Phacelocarpus peperocarpos (Poir.) M.J.Wynne, Ardré & P.C.Silva

Scientific Description

Habit and structure. Thallus medium to dark red, (10–)20–50 cm high, with a terete stipe 5–20 mm long and 1–2(–3) mm in diameter, much branched complanately with long and short branches for 3–4 orders, branches 3–5 mm broad, rachides robust, terete below and 1–1.5 mm in diameter, mostly compressed and (500–)600–1000 µm broad, with a well-developed midrib and marginal flanges. All branches bearing distichous, closely adjacent (almost touching near apices), compressed ramuli tapering to a point, 300–600 µm in basal width and 1.5–2.5 mm long, separated by rounded sinuses mostly 150–500 µm wide. Holdfast discoid-conical, 2–10 mm across; epilithic. Structure uniaxial, developing a prominent axial filament with four periaxial cells, the lateral two developing into filaments with alternate ones forming the ramuli; rhizoids densely massed around the axial filament, forming the robust midrib. Cortex pseudoparenchymatous, inner cells ovoid and 30–60 µm in diameter, outer cells 1.5–2.5 µm in diameter and L/D 1–2; refractive cells absent or inconspicuous in the cortex; rhodoplasts discoid to elongate.

Reproduction.All reproductive bodies on the rachis margin, shortly to distinctly stalked. Sexual thalli dioecious. Procarps with a group of two 2-celled carpogonial branches and an auxiliary cell. Cystocarps with a stalk 200–800 µm long, ovoid, bilabiate, 400–800 µm broad, with a thick pericarp along the ostiolar slit, enclosing the carposporophyte with a basal fusion cell and erect gonimoblast filaments with ovoid to clavate terminal carposporangia 6–10 µm in diameter. Spermatangial nemathecia short-stalked, subspherical to ovoid and 400–700 µm in diameter, with spermatangia in channels separated by sterile tissue. Tetrasporangial nemathecia with short to moderate stalks, subspherical to ovoid, 400–700 µm in diameter, with tetrasporangia in channels, 25–35 µm long and 4–8 µm in diameter, zonately divided.

Distribution.New Zealand (var. novae-zelandiae Chapman). Recherche Archipelago, W. Aust., to Collaroy, N.S.W., and the east coast of Tas.

Habitat. P. peperocarpos occurs mainly in deep water on rough-water coasts.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIA: 400–402 (1994)]