Stellaria standleyi (Baehni & J. F. Macbr.) 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 : 137

16. Stellaria standleyi (Baehni & J. F. Macbr.) Montesinos & Borsch , comb. nov.

≡ Arenaria standleyi Baehni & J. F. Macbr. in Publ. Field Mus. Nat. Hist., Bot. Ser. 13(2): 604. 1937.

– Lectotype (designated here): Peru, Ayacucho department, Mt. Razuhuillca, Prov. Huanta , 4200 m, A. Weberbauer 7489 ( F- 562398! ) .

Morphological description — Perennial herb, caespitose, densely branched, cushions 1–4 cm high and 10–15 cm in diam.; roots subwoody. Stems numerous, densely covered by stiff foliage; internodes 0.1–0.3 mm long, glabrous; leaves alternate, lamina ovate to linear-lanceolate, 3–4 mm long and 1–1.5 mm wide, thick and glossy, apex acute and base truncate, yellowish in colour and glabrous on both sides, midrib prominent on underside, margins usually folded toward underside, densely covered by a narrow band of trichomes <0.1 mm long. Plants bisexual-hermaphrodite. Flowers perigynous, terminal and axillary, on 1–2 mm long glabrous peduncles, oblong, 3–3.5 mm long and 0.8–1.1 mm wide; calyx cylindrical-turbinate, crateriform, thicker at base, 2.7–3.2 mm long and 2.5–3.4 mm wide; sepals 5, imbricate, ovate, 2.5–3 mm long and 0.5–1 mm wide, glabrous on surface, green or pale green to yellowish-translucent with age, involute, apex acuminate; petals 5, reduced, white-translucent, ovate, apex obtuse, 2–2.4 mm long and 0.3–0.4 mm wide; stamens 4, episepalous, anthers orbicular-ovate, yellowish-translucent, 0.3–0.4 mm long; ovary ovoid-turbinate, 0.6–0.9 mm long and 0.6–0.8 mm wide, style 3-fid, stigma aciculate, pale white. Capsule ovoid, 1.2– 1.5 mm long and 1.1–1.3 mm wide, glabrous, containing 3–5 seeds, these ovoid, c. 0.5 mm long, testa brown, tuberculate.

Distribution — Peru, Ayacucho department at an altitude of c. 4200 m in open grasslands in Puna ecosystems characteristic of the central Andes. No further collections were found, so this is to be considered as a rare species.

Notes — The collection A. Weberbauer 7489 shows the typical characters of Stellaria sect. Plettkea by sharing the leaf size, texture, and form, as well as the flower and seeds characteristics as described in the morphological description. Because Macbride (1937) did not mention a specific type specimen in the protologue, a lectotypification is made here, using the locality information in the protologue that matches with the Weberbauer specimen that also exhibits the morphological characters described.