Actinopluma Galea 2020, gen. nov.

Genus Actinopluma Galea gen. nov.

urn:lsid:zoobank.org:act: 5CD7421D-F5D7-4AE5-8CC7-4C13AAD95F1D

Actinopluma mirifica Galea gen. et sp. nov., designated herein (see below).

Hydroids with upright, rigid, coplanar colonies with sparingly-branched stem; stem and branches fascicled. Main tube of the stem undivided, but equivalents of internodes with a lateral apophysis and a number of nematothecae above; apophyses alternate, coplanar, each with a mamelon, continued directly into a main hydrocladium; two accessory cladia, projecting outward and slightly upward, are given off laterally from below both sides of the mamelon; main hydrocladium divided into internodes with hydro- and nematothecae; accessory cladia shorter and thinner than main counterpart, generally composed of nematothecae-bearing internodes, occasionally with 1–2 intervening hydrothecate internodes distally. Hydrothecae cup-shaped, without associated nematothecae. Gonothecae unknown.

From Ancient Greek ‘ ἀΚτίς ’, meaning ‘ray’, and Latin ‘ plūma ’, meaning ‘plume’, to describe the radiate appearance of this new hydroid genus. The gender is feminine.

Based on morphological grounds alone, the absence of lateral nematothecae flanking the hydrotheca place this genus in the family Kirchenpaueriidae Stechow, 1921. This allocation should be regarded as provisional, pending the collection of additional material suitable for molecular studies, expected to clarify unambiguously its systematic position.

In having hydrocladia provided with two accessory appendages, the colonies of this so far monotypic genus somehow resemble macroscopically Oswaldella Stechow, 1919, but in the latter, the hydrocladia branch dichotomously at the level of the proximalmost internode, the original cladium not extending beyond this internode (Peña Cantero et al. 1997).