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Electronic Flora of South Australia Species Fact Sheet
Phylum Rhodophyta – Class Florideophyceae – Order Corallinales – Family Corallinaceae – Subfamily Lithophylloideae
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.
Type from Beachport (Three Mile Rocks), S. Aust. (Campbell & Penrose, 26.ii.1988); holotype in LTB (15676); depicted in Woelkerling & Campbell (1992, p. 57, fig. 33A).
Distribution: Dempster Point, Israelite Bay, W. Aust., to Beachport, S. Aust.
Taxonomic notes: Lithophyllum 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. Thalli generally conform to the contours of the substrate and thus may be horizontally expanded or sleeve-like in appearance.
References:
WOELKERLING, W.J. & CAMPBELL, S.J. (1992). An account of southern Australian species of Lithophyllum (Corallinaceae, Rhodophyta). Bull. Br. Mus. Nat. Hist., Bot. Ser. 22, 1–107.
The Marine Benthic Flora of Southern Australia Part IIIB complete list of references.
Publication:
Womersley, H.B.S. (28 June, 1996)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIB. Gracilarialse, Rhodymeniales, Corallinales and Bonnemaisoniales
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIB 1996, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.
Illustration in Womersley Part IIIA, 1996: FIG. 97.
Figure 97 enlarge
Fig. 97. Lithophyllum irvineanum (A–E, LTB, 15676, holotype). A. Encrusting thalli on a snail. B. Surface view of layered thallus showing applanate branches. C. Surface view of tetrasporangial conceptacle. D. Section of mature tetrasporangial conceptacle lacking a columella and with tetrasporangia across the conceptacle chamber floor. E. Section of mature tetrasporangial conceptacle with a columella and peripherally situated tetrasporangia. Note enlarged cells occluding pore canal.
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