Nitella heterophylla (A.Braun) A.Braun, Hookers J.

Casanova, Michelle T. & Karol, Kenneth G., 2023, Charophytes of Australia’s Northern Territory - II. Tribe Nitelleae, Australian Systematic Botany 36 (4), pp. 322-353 : 335

Nitella heterophylla (A.Braun) A.Braun, Hookers J.

Bot. Kew Gard. Misc. 1: 198 (1849)

Chara heterophylla A.Braun , Linnaea 17: 113 (1843).

Nitella lhotzkyi f. heterophylla (A.Braun) R.D. Wood , Taxon 11: 22 (1962).

Type: in fluvio ‘ Adams River’ (Grantham), Western Australia, 7-iii- 1841, L.Preiss 1876 (holo: B n.v. [apparently destroyed]; iso: LD! [fragment], LE! [fragment]) .

Dioecious. Plants up to 40 cm high ( Fig. 7 a ); heterophyllous whorls well separated on the axis; branchlets with little clusters of dactyls at their tips, like pom-poms; frequently covered in mucus and attached debris ( Fig. 7 b ). Axes up to 800 µm wide; internodes up to 70 mm long, much longer than the branchlet whorls. Fertile branchlets 1× furcate ( Fig. 7 d, e ), in 2 whorls; primary branchlets 7 or 8 in a whorl, similar to the sterile branchlets but somewhat smaller, contracted and covered in mucus; primary segments up to 0.5 mm long, secondary segments (=dactyls), 2–8, up to 1 mm long; secondary branchlets simple or 1× furcate, up to 1 mm long, shorter than primary branchlets; sometimes also bearing reproductive structures; sterile branchlets in 2 whorls, 2 or 3× furcate ( Fig. 7 b ), 7 or 8 primary branchlets in a whorl, up to 8 mm long, primary segments up to 4 mm long, secondary segments 3–8, up to 2 mm long, tertiary segments 3–7, up to 1 mm long, some very short and divided into 3 or 4 quaternary segments, all dactyls up to 1.2 mm long; secondary branchlets ~6, simple or 1× furcate, sometimes a secondary segment becoming a central (percurrent) ray, up to 2 mm long. Dactyls usually 5–7, up to 1.2 mm long; bicellulate, the end-cell shortly conical and acute. Sterile dactyls similar to fertile; 3–8, up to 2 mm long. Heads somewhat spike-like, the upper whorls narrow and contracted and often covered in thick mucus. Gametangia at the fertile branchlet nodes. Oosporangia up to 500 µm long × 420 µm wide with ~7 helical stripes ( Fig. 7 c ); coronula up to 35 µm high. Oospores 380–420 µm long × 250–300 µm wide with 7 or 8 large flanges ( Fig. 7 g ), the ornamentation fibrous and the fibres somewhat ropey ( Fig. 7 h ), visible as fibres under the light microscope. The impressions of the basal cells are angular, maximum diameter ~40 µm ( Fig. 7 i ). Antheridia

up to 350 µm in diameter. Chromosome numbers n = 9 ( Fig. 7 f ).

Taxonomic notes

Nitella heterophylla was established as a species on the basis of its heteroclemous whorls of branchlets, the number of dactyls, the axis diameter and the size of the oospores. It was amalgamated with N. lhotzkyi by Wood (1962), but it has large fibrous oospores whereas N. lhotzkyi has smaller papillate oospores. It was initially distinguished in the Pilbara Biological Survey ( Lyons 2015) because of its dioecy and long primary branchlet segments in the primary whorls, along with the distinctive oospore. Investigation of the isotype material (fragments in LD and LE) helped in the application of the correct name for this taxon.

Recognition

Nitella heterophylla is dioecious with heteroclemous whorls and distinctive oospores. The oospores of N. heterophylla are similar to those of both N. hyalina (which is monoecious) and N. congesta (dioecious, but with ~40 accessory branchlets in the sterile whorls). Additionally, N. congesta has more furcations and uniformly shorter primary branchlet segments.

Distribution

Arid and semi-arid zones in New South Wales, the Northern Territory and Western Australia, but probably more widespread.

Etymology

The epithet heterophylla probably refers to the two different types of branchlet whorls.

Specimens examined

WESTERN AUSTRALIA: in 0–6″ [~ 0–15.2 cm] of water, black muck covered with red silt, in a pond immediately NE of railroad crossing, just N of Watheroo , 1 Oct. 1960, R. D. Wood 60-10-1-9 ( L, NY); Coondiner Pool , 5 Sep. 2003, M. N. Lyons 3000 ( PERTH); Gnalka Gnoona , 4 Sep. 2003, M. N. Lyons 3046 ( PERTH); Watrara Creek Pool, 8 Sep. 2003, M. N. Lyons 3046a ( MEL, NY, PERTH); Carawine Gorge T1 , 12 Sep. 2003, M. N. Lyons & S . D.Lyons 3035-b ( PERTH); Gnalka Gnoona CT2 , 4 Sep. 2003, M. N. Lyons & S . D.Lyons 3047-a ( PERTH); cultured from seed bank in a glasshouse in Westmere, ex Rudal River , 4 Oct. 2005, M. T. Casanova p701 ( MEL); cultured from seed bank in a glasshouse in Westmere , ex Coondiner Pool, 4 Oct. 2005, M. T. Casanova p760 ( MEL, NY); cultured from seed bank in a glasshouse in Westmere, ex Ethel Creek Claypan, 12 Oct. 2005, M. T. Casanova p768 ( MEL, NY); cultured from seed bank in a glasshouse in Westmere, ex Fortescue Marsh East , 16 Oct. 2005, M. T. Casanova p771 ( MEL, NY); Bobswim Pool T2 , 12 May 2005, M. N. Lyons & D. A . Mickle 3149 ( PERTH); pool on Lower Fortescue T1 , 22 Aug. 2005, M. N. Lyons & D. A . Mickle 3156 ( PERTH); Rocky Island Pool T2 , 9 Sep. 2005, M. N. Lyons & D. A . Mickle 3185 ( PERTH); Koodjeepindawarranna Pool , 17 Aug. 2006, M. T. Casanova p943 ( MEL); Watrara Creek Pool T1 , 3 Sep. 2006, M. N. Lyons & D. A . Mickle 3255 ( PERTH); Desert Queen Baths Adj , 2 Sep. 2006, M. N. Lyons & D. A . Mickle 3251-a ( PERTH); Pewar West T1 / T2 , 21 May 2006, D. A. Mickle & N. Y . Huang 39- 3118 ( PERTH); Coondiner Pool T1 , 15 Aug. 2006, M. T. Casanova PBS2 ( MEL); Hamersley Gorge T1 , 18 Aug. 2006, M. T. Casanova PBS20 ( MEL); Gnalka Gnoona T1 , 19 Aug. 2006, M. T. Casanova PBS36 ( MEL); Koodjeepindawarranna Pool Adj , 19 Aug. 2006, M. T. Casanova PBS39 ( MEL); Bobswim Pool T1 , 20 Aug. 2006, M. T. Casanova PBS46 ( MEL); Palm Spring on Cave Creek T2 , 21 Aug. 2006, M. T. Casanova PBS53 ( MEL); Palm Spring near Millstream T2 , 22 Aug. 2006, M. T. Casanova PBS72 ( MEL); Weeli Wolli T1 , 16 Aug. 2006, M. T. Casanova PBS8 ( MEL); Koodjeepindawarranna Pool , 31 Aug. 2006, I. J. Powling s.n ( MEL); WPT155 , 5 Sep. 2006, I. J. Powling s.n. ( MEL) . NORTHERN TERRITORY: Dingo Waterhole, Lander River , 5 Dec. 1986, P. K. Latz 81234 (DNA); 75 km NW of Lake Surprise , submerged in freshwater, 19 Aug. 1991, P. K.Latz 12209 (DNA). NEW SOUTH WALES: Dumaresq Dam, shallow water, near car park, 1 Dec. 2009, M. T. Casanova r460 ( MEL, NY) .

Figures

Fig. 7. Nitella heterophylla. (a–c) From specimen M.T.Casanova r460 (MEL). (d–i) From specimen M.T.Casanova p770 (PERTH). (a) Whole plant, scale: 1 cm. (b) Whorl of branchlets, scale: 1 mm. (c) Fertilised oogonium, scale: 200 µm. (d) Fertile female shoot, scale: 1 mm. (e) Fertile male shoot, scale: 1 mm. (f) Chromosomes in metaphase, 1000× magnification. (g) Scanning electron microscope (SEM) image of oospore in side view, scale: 100 µm. (h) SEM image of detail of oospore wall, scale: 20 µm. (i) SEM image of basal view of oospore, showing end-cell impressions on the oospore wall, scale: 100 µm.