Chara lamprothamniformis Casanova, 2023

Casanova, Michelle T. & Karol, Kenneth G., 2023, Charophytes of Australia’s Northern Territory - I. Tribe Chareae, Australian Systematic Botany 36 (1), pp. 38-79 : 61-64

Chara lamprothamniformis Casanova , sp. nov.

Type: Billabong 6 km NE of Mainoru River, S. W . Jacobs 1729, 3 May 1974. (holo: CANB!; iso: NSW!) .

Dioecious. Up to 30 cm high, flexible, delicate and narrow, occurring in clumps or swards, not calcified. Axes up to 200 µm in diameter; 2× corticated, all cells similar in size, ~18 cells around ( Fig. 14 c ). Spine cells obscure or small and triangular. Stipulodes in one whorl, regularly 2× the number of branchlets ( Fig. 14 a, b ), short or spreading and downward-pointing. Branchlets 8 or 9 in a whorl, to 8 mm long, 3 or 4 segments, the basal segment the longest (up to half the total branchlet length in female fertile parts), uncorticated, terminated by a cluster of 3–5 bract cells ( Fig. 14 a, b ). Bract cells 6–8, verticillate at the branchlet nodes ( Fig. 14 f ) and elongate on female plants (up to 0.5 mm long), smaller on male plants ( Fig. 14 e ), bracteoles 2, not distinguishable from bract cells. A small bractlet below the oosporangium ( Fig. 14 d ). Gametangia arranged singly or geminate on separate plants ( Fig. 14 d, f ), at the lowest 2 or 3 branchlet nodes. Oosporangia 400 µm long and 350 µm wide, coronula to 40 µm high. Oospores black, 360–410 µm long, 290–305 µm wide ( Fig. 14 g ). Striae of 7 or 8 flanged ridges, fossa wall 40–60 µm across, covered with verrucae 4–5 µm in diameter, 2–10 µm apart, 5–10 of them across the fossa ( Fig. 14 h ), end cell impression very small, up to 50 µm across at the widest part ( Fig. 14 i ). Antheridia up to 450 µm in diameter ( Fig. 14 e ). Chromosomes not known.

Distribution

Occurs in freshwater billabongs associated with the Mainoru River, Arnhem Land, and at Lockhart River , Queensland

Etymology

The epithet lamprothamniformis is derived from the genus name Lamprothamnium and the Latin suffix - formis, resembling, because the distinctively decumbent stipulodes, long bract cells, development of ‘fox-tails’ and verrucate oospore wall in this species resemble those in members of that genus.

Notes

Chara lamprothamniformis can be distinguished from C. schultae Casanova by dioecy, and from other dioecious members of section Agardhia by the distinctive downward pointing stipulodes, absence of spine cells, arrangement of the gametangia and delicate appearance.

Specimens examined

NORTHERN TERRITORY: s. loc, J. Schult k124 ( MEL) . QUEENSLAND: Lockhart River Community Farm , 4 Oct. 2000, Waterhouse BMW6048 ( CANB); Elliott, swamp NE of town, 27 May 1975, T. S.Henshall 979 (DNA) .

Figures

Fig. 14. Chara lamprothamniformis, from specimen T.S.Henshall 979 (DNA), (a) female fertile whorl, scale bar: 1 mm. (b) Male fertile whorl, scaleb bar: 1 mm. (c) Longitudinal view of axis, scale bar: 100 μm. (d) Fertile branchlet node with geminate oogonia, bract cells, bracteoles, and bractlet, scale bar: 0.5 mm. (e) Antheridium with smaller bract cells and bracteoles, scale bar: 0.5 mm. (f) Single oosporangium with bract cells, bractoles and bractlet, scale bar: 0.5 mm. (g) Scanning electron micrograph (SEM) of oospore, scale bar: 100 µm. (h) SEM of detail of oospore wall, scale bar: 20 µm. (i) SEM of detail of the impression of the basal cell on the oospore wall, scale bar: 50 µm.