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Electronic Flora of South Australia Species Fact Sheet
Phylum Rhodophyta – Family Rhodomelaceae – Tribe Herposiphonieae
Thallus (Fig. 138A, B) dark brown-red, (0.5–) 1–2 cm long, basally attached with free, lax, upper parts, axes frequently branched and bearing simple or branched, alternate, distichous, determinate laterals along its length (Fig. 138C), the laterals separated by one unbranched segment (Fig. 138C, D, arrows). Attachment by rhizoids, usually clumped (Fig. 138F) from cells of adjacent segments; epiphytic on various hosts, epizoic, and possibly epilithic. Structure. Apical cells dome-shaped, 15–20 µm in diameter, cutting off by oblique walls alternate laterals a cell apart. Axes compressed, with 8 pericentral cells, usually arranged with 2 slightly larger ones on each face and 2 slightly smaller ones (which may divide transversely) on each margin (Fig. 138D); smaller corticating cells occur in irregular clusters on each side, lying over the ends of the pericentral cells (Fig. 138E) and on the margins. Determinate laterals 0.5–2 mm long, simple or branched as in the axes, 60–100 (–140) µm broad, segments L/D 0.4–1.2. Axes 160–300 µm broad, segments L/D (0.2–) 0.5–1. Trichoblasts apparently absent. Rhizoids cut off from adjacent pericentral cells, unicellular with multicellular haptera. Cells probably uninucleate; rhodoplasts discoid to elongate.
Reproduction: Procarps not observed. Carposporophytes with a basal fusion cell and branched gonimoblast with clavate terminal carposporangia 25–40 µm in diameter. Cystocarps (Fig. 138G) almost sessile, ovoid, 250–400 µm in diameter; pericarp ostiolate, ecorticate, 2 cells thick, outer cells isodiametric. Spermatangial organs not observed.
Tetrasporangia in branched determinate laterals, swelling the segments, spirally arranged, one per segment, 35–70 µm in diameter, with probably 2 cover cells.
Type from Gabo I., Vic. on Rhodymenia, 24 m deep (Shepherd, 14.ii.1973); holotype in AD, A43353; syntype Gabo I., Vic., on Epymenia, 18 m deep (Shepherd, 17 .ii.1973) in AD, A43512.
Selected specimens: Point Lonsdale, Vic., pool on reef flat (Toltner & Kraft, 5.x.2001; MELU, K11097, AD, A69229). Cape Woolamai, Vic., on tunicate Herdmania momus, 15–18 m deep (Sorokin, 16.ii.1990; AD, A60202). Point Hicks, E Vic., 18–21 m deep on "Satisfaction reef" (Kraft & Watt, 8.ii.2001; MELU, 3820, 3827; AD, A69077). Gabo I., Vic., epiphytic, 1–3 m deep (Shepherd, 15.ii.1973; AD, A43378) and on Rhodymenia, 28 m deep (Shepherd, 19.ii.1973; AD, A43539). Huon I., off Ninepin Point, SE Tas., 8–14 m deep (Edgar, 31.iii.2000; AD, A68568). Great Taylor Bay, Bruny I., Tas., on Thamnoclonium, 1–2 m deep (Shepherd, 14.ii.1972; AD, A42144). Port Arthur, Tas., upper sublittoral (Cribb 37.4, 6.iii.1950; AD, A16342).
Distribution: E Victoria and SE Tasmania.
Taxonomic notes: The specific name is based on the eastern Australian distribution of this alga, within the Maugean subprovince.
References: The Marine Benthic Flora of Southern Australia Part IIID
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.
Illustration in Womersley Part IIIA, 2003: FIG. 138.
Figure 138 enlarge
Fig. 138. Gredgaria maugeana (A, C–E, AD, A43353; B, AD, A68568; F, G, AD, A43512). A. Habit, type. B. Habit, larger specimen. C. Indeterminate axis bearing branched determinate laterals (arrows to unbranched segments). D. Apex of indeterminate axis with determinate laterals (arrows to unbranched segments). E. Pattern of cortical cells lying over the pericentral cells. F. Clumped rhizoids (two, one above the other). G. Branches with cystocarps.
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