Lamprothamnium stipitatum Casanova, Austral.
Creators: name: Casanova, Michelle T.
name: Karol, Kenneth G.
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Plantae
Charophyta
Charophyceae
Charales
Characeae
Lamprothamnium
Lamprothamnium stipitatum

description: Lamprothamnium stipitatum Casanova, Austral.    Syst. Bot. 26: 285 (2013)   
 Type: Weelarrana Salt Lake, Pilbara region, WA, 6 Jan. 2011, M. T. Casanova r888 (holo: PERTH!; iso: MEL!).   
 Dioecious. Plants appearing more like a narrow species of Chara than Lamprothamnium (distinguished by the decumbent stipulodes, narrow axes and spreading bract cells, as well as the saline habitat), calcified. Axes 200–300 μm in diameter, ecorticate; internodes up to 5 cm long, a little shorter than the longest branchlets (Fig. 4 a). Stipulodes in a single row, opposite the branchlets (Fig. 4 d), up to 6 around, but often absent or reduced, downward-pointing, up to 200 μm long. Branchlets 6 in a whorl, up to 45 mm long, usually ~ 12 mm long, ecorticate, very narrow, up to 100 μm in diameter (Fig. 4 b, c), basal branchlet cell up to 2 mm long, branchlet end segments generally 2-celled, the terminal cell much shorter than the others, bract cells verticillate and spreading but usually very short, 100–200 μm long (Fig. 4 c). Fertile parts not much contracted, no real distinction between fertile and sterile whorls. Gametangia foliar and internal to the base of the branchlet whorl, sessile and stipitate, solitary and geminate. Oosporangia up to 500 μm long, 300 μm wide, stipitate (stipes up to 2 mm long) and sessile inside the base of the branchlet whorl, sometimes singular, sometimes geminate; on the branchlets, sessile and stipitate (Fig. 4 d), sometimes geminate (Fig. 4 f). Coronula of triangular cells (star-shaped from above; Fig. 4 e). Oospores black, 360–375 mm long, 200–210 μm wide, 8 or 9 striae of low, undulating ridges (Fig. 4 h), oospore ornamentation granulate (Fig. 4 i), end cell impression up to 65 mm at widest diameter (Fig. 4 j). Antheridia large, up to 550 mm in diameter, bright orange, sessile and stipitate inside the base of the branchlet whorl, sessile on the lowest two branchlet nodes (Fig. 4 b). Vegetative reproduction not known. Chromosomes n = 14 (Fig. 4 g).   Distribution  
In brackish temporary wetlands in northern inland Australia: the Pilbara region of Western Australia and the Tanami Desert.  Etymology  
 ‘ Stipitatum ’ in Latin means provided with a stipe or a stalk, this species being named for the long-stalked gametangia.   Notes  
 Lamprothamnium stipitatum is the only dioecious Lamprothamnium known from Northern Territory and has very large antheridia. It can be distinguished from dioecious L. heraldii A.García & Casanova on the basis of its stipitate gametangia and paucity of bract cells and stipulodes. This is just the second specimen seen, but it confirms the validity of the species. Lamprothamnium species frequently have gyrogonites, a character that is missing in ecorticate Chara species.   Specimens examined  
 NORTHERN TERRITORY: Fiddlers Lake, Tanami Desert, 14 Aug. 2001, P. K.Latz 17982 (DNA) [distinctive, but very poor material, intermixed with filamentous algae].
description: Published as part of Casanova, Michelle T. & Karol, Kenneth G., 2023, Charophytes of Australia's Northern Territory - I. Tribe Chareae, pp. 38-79 in Australian Systematic Botany 36 (1) on pages 45-47, DOI: 10.1071/SB22023, http://zenodo.org/record/10904227