Polysiphonia beltoniorum Huisman

Scientific Description

Habit and structure. Thallus predominantly erect from a limited prostrate base, to 6 cm tall, deep red, with several percurrent primary axes bearing lateral branches every 5–7 segments, although these often seemingly deciduous. Lower primary axes to 650 µm diam. [segment L:B c. 0.4], tapering gradually to 75–100 µm diam. distally [segment L:B c. 0.5]. Lateral branches arising from the basal cell of trichoblasts, tapering at the branch base, gently curving towards the primary axis. Trichoblasts arising in a gentle spiral, diverging by 1 pericentral, often on every third segment but not consistently so, soon deciduous, dichotomously branched 5 or 6 times, to 680 µm long, lower cells c. 25 µm diam., tapering distally to filiform upper branches. Pericentral cells 8–10.

Reproduction. Tetrasporangia arising in linear to gently spiralling series, if the latter then often in short straight series of 3 sporangia, followed by a second similar series offset by 1/10 from the previous series. Each short series corresponding to the segments between scar cells. Mature tetrasporangia spherical, 55–95 µm diam., tetrahedrally divided, distorting the bearing segment. Other reproductive structures not observed.

Distribution. Known from Montgomery Reef, and King and Conway Islands, Kimberley, Western Australia.

[After J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 562–564 (2018)]