Stellaria alpamarcae (A. Gray) 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 : 129

1. Stellaria alpamarcae (A. Gray) Montesinos & Borsch , comb. nov.

≡ Arenaria alpamarcae A. Gray, U. S. Expl. Exped., Phan. 15: 116. 1854.

– Lectotype (designated here): Peru, 1838–1842, Wilkes Expedition s.n. ( GH00037630 image!; isolectotype: NY00342438 image!) . – Fig. 1A .

Morphological description — Perennial herb, caespitose forming pulvinate dwarf cushions 2–4 cm high and 8–20 cm in diam.; root woody. Stems short or elongated erect in young plants becoming decumbent later on, usually covered by old foliage; internodes 1–2 mm long, with a scarce indumentum of trichomes <0.1 mm. Leaves imbricate, lamina ovate-lanceolate, 4–7 mm long and 0.9– 1.2 mm wide, longitudinally striate, midrib prominent on underside, margins thick, delicately folded toward adaxial surface, glabrous in distal part and at acuminate apex, turning ciliate toward base, where hairs can be dense (1–3 mm long). Plants bisexual-hermaphrodite. Flowers on 2–6 mm long, glabrous peduncles, terminal and axillary; perigynous, oblong, c. 4.5 mm long and 1.5–2.5 mm wide; calyx cylindrical-oblong; sepals 5, imbricate, oblong, 3–4 mm long and 1–2 mm wide, smooth, glabrous on surface and margins, apex acute-acuminate, usually folded and forming a cone-like cylinder that covers capsule; petals 5, strongly reduced, translucent, ovate, apex obtuse, c. 0.8 mm long and 0.5 mm wide; stamens 4 or 5, episepalous, 0.8–1.1 mm long; ovary cylindrical-turbinate, 0.6–0.9 mm long and 0.4–0.6 mm wide, style 3-fid, stigma aciculate, terete. Capsule ovoid, c. 1.5 mm long, containing 5–8 seeds, these globular in shape, c. 0.2 mm wide and 0.3 mm long; testa pale brown and cells with whitish stellate tubercles.

Distribution and ecology — Stellaria alpamarcae is endemic to Peru ( Cano & Sánchez 2006), occurring in Áncash, Huancavelica, Huánuco, Junín and Lima departments, at altitudes of 4000–4700 m. The species occurs in Puna grasslands distributed in highland passes, which are relatively humid throughout the year.

Notes — The specimen chosen as the lectotype was likely examined by Asa Gray for the description of the species. Assuming it came from the same gathering, the specimen in NY ( NY00342438 ) with a label indicating the years 1838–1842 and “ Peru ” would be an isolectotype .

The identity of further historical material annotated as isotypes of Arenaria alpamarcae available through JSTOR Global Plants ( JSTOR 2023) is less clear. The locality information on a specimen in US ( US 00103277) given as “Alpamarca above Obrajillo and Banos [possibly Baños]” corresponds to the highlands of the Lima department in central Peru , which is possibly a different place. A second specimen in NY ( NY00342437 ) lacks collector and geographical information and a specimen in P ( P00335842 ) has just a label indicating the years 1838–1842 but lacks any collector or locality data beyond “ 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.