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Genus GONATOGENIA J. Agardh 1896: 115.

Phylum Rhodophyta – Family Rhodomelaceae – Tribe Lophothalieae

Thallus erect, radially and irregularly branched, usually denuded of trichoblasts except near apices, cartilaginous and heavily corticated; holdfast discoid. Structure monopodial, trichoblasts simple, rhodoplastic, cut off from axial cells near apices, each with 3–7 small, isodiametric, basal cells with upper cells distinctly longer. Pericentral cells cut off from subapical axial cells, 5–7 which become separated by small cells and indistinct in larger branches. Cells multinucleate.

Reproduction: Reproductive organs borne on small branch systems in axils of upper lateral branches.

Gametophytes dioecious. Procarps developing on a small basal cell of trichoblasts which becomes polysiphonous. Carposporophytes with a large basal fusion cell producing gonimoblast filaments with clavate terminal carposporangia. Cystocarps ovoid to globular, without a neck; pericarp ostiolate, with small outer cortical cells. Spermatangial organs developed on trichoblasts.

Stichidia developed from axillary branch systems, bearing trichoblasts on their upper segments, with tetrasporangia in decussate pairs.

Type species: G. subulata J. Agardh 1896: 118.

Taxonomic notes: Gonatogenia is characterised by habit, the variable number of pericentral cells (5–7), by the caducous simple trichoblasts each with a row of small basal cells, and by the reproductive organs borne on branch systems in the axils of upper laterals. Spirophycus Millar (2000b) has very similar trichoblasts to Gonatogenia but the thallus is ecorticate and the tetrasporangia single per segment.

Maschalostroma Schmitz in Schmitz & Falkenberg (1897, p. 435), with type M. fastigiatum Falkenberg, is based on a denuded form of Alsidium comosum sensu J. Agardh (1890, p. 52) [referred to by Schmitz (1893, p. 230) and Falkenberg (1901, p. 231) as forma denudata] as is Gonatogenia subulata.


AGARDH, J.G. (1890). Till algernes systematik. Acta Univ. lund. 26(3), 1–125, Plates 1–3.

AGARDH, J.G. (1896). Analecta Algologica. Cont. III. Acta Univ. lund. 32, 1–140, Plate 1.

FALKENBERG, P. (1901). Die Rhodomelaceen des Golfes von Neapel und der angrenzenden Meeres-abschnitte. Fauna und Flora des Golfes von Neapel. Monogr. 26. (Friedländer: Berlin.)

MILLAR, A.J.K. (2000b). Spirophycus acicularis, a new red algal genus and species in the Lophothalieae (Rhodomelaceae, Ceramiales) from eastern Australia. Phycologia 39, 87–95.

SCHMITZ, F. & FALKENBERG, P. (1897). Rhodomelaceae. In Engler, A. & Prantl, K., Die natürlichen Pflanzenfamilien. T.1. Abt. 2, pp. 421–480. (Englemann: Leipzig.)

SCHMITZ, F. (1893). Die gattung Lophothalia, J. Ag. Ber. Deutsch. Bot. Ges. 11, 212–232.

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

Author: H.B.S. Womersley & M.J. Parsons

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.

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