Gynoxys revolutifolia R. Arias, Espinosa-Ortega & Revilla

Arias, Ruth, Espinosa-Ortega, Nelson, Revilla, Italo, Ansaloni, Raffaella & Tomasello, Salvatore, 2024, Gynoxys revolutifolia (Senecioneae, Asteraceae): A new species from southern Ecuador, Phytotaxa 644 (3), pp. 211-219 : 212-217

Gynoxys revolutifolia R. Arias, Espinosa-Ortega & Revilla , sp. nov. ( Figs 1 , 3 )

Diagnosis: —The new species differs from all other congeners by having coriaceous leaves with strongly revolute margins (giving it a concave shape) and conspicuous primary and secondary veins (8–12 pairs) on both leaf surfaces, simple and T-shaped trichomes covering the abaxial side of the leaves, involucre with 8 phyllaries with ferruginous unicellular trichomes, 4–5 ray florets with limbs 10–11 mm long and 8–9(–12) disc florets.

Type: — Ecuador. Límite provincial Loja/ Zamora-Chinchipe: sector El Tiro , junto a la vía nueva Loja/Zamora, 3°59’29”S 79°8’40”W, 2800 m, 8 September 2023 (fl), R. Ansaloni & N. Espinosa-Ortega 280 (holotype LOJA!; isotypes HA!, HUTPL!, QCA!) .

Description: —Shrubs or treelets ca. 1.5–2.5 m tall. Stems oppositely branched, with fissured bark, covered by simple, contorted, ferruginous trichomes, underlaid with T-shape trichomes. Leaves opposite, simple, petioles (0.7–)0.9–1.3(– 1.7) cm long; lamina oblong to ovate, 4–7.2(–8.6) × (0.8–)1.4–2.9(–3.7) cm, base rounded to oblique (rarely slightly cordate), apex obtuse to acute, margin revolute, coriaceous, adaxially glabrous except for the mid vein covered by adpressed trichomes, abaxially densely covered by simple and contorted ferruginous trichomes underlaid with short T-shaped adpressed trichomes ( Fig. 3 ); venation pinnate, with 8–12 pairs of secondary veins on each side, conspicuous on both lamina sides. Synflorescence corymbiform, erect and terminal. Capitula heterogamous, radiate, 10–12 × 20–26 mm; pedicels (0.56–)0.7–1.37(–1.5) cm long, with 3–5 triangular bracteoles ca. 1.7–2.6 mm long, densely yellow lanate. Involucre cylindric, with a calycle of few bracts ca. 2–2.5 mm long, densely ferruginous tomentose; phyllaries 8, uniseriate, herbaceous, the outer phyllaries lanceolate, (4.5–)5–6(–6.7) × 2 mm, ferruginous tomentose, apex obtuse, the inner phyllaries oblong-lanceolate, 5–6 × 2 mm, the dorsal ridge ferruginous tomentose, margins glabrous, apex obtuse. Ray florets pistillate, 4–5, with staminodes; corolla yellow, glabrous, tube 4–5(–6) mm long; limb oblongelliptic, 10–11 mm × 2–3 mm, 4-nerved, apex tridentate; style 7.2–7.5 mm long, style branches 1.2–1.5 mm long, triangular, with small and few hairs on the tip and lateral sides. Disc florets hermaphrodite, 8–9(–12); corolla yellow, (5.6–)6.5–7(–7.5) mm long, glabrous, tube 3–3.5(–4) mm long, with 5 lobes, 2-nerved, 2–3 × 0.65–0.7 mm; anthers ca. 2.9 mm long, apical appendage lanceolate 0.60–0.65 × 0.15–0.20 mm, anther collar cylindrical, base sagittate; style 9.3–9.5 mm long, style branches 2.3–2.5 mm long, triangular, with long and few hairs on the tip and lateral sides. Achene glabrous, 3–4 mm long (immature), 5-ribbed. Pappus stramineous, barbellate, yellowish, 7–8 mm long.

Etymology: —The specific epithet of the new species refers to the strong revolute leaf margins.

Distribution and habitat: —All known populations are found in the shrubby páramo and elfin forest, between elevations of 2800 and 3300 m ( Fig. 3 ). The species is distributed in the Ecuadorian provinces of Loja and Zamora-Chinchipe in three localities: El Tiro, Cajanuma, and Cerro Toledo ( Fig. 4 ). These localities are in the Cordillera Real Oriental, within the Podocarpus National Park territory. This zone is known for its high biodiversity and endemics ( Lozano & Bussmann 2005). Particularly, the mountain pass “El Tiro” is covered by shrubby vegetation exposed to high-speed winds, with an average temperature of 7–13 °C ( Keating 2000), high precipitation, and nutrient-poor soils ( Gradstein et al. 2008).

Phenology: —Specimens in bloom have been collected between September and November.

Chemical composition: —The distilled leaf essential oil from samples collected at El Tiro (N. Cumbicus 1986, HUTPL-14664) were previously analyzed by Maldonado et al. (2023) using GC-MS & GC-FID techniques, reporting a low yield (0.02% ± 0.004% dry weight); the main components were: α-pinene (5.3–6.0%), germacrene D (4.9– 6.5%), α-cadinol (3.8–4.4%), α-humulene (3.0–3.2%), (E)-β-caryophyllene (2.4–2.8%), δ-cadinene (2.2–2.3%), and caryophyllene oxide (1.6–2.2%).

Conservation status: —Based on the very limited EOO (201.63 km ²) and AOO (32 km ²) (B1+B2), the confirmed occurrence in only three localities so far ( Fig. 4 ) (B1+B2a) and the continuing and fast decline of south Ecuadorian forest and páramo ( Carrión-Paladines et al. 2022) (B1+B2ab(ii)), we assign a provisional category of Endangered (B1+B2ab(ii)), following the IUCN (2022) criteria.

Additional specimens examined (paratypes): — Ecuador. Loja: Parque Nacional Podocarpus El Tiro, 3°59’37” S, 79°8’43” W, 2800 m, 9 January 2002 (sterile), P. Lozano, B. Merino, T. Delgado & P. Lozano , E-33 (LOJA) ; same location, 3°59’58” S, 79°8’38” W, 2900 m, 9 January 2002 (sterile), P. Lozano & al. E-35/E-34 (LOJA) ; same location, 3°99’10” S, 79°14’57” W, 2823 m, 20 October 2015 (fl.), I. Arnelas Seco, A. Gusmán & I. Medina 9775 ( HUTPL) ; same location, 3°59’23” S, 79°8’45” W, 2790 m, 6 April 2022 (sterile), N. Cumbicus 1986 ( HUTPL) ; Parque Nacional Podocarpus, Cajanuma, sendero al mirador, 4°3’ S, 79°9’ W, 2960 m, 6 September 1997 (fl.), C. Cerón & E. Ocampo 34851 (LOJA) ; Cantón: Loja, parroquia Yangana, borde del camino Yangana-Cerro Toledo, 4°23’7.52” S, 79°7’12.56” W, 2960 m, 11 November 2023 (fl.), R. Ansaloni & N. Espinosa-Ortega 311 ( HUTPL, LOJA, QCA) . Loja / Zamora-Chinchipe: Loja-Zamora road just east of province border and pass, 3°59’ S, 79°8’ W, 2780 m, 25 November 1984 (fl.), P. M. Jorgensen 56400 ( AAU, QCNE, US) ; en la cresta de el paso, yendo hacia la loma de los Balcones, entre Loja y Zamora, 3°59’38” S, 79°8’40” W, 2900 m, 30 September 1995 (sterile), A. Garmendia & G. Paredes 390 ( QCNE) ; Loja-Zamora road, km 18 (El Tiro), 3°58’57” S, 79°8’43” W, 2800 m, 25 September 2001 (fl.), J. Madsen 8550 ( LOJA) ; límite provincial entre Loja y Zamora, 3°59’ S, 79°9’ W, 2900 m, 9 October 2004 (fl.), J. Caranqui, M. Melampy & J. Lara 1252 ( CHEP, MO) ; límite provincial Loja-Zamora Chinchipe, parte superior de Cerro toledo, borde del camino principal, 4°23’20.99” S, 79°6’49.31” W, 3300 m, 5 November 2023 (fl.), R. Ansaloni & N. Espinosa-Ortega 310 ( HUTPL, LOJA, QCA) . Zamora-Chinchipe: área del Parque Nacional Podocarpus, Cajanuma, El Mirador, [4°5’30.26” S 79°10’0.72” W], 3000 m, RBu & SL ( HUTPL) ; Reserva San Francisco, road Loja-Zamora, ca. 35 Km from Loja , 3°58’ S, 79°4’ W, 2880 m, 29 September 2012 (fl.), J. Homeier, F.A. Werner & R. Link 5022 ( GOET, HUTPL) ; cantón Palanda, parroquia Valladolid, ladera oriental de Cerro Toledo, 4°239’18.1” S, 79°6’28.1” W, 3070 m, 21 October 2023 (fl.), R. Ansaloni & N. Espinosa-Ortega 308 (G, HUTPL, LOJA, QCA) .

Discussions: —Although many Gynoxys species have leaves with revolute margins, none show concave leaves and two trichome types in the abaxial leaf surface; both features make G. revolutifolia unique among all described species so far. This species has often been misidentified as G. cuicochensis Cuatrecasas (1951: 16) or G. rugulosa Muschler (1913: 87) . The new species differs from G. cuicochensis in leaf length (4–7.2(–8.6) cm vs. 2.5–5.5 cm), leaf margin (strongly revolute vs. slightly curved margins), leaf indumentum (simple and T-shaped trichomes vs. simple trichome) and ray florets number (4–5 vs. 3). From G. rugulosa , it differs in leaf texture (coriaceous vs. subcoriaceous), abaxial leaf indumentum (simple and T-shaped trichomes vs. simple), synflorescense bracteoles (triangular vs. linear), phyllaries number (8 vs. 12–15), limb length (10–11 mm vs. 6–8 mm) and disc floret number (8–9(–12) vs. 5–6). Further differences are detailed in Table 1 .

Based on the trichome architecture, Gynoxys revolutifolia belongs to the Praegynoxys group (sensu Escobari et al. 2023), which is characterized by diversely branched trichomes. So far, the only known species with a similar trichome architecture (simple trichomes underlain by T-shaped trichomes on their stems and abaxial leaf surfaces) are G. chingualensis Robinson & Cuatrecasas (1992: 414) and G. jaramilloi Robinson & Cuatrecasas (1992: 415) . Another species exhibiting T-shaped trichomes is G. valenzuelae (H.Beltrán & J.Calvo) B.Escobari & N.Kilian in Escobari et al. (2023: 87). However, this species stands out by bearing two distinct types of T-shaped trichomes ( Beltran & Calvo 2020) and no simple ones. Because the T-shaped trichomes are found in the inner layer, they can be easily overlooked, and there might be more species of Gynoxys having this feature than reported thus far.

Figures

FIGURE 1. Lankester Composite Dissection Plate of Gynoxys revolutifolia R. Arias, Espinosa-Ortega & Revilla A. Flowering branch. B. Leaf: abaxial surface (left), adaxial surface (right). C. Synflorescence. D. Capitulum, front view. E. Capitulum, cross-section. F. Calycle. G. Bracteoles: abaxial surface (left), adaxial surface (right). H. Outer phyllaries: abaxial surface (left), adaxial surface (right). I. Inner phyllaries: abaxial surface (left), adaxial surface (right). J. Ray floret (pappus removed). K. Ray floret style. L. Disc floret (pappus removed). M. Disc floret style. N. Anther. O. Achene (immature). P. Pappus bristles. Photos and preparation by N. Espinosa-Ortega based on the isotype (QCA249764).

FIGURE 3. Gynoxys revolutifolia. A. Habit, shrub in shrubby páramo, Cerro Toledo-Loja/Zamora Chinchipe border. (R. Ansaloni & N. Espinosa-Ortega 310). B. Habit, treelet in elfin forest, Yangana-Cerro Toledo road, Loja (R. Ansaloni & N. Espinosa-Ortega 311). Photos by N. Espinosa-Ortega.

FIGURE 4. Distribution map of Gynoxys revolutifolia in Loja and Zamora-Chinchipe, Ecuador. Prepared by G. Lucero.