Electronic Flora of South Australia Species Fact Sheet

Bryopsis gemellipara J. Agardh 1887: 25.

Phylum Chlorophyta – Order Derbesiales – Family Bryopsidaceae

Selected citations: MacRaild 1974: 157. Womersley 1956: 363.

Thallus (Fig. 97C) robust, 5–15 (–20) cm high, with one to a few prominent, simple or branched, axes arising from a rhizoidal system, usually epiphytic, occasionally on rock; older plants with 3–4 orders of branching. Axes and their branches, and sometimes the laterals, bilaterally branched (Fig. 98A) with two rows of laterals or ramuli on each side, laterals with radially (usually) arranged ramuli densely clustered near their apices (Fig. 98B) or in some plants ramuli bilaterally (rarely unilaterally) arranged; axes and laterals denuded below, with prominent scars (Fig. 98B) especially on laterals; lower laterals often with descending rhizoidal outgrowths on parent axes. Axes (0.5–) 1–1.5 mm in diameter, laterals 100–250 (–300) µm in diameter and ramuli 0.3–1.5 (–2) mm long and 80–120 µm in diameter, often slightly curved. Chloroplasts subspherical to discoid, sometimes lenticular, 8–9 µm across, with a prominent pyrenoid.

Reproduction: Reproduction (MacRaild 1974): thalli dioecious, anisogamous; sporophytes only known in culture, protonemal and uninucleate, producing stephanokontic zoospores.

Type from Queenscliff, Vic.; lectotype in Herb. Agardh, LD, 15150. Isotype MEL, 26489.

Selected specimens: Streaky Bay, S. Aust., reef pools on back beach (Parsons, 25.viii.1967; ADU, A31932). Waldegrave I., Eyre Peninsula, S. Aust., 8 m deep (Shepherd, 25.x.1973; ADU, A44257). Cape Lannes, S. Aust., low eulittoral (Womersley, 17.xi.1970; ADU, A37795-"Marine Algae of southern Australia" No. 142, previously as B. vestita). Nora Creina, S. Aust., upper sublittoral pools ( Womersley, 6.vi.1982; ADU, A53202). Point Lonsdale, Vic., in rock pools (King, 1.viii.1969; ADU, A37739; MELU 4582).

Distribution map based
on current data relating to
specimens held in the
State Herbarium of SA

Distribution: From Streaky Bay, S. Aust. to Wilsons Promontory, Vic. and around Tasmania. Usually epiphytic, occasionally on rock, on rough-water coasts from low-tide level to 2 m deep.

Taxonomic notes: B. gemellipara is usually a distinctive species. Typical epiphytic plants (as in the type) are bilateral in their main branching and have the ramuli radially arranged on the laterals, but some epilithic plants (e.g. from Cape Lannes, S. Aust.) have the ramuli mostly bilaterally arranged but are otherwise very similar to the epiphytic plants. However, such "epilithic" plants may at least commence their development on small algae on the rock.

B. gemellipara is closely related to the partly bilateral form of B. foliosa Sonder from the southern west coast of Western Australia, and studies are needed to establish their distinctness. B. foliosa occurs on rock platforms and larger plants epiphytic on sea-grasses are morphologically very similar. The branching is largely bilateral on the axes and larger laterals, and often radial on the smaller laterals, but less distinctly so than in B. gemellipara; the dimensions in both species are similar, but B. foliosa is generally a more densely branched species. For the present, B. foliosa is considered restricted to the west coast of Western Australia, while B. gemellipara is confined to south-eastern Australia.

B. gemellipara and B. vestita are plants of similar robustness and dimensions, and are best differentiated on their branching patterns. New Zealand B. vestita and Australian specimens placed in this species are entirely radially branched, whereas the axes and often the laterals of B. gemellipara are not.

References:

AGARDH, J.G. (1887). Till algernes systematik. VIII. Siphoneac. Acta Univ. hind. 23, 1–180. Plates 1–5.

MacRAILD, G.N. (1974). The taxonomy, life history and cytology of Bryopsis and related genera from southern Australia. (Ph.D. thesis, Univ. Melbourne.)

WOMERSLEY, H.B.S. (1956). A critical survey of the marine algae of southern Australia. I. Chlorophyta. Aust. J. mar. freshw. Res. 7, 343–383.

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (31 May, 1984)
The Marine Benthic Flora of Southern Australia
Part I
©Board of the Botanic Gardens and State Herbarium, Government of South Australia

Illustrations in Womersley Part I, 1984: FIGS 97C, 98A,B.

Figure 97   enlarge

Fig. 97. A. Bryopsis plumosa (ADU, A53203), same scale as C. B. Bryopsis australis (ADU, A50705). C. Bryopsis gemellipara (ADU, A53202).

Figure 98   enlarge

Fig. 98. A,B. Bryopsis gemellipara (ADU, A53202). A. Apex of a young axis with bilateral, slightly displaced ramuli. B. Part of an older axis with bilateral, displaced, laterals and radially arranged ramuli. C–G. Derbesia marina (C–E, ADU, A54010; F,G. ADU, A9477). C. Habit. D. Branch with basal double septum. E. Branch with chloroplasts. F,G. Sporangia.

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