Papenfussiella extensa Womersley & A.Bailey

Scientific Description

Habit and structure. Thallus medium to dark brown, densely tomentose throughout, mucoid, attached by a small discoid holdfast, with one to a few axes 10–50 cm long and 2–6 mm in diameter, usually with a few long, simple, scattered or occasionally clumped lateral branches, occasionally with these bearing short laterals (1–4 cm long); epilithic (or epiphytic on Laurencia). Medulla of dense longitudinal filaments 10–22 µm in diameter (narrower near the periphery) with cells L/B2–4(–6), with slight production of hyphae, more so near the periphery; cells at surface of medulla irregular in shape, 4–6 µm in diameter and L/B 1.5–3,producing the cortical filaments directly or with a single subcortical cell. Cortical filaments of two lengths; shorter determinate cortical filaments 30–60 µm and (4–)6–12 cells long, usually curved and narrower below, cells 4–6 µm in diameter above and L/B1–1.5(–2),with intercalary divisions; longer (indeterminate) cortical filaments 1–2.5 mm and usually over 50 cells long, cylindrical, cells (7–)8–10 µm in diameter and L/B1–1.5 below, becoming L/B3–4 above, with cell divisions mainly in the lower part. Phaeoplasts several per cell, discoid, each usually with a pyrenoid. Phaeophycean hairs absent.

Reproduction. Unilocular sporangia forming a well defined layer outside the medulla, broadly clavate to ovoid, borne on outermost medullary cells or on a short 1–2 celled pedicel at base of cortical filaments, (30–)40–50 µm long and 16–24 µm in diameter. Plurilocular sporangia unknown.

Distribution.Cottesloe toPoint Peron, W. Aust.

Habitat. In crevices on reef edge, upper sublittoral.

[After Womersley, Mar. Benthic Fl. Southern Australia II: 110 (1987)]