Nitella axillaris A. Braun (1858: 356)

Borges, Fabio Renato & Jr, Orlando Necchi, 2018, Taxonomy and phylogeny of Nitella (Charophyceae, Characeae) from Brazil with emphasis on the midwest and southeast regions, Phytotaxa 356 (3), pp. 181-198 : 189-190

Nitella axillaris A. Braun (1858: 356)

Figs. 11–16 .

Plants monoecious, up to 26.6 cm high, without calcium carbonate deposition. Axes 299–1182 μm in diameter, internodes 0.7–4.1 cm long, 0.5–3.5 (mean 1.1) times as long as the branchlets. Branchlets sterile and fertile different; steriles (5–) 6–8 in a whorl, 0.7–3.7 cm long, 1(2) furcated but appearing simple with tiny terminal coronula; rays (5–) 6–8, constituting the entire branchlet lenght, 283–929 μm in diameter. Dactyls (2)3–4(–6), 2(3)-celled, abbreviated, 0.02–0.04 cm long, 81–279 μm in diameter, penultimate cell tapering gradually towards the base of end cell; end cell conical, acute or acuminate, often deciduous. Fertile branchlets compacted in axillary heads (rarely terminal), 1–2 furcate. Heads numerous, axillary; sessile or stipitate, densely compact or rarely loose, to 0.4cm. Gametangia sejoined or conjoined restricted to branchlet nodes of the heads (rarely at branchlet nodes out of heads). Oogonia 1–2 at a node, 191–411 μm long (excl. nucula), 140–381 μm in wide; convolutions (5)6–7; coronula 26–43 μm high, 46–71 μm wide at base, upper cells usually higher than basal cells; coronular cells convergent, persistent. Oospores brown to dark brown, 236–278 μm long, 224–264 μm wide; striae (5–)6(–7); fossa 39–59 μm across; membrane reticulate under LM and beaded imperfect reticulate to reticulate under SEM. Antheridia solitary, 104–204 μm in diameter, 8 scutate.

Specimen examined:— BRAZIL. Mato Grosso do Sul: Entrance to the Recanto da Barra Farm, BR262, near KM484, between the municipalities of Terenos and Anastácio, 20°30’6.1’’S, 55°45’34.7’’W, 13 May 2014, coll. F. R. Borges (SJRP32553). São Paulo: Pond of Ninféias, State Park, Municipality of São Paulo, 23°38’19.40”S, 46°37’19.18”W, 12 September 2014, coll. D. F. Peralta (SJRP32566).

DNA sequences: rbc L- MG004810, MG004809; ITS1- MG029146, MG004809; ITS2- MG029146, MG004809.

Figures

FIGURES 11–16. Nitella axillaris. 11. Whorl with a small, axillary, sessile, compacted head, at a node of the thallus. 12. Whorl with a long, axillary, stipitate and compacted head. 13. 2-furcated fertile branchlet of a head. The black and red arrows indicate, respectively, the primary and the secondary nodes. 14. Dactyls 2-celled, abbreviated, forming a crown. Penultimate cell tapering gradually towards the base of end cell. End cell conical, acute or acuminate. 15. Oospore membrane with reticulate aspect under LM. 16. Oospore membrane with beaded imperfect reticulate aspect under SEM.