Chara karolii Casanova, Austral. Syst. Bot.

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

Chara karolii Casanova, Austral. Syst. Bot. 27: 409 (2014)

Type: VICTORIA: temporary wetland on ‘ Lurnea’, Casanova Road, Westmere , 18 Nov. 2008, M. T. Casanova r167 (holo: MEL!; iso: B!, NY!) .

Chara aff. muelleri ‘Karol’: M. T.Casanova & I. J.Powling. Algae collected for the Lake Condah, Budj Bim Indigenous Protected Area Bush Blitz: 11 [Charophyte Services, Lake Bolac (2011)].

Monoecious. Plants robust, up to 60 mm high, without calcium carbonate deposition ( Fig. 13 a ). Axes up to 400 µm in diameter, 3-corticate in the upper internodes, isostichous, 24–27 cells around ( Fig. 13 ), ecorticate on the lower internodes; spine cells absent or rudimentary. Stipulodes in 1 whorl, alternate, the same number as the number of branchlets, up to 300 µm long ( Fig. 13 b ). Branchlets 8 or 9 in a whorl, up to 20 mm long, segments 3 or 4, ecorticate ( Fig. 13 b ), terminated by a corona of ~3 cells ( Fig. 13 e ). Bract cells 2 or 3 at branchlet nodes, bracteoles 2, as long as the oosporangia ( Fig. 13 d ). Gametangia conjoined, geminate or clustered at the lowest 2 branchlet nodes ( Fig. 13 f ), as well as basal oosporangia. Oosporangia 500–600 µm long (including coronula), 250–300 µm wide, 8 or 9 stripes of helical cells, coronula up to 150 µm high. Oospores black 480–660 µm long, 280–400 µm wide, 7 or 8 striae of low ridges ( Fig. 13 g ), basal-cell impression 85–103 µm in diameter ( Fig. 13 j ) (25–30% of the diameter of the oospore), oospore wall with a reticulate pattern, when well developed, the reticulum is constructed of small papillae on low ridges, the reticulae ~5 µm in diameter, the papillae ~0.5 µm in diameter on ridges ~0.5 µm high ( Fig. 13 h, i ). Antheridia up to 200 µm in diameter. Chromosomes n = 14 ( M. T.Casanova r933) ( Fig. 13 k ).

Distribution

Abundant in temporary wetlands in western Victoria. There is a single specimen collected from the Northern Territory ( R.Breen s.n., 25 Aug. 2014 ( MEL)), which keys out to Chara karolii (partly corticated axes and geminate gametangia) and is included here pending further study.

Etymology

Named for Kenneth G. Karol from the New York Botanical Garden, who first distinguished this species from Chara muelleri (A.Braun) F.Muell. on the basis of nucleotide analysis.

Notes

Chara karolii has corticated axes and regularly clustered gametangia (i.e. in twos and threes at each node), with the occasional occurrence of basal oosporangia, and granular or reticulately patterned oospores. Cortication is usually absent from the lowest axial internodes and can be restricted to the very youngest internodes. Sometimes cortication is difficult to discern and a thorough check of the upper internodes is necessary. Chara braunii , which might also occur in the Northern Territory, has no cortication whatsoever, and is generally somewhat ‘inflated’ (so that the branchlets appear like a string of sausages, constricted at the nodes). Chara muelleri is distinguished by its singular conjoined gametangia, absence of basal gametangia and more completely corticated axes.

Specimens examined

NORTHERN TERRITORY: creek above John Hayes Rockhole (Trepina), 25 Aug. 2014, R. Breen s.n. ( MEL) . VICTORIA: Muldoons Sinkhole, Budj Bim Indigenous Protected Area , 28 Mar. 2011, M. T. Casanova r941 ( MEL); Streatham–Eurumbeen Road , roadside ditch, 23 Feb. 2011, M. T. Casanova r931 ( MEL) .

Figures

Fig. 13. Chara karolii, from specimen (a) M.T.Casanova r931 and (b–j) M.T.Casanova r941. (a) Whole plant, with somewhat contracted fertile whorls; scale bar: 1 cm. (b) Whorl of branchlets; scale bar: 1 mm. (c) Transverse section of axis showing cortical cells; scale bar: 500 µm. (d) Gametangia arranged singly, with bract cells behind and beside the branchlet node, and bracteoles arising from the base of the gametangia; scale bar: 500 µm. (e) Branchlet tips with coronae; scale bar: 300 µm. (f) Clustered gametangia; scale bar: 500 µm. (g) Scanning electron micrograph (SEM) side view of oospore with eight striae; scale bar: 100 µm. (h, i) Detail of oospore wall, showing incomplete and complete development of reticulate ornamentation; scale bars: 20 µm. (j) End-cell impression on the oospore wall; scale bar: 50 µm. (k) Chromosomes in two spermatogenous cells in metaphase, at 1000× magnification, n = 14.