Campylosaccion decumbens Huisman

Scientific Description

Habit and structure. Thallus erect to decumbent, to 6 cm tall, pale brownish red, with a short cartilaginous stipe bearing elongate clavate vesicles 15–40 mm long and 3–8 mm diam. Secondary digitate outgrowths arising from distal regions of vesicles and forming secondary attachments to the substratum. Apical structure with a subcortical network of stellate cells; when mature these forming the bearing cells of vesicular cells. Cellular tissue 5 or 6 cell layers thick; innermost layer of large hyaline cells that are equidimensional or slightly longitudinally elongate, 200–340 µm long, 150–200 µm diam., grading to smaller pigmented cortical cells; outermost cells irregularly shaped in surface view, 5–25 µm diam., forming a relatively complete layer over the underlying cells, with scattered darkly staining (possibly vesicular) cells. Vesicular cells spherical to pyriform, 20–30 µm diam., solitary or in pairs directly on the inner cells of the cellular layer or on specialised cells. Bearing cells of vesicular cells often interconnected by thin processes, these remnants of arms of apical subcortical stellate cells.

Reproduction. Tetrasporangia scattered in the outer cortex, mostly concentrated near vesicle apices, intercalary, spherical, 50–60 µm diam., tetrahedrally divided. Other reproductive structures not observed.

Distribution. Known from Broome, Barrow Island and the Dampier Archipelago, north-western Australia.

Habitat. Epilithic in the intertidal and shallow subtidal.

[After J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 335–337 (2018)]