Electronic Flora of South Australia Genus Fact Sheet

Genus HELMINTHORA J. Agardh 1852: 415, nom. cons.

Phylum Rhodophyta – Class Florideophyceae – Order Nemaliales – Family Liagoraceae

Thallus (gametophyte) usually much branched dichotomously or laterally, multiaxial with a medulla of longitudinal filaments of relatively large cells and a cortex of subdichotomous assimilatory filaments with smaller terminal cells. Cells with stellate rhodoplasts, each with a central pyrenoid.

Tetrasporophyte minute, filamentous, branched (known only in H. divaricata in culture - Boillot 1972, p. 226, fig. 8, pl. 3).

Reproduction: Carpogonial branches lateral, curved, 3 (–4)-celled, with a slightly dumbbell shaped carpogonium. First zygote division transverse, the upper cell producing the carposporophyte. Sterile post-fertilization filaments arising from cortical cells adjacent to (usually just above) the supporting cell, bridging the carpogonial branch and forming upwardly an involucre around the carposporophyte, and below a tuft of rhizoidal filaments growing towards the medulla. Spermatangia cut off from outer cortical cells.

Tetrasporangia terminal on filaments, cruciately divided.

Life history (where known) triphasic, with macroscopic gametophytes and minute tetrasporophytes.

Type species: H. divaricata (C. Agardh) J. Agardh 1852: 415.

References:

AGARDH, J.G. (1852). Species Genera et Ordines Algarum. Vol. 2, Part 2, pp. 337–720. (Gleerup: Lund.)

BOILLOT, A. (1972). Cycle biologique de quelques Némalionales. Le Botaniste 55, 207–250.

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 HELMINTHORA

1. Thallus 2–10 cm high, subdichotomous, often with short laterals near the base. Spermatangia densely clustered over the end 3–6 cells of cortical filaments. Sterile post-fertilization filaments with a strongly developed tuft of rhizoids 200–400 long

H. lindaueri

1. Thallus 3–20 (–25) cm high, irregularly and laterally branched. Spermatangia on branched ends of cortical filaments, paniculately to digitately arranged. Sterile post-fertilization filaments with a usually weakly developed tuft of rhizoids 50–200 (–320) µm long

H. australis


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