Lithophyllum chamberlainianum Woelk. & S.J.Campb.

Scientific Description

Habit and structure. Thallus normally pinkish, encrusting to layered, mostly 0.05–2.5 mm across and 0.04–0.5 mm thick, epigenous and partially or completely affixed by cell adhesion or envelopment of host axes; 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 5–18 µm long and (13–)20–75(–90) µm high, and additionally of epithallial cells that arise dorsally and more or less perpendicularly from most cells of ventral layer filaments and are 4–12 µm in diameter and 2–7 µm long with distal walls rounded or flattened but not flared; cells of adjacent filaments joined by secondary pit-connections; cell-fusions, haustoria and trichocytes unknown.

Reproduction.Vegetative reproduction unknown. Gametangia, carposporangia, tetrasporangia and bisporangia produced in uniporate conceptacles; gametangia and carposporangia formed on thalli separate to those bearing tetrasporangia and bisporangia. Gametangial thalli probably dioecious. Carpogonia terminating 2- or 3-celled filaments arising from the female conceptacle chamber floor. Mature female-carposporangial conceptacle roofs protruding above surrounding thallus surface, 60–110 µm thick, composed of 7–10 layers of cells above the chamber, conceptacle chambers 160–225(–259) µm in diameter and 81–115(–209) µm high. Carposporophytes composed of a conspicuous central fusion cell and several-celled gonimoblast filaments bearing terminal carposporangia 20–30(–52) µm in diameter. Spermatangial filaments unbranched, borne across the male conceptacle chamber floor, mature male conceptacle roofs protruding above surrounding thallus surface, 35–60 µm thick, composed of 5–7 layers of cells above the chamber, male conceptacle chambers 160–200 µm in diameter and 29–55 µm high. Tetrasporangial/bisporangial conceptacle roofs protruding above surrounding surface, 2–4(–5) cells thick above the chamber, pore canals completely occluded by a conglomerate of elongate, more or less tubular and sometimes inflexed cells that arise from at least the first two rows of roof filaments flanking the pore canal and that usually project above the surrounding roof surface, conceptacle chambers (145–)175–210(–252) µm in diameter and (60–)80–120(–159) µm high, floor of mature chambers usually one cell below thallus surface; tetrasporangia and bisporangia scattered across the conceptacle chamber floor or peripheral to a central columella, each mature sporangium (16–)20–35(–47) µm in diameter and (35–)55–95(–118) µm long, containing zonately arranged tetras pores or bispores.

Distribution.Shark Bay, W. Aust., to Refuge Cove, Wilsons Promontory., Vic., and the northern and eastern coasts of Tas.

Habitat. L. chamberlainianum has been found on limpets, snails, abalone shells, the seagrass Amphibolis antarctica and a variety of algae in intertidal pools and subtidally to depths of 10 m.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIB: 219–221 (1996)]