Electronic Flora of South Australia Genus Fact Sheet

Genus HILDENBRANDIA Nardo 1834:676, nom. & orth. cons.

Phylum Rhodophyta – Class Florideophyceae – Order Hildenbrandiales – Family Hildenbrandiaceae

Thallus crustose, usually thin, firm and cartilaginous, surface smooth or in one species with irregular excrescences. Structure of a basal layer of tightly adherent, radiating, branched filaments with each cell producing an erect, laterally coherent, simple or occasionally branched erect filament of small cuboidal cells; rhizoids absent. Pit-connections primary and secondary, plugs with a single cap layer.

Reproduction: Sexual reproduction unknown.

Tetrasporangia (apomeiotic) formed in subspherical to urceolate ostiolate conceptacles, clavate, arising from any wall cell, zonately or irregularly divided, with or without paraphyses.

Type species: H. prototypus Nardo 1834: 675 [= H. rubra (Sommerfelt) Meneghini].

Taxonomic notes: Hildenbrandia is credited with 9 species by DeCew & West (1977, p. 32), all of which are tightly adherent crustose algae (without rhizoids) in the intertidal or subtidal, often very thin but up to 1 mm thick in some species, with protuberances to 5 mm high in H. lecannellieri. All reproduce by tetrasporangia formed within conceptacles opening to the surface, the tetrasporangia being transversely or obliquely zonate or irregularly divided; sexual reproduction is unknown, and De Cew & West (1977) have shown two species to be apomeiotic.

References:

DECEW, T.C. & WEST, J.A. (1977). Culture studies on the marine red algae Hildenbrandia occidentalis and H. prototypus (Cryptonemiales, Hildenbrandiaceae). Bull. Jap. Soc. Phycol. 25 (suppl.), 31–41.

NARDO, G.D. (1834). De novo genere Alganim cui nomen est Hildbrandtia prototypus. Oken's Isis 1834, fasc. 6, pp. 675–676. (Leipzig.)

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (14 January, 1994)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIA, Bangiophyceae and Florideophyceae (to Gigartinales)
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIA 1994, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

KEY TO SPECIES OF HILDENBRANDIA

1. Thallus thin (80–240 µm thick), on intertidal rock

, .2

1. Thallus thick (300 µm to 5 mm thick), in pools or subtidal

3

2. Tetrasporangia irregularly divided

H. rubra

2. Tetrasporangia zonately and usually obliquely divided

H. crouanii

3. Thallus including the profuse, more or less erect, knobby protrusions, usually 3–6 mm thick

H. lecannellieri

3. Thallus surface smooth, mostly 300–500 µm thick

H. expansa


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