Oritrophium yacuriense Arnelas & J. Calvo, 2017

Arnelas, Itziar, Armijos-Barros, J. L. & Calvo, Joel, 2017, Oritrophium yacuriense (Astereae, Compositae), an overlooked new species from southern Ecuador, Phytotaxa 302 (3), pp. 273-278 : 274-276

Oritrophium yacuriense Arnelas & J. Calvo , sp. nov. ( Fig. 1 )

Type: — ECUADOR. Loja: Espíndola, Jimbura, Parque Nacional de Yacuri, near Laguna Negra, 4º42’45’’S, 79º25’48’’W, 3395 m, 11 Dec 2016, I. Arnelas Seco & J. L. Armijos Barros 500 (holotype: HUTPL-10851, isotypes: QCNE).

Oritrophium yacuriense differs from all other Oritrophium species in its leaves, which are lanceolate, slightly conduplicate, distantly short-dentate, glabrous, arranged in a dense rosette and covered with a mucilaginous substance.

Small scapose perennial herb, rhizomatous, 7−11 cm tall. Leaves 28−57 in a dense rosette, 9−13(−22) × (1.6−) 2−3.3 mm, narrowly lanceolate, slightly conduplicate, obtuse, attenuated in a short petiole 0.8−1 mm long, with (1−)2−3 short brown teeth on the upper half of each margin, glabrous, bright green, mucilaginous, with prominent central and lateral veins beneath; basal sheath with deciduous silky unicellular hairs, brownish coloured, covering the rhizome. Scapes 1−2, 6−9 cm long, covered with multicellular trichomes 0.5−1.5 mm long; bracts 4.5−6.5 × 0.8−1 mm, alternate, oblong to narrowly lanceolate, obtuse, glabrous or sparsely pubescent. Capitulum 13−17 mm in diam., solitary; involucre 6−7.5 × (2−) 2.8−3 mm, cylindrical, 4-seriate; involucral bracts unequal, glabrous, mucilaginous, green, with purple or brownish membranaceous margins (sometimes slightly fimbriate); outer and middle involucral bracts oblong, obtuse, rarely acute, mucronate or shortly fimbriate; inner involucral bracts linear, acute, slightly fimbriate. Ray florets 24−28, pistillate, 6.5−7.5 mm long; limb 4−4.5 × 0.7−1.6 mm, with 2−3 teeth at the apex, white; tube 2.5−3 mm long, light green, with scattered multicellular trichomes; style 2.7−3.8 mm long, with branches 0.7−0.9 mm, brownish on the margins. Disc florets 24−28, functionally staminate, 3−4 mm long, funnelform, with 5 equal triangular acute lobes 0.4−0.9 mm, with scattered unicellular trichomes, yellow; style 4.3−4.6 mm long, with branches 0.9 mm, densely papillate; anthers 0.8−1 mm, bright yellow when fertile, often with dark brown connective, apical appendage ca. 0.2 mm. Achenes of ray florets 2−2.6 × 0.5−0.6 mm, fusiform, compressed, 3-ribbed, brown, highly sericeous; pappus simple, 3−3.5 mm, pale yellow to brownish, barbellate; achenes of disc florets sterile, sericeous, whitish; pappus 3.2−3.7 mm, pale yellow-brown, barbellate. Chromosome number: unknown.

Distribution and habitat: — Oritrophium yacuriense is only known from the lagoon complex of the Yacuri National Park in southern Ecuador ( Fig. 2A, 2B ). However, the occurrence of the species in northern Peru is possible given the proximity to the Ecuador –Peruvian border. This species grows in wet herbaceous páramos next to the lakes, between 3300−3550 m.

Etymology: —The epithet yacuriense refers to the name of the National Park, “Yacuri”, where the new species was found. The Park was named after one of its main features, the Yacuri lagoon complex. In the Quechua language “Yacu” means water and “curi” means gold, which probably reflects the presence of gold in its waters. Indeed, this metal is currently extracted in the area.

Additional specimens examined (paratypes): — ECUADOR. Loja: cordillera de Amaluza, lagunas de Jimbura, ladera al lado de la laguna Grande, 4º42’S, 79º25’W, 20 July 1999, O. Cabrera 435 (LOJA) ; muletrack Amaluza-Palanda, 4º37’S, 79º19’W, 4 Apr 1985, B. Eriksen 59184 ( QCA, QCNE) ; cordillera de Las Lagunitas, Amaluza- Jimbura-Zumba km 36, 4º43’S, 79º26’W, 22 Nov 1994, P. M. JØrgensen & al. 743 (LOJA, MO, QCA, QCNE) ; Lagunas Negras de Jimbura, 4º42’S, 79º25’W, 10 Sep 2001, P. Lozano & R. Bussmann 54 (LOJA) ; muletrack Amaluza-Palanda, western slope, near the pass (at laguna Areviatadas Pilares), 4º35’S, 79º20’W, 22 Sep 1976, B. Øllgaard & H. Balslev 9716 ( AAU) ; Cordillera las Lagunillas (de Sabanilla), páramo de las Lagunas Negras, 4º42’S, 79º26’W, 16 June 2009, P. Sklenář, J. Macková & P. Macek 12032 ( QCA) ; Amaluza, laguna Chuquiragua, 4º36’S, 79º21’W, 1 Dec 1983, F. Vivar & B. Merino 1958 (LOJA) ; páramos de Jimbura, 4º44’S, 79º25’W, 11 July 2006, A. Zhofre & al. 466 (LOJA) .

Discussion: —In morphology, O. yacuriense resembles O. repens . However, they can be easily differentiated by the leaf characters ( Fig. 1C , 3B, 3C ). The new taxon possesses the leaves lanceolate (vs. oblong-elliptic, rarely lanceolate), smaller, distantly short-dentate (vs. entire), slightly conduplicate (vs. not conduplicate), and plane (vs. revolute) (see Table 1). Moreover, in O. yacuriense the leaves are arranged in a denser rosette and are covered by a mucilage. On the basis of the specimens studied, the distribution areas of these species do not overlap. It is noteworthy that the populations of O. yacuriense are surrounded by the wider distribution of O. repens , which occurs from northern Loja in Ecuador to the highlands of Lambayeque and Cajamarca in Peru (with an isolated collection from Pasto Province in Central Peru, F-1959393) ( Fig. 2A , and see Appendix 1 for details on specimens examined). Our field trips to the Ecuadorian populations of both species let us report some differences in their habitats. Oritrophium yacuriense was always observed on rocky soils next to the shore of lagoons and headwaters, while O. repens tends to grow on organic soils and is not restricted to shorelines.

Another taxon with leaves oblong-elliptic and glabrous, or almost so, is O. limnophilum subsp. mutisianum ( Cuatrecasas 1935: 21) Cuatrecasas (1961: 29) but any confusion with this taxon is very unlikely because of its broad outer involucral bracts. In addition, its leaves are entire, usually remarkably larger, and not as shiny as in O. yacuriense . Their distribution areas do not overlap.

Conservation status: —The new species is only known from two near localities within the National Park Yacuri ( Fig. 2B ), situated within less than 5,000 km 2. The number of matured individuals observed in one of the two localities was less than 20 individuals. However, further field work is needed to locate new populations. On this basis, we preliminary consider this species to be Endangered (EN) according to B1ab(v) criteria of IUCN category (2001).

Figures

FIGURE 1. Oritrophium yacuriense. A. Habit. B. Capitulum. C. Detail of rosette. Plant from type locality.

FIGURE 2. Distribution map of Oritrophium yacuriense (red triangle) and O. repens (black triangle). A. General distribution. B. Ecuadorian and northernmost Peruvian populations.

FIGURE 3. Oritrophium repens. A. Habit. B, C. Detail of rosette. D. Capitulum. Plant photographed at Podocarpus National Park (I. Arnelas Seco & J.L. Barros-Armijos 506, HUTPL-10853).