extensive basal mats as seen in one specimen of Acrossota described above. But, it is quite possible that specimens may be found in the future with a similar growth form, as it is not rare for taxa that are mainly stolonate to be found with broad, coalescing, basal ribbons, especially if luxuriant (e. g. Clavularia australiensis in Hickson, 1894: 338; Clavularia viridis, C. inflata in Roxas, 1933: 57 – 58; Sansibia in Alderslade, 2000: 243; Orangaslia in Alderslade 2001: 42 ­ 49; and Acrossota above.) At present, specimens of Acrossota and Knopia that have only stolons cannot easily be distinguished unless the tentacles are extended. Both of these genera can also be confused with an as­yet­undescribed taxon figured by Fabricius and Alderslade (2001: 68) that has pinnulated tentacles and no sclerites. Dissection to establish tentacle form is necessary in such instances.

Etymology. The genus is named for Daniel Knop who collected most of the material and supplied colour images of live colonies. Gender feminine, as is traditional.

Type species. Knopia octocontacanalis n. sp., by original designation and monotypy.