Electronic Flora of South Australia Species Fact Sheet
Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Acrotylaceae
Gigartina ovata Lamouroux 1813: 136, pl. 10 fig. 7. J. Agardh 1852: 355.
Rhabdonia globifera Lamouroux ex J. Agardh 1852: 355; 1872: 39; 1876: 595. Harvey 1860b: pl. 129. Kylin 1932: 20.
Thallus (Fig. 124C, D) medium to dark red-brown, branches cartilaginous and ramuli soft, 10–20 (–30) cm high, irregularly branched with long, terete, main branches 1–3 mm in diameter, bearing short, segmented (1–3 times) ramuli 5–10 (–15) mm long and 1.5–2.5 mm in diameter, arising near the segmented branch apices and proliferously below. Holdfast discoid, 2–6 mm across, with a single frond; epilithic or on shells. Structure multiaxial, developing a broad, laxly filamentous, reticulate medulla (Fig. 123L) of interconnected cells (many stellate), becoming dense with slender rhizoids in lower branches, and a pseudoparenchymatous cortex (Fig. 124E) 2–3 cells thick, inner cells slightly larger than the ovoid outer cells (6–12 µm in diameter); outer cortex of main branches becoming meristematic, forming files of elongate cells. Rhodoplasts discoid, several per cell.
Reproduction: Sexual reproduction probably procarpic. Carpogonial branches (Fig. 123M, 124E) 3-celled, borne on inner cortical cells sub-apically, inwardly directed with reflexed trichogynes. Supporting cell acting as auxiliary cell, producing several gonimoblast initials inwardly as adjacent vegetative cells produce a prominent pericarp around the disintegrating auxiliary cell. Gonimoblast filaments entering the pericarp and connecting to its cells, then forming centripetal branched tufts of filaments (Fig. 124F) in the developing cavity, with single, terminal, ovoid to clavate carposporangia 10–18 µm in diameter. Cystocarps (Fig. 124D, F) embedded, 0.7–1.2 mm across, with filamentous enveloping tissue and a cortical ostiole. Spermatangia unknown.
Tetrasporangia scattered in the cortex, laterally pit-connected, ovoid, 28–40 µm long and 24–30 µm in diameter, zonately divided.
Type from "Nouv. Holl."; holotype in Herb. Lamouroux, PC.
Selected specimens: Geraldton, W. Aust., drift at Separation Point (Gabrielson & Kraft, 15.xii.1980; MELU, A39851). Flat Rocks, 40 km S of Geraldton, W. Aust., drift (Mitchell, 17.ix.1966; AD, A31080). 7 Mile Beach, N of Dongara, W. Aust., drift (Kraft & Allender, 9.viii.1979; MELU, K7077 and Womersley, 17.ix.1979; AD, A51352). Port Denison, W. Aust., drift (Gordon, 8.xi.1968; AD, A33615). Yanchep, W. Aust., drift (Womersley, 22.ix.1979; AD, A51275). Miami, W. Aust., drift (G. & C. Kraft, 10.iii.1978; MELU, K6570). Point Clune, Rottnest 1., W. Aust., 13–14 m deep (Kraft & Ricker, 2.xii.1980; MELU, K7117). Eyre, W. Aust., drift (Gordon, 22.xi.1968; AD, A34228). 16 km E of Eucla, S. Aust., drift (Womersley, 3.ii.1954; AD, A19293).
Distribution: Geraldton, W. Aust., to 16 km E of Eucla, S. Aust.
Taxonomic notes: Claviclonium ovatum is a moderately deep water alga of western affinities.
AGARDH, J.G. (1852). Species Genera et Ordines Algarum. Vol. 2, Part 2, pp. 337–720. (Gleerup: Lund.)
AGARDH, J.G. (1872). Bidrag till Florideernes Systematik. Acta Univ. hind. 8, 1–60.
AGARDH, J.G. (1876). Species Genera et Ordines Algarum. Vol. 3, Part 1 - Epicrisis systematis Floridearum, pp. i-vii, 1–724. (Weigel: Leipzig.)
HARVEY, W.H. (1860b). Phycologia Australica. Vol. 3, Plates 121–180. (Reeve: London.)
KYLIN, H. (1932). Die Florideenordnung Gigartinales. Lunds Univ. Årsskr. N.F. Avd. 2, 28 (8), 1–88, Plates 1–28.
LAMOUROUX, J.V.F. (1813). Essai sur les genres de la famille des thalassiophytes non articulées. Ann. Mus. Hist. Nat., Paris 20, 21–47, 115–139, 267–293, Plates 7–13 (1–7).
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.
Illustrations in Womersley Part IIIA, 1994: FIGS 123L, M, 124 C–F.
Figure 123 enlarge
Fig. 123. A–F. Amphiplexia hymenocladioides (AD, A44750). A. Surface pattern with rosettes of outer cortical cells. B. Section of cortex with hairs and a carpogonial branch. C. Auxiliary cell with a carpogonial branch (carpogonium connected to auxiliary cell) and producing gonimoblast filaments. D. Carposporangia produced centripetally from cells lining the cystocarp cavity. E. Section of cortex with sunken clusters of spermatangia. F. Section of cortex with immature and mature tetrasporangia. G–K. Antrocentrum nigrescens (G, MELU, PG027; H, MELU, K5803; I, J, AD, A33437; K, AD, A28638). G. Branch apex showing paired periaxial filaments. H. Transverse section of a branch. I. Section of cortex with a 3-celled carpogonial branch. J. Section of cortex with spermatangia) clusters. K. Section of cortex with immature and mature tetrasporangia. L, M. Claviclonium ovatum (L, MELU, K6570; M, AD, A33615). L. Transverse section of a clavate lateral branch. M. Section of cortex with 3-celled carpogonial branches. [A–F after Kraft 1977a; G–M after Kraft & Min-Thein 1983.]
Figure 124 enlarge
Fig. 124. A, B. Antrocentrum nigrescens (A, MELU, K5803; B, MELU, K4485). A. Habit of liquid-preserved cystocarpic plant, with fibrous holdfast. B. Cross section of cystocarp, with ostiole. C–F. Claviclonium ovatum (C, AD, A51275; D–F, MELU, K7077). C. Habit. D. Habit of a branch with cystocarps (arrows). E. Section of branch apex with several carpogonial branches. F. Section of a cystocarp with centripetal sporogenous filaments, and ostiole. [A, D, E, F as in Kraft & Min-Thein 1983.]
State Herbarium of South Australia