Chara benthamii A.Braun

Casanova, Michelle T. & Karol, Kenneth G., 2023, Charophytes of Australia’s Northern Territory - I. Tribe Chareae, Australian Systematic Botany 36 (1), pp. 38-79 : 54-55

Chara benthamii A.Braun in C. F. O.Nordstedt, Abh. Königl. Akad. Wiss. Berlin 1882: 117 (1883), as ʻ Benthamiʼ

Chara fibrosa subsp. benthamii (A.Braun) Zaneveld, Blumea 4: 156 (1940). Type: ditches in Little Hong Kong, Feb. 1858, I.Wilford 238 (lecto: BM!; isolecto: L!, LD!, fide Wood and Imahori 1965: 290) .

[ Chara fibrosa var. fibrosa f. fibrosa auct. non C.Agardh ex Bruzelius: R.D.Wood, Taxon 11: 13 (1962).]

Monoecious. Plants 120–200 mm high, branching in the lower parts, upper internodes condensed with a ‘fox-tail’ habit, generally without calcification ( Fig. 9 a, b ). Axes 450–550 μm wide, internodes 9–35 mm long, irregularly 2× corticated, primary cortical cells slightly bigger than secondary cortical cells (tylacanthous) or all similar, 18–20 cells around ( Fig. 9 e ). Spine cells sparse, up to 0.8 mm long near the nodes. Stipulodes up to 1 mm long and 200 µm wide, in a single whorl, at least one per branchlet, but fewer than 2 per branchlet ( Fig. 9 c ). Branchlets ecorticate, 8–13 in a whorl, 8–11 mm long, 0.2–0.3 mm wide, with 4–6 segments, the lowest segment the longest, all others decreasing in size, the end segment sometimes 2-celled ( Fig. 9 c ). Bract cells up to 2.6 mm long, somewhat verticillate (internals slightly longer than externals), 2–6 of them, decreasing in size and number at higher branchlet nodes ( Fig. 9 d ). Bracteoles 2, as long as, or shorter than the bract cells, 2 or 3 times as long as the oosporangium. Gametangia conjoined singly at the lowest 2 or 3 branchlet nodes. Oosporangia 500 µm long, 380 µm wide, 8 or 9 stripes of helical cells, coronula 70–80 µm high, 140–170 µm wide, cells somewhat rounded. Oospores black, broadly oval, 330–510 µm long, 253–430 µm wide (dry) with 7 or 8 striae ( Fig. 9 f ), oospore wall smooth to slightly rugose ( Fig. 9 h ), fossa to 54–72 µm in diameter ( Fig. 9 g ), basal cell impression 78 µm wide at the widest point with edges 52 µm long. Antheridia to 360 µm in diameter. Chromosomes not known.

Distribution

South-East Asia and northern Australia, with outliers in southern New South Wales and the south-west of Western Australia, in ditches, drains, rivers and wetlands. The taxon (as C. fibrosa var. benthamii ) has also been recorded from Europe ( Soulié-Märsche et al. 2013; Mouronval et al. 2015). It appears to be restricted to freshwater.

Etymology

Named for George Bentham (1800–1884), a leading systematic botanist of the 19th century ( Jackson 1885).

Notes

Only a few Australian specimens are unequivocally determined as Chara benthamii (on the basis of oospore shape and size and vegetative morphology); many of the specimens allocated to C. benthamii in this study have more bract cells, larger oospores and less tylacanthous cortex. They could possibly be assigned to C. gymnopitys , which is typified on the basis of south-eastern Australia –Tasmanian material. In the absence of a more thorough review of typification of C. gymnopitys and the plethora of form and variety names assigned; Australian monoecious specimens with black oospores, verticillate bract cells and more than one times but fewer than two times stipulodes are here assigned to C. benthamii . In general, Australian specimens have more branchlets (up to 13) than the type specimen.

Chara benthamii was recognised as a species for Queensland (e.g. Bailey 1913) but Groves and Allen (1935) amalgamated it with C. gymnopitys . All the specimens they saw from Queensland conformed to their concept of C. gymnopitys var. benthamii , although the stipulodes (or plants?) were shorter and stouter than for the type of C. benthamii , and plants differed from C. gymnopitys var. gymnopitys by having fewer, shorter and wider ‘bracteal appendages’ (bract cells and bracteoles). Zaneveld (1940) retained C. benthamii as a subspecies of C. fibrosa . Wood and Imahori (1965) and Wood (1971) amalgamated C. benthamii with C. fibrosa and did not recognise it even as a form or ‘microspecies’.

Distinguished on the basis of uneven two times tylacanthous cortex, one times stipulodes, plus several more, but never so many as to be two times, short branchlets, few branchlet cells, the basal cells longest, few, small spine cells, and oval, black oospores. Chara benthamii differs from C. arnhemensis and C. lamprothamniformis Casanova by the overall spiny appearance of those species, from C. duriuscula (A.Braun) Casanova & Karol by having a tylacanthous cortex, verticillate bract cells and consistently more stipulodes. Chara wightii (A.Braun) Casanova is distinguished by oospore colour (brown in C. wightii ).

Specimens examined

NORTHERN TERRITORY: Daly River, Camp site 5, 6 Sep. 2010, M. T. Casanova r783 ( MEL); Katherine River , low-level site, 7 Nov. 2005, J. Schult A411 ( MEL); Yirrkala, in a freshwater stream, 11 Aug. 1948, R. L. Specht A75 ( AD-A21397 ). Carpentaria Highway, Calvert River crossing, 7 July 1998, C. R. Michell & J . Risler 1615 (DNA); 25 km SW of Goyder River Crossing, 16 June 1972, J.Must 1012 (DNA); WESTERN AUSTRALIA: Glen Herring Pool, Pilbara Biological Study site PSW022 , 23 May 2004, M. N. Lyons & D. A . Mickle ( PERTH); Kalgan Creek pool near Newman, Pilbara Biological Study site PSW066 , 24 Sep. 2004, D. A. Mickle & N. Y . Huang 4520 ( PERTH); Perry Lake , 13 Oct. 1960, R. D. Wood 60-10-13-4- A ( AD-A39012 ) . QUEENSLAND: Moreton Bay , s.dat., C. Stuart 219 ( MEL); Broadwater Road, N of Mt Cotton Road , 10 miles [~ 16 km] S of Brisbane, in a field dam down to 30-cm depth, 24 Nov. 1960, R. D. Wood 60-11-24-1 & A. B . Cribb ( AD-A31950 ) . NEW SOUTH WALES: Deua River (Moruya River), Araluen Road , M. T. Casanova r518 ( MEL) .

Figures

Fig. 9. Chara benthamii A.Braun, from the isolectotype specimen I.Wilford 238 (BM). (a) Habit of whole plant, scale bar: 5 cm. (b) Fertile branch apex, scale bar: 10 mm. (c) Branchlet whorl, scale bar: 5 mm. (d) Fertile node with oosporangium, antheridium, bracteoles and bract cells, scale bar: 1 mm. (e) Transverse section of axial cortex, scale bar: 0.5 mm. (f) Oospore with 7–8 striae and a smooth fossa wall, scale bar: 100 µm. (g) Detail of oospore wall, scale bar: 20 µm. (h) Minutely patterned oospore wall construction, scale bar: 2 µm.