Sertularella robusta
Stems simple, rarely branched, to 1 cm long, arising from a tubular hydrorhiza. Stem internodes variable in length, 0.42-1.14 mm, but fairly constant in maximum width, 0.15-0.18 mm, measured just below hydrotheca.
Hydrothecae distal on long internodes, occupying most of the length of short internodes. Length of free adcauline wall 0.3 mm, fixed adcauline wall 0.24 mm; abcauline wall 0.42 mm; maximum width of hydrotheca, 0.24 mm. Thecal walls moderately to faintly annulated with 2-3 broad undulations passing around widest part of hydrotheca.
Mediterranean, South Atlantic, southern Pacific (Australia: Queensland, South Australia, Tasmania, Victoria, Western Australia).
Subtidal, epiphytic on algae, epizoic on bryozoans, sponges and other benthic fauna.