Oswaldella Stechow 1919

Oswaldella Stechow, 1919

Oswaldella Stechow, 1919: 853; type, by original designation: Schizotricha bifurca Hartlaub, 1904.

Diagnosis (modified from Peña Cantero & Vervoort 2004). Feather-like, colonial hydroids with branched or unbranched stem, divided into internodes or undivided, mono- or polysiphonic, usually with two longitudinal rows of apophyses (three in O. laertesi Peña Cantero, 2007), alternately arranged in one plane and supporting hydrocladia. Cauline apophyses with varied number of nematophores on upper surface, emerging through raised, perforated part of periderm (‘mamelon’) and/or through simple axillary holes in perisarc, with or without reduced nematothecae. Stem without nematophores. Hydrocladia typically branched. Degree of branching varied. Hydrocladia homomerously divided into hydrothecate internodes (except for Oswaldella herwigi El Beshbeeshy, 2011), each with one hydrotheca and two mesial nematophores: first one placed behind free adcauline hydrothecal wall and emerging through simple hole in perisarc; second nematophore situated below hydrotheca at a more or less distinct elevation of internode and with or without rudimentary, scale-shaped nematotheca. Hydrothecae cupshaped to tubular. Colonies dioecious, with sexual dimorphism. Gonothecae inserting on hydrocladia below hydrotheca, next to mesial inferior nematophore. Cnidome composed of microbasic mastigophores, typically in two size classes.