Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Class Florideophyceae – Order Gelidiales – Family Gelidiaceae
Thallus usually less than 2 cm high, with prostrate stolons attached by rhizoidal clumps, bearing simple or irregularly pinnate, erect, cartilaginous branches; usually epilithic. Structure uniaxial, with a relatively conspicuous apical cell, differentiating into a medulla of numerous longitudinal filaments and a (1–) 2–3 cell thick cortex of ovoid cells each with several small rhodoplasts; the axial filament and lateral rows of the first order remaining visible, or not, in transverse section; rhizines absent or very few (in the holdfast of G. calcicola Maggs & Guiry and in some axes of G. minima).
Reproduction: Sexual plants known only from Sreenivasa Rao & Trivedi (1986) and Guiry & Womersley (1992). Cystocarps unilocular with a single ostiole; carposporangia in short chains. Spermatangia in subterminal sori, cut off from outer cortical cells.
Tetrasporangia formed in small stichidioid lateral ramuli, or in terminal stichidia on erect branches, lying within the inner cortex and outer medulla, decussately cruciately or irregularly divided.
Life history probably triphasic with isomorphic gametophytes and tetrasporophytes; most species known only with tetrasporangia.
Lectotype species: G. acerosa (Forsskal) Feldmann & Hamel 1934: 534.
Taxonomic notes: A genus of some 22 species (Maggs & Guiry 1987, p. 429; Guiry & Womersley 1992), in need of monographic revision, differing from Gelidium in the virtual absence of rhizines in the vegetative thallus. G. calcicola Maggs & Guiry (1987) possesses rhizines in the holdfasts and G. minima (see below) possesses very few, thus obscuring this previously clear distinction between the two genera.
Most species of Gelidiella occur in warm temperate and tropical waters, a few in cold temperate regions. Fertile material of G. antipai and G. minima has been found in southern Australia, other sterile specimens of Gelidiella are present in AD, and G. ramellosa from Western Australia is described below since it may occur on the south coast.
Beanland & Woelkerling (1982, p. 96) recorded Gelidiella nigrescens (Feldmann) Feldmann & Hamel and G. tenuissima Feldmann & Hamel from mangrove pneumatophores in Spencer Gulf. Their specimens of the former are Capreolia implexa and those of the latter are, at least mostly, slender forms of Gelidium pusillum.
BEANLAND, W.R. & WOELKERLING, W.J. (1982). Studies on Australian mangrove algae: II. Composition and geographical distribution of communities in Spencer Gulf, South Australia. Proc. R. Soc. Vic. 94, 89–106.
FELDMANN, J. & HAMEL, G. (1934). Observations sur quelques Gélidiacées. Rev. Gen. Bot. 46, 528–549.
GUIRY, M.D. & WOMERSLEY, H.B.S. (1992). Gelidiella minima sp. nov. (Rhodophyta) from Victoria, Australia: implications for the generic classification of the Gelidiaceae. Br. phycol. J. 27, 165–176.
MAGGS, C.A. & GUIRY, M.D. (1987). Gelidiella calcicola sp. nov. (Rhodophyta) from the British Isles and northern France. Br. phycol. J. 22, 417–434.
SREENIVASA RAO, P. & TRIVEDI, M.K. (1986). Reproduction in Gelidiella. In Desikachary T.V. (Ed.), Taxonomy of Algae, pp. 255–260. (Univ. Madras: Madras.)
The Marine Benthic Flora of Southern Australia Part IIIA complete list of references.
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 GELIDIELLA
1. Thallus about 1 cm high, erect branches
State Herbarium of South Australia