Gynoxys yasgolgensis Revilla & Coronel-Castro, 2025

Revilla, Italo, Coronel-Castro, Elver, Meza-Mori, Gerson & Amasifuen Guerra, Carlos A., 2025, Gynoxys yasgolgensis (Asteraceae, Senecioneae): A new species from northern Peru, Phytotaxa 684 (2), pp. 139-146 : 140-144

Gynoxys yasgolgensis Revilla & Coronel-Castro , sp. nov. ( Figure 1 )

urn:lsid:ipni.org:names:77355476-1

Type: — PERU. Provincia de Chachapoyas : Cordillera Yasgolga, road to Chilchos, 6°40’03”S 77°42’52”W, 2800 m, 18 May 2023 (fl.), E. Coronel ECC-194 (holotype: KUELAP!; isotype: HSP!) .

Diagnosis: —The new species is characterized by a woolly simple tomentum on the leaf underside with 6–8 mm trichomes. Secondary veins are partially inconspicuous, and a reticulated tertiary venation becomes conspicuous when the leaf is dried. Synflorescences have a yellowish ferruginous pubescence, with linear bracts of the calyculus (3–5 mm) that can be half the length of the phyllaries (4.5–6 mm).

Description: —Treelets or shrubs ca. 2–3 meters tall. Main stem with fissured bark, terminal twigs with yellow-rusty indumentum, composed of simple woolly trichomes. Leaves opposite, simple, petioles 1.5–2 cm long, lamina entire, coriaceous, oblong to ovate, with revolute margins, 4–5 × 1.4–1.8 cm long, base rounded, apex acute. Adaxial surface glabrescent, with scattered trichomes, midvein with trichomes. Abaxial surface with woolly pubescence, consisting of two layers of trichomes, upper layer with long yellowish coiled and simple trichomes, 6–8 mm long, inner adpressed layer composed of short simple trichomes 1–2 mm long. Venation pinnate, with 12–14 pairs of slightly visible secondary veins, prominent reticulate tertiary venation upon drying. Synflorescences thyrsoid, terminal with 2– 3 branches. Capitula radiate, 8–10 mm long and 7–10 mm wide; pedicels 0.5–1 cm long, with 2–3 linear bracts 3.7–5 mm long, densely woolly pubescent with simple yellow-rusty trichomes, 0.6–1 mm long. Involucre cylindrical, with a calyculus generally of 2 linear bracts 3–5 mm long, densely ferruginous tomentose; phyllaries 8(–10), uniseriate and membranous, outer phyllaries lanceolate, 4.5–6 × 1.5 mm, apex acute, inner phyllaries oblong-lanceolate, 4.5–6 × 2 mm, margins glabrous, apex acute. Ray florets 6–8, without staminodes; corolla yellow, glabrous, tube 4–4.2 mm long; limb oblong-elliptic, 6–7 × 2–2.5 mm, nerves 3 to 4, apex 2–3-dentate; style 4–5.2 mm long, style branches 0.8–1.3 mm long with acute, glabrous apex. Disc florets 21, corolla yellow, glabrous, 6–7 mm long, tube 5–5.5 mm long, with 5 lobes, 1–1.4 × 0.4–0.5 mm; anthers 2 mm long, apical appendage lanceolate, 0.70–0.72 × 0.2–0.25 mm, pollen sacs 1.2–1.3 mm long, anther bases sagittate, 0.1 mm long, linear, filaments 0.4–0.5 mm long with distal thickening 0.5 mm long; style 8–8.8 mm long, style branches 1.3–1.8 mm long, apex of style branches with lateral and distal hairs. Achene glabrous, 1 mm long (immature). Pappus straw-colored, barbellate, 6–7.2 mm long, apex slightly thickened, reddish at anthesis.

Etymology: —The epithet refers to the Cordillera Yasgolga where the type was collected. This mountain extends from the north of the Department of San Martín to the east of La Jalca Grande, located in the Amazonas department. Elevations vary between 2900 and 3300 meters above sea level. Hydrographically, this morphostructural feature constitutes the divortium acuarium of the Utcubamba River (to the west) and Shocol River (to the east) watersheds, an important source of water for the Amazonas department ( Rodríguez et al. 2012).

Distribution and habitat: — Gynoxys yasgolgensis grows in the transitional formation between the shrubby vegetation of the ‘jalcas’ and the montane cloud forest, recorded at an elevation range between 2800 and 3500 meters above sea level ( Figure 2 ). The species is distributed in northeastern Peru, Amazonas region, south of the Huancabamba depression. The recorded populations are in the private conservation area “Yasgolga – Santa Lucia ” ( Figure 3). This area of Amazonas is known for its high diversity of Gynoxys , Clusia, Weinmannia and Cinchona populations ( Beltrán et al. 2006, Coronel-Castro et al. 2023).

Phenology: —Immature flowers of G. yasgolgensis were observed from February to April, and mature flowers (full bloom) between late March and June.

Conservation status: —The new species inhabits the eastern slopes of the high Andes, located at the southern end of the Yasgolga mountain range. Its primary threat is population decline, driven by the recent construction of roads to the town of Los Chilchos, which has led to habitat degradation in high-altitude areas. This degradation is caused by the expansion of agricultural activities and the establishment of intensive livestock farming, encouraged by both local populations and migrants (Castañeda et al. 2018). Additionally, forest fires in the páramos and excessive logging in the Andean cloud forests of northern Peru —particularly in the Amazonas department—have exacerbated the situation ( Global Forest Watch 2022).

The Extent of Occurrence (EOO) and Area of Occupancy (AOO) were analyzed based on known occurrences of G. yasgolgensis , as well as nearby localities where it is not present, information gathered during the team’s search expeditions in the Yasgolga mountain range. The EOO was calculated to be 85 km ², and the AOO 92 km ², placing the species between Critically Endangered and Endangered categories. A population study conducted at one of the locations found fewer than 100 mature individuals, with estimates suggesting that no subpopulation contains more than 250 mature individuals. As a result, the species is classified as Endangered (EN B1+C2a(i)) according to the IUCN criteria (2022).

Additional specimens examined (paratypes): — PERU. Provincia de Chachapoyas: Cordillera Yasgolga camino a Valle de los Chilchos en el sector denominado “El Rayo” en el territorio del ACP Yasgolca-Santa Lucía, 6°39’46” S, 77°42’49” W, 3374 m, 21 March 2024, E. Coronel ECC-220 ( KUELAP, HSP).

Discussions: — Gynoxys yasgolgensis differs from the other species of the genus by its markedly oblong-obovate coriaceous leaves, with woolly pubescence completely covering the underside of the leaf. However, it has certain similarities with G. oleifolia , G. revolutifolia and G. ferreyrae . It differs from G. oleifolia in leaf length (4–5 cm vs. 6–12 cm), shape and length of the synflorescence bracts (linear, 4–5 mm vs. linear-oblong, 6–12 mm), and number of phyllaries (mostly 8 vs. 11–12). It differs from G. revolutifolia in leaf margin (revolute vs. strongly revolute), leaf indumentum (simple vs. simple and T-shaped trichomes), and number of radiate and discoid flowers (6–8 and 21 vs. 4–5 and 8–9(–12)). Finally, it differs from G. ferreyrae in shape and length of synflorescence bracts (linear, 4–5 cm vs. oblong-spatulate, 6–12 mm), number of phyllaries (mostly 8 vs. 12–13), and number of discoid flowers (21 vs. 12–14). Other differences are detailed in Table 1.

Figures

FIGURE 1. Gynoxys yasgolgensis Revilla & E. Coronel-Castro. A. Flowering branch. B. Inflorescence. C. Capitulum. D. Ray floret (ligule). E. Disc floret (with pappus). F. Detail of leaf indumentum: adaxial surface (up), abaxial surface (down). Drawn by Maricruz Bedoya Cuno, based on E. Coronel ECC-194 (KUELAP).

FIGURE 2. Gynoxys yasgolgensis. A. Adaxial leaf surface. B. Adaxial leaf surface. C. Inflorescence bract. D. External phyllaries, ventral shape. E. External phyllaries, dorsal shape. F. Internal phyllaries, ventral shape G. Internal phyllaries, dorsal shape. H. Synflorescence. I. Habit. Source: E. Coronel ECC-194 (KUELAP, HSP).