Electronic Flora of South Australia Genus Fact Sheet

Genus NITOSPINOSA Womersley, gen. nov.

Phylum Rhodophyta – Family Delesseriaceae

Thallus erect, complanately branched with much branched laterals or foliose and lobed, with or without a distinct midrib. Margins with few to numerous short spinous dentations; holdfast fibrous. Structure. Growth partly to mainly from the numerous marginal spines, each with a distinct apical cell segmenting transversely but with recognisable axial and second-order cell rows only within the base of the spines; between the spines, some to most marginal cells divide by anticlinal walls; cell divisions below irregular and intercalary, cell rows not recognisable. Blades monostromatic when young, soon tristromatic and centrally polystromatic; cortical cells equivalent. Cells multinucleate.

Reproduction: Gametophytes dioecious. Procarps scattered, with the primary (supporting) cell bearing a sterile cell (often subdivided) and a 4-celled carpogonial branch. Carposporophyte with a basal, branched, fusion cell and much branched gonimoblast bearing short terminal chains of maturing ovoid carposporangia. Cystocarps scattered, swollen to hemispherical, ostiolate, pericarp of anticlinal rows of cells. Spermatangial sori scattered, with a layer of initials on each side of the primary cells, producing outer elongate spermatangia.

Tetrasporangial sori scattered with tetrasporangia in 2 layers, cut off from inner cortical cells and covered by outer cortical cells.

Type species: N. pristoidea (Harvey) Womersley, comb. nov.

Taxonomic notes: A genus of 3 species, the type, N. tasmanica and N. littledipensis, distinguished by the frequent to occasional spinous, apical cell-bearing, dentations on the margins, with few to many marginal cells dividing by anticlinal walls, and with cell divisions irregular below the base of the spines where axial and cell rows are not recognisable. The carposporangia mature terminally and subterminal cells then mature rapidly; thus short chains of carposporangia may occur, especially in N. littledipensis. While some species credited to Myriogramme [e.g. M. prostrata (Dawson et al.)Wynne 1990, p. 330, figs 8–13] have small marginal spines, the marginal apices are generally smooth and develop by predominantly anticlinal divisions in the marginal cells. Myriogramme also has carposporangia in chains.

Nitospinosa is closely related to Papenfussia Kylin (1938, p. 15) from South Africa, differing in being monostromatic for some distance from the apices, in having equivalent cortical cells (dimidiate in Papenfussia) and in having only oval tetrasporangial sori with tetrasporangia cut off from adjacent inner cortical cells; in Papenfussia laciniata (the type species) sori are linear and near the blade margins and are less well defined, with tetrasporangia separated by sterile inner cortical cells. Comparison of female plants cannot be made since these are inadequately described in Papenfussia .

Nitospinosa and Robea (see below) are probably closely related and belong to a separate group.

Nitospinosa is named from the numerous spines on and near the apices and its nitophylloid relationships.

References:

KYLIN, H. (1938). Verzeichnis einiger Rhodophyceen von Stidafrika. Lunds Univ. Årsskr. N.F. Avd. 2, 34 (8), 1–26, Plates 1–8.

WYNNE, M.J. (1990). Observations on Haraldia and Calloseris, two rare genera of Delesseriaceae (Rhodophyta) from the western Atlantic. Contr. Univ. Michigan Herb. 17, 327–334.

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

Author: H. B. S. Womersley

Publication: Womersley, H.B.S. (24 February, 2003)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIID. Ceramiales – Delesseriaceae, Sarcomeniaceae, Rhodomelaceae
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIID 2003, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

KEY TO SPECIES OF NITOSPINOSA

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