Chara submollusca Nordstedt

Casanova, Michelle T. & Karol, Kenneth G., 2023, Charophytes of Australia’s Northern Territory - I. Tribe Chareae, Australian Systematic Botany 36 (1), pp. 38-79 : 72

Chara submollusca Nordstedt , Hedwigia 27: 189 (1888)

Type: QUEENSLAND: Rockinghams Bay , s.d., J.Dallachy s.n. (lecto: LD!; isolecto: BM!, fide R.D.Wood in R.D.Wood & K.Imahori (eds), Rev. Characeae 1: 316–317 (1965)) .

Dioecious. Plants up to 250 mm high, not much branched, elongate and flexible, not calcified ( Fig. 20 a, b ). Axes 200–555 µm in diameter, irregularly 1× corticated ( Fig. 20 i ). Internodes 9–36 mm long. Spine cells solitary, small, conical with an acute tip, up to 120 µm high, stipulodes in 1 row, 2× the number of branchlets ( Fig. 20 d ), 0.4–1.5 mm long, small and conical. Branchlets 7–10 in a whorl, ecorticate ( Fig. 20 g ), 3 or 4 cells long, basal branchlet cell long, branchlet end segment usually a single cell with some smaller subtending bract cells, sometimes 2 or 3 equally long cells, bract cells 2–6 ( Fig. 20 e, f ), unilateral, internally up to 0.6 mm long, externally small, conical, frequently absent. Bracteoles 2, 1 mm long, bractlet present in place of an antheridium on oosporangial plants. Gametangia on separate plants, solitary at the lowest 2 or 3 branchlet nodes ( Fig. 20 c ). Oosporangia up to 750 µm long, 405–450 μm wide, coronula short. Oospores 360–570 µm long, 290–350 µm wide, with 8 or 9 striae of prominent ridges ( Fig. 20 j ), the oospore wall appearing smooth, somewhat granulate to roughened at high magnification ( Fig. 20 k ), basal-cell impression up to 88 µm in diameter ( Fig. 20 l ). Antheridia up to 600 µm in diameter. Chromosomes not known. Vegetative reproductive organs (bulbils) often present at the apices of the branches ( Fig. 20 h ), consisting of shortened shoots with starchfilled basal branchlet segments.

Distribution

Tropical north and eastern Australia in shallow freshwater waterbodies, rivers and ponds.

Etymology

From Latin ‘ sub ’ meaning somewhat, and ‘ mollis ’ meaning soft or flexible.

Notes

Chara submollusca was described as a species by Nordstedt (1888) and included in C. section Agardhia by Wood (1962). However, when Wood examined the Australian charophyte flora he amalgamated C. submollusca with Chara fibrosa var. fibrosa ( Wood 1971) .

Chara submollusca is characterised by dioecy, haplostichous cortex and very long primary branchlet segments. The presence of specialised opaque branch apices (with starchfilled branchlet segments) is distinctive in this tropical species.

Specimens examined

NORTHERN TERRITORY: Manton Dam Recreation Area , 5 Sep. 2010, M. T. Casanova r756 ( MEL, NY); roadside borrow-pit on the Arnhemland Highway, 8 Sep. 2010, M. T. Casanova r786 ( MEL, NY); Darwin River Dam, 22 Apr. 1977, J. Must 1467 (DNA); Jabiru Lake, Jabiru , 27 Aug. 1983, I. Cowie s.n. (DNA); Cathedral Billabong, Arnhemland , 29 July 1983, I.D.Cowie s.n. (DNA). QUEENSLAND: Barrow River , 1891, G. Podenzana s.n. ( BM); Browns Creek, Pascoe River , 13 July 1948, L. J. Brass 19560 ( BM, L) .

Figures

Fig. 20. Chara submollusca, (a–i) from specimen M.T.Casanova r786 (MEL), (j–l) from isolectotype specimen J.Dallachy, Rockinghams Bay (BM). (a) Habit of female plant, scale bar: 10 mm. (b) Habit of male plant, scale bar: 10 mm. (c) Oogonia, bract cells and bractlets, scale bar: 500 μm. (d) Stipulodes at the base of the branchlets, scale bar: 1 mm. (e) Fertile female whorl of branchlets, scale bar: 5 mm. (f) Fertile male whorl of branchlets, scale bar: 1 mm. (g) Sterile whorl of branchlets, scale bar: 5 mm. (h) Bulbil consisting of the apex of a branch with starch-filled branchlet cells, scale bar: 1 mm. (i) Axis with partial cortication and inconspicuous spine cells, scale bar: 1 mm. (j) Scanning electronmicrograph (SEM) of oospore in side view, scale bar: 100 μm. (k) SEM of detail of oospore wall, scale bar: 20 μm. (l) SEM of impression of basal cell, scale bar: 100 μm.