Magnolia vargasiana A.Vázquez & D.A.Neill, 2015

Vázquez-García, J. Antonio, Neill, David A., Asanza, Mercedes & Recalde, Luis, 2015, Magnolia vargasiana (Magnoliaceae), a new Andean species and a key to Ecuadorian species of subsection Talauma, with notes on its pollination biology, Phytotaxa 217 (1), pp. 26-34 : 27-31

Magnolia vargasiana A.Vázquez & D.A.Neill , sp. nov., Figs. 1–3

Type:— ECUADOR. Tungurahua: near the Pastaza boundary, Cordillera Llanganates, ca. 7 km (straight line) northeast of Topo, east of Río Zuñac, 01°22’06” S, 78°08’59” W, 2000 m, 23 August 2014 (fl bud, fl), Vázquez-García 10118 with D. Neill, A. Rosillo and the Recalde family (holotype: ECUAMZ!, isotypes: IBUG!, MO!, QCNE!).

Diagnosis: Magnolia vargasiana shares with Magnolia kichuana the sub-orbicular leaves and a similar number of carpels, but it differs from the latter in having a narrower leaf 7.50–11.0 vs. 13.3–22.0 cm; smaller obovate-spathulate outer petals 3.5–3.8 vs. narrowly oblanceolate (4.3–) 5.8–8.2 cm long; and a greater number of stamens 50–54 vs. 38–42(–50) ( Table 2).

Trees 11–26 m tall, 20–50 cm dbh, first branches at 6–10 m; bark longitudinally and narrowly striate with lenticels, apparently smooth, greyish; terminal twig internodes 4.0–8.0(–10.0) × 2.8–4.0 mm, lenticellate, glabrous; petioles 4.0–6.50 × 0.2–0.3 cm, stipules c. 3.4 cm long, covering the entire length of petiole; mature leaf blades 6.0–10.5 × 7.5–11.0, suborbicular, broader in the lower half, rarely wider than long, subcordate to cordate at the base, obtuse or rarely emarginate at the apex, coriaceous, glabrous, 6–7 lateral veins per side; hypsophylls (2.0–)3.5–2.8 × 2.5–3 cm, peduncle 1.0– 1.8 cm, flower buds ellipsoidal 1.5–2.8 × 1.5–1.7 cm, glabrous; open flower 7.0– 7.5 cm in diameter; sepals elliptic 3.6–3.7 × 1.8–2.0 cm, adaxially creamy white, abaxially dark grayish at the base and axis, fading to creamy white at the margins; petals 8, obovate to spathulate and concave, unequal in size, 2.7–3.8 × 0.8–2.0 cm, creamy white; stamens 50–54, 1.20 × 0.15 cm, creamy white; gynoecium ellipsoid, 1.5–1.7 × 0.7–0.8 cm, pale yellowish green; carpels 10, stylar tips 1.5 mm long, black. Fruit and seeds unknown.

Distribution and ecology:— Magnolia vargasiana is endemic to the Cordillera de los Llanganates, Tungurahua ( Ecuador) and is thus far only known from the type locality, consisting of two trees> 10 cm dbh within a permanent forest inventory plot of 0.25 ha at 2000 m elevation in the Río Zuñac Reserve (Zuñac Plot 2). The Río Zuñac Reserve is a privately held conservation area privately owned by an Ecuadorian non-government organization, the EcoMinga Fundation. The plot itself is about 1 km outside the boundary of Llanganates National Park, located on a steep mountain ridge above the canyon of the upper Rio Zuñac; this portion of the Llanganates is also known as the Cordillera Abitagua. The climate is perhumid with annual rainfall greater than 4000 mm (Ministerio del Ambiente, 2012). Vegetation is described as being a dense cloud forest, with about 800 trees ≥ 10 cm DBH per hectare and a closed canopy about 25 m tall with abundant vascular epiphytes and bryophytes. In the classification system of terrestrial ecosystems of Ecuador (Ministerio del Ambiente, 2012) the vegetation type at the site is “bosque siempreverde montano del Norte de la Cordillera Oriental de los Andes”. The dominant tree species recorded in the 0.25 hectare include Wettinia fascicularis ( Arecaceae ), Brunellia pallida ( Brunelliaceae ), Weinmannia pinnata ( Cunoniaceae ), Dicksonia sellowiana ( Dicksoniaceae ), Abarema killipii ( Fabaceae ), Croton pachypodus ( Euphorbiaceae ), Lozania mutisiana ( Lacistemataceae ), Eschweilara sessilis ( Lecythidaceae ), Hieronyma duquei and H. macrocarpa ( Phyllanthaceae ). The likely pollinator is an undetermined species of “flea beetle” in the tribe Alticini ( Coleoptera : Chrysomelidae ; Fig. 2F ). There were no seedlings or saplings of this species recorded within the forest inventory plot. Flowering of M. vargasiana is recorded from late August to late February but with just a single flower on each occasion. Fruiting possibly takes place in May (pers. comm. by EcoMinga forest ranger Fausto Recalde).

Timing of flowering:— Once the last hypsophyll has fallen from the flower bud, it is likely that the flower will open within about five days ( Fig. 2E ). A slightly swollen top of flower bud ( Fig. 2F ) is a sign that the female phase, day zero (0D) has started. At this phase, the flower will start opening for the first time in the afternoon from 16:49 to 18:00 h until the sepals (3) rotate ca. 90 degrees while the outer petals (5) open nearly 30 degrees and inner petals (3) open <15 degrees only ( Figs. 3A–D ); the flower remains partially open for nearly 3 h in order to receive incoming pollinators, “flea beetles” (Tribe Alticini , Chrysomelidae ) ( Fig. 3E,K ). The petals will close at about 21:00 h in the evening, trapping pollinators inside overnight, whereas the sepals stay open overnight until they complete a rotation of ca. 180 degrees ( Figs. 3F–H ). The following day, the male phase, first day (1D) the petals re-open earlier in the afternoon, beginning at about 14:00 h, when inner the outer petals rotate simultaneously until reaching ca. 90 degrees at about 15:00 h with most of the stamens detached and held in the concave naviculate petals, exposing the pollen and its likely pollinator fully covered in pollen ( Figs 3I–L ). The outer petals will continue rotating until reaching about 135 degrees at about 18:30. The flower will remain basically unchanged the rest of the day, overnight, throughout most of the following two days ( Figs. 2D , 3D ) until some or all petals fade and start falling ( Figs. 3M–O ). Flowers visited by “flea beetles” show signs of petal damage and then stamen dehiscence takes place sooner (Fig. 31J,L), unlike flowers not visited by the putative pollinators (Fig. M–O). Fragrance is stronger during first opening/reopening of flowers and absent at other times.

Eponymy, ethnobotany and conservation:— This species is named after Dr. Julio Cesar Vargas Burgos, Rector of the Universidad Estatal Amazónica, in recognition of his support for botanical research and development of the ECUAMZ herbarium. No use is yet recorded for this species. Larvae of an unidentified insect were observed eating stamens and petals and damaging some carpels. Several flower buds fell off before completing full development for no evident reason. This species has a narrow distribution, is locally endemic, has a low population density, fails to secure establishment of seedlings and frequently has damaged flower buds. All these features place M. vargasiana at high risk of extinction, unless additional and larger populations of this species are found. Based on the information currently available, we recommend the new species be classified as Vulnerable (VU) within the IUCN Red List system ( IUCN, 2001).

Other specimens examined:— ECUADOR. Tungurahua: near the Pastaza boundary, Cordillera Llanganates, ca. 7 km (straight line) northeast of Topo, east of Río Zuñac , plot Zuñac 2, quadrat 4, 01°22’06” S, 78°08’59” W, 2000 m, 9 May 2014 (sterile), Clark, Neill & Clavijo 14240a (tree 20), 14240b (tree 48) ( ECUAMZ!, IBUG!) ; loc. cit., plot and quadrat, September 2014 (fl, fl bud) Merino-Santi s.n. a (tree 48) and b (tree 20) with Malucín, Jost & the Recalde family ( ECUAMZ!, IBUG!) ; loc. cit., 28 Feb 2014 (fl, & fl bud), Vázquez-García 10121 with Merino-Santi, Dahua- Machoa, Jost & the Recalde family ( ECUAMZ!, IBUG!) .

Figures

FIGURE 1. Magnolia vargasiana. A. Gynoecium. B. Stamen. C. Inner petal. D. Outer petal. E. Sepal. F. Flowering branch. G. Leaf. H. Flowering bud. I. Hypsophylls. Drawing by Efrén Merino-Santi, Kichuan artist and student at Universidad Estatal Amazónica, based on Merino-Santi et al. s.n.

FIGURE 2. Magnolia vargasiana A. Yajaira Malucín, student at Universidad Estatal Amazónica, holding a flower bud, with sepals all the way down in day one (male phase) at 9:16 hrs, where flea beetles had just overnighted and are about to leave the flower in the afternoon. With dense “bosque siempreverde montano” in the background. B. Foliage. C. Detaching stipule. D. Branch with flower bud including second hypsophyll. E. First hypsophyll. F. Flower bud in day 0 (0D, female phase), without hypsophylls. G. Flea beetles (Tribe Alticini, Chrysomelidae) covered with pollen. (Photographs: B, C & E by Fausto Recalde, from the holotype; A, D, F & G by Lou Jost, from Merino-Santi et al. s.n., ECUAMZ, IBUG).

FIGURE 3. Magnolia vargasiana. Flowering timing.A. Day zero (0D, female phase), 16:49 hrs. B. 0D 17:16 hrs. C. 0D 17:28 hrs. D. 0D, 18:00–19:58 hrs. E. Flea beetle, orange brownish (Tribe Alticini, Chrysomelidae). F. 0D 21:04 hrs. G. Day one (1D, male phase) 4:23 hrs. H. 1D, ca. 9:13 hrs. I. 1D, 14.05 hrs J. 1D, 14:25 hrs. K. Flea beetle, bright green. L: 1D, 14:55 hrs. M. 1D, 18:27 hrs. N. 1D, 18:27 hrs. (side view). O. 2D, 2:43–6.19 hrs. (Photographs:A–D, F–G, & M–O by Antonio Vázquez, from Vázquez-García et al. 10131; E & I–K by Lou Jost, basaed on Merino s.n., ECUAMZ, IBUG; and H by Efrén Merino, based on Merino-Santi s.n., ECUAMZ, IBUG).