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Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Rhodocallideae
Thallus erect, much branched complanately and pinnately with compressed indeterminate laterals bearing close set, alternate, terete to compressed, tapering determinate branchlets 1–4 mm long. Structure. Axial filaments cutting off 2 lateral, and 2–6 transverse periaxial filaments on each side, the lateral filaments forming indeterminate laterals or determinate branchlets on alternate sides and 2–4 axial cells apart; older branches with extensive rhizoid development around the axial and inner cells; cortex compact, pseudoparenchymatous, with outer cells small and isodiametric. Cells uninucleate.
Reproduction: Carpogonial branches unknown. Carposporophytes occur in small tufts of simple filaments borne on short branchlets, rounded, with ovoid carposporangia, without separate involucres. Spermatangia unknown.
Tetrasporangia borne on branched filaments outside the cortex, originating from the periaxial filaments, or in special siliculose branchlets borne adaxially on the determinate branchlets.
Type species: P. striata (Harvey) Schmitz 1896: 7.
Taxonomic notes: A genus of 3 species, 2 from Australia and both in need of detailed study, and P. dentata (Okamura) Kylin (1956: 395) from Japan.
References:
KYLIN, H. (1956). Die Gattungen der Rhodophyceen. (Gleerups: Lund.)
SCHMITZ, F. (1896). Kleinere beitrage zur kenntniss der Florideen. Nuova Notarisia, Padova 7, 1–22.
The Marine Benthic Flora of Southern Australia Part IIIC complete list of references.
Publication:
Womersley, H.B.S. (24 December, 1998)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIC. Ceramiales – Ceramiaceae, Dasyaceae
©State Herbarium of South Australia, Government of South Australia
KEY TO SPECIES OF PSILOTHALLIA
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1. Surface view of branches showing transverse striations corresponding to the larger axial cells; extensive rhizoid development around the axial cells; axial filaments producing alternate determinate branchlets every 2 (–3) axial cells; tetrasporangia on branched filaments on the adaxial (and abaxial) sides of branchlets | P. striata |
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1. Surface view of branches not striated; rhizoid development around the axial cells present but not extensive; axial filaments producing alternate determinate branchlets every (2–) 3 (–4) axial cells; tetrasporangia formed on filaments of densely branched, elongate, siliculose branchlets adaxial on determinate branchlets | P. siliculosa |
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