Lamprothamnium compactum 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 : 43-45

Lamprothamnium compactum Casanova, Austral. Syst. Bot. 26: 276 (2013)

Type: in ~ 6 inches [~ 15 cm] of clear salty water, south-east shore of a small lake near road on the Ararat – Hamilton road, 27 Oct. 1961, R. D.Wood 61-3-27-10: (holo: NY!; iso: AD!, BM!) .

Lamprothamnium papulosum f. compactum 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. Plants often growing as a ‘lawn’ of closely packed shoots with dense ‘fox-tails’, sometimes with inflated branchlets, or branchlet segments, near the base of the plant, but never inflated in the fertile whorls, smelling somewhat of garlic. Axes up to 400 μm in diameter, ecorticate, internodes up to 4 mm long ( Fig. 3 a ). Stipulodes opposite the branchlets, downward-pointing, long, thin and pointed, up to 3 mm long, and also within the whorls of sterile branchlets ( Fig. 3 b ). Branchlets 6–9 in a whorl, with 4 or 5 cells, short, overlapping and markedly incurved, basal branchlet cell up to 1 mm long, branchlet end segments generally 2 cells long, bract cells long and verticillate, 4 or 5 at each node, up to 2 mm long (shorter in Northern Territory specimens; Fig. 3 c ). Fertile parts contracted into dense ‘fox-tails’, so that observation of the arrangement of the gametangia requires dissection of the whorls. Gametangia aggregate inside the base of the branchlet whorl and solitary on the branchlets. Oosporangia sessile and aggregate inside the base of the branchlet whorl, rarely 1 on one of the first branchlet nodes, up to 800 μm long with 10 stripes of helical cells, coronula up to 65 μm high. Oospores black, 564–675 μm long, 240–350 μm wide, 11 or 12 striae of low undulating ridges and fossa with granulate ornamentation. Antheridia solitary on the lowest node of the branchlets ( Fig. 3 b ), up to 450 μm in diameter, never at the base of the whorl. Vegetative reproduction by spherical white bulbils attached to the rhizoid nodes. Chromosomes not known.

Distribution

Coastal South Australia including Kangaroo Island , inland salt lakes in southern Northern Territory, coastal and inland salt lakes in western Victoria, northern Tasmania and the south-west of Western Australia.

Habitat

Saline lakes and bores.

Etymology

‘ Compactum ’ from Latin, compact, here referring to the closely compact whorls of fertile branchlets.

Notes

Lamprothamnium compactum is a low-growing meadowforming species that forms extensive beds in shallow water down to ~ 2 m deep. It is distinguished from L. macropogon by a dense fox-tail morphology and the absence of antheridia inside the base of the fertile whorls. Northern Territory material seen so far differs from southern Australian specimens in having smaller and less compact fertile whorls.

Specimens examined

NORTHERN TERRITORY: Fitz Bore, Elkedra Station , 27 June 1984, R.Dance 672 (DNA); loc. Not given, n.d., P.Dostine 12DW23- 2 (DNA) .

Figures

Fig. 3. Lamprothamnium compactum, from P.Dostine 12DW23-2. (a) Habit of elongate shoot, scale bar: 1 mm. (b) Compact shoot with antheridia, scale bar: 1 mm. (c) Fertile whorl, scale bar: 1 mm. (d) Sterile branchlet, scale bar: 100 µm.