Nitella myriotricha A.Braun ex Kütz.

Casanova, Michelle T. & Karol, Kenneth G., 2023, Charophytes of Australia’s Northern Territory - II. Tribe Nitelleae, Australian Systematic Botany 36 (4), pp. 322-353 : 340-343

Nitella myriotricha A.Braun ex Kütz. Tab. Phycol. 7: 15, pl. 39. (1857)

Type: Prope McIvor, 1852?, F. v. Mueller 819 (holo: MEL!; iso: MEL!) .

Dioecious. Plants elongate, fine and flabellate with thick mucus on the upper whorls; up to 210 mm high ( Fig. 11 a ). Axes 800–950 µm in diameter; internodes 28–60 mm long; branchlets up to 30 mm long. Fertile branchlets contracted and covered in mucus ( Fig. 11 e ); 5 or 6 in a whorl, usually 3× but up to 4×furcate. Primary segments 1–2 mm long, furcate into 5–7 secondary segments up to 500 µm long; these again furcate into 4 or 5 tertiary segments ~500 µm long; these again furcate into 2–5 quaternary segments (dactyls), each 2 cells long and 500–1500 µm long. The end-cells are elongate (200–300 µm long) and briefly apiculate. Sterile branchlets 6 in a whorl, 3 or 4×furcate, to 30 mm long; primary segments approximately half the branchlet length, up to 15 mm long and 200 µm wide; secondary segments 5 or 6, 2–3 mm long and 100 µm wide; tertiary segments 2–4 to 2–3 mm long and 20 µm wide; quaternary segments 1–4, up to 2 mm long and 15 µm wide; quinary segments (where present) 3–5, up to 3 mm long and 10 µm wide ( Fig. 11 c ). Sterile dactyls 3 or 4 cells long ( Fig. 11 b ); end-cells variable but generally elongate and apiculate ( Fig. 11 d ). Gametangia at all furcations. Oosporangia up to 310 µm long; coronula ~20 µm high, upper row of cells similar to lower row of cells

( Fig. 11 e ). Oospores dark brown, 210–280 µm long, 190–210 µm wide with 7 or 8 striae with smooth flanges 10–30 µm high ( Fig. 11 f ), uniting into a crest at the apex of the oospore. Ornamentation of a smooth reticulum, the ridges sometimes developing small papillae. The specimen illustrated appears to have an incomplete reticulum ( Fig. 11 g ). Basal-cell impressions rectangular and triangular ( Fig. 11 h ). Antheridia not known. Chromosome numbers not known.

Distribution

Rivers and streams from Victoria to Queensland. This is the first record from the Northern Territory.

Specimens examined

NORTHERN TERRITORY: Parkin Road , 6 May 2010, P. Dostine 59DW73-2 ( MEL); Billabong next to the Darwin River , 4 May 2011, J. Schult t842 ( MEL) .

Figures

Fig. 11. Nitella myriotricha (a, b) from specimen J.Schult t842 (MEL), (c–h) from specimen P. Dostine 59DW73-2 (MEL). (a) Habit of shoot, scale: 10 cm. (b) Sterile branchlet tips, scale: 0.5 mm. (c) Sterile whorl, scale: 5 mm. (d) Branchlet tips, scale: 100 µm. (e) Female fertile branchlet, scale: 5 mm. (f) Scanning electron microscope (SEM) image of oospore, scale: 100 µm. (g) SEM image of detail of oospore wall, scale: 20 µm. (h) Impression of end-cells on oospore wall, scale: 50 µm.