Botryocladia crassa Huisman

Scientific Description

Habit and structure. Thallus erect, to 30 cm tall, red to brownish, arising from a consolidated base bearing several erect axes, sparingly subdichotomously or unilaterally branched. Axes with cartilaginous stems to 4 mm diam., denuded below, but mostly bearing numerous small spherical short-stalked vesicles less than 1 mm diam. Stems pseudoparenchymatous, with a medulla of large hyaline cells grading to an outer cortex of smaller anticlinally orientated pigmented cells. Vesicles hollow, their walls 3 or 4 cells thick, consisting of an inner medulla of large hyaline cells 30–60 µm diam., and progressively smaller and more pigmented cortical cells. Surface cells 3–8 µm diam., forming a continuous layer, rarely in weak rosettes, but these not exposing the inner large medullary cells. Vesicular cells spherical to pyriform, 10–25 µm diam., borne 1–2 (–3) directly on the inner surface of the medullary cells, or rarely on specialised cells borne on medullary cells.

Reproduction. Tetrasporangia scattered in the outer cortex of vesicle walls, intercalary, subspherical to ellipsoidal, cruciately or decussately divided. Other reproductive structures not observed.

Distribution. Known from only a single specimen in north-western Australia.

[After J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 332–334 (2018)]