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Electronic Flora of South Australia Genus Fact Sheet

Genus HOLMSELLA Sturch 1926: 603

Phylum Rhodophyta – Class Florideophyceae – Order Gracilariales – Family Pterocladiophilaceae

Thallus colourless, pulvinate to hemispherical, parasitic on Gracilaria. Structure multiaxial, with slender filaments penetrating between the host cells and pit-connecting with them, producing outwardly a mass of compact filaments of either slender or ovoid cells, with a cortex of anticlinal filaments.

Reproduction: Gametangial thalli dioecious. Carpogonial branches 2-celled, borne on an intercalary cell of a cortical filament; fertilized carpogonium possibly fusing with adjacent vegetative cells. Carposporophyte spreading, with a basal layer of filaments and erect gonimoblast filaments producing chains of carposporangia; pericarp and ostiole absent. Spermatangia borne in chains on outer cortical cells.

Tetrasporangia developed from terminal cortical cells, ovoid, cruciately divided.

Life history triphasic, with isomorphic gametophytes and tetrasporophytes.

Holotype species: H. pachyderma (Reinsch) Sturch 1926: 603.

Taxonomic notes: A genus of two species, the type from N. Europe and parasitic on Gracilaria "verrucosa", and the southern Australian H. australis.

References:

STURCH, H.H. (1926). Choreocolax polysiphoniae Reinsch. Ann. Bot. 40, 585–605.

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

Author: H.B.S. Womersley

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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