Magnolia mercedesiarum D.A.Neill, A.Vázquez & F.Arroyo, 2018

Vázquez-García, J. Antonio, Neill, David A., Shalisko, Viacheslav, Arroyo, Frank & Merino-Santi, R. Efrén, 2018, Magnolia mercedesiarum (subsect. Talauma, Magnoliaceae): a new Andean species from northern Ecuador, with insights into its potential distribution, Phytotaxa 348 (4), pp. 254-268 : 258-264

Magnolia mercedesiarum D.A.Neill, A.Vázquez & F.Arroyo , sp. nov. ( Figs. 1 , 2 )

Type:— ECUADOR. Napo: Cosanga, Cordillera de Guacamayos , Reserva Ecológica Antisana, ca. 6 km SE of Cosanga, along trail below parking lot at viewpoint ; after reaching the pipeline 50 m west on the right side of the trail, wet montane tropical forest, 00°38’S, 77°50’W, 1940 m, 3 January 2015 (fl bud, fr), Efrén Merino-Santi 1, with Alex Dahua-Machoa, D. Yajaira Malucín-Andrade & Alex Rosillo (holotype: ECUAMZ!; isotypes: IBUG!, K!) .

Magnolia mercedesiarum is similar to M. vargasiana but differs in having broadly elliptic leaves that area obtuse at the base vs. suborbicular and subcordate to cordate, glabrous stipular scars, more numerous lateral veins per side and fewer stamens. It is also similar to M. llanganatensis in having similar size of flowers and glabrous leaves; however, it differs from the latter in having leaf blades broadly elliptic vs. elliptic, longer petioles (2.0–) 4.0–8.5 vs. 1.0– 1.5 cm, fewer lateral veins per side 9–10 vs. 16–17, more numerous petals (8 vs. 6) and carpels (8–10 vs. 4–6) and larger fruits (3.8–5.0 × 2.7–3.6 cm vs. 3.0 × 2.0 cm; Table 2).

Trees 15–20 m tall, with trunk 8–24 cm in diameter at breast height, first branch at 9 m; bark creamy white to pale brown. Twig internodes 1.0–2.0 × 0.3–0.5 cm, glabrous. Petioles (2.0–)4.0–8.5 × 0.1–0.2 cm, glabrous, with the stipular scar along its length; leaf blades broadly elliptic, 10.0–16.0 × 4.5–9.0(–10.0) cm, glabrous; 9–10 lateral veins per side. Hypsophylls 2–3, pubescent. Flower buds 1.8–2.7 × 1.3–2.0 cm, ellipsoid; open flowers 7 cm in diameter, fragrance smelling of ketone solvents. Sepals 3, greenish white, turning brownish purplish. Petals 8, obovate, 3.0–4.0 × 1.0–2.0 cm, cochleate, creamy white, but soon oxidizing to brownish, the outer three, larger, widely obovate and subequal, the next three subequal and the inner two narrower and spathulate; stamens 23–29, linear, acute at the apex, pale yellowish. Gynoecium ellipsoid, carpels 8–10, 2.7–3.5 × 1.0– 1.3 cm. Fruit asymmetrical, ovoid, costate, 3.8–6.0 cm × 2.7–4.0 cm, nearly half of the fruit green the other half reddish, where lenticels become more evident, fragrance like Annona cherimola . Seeds 1.0–2.0 × 0.5–0.7 cm, covered with a red aril when mature.

Distribution habitat, and phytogeography:— The species is confined to four localities, three of them in Napo Province: 1) the Cordillera Guacamayos in the eastern Andean slopes of northern Ecuador, near the Urcu Siki creek, a tributary of the Upper Jondachi watershed; 2) on the southern slopes of Volcán Sumaco in Sumaco Napo-Galeras National Park, 3) the private Alto Coca Reserve; and 4) Sucumbíos Province in the upper Río Due watershed, Parroquia Reventador. It grows in dense, wet, tropical cloud forest at 1800–2000 m. At the type locality in the Cordillera de Guacamayos, the common tree species that occur in association with M. mercedesiarum include Erythrina edulis Triana ex Micheli (1892: 145 ; Fabaceae ), Morus insignis Bureau (1873: 247 ; Moraceae ), Weinmannia pinnata Linnaeus (1759: 1005 ; Cunoniaceae ), Endlicheria griseosericea Chanderbali (2004: 100-102 ; Lauraceae ), Calatola costaricensis Standley (1926: 416–418 ; Metteniusaceae ), Schefflera minutiflora Harms (1908: 153 ; Araliaceae ), Elaeagia mariae Weddell (1849: 94) and Joosia ulei Steyermark (1975: 255 ; both Rubiaceae ).

Species distribution modelling: — The distribution of Magnolia mercedesiarum as currently known is restricted to four localities in Napo and Sucumbíos provinces. The extent of occurrence ( IUCN, 2012), i.e., the minimum convex polygon containing all points of occurrence ( Fig. 4 ) is 901 km ². The probable presence area of M. mercedesiarum was estimated as restricted to wet habitats in eastern slopes of the Ecuadorian Andes, using the species distribution model of MaxEnt, and measures 3307 km ² considering MTSS (maximum sum of training specificity with sensitivity) or 2701 km ² considering ETSS (equal training sensitivity and specificity; Fig. 5 ).

Phenology: — Unpredictable because the species has been found sterile in May, September and October, in bud in January, May and November and fruiting in January and April. It has not been found with open flowers.

Eponymy:— The species is named in honour of two Ecuadorian women named Mercedes who have contributed to botanical science and conservation in their native country: Mercedes Asanza, professor at the Universidad Estatal Amazónica, administrative curator of the ECUAMZ herbarium at that university, and specialist in taxonomy and ecology of ferns; and Mercedes Mamallacta, a Kichwa ethnobotanist from Archidona, Napo Province, gardener, native plant propagator and inheritor and guardian of millennia of Kichwa plant lore.

Ethnobotany:— No uses are recorded for the species in the type locality. However, according to informant Antonio Naranjo (Cerón & Ayala 9896, from Río Due), the plant is known as “orejas de burro” (donkey ears). It is aromatic, and leaves mixed with urine and salt are used to clean sick animals.

Conservation status:— Following IUCN (2012) Red List threat criteria Magnolia mercedesiarum was assessed as endangered ( EN): B1 ab (i, ii, iii) ; an extremely rare tree, only known from four locations and endemic to the Napo and Sucumbíos Provinces of Ecuador, with a potential distribution area of less than 3307 km ² on the eastern slopes of the Andes. Only two adult trees and one juvenile (3 m tall) were observed in the type locality. A fallen fruit showed signs of predation, most likely by rodents, leaving only the empty torus without any seed. No seeds or seedlings were observed below or near the adult tree. Efforts to propagate the tree from seeds and cuttings have failed. Fortunately, it is protected within the Antisana Ecological Reserve , Sumaco Napo-Galeras National Park and the private Alto Coca Reserve .

Additional specimens examined:— ECUADOR. Sucumbíos: Gonzalo Pizarro, Parroquia Reventador, PreCooperativa García Moreno , Tercera Línea al N de la carretera, cerca al Río Dué [transecto 5 (50 × 2 m), 70], 00°03’N 77°35’W, 1800 m, 23 May 1990 (sterile), Cerón & Ayala 9896 ( MO). Napo: Cordillera de Guacamayos. ca. 6 km SE of Cosanga (plot 7, tree label 171), 00°38.551’S, 77°50.214’W, 1940 m, 28 Sep 2005 (sterile), Homeier, Chicaiza & Moreno 1737, ( GOET, MO, QCA, QCNE) ; Cordillera de Guacamayos , ca. 6 km SE of Cosanga (plot 54, tree label 1613), 00°38.196’S, 77°50.384’W, 2000 m, 24 Octr 2007 (sterile) Homeier, Chinchero, Jaramillo & Guachamin 3135 ( GOET, MO, QCA, QCNE) ; Quijos, Cosanga, Cordillera de Guacamayos , ca. 6 km SE of Cosanga, 1.5 horas de distancia caminando (ca. 4 km) al sur por Sendero Jumandy , wet montane tropical forest, 00°38’S 077°50’W, 1940 m, 13 Nov 2014 (fl bud), Vázquez-García, Neill, Mamallacta & Rosillo 10126 ( ECUAMZ, IBUG) ; Cosanga, Cordillera de Guacamayos, ca. 6 km SE of Cosanga, 1.5 horas de distancia caminado (ca. 4 km) al sur por Sendero Jumandy , 00°38’S, 77°50’W, 1940 m, 3 Jan 2015 (fl bud, fr), Vázquez et al. 10128 ( ECUAMZ, IBUG) ; Reserva Alto Coca , 0°10’58”S, 77°38’36”W, ca. 1800 m, 8 Apr 2015 (fr), Clark s.n. (four images by JLC) ; Parque Nacional Sumaco Napo-Galeras, pendiente sur del Volcán Sumaco , 1780 m, 15 May 2005 (fl bud), Homeier & Chinchero 1869 ( GOET, QCNE) .

Notes:— Magnolia mercedesiarum is the first species of Magnolia described from the eastern slopes of the Andes in northern Ecuador; it is the third confirmed species of Magnolia in Napo Province after Magnolia pastazaensis and M. “napoensis ” ined. ( Vázquez-García et al. 2016a), the last two at lower elevation and sympatric at Jatun Sacha Biological Station. Its occurrence in the Due River area represents the second species of Magnolia recorded from Sucumbíos Province after M. neillii in the Amazon lowlands of northeastern Ecuador ( Vázquez-García et al. 2016a).

Magnolia discoveries in Ecuador and the Neotropics:— Including Magnolia mercedesiarum , there are now 18 (82%) species of Magnolia from Ecuador published in the last decade, representing a third of all Neotropical species of Magnolia published in the last decade. It is noteworthy that over half of all magnolias from Ecuador were first discovered or at least located during systematic vegetation sampling of permanent plots in selected natural protected areas ( Table 3). Most Ecuadorian species of Magnolia are rare canopy or subcanopy trees, inconspicuous in dense forest and easily overlooked, especially when they are not in flower; many have been discovered only because the tree plot inventories require careful sampling of all trees within the plot boundaries. As a result of the more numerous discoveries of magnolias from Neotropical areas in the last decade, the proportion between Old World vs. New World species has shifted from 2:1 to 1:1 (ca. 350 Magnolia species presently known worldwide; Vázquez et al. 2016a). Insufficient flowering and fruiting material have prevented understanding of the family in Ecuador for decades, and intensive, systematic fieldwork has proven to be fundamental. We are just beginning an era of finding the rarest and least accessible species in the most remote and often risky areas of the world.

Conservation status:— The conservation status of M. mercedesiarum using IUCN (2012) criteria resulted as endangered, not vulnerable as reported previously by Vázquez-García et al. (2016a). The great number of recent discoveries of Neotropical magnolias has made necessary the update of the IUCN Red List of Magnoliaceae ( Rivers et al. 2016) , a substantial increase of from the previous version ( Cicuzza et al. 2007). The majority (3/4) of the magnolia species in Ecuador including the species described here are threatened with extinction, and a quarter of all magnolias of Ecuador are critically endangered (CR; Vázquez-García et al. 2016a); local, national and international authorities should act immediately before the species and their habitats are lost forever.

Species distribution modelling and conservation status:— The comparatively sparse distribution of this new species and its estimated potential distribution extend the distribution of Magnolia to the eastern Andes of northern Ecuador, where no other species have been recorded (Vázquez et al. 2016a). The two new hypotheses on potential distribution areas for M. mercedesiarum are 28% (ETSS) and 12% (MTSS), more conservative than the area of “potential habitat” (3742 km ²) estimated in the monograph of magnolias of Ecuador (Vázquez-García et al. 2016), the latter based on the ecosystem map of the Ministerio del Ambiente of Ecuador (MAE) and taking into account forested cover, elevation, and natural boundaries (including rivers of third and fourth order). The advantage of the modelling approach in this paper compared to that of Vazquez et al. (2016a) consists of producing reproducible hypotheses of species distribution based on available presence data and individual response of species to complex environmental gradients without arbitrary presumptions of relationships between drainage basins, elevation ranges and species boundaries. The two models used, as well as the IUCN (2012) method, predict that the species could be found in Orellana Province, in addition to Napo and Sucumbíos. In contrast, the model does not predict a probable presence in the neighbouring area of Nariño, Colombia.

Figures

FIGURE 1. Magnolia mercedesiarum. A. Flower bud. B-C. Fruit before and during dehiscence. D. Flowering and fruiting branch. E. Flower (forced to open from mature flowerbud). F. Stamens.All from the type material. Drawing by Efrén Merino Santi.

FIGURE 2. Magnolia mercedesiarum. A. Tree. B. Flower (forced to open from mature flowerbud). C. Leaf and lateral veins. D. Flower bud. E. Fruit before dehiscence. Photographs A and E by Efren Merino-Santi. B, C and D. by Antonio Vázquez. A tree. B and E from the holotype. C and D from Vázquez et al. 10126.

FIGURE 4. Localitiesof M.mercedesiarum and minimal convex polygon.Basemap from GMTED2010 digital elevation model (Danielson and Gesch 2011) and ESRI World administrative divisions (ESRI 2017). Colour gradient represents elevation. Extent of occurrence as defined by the IUCN (2012) is 901 km².

FIGURE 5.Potential distribution area of Magnolia mercedesiarum after threshold application.Both conservative (equal training sensitivity and specificity, ETSS) and less conservative (maximum sum of training specificity and sensitivity, MTSS) thresholds included. Colour indication for MTSS is the additional area included in potential distribution around the edges of the coverage with the MTSS threshold. Base map is the same as in Figure 4.