Lejolisia aegagropila (J.Agardh) J.Agardh

Scientific Description

Habit and structure. Thallus medium red to dark red-brown, 2–15 mm high, forming dense and extensive tufts on various hosts. Attachment by haptera; epiphytic on Amphibolis, Codium galeatum, Lenormandia and other algae. Structure. Prostrate and erect filaments irregularly branched, the erect filaments sometimes unilateral and tapering only slightly. Cell size variable on different hosts, prostrate axes 70–110 µm in diameter and L/D 1.5–3, erect axes (25–)65–80(–105) µm in diameter with cells L/D 2–5, extended hair-like ends 18–20 µm in diameter and L/D up to 15. Cells multinucleate; rhodoplasts discoid to elongate.

Reproduction. Gametophytes dioecious; mixed phase plants occur rarely. Female axes terminal, the last 3 cells short and the fourth (subhypogenous cell) 2–4 times as long as the hypogenous cell; subapical cell bearing 2 sterile periaxial cells and the supporting cell with a terminal sterile cell and lateral carpogonial branch. Fertilized carpogonium producing connecting cells and the auxiliary cell dividing to form gonimoblast filaments of small cells which fuse as radiating arms but cut off terminal ovoid carposporangia 40–50 µm in diameter. The apical cell, sterile periaxial cells and sterile cell on the supporting cell divide to produce four erect, slightly branched filaments, forming an urceolate and ostiolate pericarp 150–200 µm in diameter, enclosed in a firm gelatinous sheath. Spermatangial heads are slightly ovoid, 40–45 µm in diameter, terminal on short lateral branchlets of erect filaments. Tetrasporangia are terminal on 1–3 short pedicel cells, lateral on erect filaments, 70–80 µm in diameter, tetrahedrally divided.

Distribution.Houtman Abrolhos and Flat Rocks, S of Geraldton, W. Aust., to Twofold Bay, N.S.W.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIC: 210–212 (1998)]