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Electronic Flora of South Australia Genus Fact Sheet

Genus JANCZEWSKIA Solms-Laubach 1877: 209

Phylum Rhodophyta – Family Rhodomelaceae – Tribe Laurencieae

Thallus grey-white to pink, subspherical to pulvinate and a few mm across, with a basal parenchymatous cushion bearing surface tuberculate excrescences or elongate, terete, branches a few mm long. Attachment to host by rhizoids; parasitic on species of Laurencia, Chondria, and one species on Cladhymenia. Structure. Branches or excrescences with truncated apices and an apical depression around the axial filament which bears trichoblasts and pericentral cells (number uncertain, probably 2 in J. tasmanica); axial and pericentral cells soon obscure in the cellular cortex, epidermal cells with secondary pit-connections. Cells with few, pale rhodoplasts.

Reproduction: Gametophytes dioecious. Procarps little known, borne on lower cells of apical trichoblasts. Carposporophytes with a basal fusion cell and branched gonimoblast bearing clavate terminal carposporangia. Cystocarps sunken in tubercles or on erect branches, sessile, ovoid; pericarp ostiolate, corticated, several cells thick. Spermatangia borne on modified trichoblasts in apical depressions.

Tetrasporangia situated in the outer cortex in parallel arrangement, cut off abaxially from the ends of elongate pericentral (or outer) cells, tetrahedrally or decussately divided.

Type species: J. verrucaeformis Solms-Laubach 1877: 209, pl. 3, described in detail by J. & G. Feldmann (1958).

Taxonomic notes: A genus of about 8 species, most of which were included in the general account of Setchell (1914), most species parasitic on species of Laurencia, a few on species of Chondria, one on Cladhymenia.

The southern Australian J. tasmanica was the second species to be described, differing from the type species in having distinct outer, terete, branches.

One species occurs on southern Australian coasts, the crediting of the Mediterranean J. verrucaeformis to Australia by Goff (1982, p. 302) being incorrect.


GOFF, L.J. (1982). The biology of parasitic red algae. Progr. Phycol. Res. 1, 289–369.

SETCHELL, W.A. (1914). Parasitic Florideae, I. Univ. Calif. Pubis Bot. 6(1), 1–34, Plates 1–6.

SOLMS-LAUBACH, H. (1877). Note zur Janczewskia, nouvelle Floridée parasite du Chondria obtusa. Mémoir. Soc. Scienc. Nat. de Cherbourg 21, 209–224, pl. 3.

The Marine Benthic Flora of Southern Australia Part IIID complete list of references.

Publication: Womersley, H.B.S. (24 February, 2003)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIID. Ceramiales – Delesseriaceae, Sarcomeniaceae, Rhodomelaceae
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIID 2003, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

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