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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 warty, lumpy or layered, mostly 30–40 mm across and 0.2–1.0 mm tall or thick, 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 composed of palisade and/or non-palisade cells 8–12 µm long and 5–25 µm high, and additionally of simple or branched, laterally cohering, filaments that arise dorsally and more or less perpendicularly from most cells of ventral layer filaments and are each usually composed of 10 or more cells 5–10 µm in diameter and 8–30 µm long; epithallial cells 6–9 µm in diameter and 4–6 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, haustoria, and trichocytes unknown.
Reproduction: Vegetative reproduction unknown. Gametangia, tetrasporangia and bisporangia produced in uniporate conceptacles; gametangia formed on thalli separate to those bearing tetrasporangia or bisporangia.
Gametangial thalli probably dioecious. Carpogonia and carposporophytes unknown. Spermatangial filaments unbranched, borne across the conceptacle chamber floor, mature male conceptacle roofs flush with or slightly protruding above surrounding thallus surface, 12–25 µm thick, composed of 2–3 layers of cells above the chamber, male conceptacle chambers 80–100 µm in diameter and 32–47 µm high.
Tetrasporangial/bisporangial conceptacle roofs more or less flush with surrounding surface, 2–4 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 130–155 (–196) µm in diameter and 65–108 µm high, floor of mature chambers mostly 8–20 cells below thallus surface; tetrasporangia and bisporangia scattered across the conceptacle chamber floor, each mature sporangium 27–35 (–45) µm in diameter, 45–70 µm long, containing zonately arranged tetraspores or bispores.
Type from Port Fairy, Vic. (Woelkerling, 4.i.1979); holotype in LTB (11724); depicted in Woelkerling & Campbell (1992, p. 62, fig. 36A).
Distribution: From Cape Willoughby, Kangaroo I., S. Aust., to Port Fairy, Vic., and Coles Bay, Tas.
Taxonomic notes: Lithophyllum johansenii has been found on rock and on the holdfasts of the brown alga Ecklonia radiata in intertidal pools and subtidally to depths of 2.5 m. Male thalli are known from a single dried collection (LTB, 12446). Bisporangia have not been found on the same thalli as tetrasporangia, and it is unknown whether bispores give rise to new bisporangial thalli or to gametangial thalli.
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. 94.
Figure 94 enlarge
Fig. 94. Lithophyllum johansenii (A, E, LTB, 11724; B, D, LTB, 13134; C, LTB, 12446). A. Encrusting to lumpy thallus from holotype collection. B. Encrusting thallus on rock. C. Section of male conceptacle with unbranched spermatangial filaments arising from chamber floor. D. Fracture through sporangial conceptacle showing occluded pore (arrow) in surface view. E. Section of mature tetrasporangial conceptacle with occluded pore canal (arrow).
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