Stellaria keraiopetala (Mattf.) Montesinos & Borsch, 2023

Montesinos-Tubée, Daniel B. & Borsch, Thomas, 2023, Molecular phylogenetics and morphology reveal the Plettkea lineage including several members of Arenaria and Pycnophyllopsis to be a clade of 21 South American species nested within Stellaria (Caryophyllaceae, Alsineae), Willdenowia 53 (3), pp. 115-148 : 133-134

8. Stellaria keraiopetala (Mattf.) Montesinos & Borsch , comb. nov.

≡ Pycnophyllopsis keraiopetala Mattf. in Schriften Vereins Naturk. Unterweser, n.s., 7: reprint p. 22 (26). 1934.

– Holotype: Bolivia, zwischen Palca und La Paz , an Felsen , 4800 m, Apr 1908, K. Pflanz 233 ( B †). – Neotype (designated by Timaná 2017: 6): Bolivia, La Paz, Murillo, Cordillera Real , road to nevado Chacaltaya , N of Milluni crossing E of Lake Milluni along roadsides , 4600–4900 m, 25 Jan 2000, Timaná 3804 ( LPB0000524 ; isoneotypes: BM, K, LL, MCSN, MICH, USM) .

Morphological description — See Timaná (2005).

Distribution — The species is endemic to Bolivia and based on two collections and according to Timaná (2017), it is known to occur at altitudes of 4600–5100 m.

Notes — The neotype located at the Herbario Nacional de Bolivia, Universidad Mayor de San Andrés (LPB) was designated by Timaná since the original material collected by K. Pflanz 223 was lost (B†). According to Timaná (2017), Pycnophyllopsis keraiopetala (now Stellaria keraiopetala ) is the only species with trimerous petals and stamens, although tetramerous and pentamerous forms are also found (sometimes all three forms in the same plant). Stellaria keraiopetala is the sister to S. weberbaueri , and both share the habit of dense small cushions with stems covered by overlapping leaves. Stellaria keraiopetala and S. weberbaueri appear to be geographically vicariant species due to its distribution in the highest parts of the Andes in Bolivia and Peru, respectively.