Stegolaria Stechow, 1913

Amended diagnosis [after Bouillon et al. (2006); amendments in italics]. Colony erect, flabelliform, stem with alternate or subalternate side branches all in the same plane, strongly polysiphonic, distal parts often monosiphonic and geniculate; hydrothecae in two alternate rows in the same plane as ramifications, tubular, curved outwards, adnate to stem or branch for up to two-thirds height and immersed among peripheral tubes in well developed colonies; no true diaphragm but a faint lamella of perisarc at the base of the hydrotheca; abcauline wall smooth or with an indentation; operculum consisting of smooth or plicated valves seated in the embayments between two gable-like processes of hydrothecal margin; gonophores fixed sporosacs with up to six ova, gonotheca sac-shaped, completely adnate to hydrocaulus or hydrocladium, aperture facing outwards with an operculum of one or more segments.