- Reference
- Bull.Brit.Mus.(Nat.Hist.),Bot. 56-61, Figs 33-35 (1992)
- Conservation Code
- Not threatened
- Naturalised Status
- Native to Western Australia
- Name Status
- Current
Scientific Description
Habit and structure. Thallus normally pinkish, encrusting to layered, mostly 3–35 mm across and 0.05–1.0 mm thick or tall, epigenous and completely affixed by cell adhesion; lamellate branches applanate and inconspicuous. Structure pseudoparenchymatous with dorsiventral organisation throughout; construction dimerous, consisting of a single ventral layer of branched, laterally cohering, filaments each usually composed of palisade cells 5–12 µm long and (15–)25–70(–80) µm high, and additionally of epithallial cells or rarely two-celled filaments that arise dorsally and more or less perpendicularly from most cells of ventral layer filaments and are each composed of a terminal epithallial cell 4–9 µm in diameter and 2–6 µm long and rarely a subtending cell 5–12 µm in diameter and 30–60 µm long; distal walls of epithallial cells rounded or flattened but not flared; cells of adjacent filaments joined by secondary pit-connections; cell-fusions, haustoria and trichocytes unknown.
Reproduction.Vegetative reproduction, gametangial thalli, carposporophytes and tetrasporophytes unknown. Bisporangia produced in uniporate conceptacles. Bisporangial conceptacle roofs protruding above surrounding surface, (2–)3–4 cells thick above the chamber, pore canals completely occluded by 2 or 4 enlarged angular cells that arise from the row of roof filaments flanking the pore canal and that do not project above the surrounding roof surface; conceptacle chambers (180–)215–245(–263) µm in diameter and 82–125 µm high, floor of mature chambers usually 1(–3) cells below thallus surface; bisporangia scattered across the conceptacle chamber floor or peripheral to a central columella, each mature sporangium (29–)40–55 µm in diameter and 68–88(–101) µm long, containing two bispores.
Distribution. Dempster Point, Israelite Bay, W. Aust., to Beachport, S. Aust.
Habitat. L. irvineanum has been found on snails, mussel shells, holdfasts of the brown alga Ecklonia radiata and on the red alga Osmundaria at depths of 1–11 m.
[After Womersley, Mar. Benthic Fl. Southern Australia IIIB: 221–223 (1996)]