Charophytes of Australia’s Northern Territory - I. Tribe Chareae Author Casanova, Michelle T. Author Karol, Kenneth G. text Australian Systematic Botany 2023 2023-03-30 36 1 38 79 http://dx.doi.org/10.1071/sb22023 journal article 10.1071/SB22023 1446-5701 10904227 Chara wightii (A.Braun) Casanova, Austral. Syst. Bot. 26: 293 (2013) Chara flaccida var. wightii A.Braun, Hooker ’ s J . Bot. Kew Gard. Misc. 1: 296 (1849) . Type : Madras (Chennai), India , between 1819 and 1849, R .Wight 133 (holo: BM !; iso: L !). Chara fibrosa subsp. flaccida Zaneveld , nom. inval. : J . S .Zaneveld, Blumea 4: 162 (1940) p.p. Chara fibrosa var. flaccida J.C.van Raam , nom. inval. [ Chara fibrosa auct . non C .Agardh ex Bruzelius: R .D.Wood, Taxon 11: 13 (1962) , p.p. ] [ Chara fibrosa f. fibrosa auct. non C .Agardh ex Bruzelius: R .D.Wood, Rev. Characeae 1: 289 (1965) , p.p. ] Monoecious. Plants 100–250 mm high, often calcified, somewhat shrubby ( Fig. 21 a ). Axes up to 700 µm in diameter; internodes regularly 2× corticated axis, isostichous or tylacanthous (20–22 cells around) ( Fig. 21 d ). Spine cells small and conical on older axes, longer on young axes, occurring singly, 130–185 μm long and 20–40 μm wide. Stipulodes in a single whorl, the same number as the number as branchlets in each of the whorls ( Fig. 21 b ), 1–2 mm long. Branchlets 9–11 in a whorl, 5–14 mm long, segments 4–6, the basal cell shorter than the second cell in fertile whorls ( Fig. 21 b ). Bract cells 4–6 verticillate at the branchlet nodes, up to 0.4–2.5 mm long, bracteoles 2, similar to bract cells ( Fig. 21 c ). Gametangia conjoined singly or geminate at the lowest 2–4 branchlet nodes. Oosporangia up to 500 µm long and 375 µm wide, 10 or 11 stripes of helical cells, coronula up to 75 µm high, cells apiculate and spreading slightly. Oospores chestnut brown at maturity, 400–470 µm long, 250–310 µm wide ( Fig. 21 e ). Striae of 7–10 low ridges (in Australian material usually 7 or 8), fossa wall 64 μm across ( Fig. 21 f ), basal cell impression ~80 µm wide at the widest point ( Fig. 21 g ). Antheridia up to 500 µm in diameter, octoscutate. Chromosomes not known. 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. Fig. 21. Chara wightii , ( a–d ) from specimen S.McCune 7 & P.Munns (DNA), ( e–g ) from the holotype material R.Wight 133 (BM) ( a ) Longitudinal view of the axis with cortication and spine-cells, scale bar: 1 mm. ( b ) Fertile whorl, scale bar: 5 mm. ( c ) Gametangia at branchlet node with bract cells and bracteoles, scale bar: 5 mm. ( d ) Transverse section of the corticated axis, scale bar: 1 mm. ( e ) Scanning electron micrograph (SEM) of oospore, scale bar: 100 µm. ( f ) SEM of detail of oospore wall, scale bar: 20 µm. ( g ) SEM of basal view of oospore showing impression of the basal cell, scale bar: 100 µm. Distribution Northern Australia , India and South-East Asia ( Pal 1932 ; Pal et al. 1962 ; Han and Li 1994 ; Langangen and Leghari 2001 ). Mostly freshwater. Etymology Named for the collector of the type material, Robert Wight (director of the Botanic Garden in Madras [now Chennai ] from 1819 to 1853) . Notes Chara wightii has a corticated axis and naked branchlets and it is often encrusted with calcium carbonate; it is characterised by brown oospores and occasional geminate gametangia, in contrast to C. benthamii and C. duriuscula , which have black oospores and singular gametangia. It can be distinguished from C. erythrogyna (which has sejoined gametangia) by its consistently conjoined gametangia and brown oospores. Australian material tends to be isostichous rather than tylacanthous, but it is included within C. wightii pending further investigation. Specimens examined NORTHERN TERRITORY : 20 km SW of Wombungi , Fitzmaurice River area , 15 May 1994 , S . McCune 7 & P . Munns (DNA); lagoons on upper Elkedra River , 7 May 1977 , T . S . Henshall 1745 (DNA); Port Darwin , 9 Apr. 1896 , T . B . Blow A102 ( BM ) . WESTERN AUSTRALIA : Caliwingina Spring , 1 Aug. 2011 , M .Curran 1 ( PERTH ); Arnhem Land, Wilton River , near Bulman, 9 Nov. 1987 , G . J .Leach & C . R .Dunlop 1633 (DNA) .