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Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Class Florideophyceae – Order Bonnemaisoniales – Family Bonnemaisoniaceae
Thallus erect, membranous, much branched more or less complanately and irregularly from the margins, branches flat, linear, 1–2 mm broad, with slight to distinct marginal serrations, basally constricted; axial filament present throughout forming a slight midrib, with opposite microscopic veins; holdfast discoid. Structure uniaxial, apical cell distinct, segmenting slightly obliquely, with each axial cell cutting off two opposite periaxial cells, one slightly prior to the other and alternating, with the first producing better developed abaxial tertiary rows with more cortical cells and the end protruding as the marginal serrations; each secondary cell cuts off four primary cortical cells which cut off further cortical cells and then the outer cortical layer; near the apex the flat surfaces show a slight gap above the axial cells, due to the lack of transverse periaxial cells, but this gap is closed as cortical cells are cut off from the first cells of the secondary filaments. Branches in sectional view with a prominent central axis and cortex 4–5 cells thick; gland cells absent.
Reproduction: Gametangial thalli dioecious or monoecious. Carpogonial branches unknown. Carposporophyte with a basal fusion cell and a tuft of branched gonimoblast filaments with terminal ovoid carposporangia. Cystocarps urceolate, sessile on the surface of lesser branches, with a thick ostiolate pericarp. Spermatangia in sori near branch ends, cut off via initials from outer cortical cells.
Tetrasporangia in raised, mucilaginous, nemathecia on both sides of the midrib, accompanied by paraphyses of uniseriate cells, irregularly obliquely divided.
Life history triphasic with isomorphic gametophytes and tetrasporophytes.
Type (and only) species: L. conferta (R. Brown ex Turner)J. Agardh 1876: 676.
Taxonomic notes: Leptophyllis appears to be a member of the Bonnemaisoniales though the details of female reproduction need study. It differs from Ptilonia in habit, in formation of only lateral periaxial cells, and in having isomorphic gametophyte and tetrasporophyte generations. In these respects it appears adequately distinct from Ptilonia (see Bonin & Hawkes 1988b, p. 642).
References:
AGARDH, J.G. (1876). Species Genera et Ordines Algarum. Vol. 3, Part 1 — Epicrisis systematis Floridearum, pp. i-vii, 1–724. (Weigel: Leipzig.)
BONIN, D.R. & HAWKES, M.W. (1988b). Systematics and life histories of New Zealand Bonnemaisoniaceae (Bonnemaisoniales, Rhodophyta): III. The genus Ptilonia. N.Z. J. Bot. 26, 633–644.
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.
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