Lamprothamnium capitatum Casanova, Austral.

Casanova, Michelle T. & Karol, Kenneth G., 2023, Charophytes of Australia’s Northern Territory - I. Tribe Chareae, Australian Systematic Botany 36 (1), pp. 38-79 : 43

Lamprothamnium capitatum Casanova, Austral.

Syst. Bot. 26: 274 (2013)

Type: in 2–4 inches [~ 5–10 cm] of clear water, long shallow drain west of the road, 6 miles [~ 9.7 km] south of Kingston SE, Coorong Region, 7 Nov. 1960, R. D.Wood 60-11-7-7 (holo: NY!; iso: AD!, BM!, L!, PC!) .

Lamprothamnium papulosum f. capitatum R.D.Wood , Nova Hedwigia 22: 38 (1971), nom. inval., nom. prov.

[ Lamprothamnium papulosum auct. Non (Wallr.) J.Groves: R.D.Wood, Nova Hedwigia 22: 38 (1971), p.p.]

Monoecious. In the Northern Territory, plants occurring in a dense sward. Axes up to 100 μm in diameter, ecorticate, internodes up to 2 cm long ( Fig. 2 a ). Stipulodes in 1 row, opposite the branchlets, 0.2–0.8 mm long, downward pointing. Branchlets 7 or 8 in a whorl, ecorticate, narrow in all parts ( Fig. 2 c ), coalescing into ‘fox-tails’ at the axis apices, basal branchlet cell up to 2 mm long (in southern Australian specimens), branchlet end segments usually 1, bract cells 2–5, verticillate, 0.2–1 mm long, much reduced at upper branchlet nodes ( Fig. 2 b ). Fertile parts contracted into loose foxtails, occurring apically and in the axils of lower branchlets. Gametangia foliar and basal, inside and outside the whorls ( Fig. 2 c ). Oosporangia up to 900 μm long, stipitae inside the base and below the branchlet whorl ( Fig. 2 d ), 10 or 11 stripes of helical cells, coronula up to 85 μm high, of oval cells. Oospores black, 600–740 μm long and 270–285 μm wide with 10 or 11 striae of undulating ridges. Ornamentation smooth to granulate, the grains sometimes arranged in rows. Antheridia up to 300 μm in diameter, solitary or geminate on the first branchlet node ( Fig. 2 c ). Chromosomes not known.

Distribution

Brackish to saline wetlands in coastal and inland Victoria, South Australia and Northern Territory. The specimen from Cotton Island is the first confirmed record of Lamprothamnium in a saline coastal habitat north of the New South Wales – Queensland border in Australia.

Habitat and ecology

Grows in temporary saline waters.

Etymology

From Latin ‘ capitatum ’, head, referring to the ‘head-like’ appearance of the axial and terminal ‘fox-tails’ in the southern Australian material.

Notes

The specimens listed here most closely align with L. capitatum on the basis of the arrangement of the reproductive structures; however, specimens are less robust, do not appear to have foliar oosporangia, and the oospores are significantly larger. It appears to grow in a low carpet or sward, which differs from the isolated individuals previously examined ( Casanova 2013 a). Further collections from Northern Territory are required to confirm this determination.

Specimens examined

NORTHERN TERRITORY: Cotton Island, North West Lake , 19 Aug. 1996, C. P.Mangion 287 (DNA); Purnie Bore, Simpson Desert, 17 Sept. 1987, G.Leach 1438 (DNA) [mixed with Chara sp. ] .

Figures

Fig. 2. Lamprothamnium capitatum, from C.P.Mangion 278. (a) Axis of mature, fertile plant, scale bar: 10 mm. (b) Two sexually reproducing nodes showing internal and external basal oogonia and foliar antheridia, scale bar: 1 mm. (c) Fertile branchlet with stipitate oogonia and geminate antheridia, scale bar: 1 mm. (d) Part of an axis node with long-stipitate oosporangia at the base of branchlets, scale bar: 500 µm.