Stellaria congesta 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 : 130-131

4. Stellaria congesta Montesinos & Borsch , nom. nov.

≡ Cherleria nitida Bartl. in Presl, Reliq. Haenk. 2: 12. 1831 ≡ Arenaria nitida (Bartl.) Rohrb. in Linnaea 37: 249. 1872 [non Stellaria nitida Hook. in Scoresby, J. Voy. North. Whale-Industry: 411. 1823].

– Lectotype (designated here): Peru, Cobradillo [illegible, possibly misspelled as Obrajillo, town located in Canta, Lima], 1821, Haenke s.n. ( GOET000573 !) . – Fig. 1B .

Morphological description — Perennial herb, caespitose, forming cushions or small mats, c. 4 cm high and up to 20 cm in diam.; root woody. Stems procumbent, numerous, forming a densely congested structure, with 6–10 cm long branches; internodes short, c. 0.1 mm long, glabrous. Leaves imbricate dense, rigid, lamina thick, ovate, 4–7 mm long and 1–1.2 mm wide, acute or slightly mucronate at apex, base scarcely attenuated, margins glabrous, also at base, margins involute, midrib prominent on underside. Plants bisexual-hermaphrodite. Flowers on 2.5–3 mm long, glabrous peduncles, terminal and axillary; perigynous, oblong, 3.5–4.5 mm long and 1–1.5 mm wide; calyx cylindrical-turbinate; sepals 5, imbricate, lanceolate, involute, 2–2.5 mm long and 1–2 mm wide, pale green to yellow, glabrous on surface and margins, apex acute-acuminate, folded and forming a cone-like cylinder that covers capsule; petals 5, strongly reduced, translucent, ovate, apex obtuse, 0.8–1 mm long and 0.5–0.7 mm wide; stamens 4 or 5, episepalous, 0.8–1.1 mm long; ovary cylindrical-turbinate, 0.8–1.2 mm long and 0.8–1.1 mm wide, style 3-fid, stigma aciculate. Capsule narrowly ovoid, shorter than calyx when mature, 1.5–2 mm long, opening with 6 valves, containing 6 seeds, these suborbicular, lentiform, 0.2–0.3 mm in diam.; testa pale brown, bearing whitish protuberances.

Distribution — The species is endemic to Peru ( Cano & Sánchez 2006) and is known to occur in Áncash, Huánuco, La Libertad and Junín departments according to the material revised and at altitudes of 3900–4500 m.

Etymology — The epithet congesta refers to the uniform and compact growth of the species.

Notes — The specimen at GOET has the annotation “rel. Haenk. II, 12 (cum descriptione)”, which indicates that the specimen may have been used to make a description.

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.