Lithophyllum corallinae (P.Crouan & H.Crouan) Heydr.

Scientific Description

Habit and structure. Thallus normally pinkish, encrusting to layered, warty, lumpy or fruticose, mostly 10–50 mm across and 0.2–1(–5) mm thick or tall, epigenous and partially or completely affixed by cell adhesion; protuberant branches simple or branched, mostly 1–7 mm in diameter and 3–7 mm long; lamellate branches applanate and inconspicuous, mostly 3–12 mm across and 1–2 mm long. Structure pseudoparenchymatous, organisation dorsiventral in crustose portions and lamellate branches but radial in protuberant branches; construction dimerous, dimerous and monomerous or largely monomerous; dimerous portions consisting of a single ventral layer of branched, laterally cohering, filaments each composed of palisade and/or non-palisade cells 5–20 µm long and (13–)20–65(–82) µm high, and additionally of simple or branched, laterally cohering, filaments that arise dorsally and more or less perpendicularly from cells of ventral layer filaments and are each usually composed of cells 5–16 µm in diameter and 5–40(–55) µm long; monomerous portions consisting of a single system of branched, laterally cohering, filaments that collectively contribute to a ventrally or centrally situated core and a peripheral region where portions of core filaments or their derivatives curve outwards towards the thallus surface, with each filament composed of cells 5–14 µm in diameter and 5–35(–55) µm long; epithallial cells 4–9 µm in diameter and 2–6 µm long, terminating most filaments at the thallus surface, with distal walls rounded or flattened but not flared; cells of adjacent filaments joined by secondary pit-connections; cell-fusions and haustoria unknown; trichocytes rare, single.

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 monoecious or dioecious. Carpogonia terminating 2- or 3-celled filaments arising from the female conceptacle chamber floor. Mature female-carposporangial conceptacle roofs flush with or somewhat protruding above surrounding thallus surface, 50–115 µm thick, composed of 5–12 layers of cells above the chamber, conceptacle chambers 185–233(–305) µm in diameter and 60–110(–140) µm high. Carposporophytes composed of a conspicuous central fusion cell and several-celled gonimoblast filaments bearing terminal carposporangia 27–40(–57) µm in diameter. Spermatangial filaments unbranched, borne in groups of 1–3 on initials across the male conceptacle chamber floor, mature male conceptacle roofs flush with or slightly protruding above surrounding thallus surface, 25–40 µm thick, composed of 2–5 layers of cells above the chamber, male conceptacle chambers 115–145 µm in diameter and 30–50 µm high. Tetrasporangial/bisporangial conceptacle roofs non- or slightly protruding above surrounding surface, mostly 2–4 cells thick above chamber, pore canals lined with somewhat projecting cells that do not completely occlude the canal, conceptacle chambers (155–)190–235(–280) µm in diameter and 68–105(–136) µm high, floor of mature chambers usually 6 or more cells below thallus surface; tetrasporangia and bisporangia scattered across the conceptacle chamber floor or peripheral to a central columella, each mature sporangium (15–)25–55(–95) µm in diameter and (35–)50–95(–125) µm long, containing zonately arranged tetras pores or bispores.

Distribution.Probably widespread; many records outside Europe, however, require confirmation. In Australia, Eyre, W. Aust., to Anglesea, Vic., and the E coast of Tas.

Habitat. L. corallinae has been found in southern Australia on rock, snails, limpets, abalone shells and sea urchins in intertidal pools, on reef edges and subtidally to depths of 9 m.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIB: 231–233 (1996)]