Electronic Flora of South Australia Species Fact Sheet

Bangia atropurpurea subsp. brevisegmenta Womersley, subsp. nov.

Phylum Rhodophyta – Class Bangiophyceae – Order Bangiales – Family Bangiaceae

Thallus (Fig. 4A) dark red-brown, occurring as tufts of flaccid, simple filaments, 1–3 cm long and 16–75 µm in diameter, with a prominent mucilaginous sheath, each filament basally attached by rhizoids from 2–6 (–15) suprabasal cells; epizoic on mussels. Filaments (Fig. 4A–C) uniseriate below with diffuse divisions, above becoming 2–6 cells broad by longitudinal divisions producing radially elongate, cuneate, cells. Cells (Fig. 4C) in uniseriate parts L/D 0.5–1.5 (–2) within a few cells of the base, then very short for 1–2 mm above the base (20–35 µm in diameter and L/D 0.3–0.15), in thicker parts the cells more or less isodiametric in surface view, 10–15 µm across, each with a single stellate rhodoplast with a central pyrenoid.

Reproduction: Sexual plants dioecious; carpogonia (Fig. 4E, F) with or without a slight prototrichogyne; carposporangia (Fig. 4E, F) formed in vague groups of 8–16, elongateclavate radially, in surface view isodiametric and 7–10 µm across; spermatangia (Fig. 4D, G) formed in elongate transverse masses 40–70 µm long and 4–10 µm broad, corresponding to the parent cells, separated by a clear matrix, pale grey in colour, with 16–32 (–64) spermatia (each 2–3 µm in diameter).

Type from Warrnambool, Vic., lower eulittoral on the mussel Xenostrobus pulex (Lamarck) in sand, inner side of Middle I. (Womersley, 14.x.1985; AD, A57022).

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

Distribution: Only known from the type locality; not present in May 1988.

Subsp. brevisegmenta differs from subsp. atropurpurea in having very short cells for 1–2 mm of the lower thallus, in the more distinct prototrichogynes, and in the spermatangia forming well-defined transverse masses across the filaments. It occurs at a lower intertidal level in a different habitat to that of the type species.

Taxonomic notes: While subsp. brevisegmenta appears distinct from subsp. atropurpurea, it is not possible to compare it satisfactorily with other species of the genus due to lack of a world monograph and detailed accounts of other species.

References: The Marine Benthic Flora of Southern Australia Part IIIA

Author: H.B.S. Womersley

Publication: 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.

Illustration in Womersley Part IIIA, 1994: FIG. 4.

Figure 4   enlarge

Fig. 4. A–G. Bangia atropurpurea subsp. brevisegmenta (AD, A57022). A. Habit. B. Lower filaments. C. Mid filament with very short cells. D. A male (horizontal) and a female filament. E. A female filament in surface view, with spermatia (on right) and groups of carposporangia. F. Ditto, in mid sectional view. 6. A male filament with transverse packets of spermatangia.

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