Jania verrucosa J.V.Lamour.

Scientific Description

Habit and structure. Thallus light to medium red-brown, fading to grey-white, (2–)3–5(–10) cm high, usually densely tufted and fastigiate, loose and spreading in calm habitats. Fronds dichotomous in various planes at intervals of (2–)5–15(–20) intergenicula with occasional lateral branches below; angles at most dichotomies <30 degrees. Intergenicula terete, in lower parts of fronds (150–)200–350(–400) µm in diameter, in upper parts (120–)150–220(–240) µm in diameter, length variable, 0.4–3.0(–4.0) mm long, L/D 2–8(–16). Holdfasts at first discoid and spreading, 0.5–6 mm in diameter, stolons plentiful, arising from lower parts of fronds, tending to recurve, 100–200 µm in diameter; epilithic, rarely epiphytic. Structure of 4–20(–25) tiers of medullary cells each 90–160 µm long per intergeniculum; cortex 2(–3) cells thick; hairs common. Genicula 80–200 µm long.

Reproduction. Gametangial thalli dioecious. Female conceptacles amphoroid, external diameter 300–470 µm, internal diameter 240–325 µm, carposporangia subspherical, 65–100 µm in diameter. Male conceptacles externally 450–600 µm long and 180–250 µm in diameter, chambers 120–180 µm in diameter, canals 60–100 µm long. Tetrasporangial conceptacles amphoroid, external diameter 240–600(–700) µm, chamber diameter 160–400 µm; tetrasporangia 170–220(–360) µm long and 40–80 µm in diameter.

Distribution.Rottnest I., W. Aust., around southern Australia and Tas., to Coffs Harbour, N.S.W. (probably further north). New Zealand; South Africa; California, D.S.A.; Baja California, Mexico; Peru.

Habitat. J. verrucosa is almost entirely epilithic, occurring in shallow eulittoral pools or on rocks near low tide level.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIB: 305–307 (1996)]