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![(a) Oospore (minus gyrogonite) of specimen p244 Chara contraria var. australis (= C. vulgaris var. vulgaris sensu RD Wood) from Port Fairy, Victoria [M.T. Casanova p244; author's collection] with 15-16 low striae, (scale bar = 200 µm), (b) oospore wall appears rugulose (scale bar = 2 µm).](profile/Michelle-Casanova-4/publication/264240561/figure/fig1/AS:652977647935505@1532693411414/a-Oospore-minus-gyrogonite-of-specimen-p244-Chara-contraria-var-australis-C.png)
(a) Oospore (minus gyrogonite) of specimen p244 Chara contraria var. australis (= C. vulgaris var. vulgaris sensu RD Wood) from Port Fairy, Victoria [M.T. Casanova p244; author's collection] with 15-16 low striae, (scale bar = 200 µm), (b) oospore wall appears rugulose (scale bar = 2 µm).
Source publication
Charophytes (family Characeae) are a cohesive group within the green algae. The genus Chara is abundant and diverse in a variety of Australian habitats. Approximately 37 taxa of Chara have been described on the basis of Australian collections. The current status of charophyte taxonomy is confused. RD Wood revised Australian charophytes in 1972 on t...
Contexts in source publication
Context 1
... et al. 1990;Casanova 1997;Soulié-Märsche 1999) or no experimental support for their taxonomic value, but have been widely used to support species determinations, and these also display a greater degree of polymorphisms than Wood's characters. In relation to these results and the variation in oospore characters (Figs 1-19), the status of each Australian species (sensu Wood 1972) is outlined below within their sections. b a b a ...
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... always be determined from preserved material. Representatives conforming to both C. vulgaris and C. contraria have been found in Australia. Some Australian specimens have naked, or only partly corticated branchlets, and the second row of stipulodes is often obscure. Braun (1852) described two taxa for Australia C. contraria var. australis ( Fig. 1) and var. behriana (Fig. 2) that Wood incorporated into C. vulgaris var. vulgaris and var. gymnophylla. Grant and Proctor (1971) found that ecorticate and corticate clones of C. vulgaris were reproductively isolated. Some specimens have significantly different oospores ( Fig. 3) with 17-19 striae, more than has been recorded for any ...
Context 3
... status of the two Australian varieties in this group (vars australis and behriana) needs examination. The variation in oospores in this group found so far (Figs 1-3) indicates that there is more than one, and possibly three, good species in Australia, one of which awaits description. ...
Context 4
... the broad description of C. muelleri in Australia there is a large degree of variation in vegetative morphology and oospore features (e.g. Figs 10, 11, cf. Casanova 1997), so further revision of this taxon is needed. ...
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... Agardhia in Australia contains C. fibrosa, C. leptopitys and C. ecklonii (Wood 1972). Woods concept of C. leptopitys included all taxa in subsection Agardhia with basal gametangia, and included Nordstedt's (1891) subspecies subebracteata as a form. There is some variation in C. leptopitys, with apparently distinct entities in Tasmania (Fig. 14), Western Australia (Fig. 15) and Victoria, and if gametangial arrangement is diagnostic of species differences (Proctor 1975) then the arid zone taxon subebracteata should also be considered separate at the species level because this is the only taxon in Chara in which gametangia are clustered outside the base of the whorl (cf. ...
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... contains C. fibrosa, C. leptopitys and C. ecklonii (Wood 1972). Woods concept of C. leptopitys included all taxa in subsection Agardhia with basal gametangia, and included Nordstedt's (1891) subspecies subebracteata as a form. There is some variation in C. leptopitys, with apparently distinct entities in Tasmania (Fig. 14), Western Australia (Fig. 15) and Victoria, and if gametangial arrangement is diagnostic of species differences (Proctor 1975) then the arid zone taxon subebracteata should also be considered separate at the species level because this is the only taxon in Chara in which gametangia are clustered outside the base of the whorl (cf. Lamprothamnium in which at least two ...
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... in which at least two species have this arrangement). The variation in C. leptopitys is also apparent in the oospores (Figs 14, 15). ...
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... ecklonii (as amended by Wood) was the product of amalgamating endemic Tasmanian C. mollusca (Fig. 12) and African C. ecklonii (Wood 1965), maintaining the Tasmanian material as a separate variety. Wood (1972) added C. ecklonii var. albaniensis (Fig. 13) on the basis of a single incomplete male specimen collected in Albany, WA (Wood 1972). It is possible that C. ecklonii in southern Africa and var. albaniensis in southern Western ...
Context 9
... ecklonii (as amended by Wood) was the product of amalgamating endemic Tasmanian C. mollusca (Fig. 12) and African C. ecklonii (Wood 1965), maintaining the Tasmanian material as a separate variety. Wood (1972) added C. ecklonii var. albaniensis (Fig. 13) on the basis of a single incomplete male specimen collected in Albany, WA (Wood 1972). It is possible that C. ecklonii in southern Africa and var. albaniensis in southern Western Australia are related, since there are common elements in the vascular flora of the two regions (e.g. family Proteaceae). However, given the disjunct ...
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... in lumping C. gymnopitys and C. fibrosa, but by the time he was working on the Australian specimens he saw fit to amalgamate at least 15 species that were described previously into C. fibrosa. Within that he was able to distinguish three varieties: var. fibrosa (with 20 forms, e.g. Figs 16, 17, 19; cf. Casanova 1997), var. hookeri (two forms e.g. Fig. 18) and var. myriophylla in Australia (Wood 1972). The variation in vegetative morphology among these entities is large, and there are correspondingly large differences in the oospores (Casanova 1997;Figs 16-19). Initial analyses indicate there are between six and 20 good species in this group (MT Casanova, A García unpubl. ...
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Citations
... This was recognised as a useful taxonomic character very early on (Braun 1849), and was termed a corona of cells (not to be confused with the coronula or 'little crown' of cells at the apex of the oogonium). The family Characeae was revised for Australia by Wood (1971); however, that revision resulted in an unusable taxonomy (Casanova 2005(Casanova , 2009, and some sections have since been revised (Casanova 2013a;Casanova and Karol 2014). In the present revision, Australian species of Chara sect. ...
... Reticulate ornamentation on oospores in Chara is unusual. All other Chara species known possess either smooth, pustulate or porate, fibrous or granulate oospores , Leitch et al. 1990Casanova 2005). Cortication is usually absent from the lowest axial internodes, and can be restricted to the very youngest internodes. ...
Australian species of Chara L. sect. Charopsis (Kütz.) Leonh. are revised. Multivariate analysis supports recognition of four species: Chara braunii C.C.Gmel., C. evanida Casanova, C. karolii Casanova and C. muelleri (A.Braun) F.Muell. These taxa are described and illustrated, and a key is provided.
... Swamps are almost exclusively on private land, and access to a diversity of swamps is limited. The angiosperms and charophytes collected were identified to species with the aid of Walsh andEntwisle (1994-1999), Casanova (2005Casanova ( , 2009Casanova ( , 2013 and Casanova and Karol (2014). Additional records of angiosperm occurrence were provided by Australia's Virtual Herbarium (www.chah.gov.au, ...
Freshwater temporary wetlands are a little-studied ecosystem world-wide. They have been recognised as critically endangered in south east Australia under Australian biodiversity conservation legislation. However, little has been recorded about their hydrology, functioning or biodiversity values; i.e. the factors that make them intrinsically âswampyâ. In this paper we develop a simple threshold model of wetland hydrology based on historical rainfall records and calculated evaporation records matched to records and recollections of the owners of swamps, and document water plant and microalgal species richness. The model indicates that swamps were inundated to at least 10 cm depth in an average of 6.3 years per decade for most of the 20th century. The average dry time between inundations was 1.27 years (maximum of 4.5 years). Since 1998 the frequency of inundation appears to have decreased, and the average dry times have increased. Despite, or because of, their temporary nature, these swamps have high biodiversity values among the vegetation and the microalgae, more than has been recorded for near-by permanent wetlands. There is no evidence that a drier and warmer climate will impact negatively on biodiversity values, however land management is likely to be important for maintaining these systems as the climate changes.
... The genus Chara L. is characterised by a five-celled coronula on the oogonium (oosporangium), placement of the oogonium above the antheridium where they occur together, whorls of accessory cells below the branchlet whorls (stipulodes) and essentially monopodial branchlet structure. The family Characeae was revised for Australia by Wood (1971); however, Wood's revision resulted in an unusable taxonomy (Casanova 2005(Casanova , 2009 and recent studies have shown that the lumping of Australian species with those in the northern hemisphere, and the delineation of numerous subtaxa (varieties, forms) do not represent reality, or enhance utility. There are many more species in Australia than were recognised by Wood (1971) (Casanova 2005(Casanova , 2009(Casanova , 2013García and Chivas 2006) and current advances in charophyte taxonomy, including investigation of oospore morphology with scanning electron microscopy, have allowed a new approach to the systematics of this group. ...
... The family Characeae was revised for Australia by Wood (1971); however, Wood's revision resulted in an unusable taxonomy (Casanova 2005(Casanova , 2009 and recent studies have shown that the lumping of Australian species with those in the northern hemisphere, and the delineation of numerous subtaxa (varieties, forms) do not represent reality, or enhance utility. There are many more species in Australia than were recognised by Wood (1971) (Casanova 2005(Casanova , 2009(Casanova , 2013García and Chivas 2006) and current advances in charophyte taxonomy, including investigation of oospore morphology with scanning electron microscopy, have allowed a new approach to the systematics of this group. ...
Protochara, comb. et stat. nov. Abstract. A revision of a group of ecorticate species of Chara is presented, on the basis of fresh, pressed and spirit-preserved material. The following seven species are recognised, characterised by a very simple morphology, with few or inconspicuous accessory cells (cortication, stipulodes, bract cells, bracteoles) and large gametangia: Chara australis R.Br., C. lucida (A.Braun) Casanova & Karol comb et. stat. nov., C. porteri Casanova, sp. nov., C. protocharoides Casanova & Karol, nom. nov. (=Protochara australis Womersley & Ophel) and C. stuartiana (Kütz.) Casanova & Karol comb. et. stat. nov. from Australia, and C. corallina Klein ex Willd. and C. wallichii A.Braun from Asia. A new section, Chara subg. Charopsis sect. Protochara (Womersley & Ophel) Casanova & Karol, comb. et stat. nov., is erected to accommodate these taxa, formerly placed in sect. Charopsis.
... Agardhia R.D. Wood (see Wood 1965) is characterised by a corticated axis and naked (ecorticate) branchlets; the branchlets are terminated by an end cell surrounded by a group of bract cells. There are at least 30 species described in the subsection (on the basis of the microspecies index of Wood (1965) and following the taxonomy of Casanova 2005), the type species of which is Chara fibrosa C.Agardh. ex Bruzelius (Bruzelius 1824 n.v.;Agardh 1824). ...
... In all these works, the true nature and identity of C. fibrosa has become obscured through amalgamation with other taxa. Recent approaches to the systematics of Characeae (McCourt et al. 1999;Casanova 2005;Boegle et al. 2007;Sakayama 2008) have revealed that entities with minor morphological differences can be distinguished as species, so it is likely that several taxa that were amalgamated with C. fibrosa are different species in their own right. The present paper aims to describe the morphology and distinguishing features of C. fibrosa and C. flaccida var. ...
Taxonomic circumscriptions of the charophyte taxa Chara fibrosa C.Agardh ex Bruzelius. and C. flaccida var. wightii A.Braun are revised, and both taxa are recognised at species rank, as C. fibrosa and C. wightii (A.Braun) Casanova. Both species are illustrated and a review of relevant morphological characters is also presented.
The response of swamp vegetation to cropping was measured by analysis of the seed bank present (as a measure of swamp resilience) and a survey of the extant vegetation (as a measure of swamp integrity). Samples of seed bank were exposed to a germination stimulus, the plants that germinated and established were identified, and the density of emergent vegetation was assessed. Surveys of the extant vegetation after flooding in cropped and uncropped swamps indicated that the plant communities establishing after the different treatments were different. Cropping results in a reduced diversity and density of plants, although swamp plant communities retain some resilience to such disturbances. Cropping also affects germination from the seed bank of these wetlands. The degree to which cropping is a threatening process to swamp plant communities and their dependent fauna will depend on whether vulnerable elements can return to swamps, which in turn depends on swamp management, connectivity and landscape level processes. As the climate changes and wetlands become more temporary and flooding less reliable, recognition and conservation of the processes that maintain biodiversity in the landscape will become more important.
