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Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Nemastomataceae
Thallus erect, subdichotomously or laterally branched with compressed branches to foliose, mucilaginous. Structure multiaxial, with a cortex of discrete subdichotomous branch systems, without gland cells, and a medulla of entangled filaments.
Reproduction: Sexual thalli monoecious or dioecious. Carpogonial branches 3 (–4)-celled, borne on inner cortical (supporting) cells, trichogyne straight or coiled; auxiliary cells in a similar position to the supporting cells. Gonimoblast arising outwardly from the auxiliary cell, carposporophyte with all cells becoming carposporangia, lying between cortical branch systems with no pore. Spermatangia arising from outer cortical cells. Tetrasporophytes isomorphic, with cruciately to obliquely divided tetrasporangia.
Life history triphasic with isomorphic gametophytes and tetrasporophytes.
Type species: T. nakamurae (Yendo) Fan & Fan 1962: 191.
Taxonomic notes: Tsengia differs from Nemastoma and Adelophycus in the absence of gland cells, by the intercalary position of both auxiliary cells and supporting cells in normal cortical filaments, and in development of the gonimoblast from the auxiliary cell rather than from the adjacent connecting filament, and is unique in the family in having isomorphic gametophytes and tetrasporophytes.
As well as the three southern Australian species previously referred to Nemastoma and described below, N. damaecornis Harvey (1855a, p. 557) was described from Fremantle and Rottnest I., W. Aust., but is still little known, and N. palmatum Harvey (1863, pl. 262) was described from Tasmania; the latter is clearly not a Nemastoma but its position is uncertain.
References:
FAN, K.C. & FAN, Y.P. (1962). Studies on the reproductive organs of red algae. I. Tsengia and the development of its reproductive systems. Acta Bot. Sinica 10, 194–196, Plates 1, 2 (in Chinese, pp. 187–193).
HARVEY, W.H. (1855a). Some account of the marine botany of the colony of Western Australia. Trans. R. Ir. Acad. 22, 525–566.
HARVEY, W.H. (1863). Phycologia Australica. Vol. 5, Plates 241–300, synop., pp. i-lxxiii. (Reeve: London.)
The Marine Benthic Flora of Southern Australia Part IIIA complete list of references.
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 TSENGIA
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1. Thallus furcate | T. laingii |
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1. Thallus subdichotomous, branches either bare or with numerous slender lateral proliferations | 2 |
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2. Thallus many times subdichotomous, with no or few proliferations, branches (2–) | T. feredayae |
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2. Thallus with compressed subdichotomous axes | T. comosa |
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