Gelidium minusculum (Weber Bosse) R.E.Norris

Scientific Description

Habit and structure. Thallus forming creeping prostrate axes attached by clustered rhizoids, bearing sparse perpendicular erect axes c. every 500–700 µm, although these often more frequent or absent for long distances. Prostrate axes terete, 100–120 µm diam. Erect axes terete, to 3 mm tall, 70–100 µm diam., mostly simple, with pointed apices. Regrowth from damaged apices typically more slender. Structure uniaxial, when mature with a medulla of longitudinal filaments, these cross-linked by pit connections, and a cortex of 2–4 layers of smaller pigmented cells. Outer cells rounded to transversely elongate in surface view, 10–18 µm long, 5–8 µm wide, in vague meandering longitudinal lines. Rhizines inconspicuous, in small bundles at the medulla/cortex interface.

Reproduction. Tetrasporangial nemathecium (one seen) at branch apex, 220 µm long, 190 µm wide, with irregularly arranged cruciately divided tetrasporangia, when mature 25–30 µm long, 20–25 µm diam.

Distribution. Widespread in warmer seas.

Habitat. Epiphytic on mangrove pneumatophores or epilithic in the intertidal.

[After J.M. Huisman, G.H. Boo & S.M. Boo in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 250–251 (2018)]