Stellaria pedunculosa (Wedd.) 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 : 135-136

13. Stellaria pedunculosa (Wedd.) Montesinos & Borsch , comb. nov.

≡ Arenaria pedunculosa Wedd. in Ann. Sci. Nat., Bot., ser. 5, 1: 294. 1864.

– Lectotype (designated here): Bolivia, La Paz, Ravin de Chuquiaguillo, 1851, H. Weddell s.n (P [ P 00274242 image!]) . – Fig. 1E .

Morphological description — Annual herb, forming small caespitose tufts, 1–2 cm high and 2–3.5 cm in diam.; roots fibrous. Stems few, often further ramified at base; internodes 1–4.5 mm long, glabrous. Leaves opposite, sessile; lamina oblong-ovate, 4–6 mm long and 1–1.6 mm wide, thin, to some extent curved at tip, rarely involute, scarcely covered by tomentulose hairs on upper- and underside, midrib inconspicuous; base truncated and apex acute, margin tomentulose with multicellular hairs 0.1–0.25 mm long (occasionally mammillate and without distinct trichomes), usually persistent on older foliage; leaves pale green to yellow-brownish with age. Plants bisexual-hermaphrodite. Flowers perigynous, on rigid 8–11 mm long peduncles covered with minute papillae, terminal, ovoid, 2–2.6 mm long and 1–1.6 mm wide; calyx cylindrical-campanulate, crateriform; sepals 5, ovate, 1.8–2.4 mm long and 0.8–1 mm wide, slightly involute, green to yellowish-translucent with age, cupuliform at base, apex acute, mucronate, pale green to yellowish, surface glabrous, margins with scattered papillae, 0.08–0.1 mm long; petals 5, reduced, light green, ovate, obtuse, equalling sepals or shorter, 1.2–1.5 mm long and 0.6–0.8 mm wide; stamens 5, very short, 0.2–0.4 mm long, episepalous; style 3-fid, glandular, 0.25–0.35 mm long, aciculate; ovary ovoid, 0.2–0.5 mm long and 0.3– 0.5 mm wide. Capsule ovoid, c. 1 mm long, glabrous, containing 2–5 seeds, these orbicular, 0.6–0.8 mm in diam., testa brown-yellowish, granulate.

Distribution — Based on two collections (DBMT 5395b, 4565), Arenaria pedunculosa is located at the lower slopes SE of Ticsani volcano (Moquegua department), on volcanic pumice soils at altitudes of 4500–4820 m. Flowers and fruits were observed between February and March. In Bolivia the species is known only from the type collection, and a search of material at LPB in 2019 provided no evidence that the species has been collected again.

Vernacular name — Jiska Volcanqura Panqara, given in Aymara language (Kent Chicalla, Moquegua, pers. comm.).

Notes — Even though the intense survey done at the herbaria mentioned in the methods, no specimens have been found as additional collections for Bolivia, but two specimens have been found from the Moquegua department in Peru.

Figures

Fig. 1 (p. 120). Habit in natural environment of some species of the Plettkea clade of Stellaria. – A: S. alpamarcae, Huánuco, Huamalies, 4400 m (Montesinos 5487, CAR440); B: S. congesta, Huánuco, Huamalies, 4200 m (Montesinos 4900, CAR661); C: S. galianoi, Cusco, Urubamba, near Malaga pass, 4240 m, shady rocky slopes in moist grasslands (Montesinos & von Mering 4523, CAR677); D: S. macbridei, Huánuco, Lauricocha, 4790 m (Montesinos 4590, CAR630); E: S. pedunculosa, Moquegua, near Ticsani volcano, 4818 m, pumice slopes (Montesinos & Chicalla 5395d, CAR777); F: S. utcubambensis, Amazonas, Chachapoyas, Leymebamba, Tajopampa, 3700 m, rocky summits of recently burnt slopes (Montesinos & Garcia 4979, CAR433); G: S. weberbaueri, Arequipa, 4876 m, forming cushions with eventually elongated stems (Montesinos & von Mering 4496, CAR670); H: S. xanthophylla Amazonas, S Leymebamba, 3540 m, forming dense mats (Montesinos 6970a, CAR691). – All photographs by Daniel B. Montesinos-Tubée.