Magnolia alejandrae García-Morales & Iamonico, 2017

García-Morales, Leccinum J., Iamonico, Duilio & Jiménez, Jesús García, 2017, Nomenclatural remarks on Magnolia sect. Macrophylla (Magnoliaceae), with description of a new species from North America (Tamaulipas, Mexico), Phytotaxa 309 (3), pp. 238-244 : 239-241

Magnolia alejandrae García-Morales & Iamonico , sp. nov. ( Fig. 1 ).

Type:— MÉXICO. Tamaulipas: Municipio de Victoria, Rancho El Molino, bosque mesófilo de montaña, 23°45’56.02”N, 99°19’31.27”O, 1500 m, 1 May 2016, García-Morales 5435 (holotype: ITCV (two sheets), isotypes GBH, HFLA, HUAP, ITCV, MEXU, SLPM, UAT] ( Fig. 2 ). Due to the large size of the material, the holotype and all isotypes except that deposited at HFLA, consist of two sheets, both from the same plant: the first specimen bears one flower, and the other one bears leaves ( Fig. 2 , the holotype).

Diagnosis: ― Magnolia alejandrae is morphologically similar to M. nuevoleonensis , M. rzedowskiana and M. vovidesii . It differs from M. nuevoleonensis in having flowers of greater diameter (30‒34 cm vs. 20‒24 cm), smaller fruits (7.0 × 4.5 cm vs. 8.5 × 7.0 cm) and more carpels (42‒54 vs. 30‒42); from M. rzedowskiana it differs in having fewer stamens (192‒216 vs. 290‒310), smaller fruits (7.0 × 4.5 cm vs. 10.0 × 6.0 cm), fewer carpels (42‒54 vs. 50‒65) and presence of a purple blotch on the petals; from M. vovidesii it differs in having fewer stamens (192‒216 vs. 308‒352), smaller fruits (7.0 × 4.5 cm vs. 12.0 × 7.0 cm), fewer carpels (42‒54 vs. 60‒78) and smaller purple blotch on the petals.

Description: ―Trees, 8‒16 m tall, deciduous, trunk 10‒20 cm in diameter at breast height, with bark grayish brown with greenish patches; first branches appearing at 1‒2 m from ground level, each branch 1.5‒4.0 m long, the terminal ones twigs with (5‒)6‒8(‒9) leaves, twigs glabrous, 10‒20 mm in diameter, grayish to greenish, preserving the scars of petiole bases, with two types of lenticels: a smaller (about 0.5 mm long) rounded-oval, a bigger one (1‒3 mm long) type lenticels oval shaped or almost a diamond to quadrangle, all slightly raised above the bark, whitish and widespread between internodes. Petioles pale glaucous green, circular in trasverse section, except for the first onethird, which is flattened above, 50‒80 mm long, 3‒5 mm in diameter, with the bases widened up to 8 mm from the base, uniformly densely pubescent, white-hyaline, the hairs about 1 mm long. Leaves obovate with a silky texture, dull dark green above and grayish glaucous, waxy beneath, (27‒)30‒45(‒55) × 12‒20 cm, leaf bases cordate, the apices acute or attenuate, 25‒35 pairs of veins, the veins prominent beneath, forked at the sides, the middle vein yellowish green. Stipules lanceolate, 70‒90 × 25‒28 mm, the bases truncate, brown, apex rounded, attached approximately 2/3 from the base. Flower bud lanceolate-ovate, 90‒110 × 25‒30 mm, yellowish green, emerging from a base 2‒4 cm long, 1 cm in diameter, covered by two bracts, 80 × 60 mm long, yellowish green, the apex acute, reddish, glabrous. Sepals 3, greenish yellow or cream, glabrous, oblong-lanceolate, 12‒15 × 40‒45 mm, the apex rounded or acute. Open flowers 30‒34 cm diameter; petals 6, arranged in two rows, internal petals 3, leathery, oblong (14‒16 × 55‒70 mm), with bases narrowed, external petals 3, ovoid, 14‒17 × 70‒80 mm, all petals creamy white, glabrous, with 5 or 7 well-marked stripes from the base to the apex, with a medium purple blotch close to their truncated bases, glutinous around the blotch; flowers with a sweet smell, similar to citrus flowers. Stamens 192‒216, linear with apexes subacute or obtuse, bases rounded or subtruncate, velutionous, pale yellow-cream first, later darkening, arranged in 24 spiral rows, each with 8‒9 stamens; stamens 15‒20 × 2‒3 mm, channeled on ventral side, with a medium elevated keel. Gynoecium ovoid-oblong, velutionous, styles 42‒54, linear, erect at first, later curving outward, arranged in 12 whorled series of 3‒5 stamens, 5‒7 × 1 mm, with bases widened, flattened, channeled on the ventral side, with the apex acute or truncate, when truncate clearly with channel on the ventral side continuing to the apex, yellowish cream at first, later turning brownish, and blackish at sides and apex. Fruting follicles ovoid, 40‒70 mm × 30‒45 mm, not including the stamen base, follicles 35‒42, beaked, each beak 3‒8 mm long; seeds polymorphic, round-ovoid, pyriform-oblong or reniform, keeled at the sides, 10‒13 × 6‒8 mm, with a reddish rugose-striate sarcotesta, brilliant when ripe and dried.

Etymology: ―The species is dedicated to Alejandra Escobar Morín, wife of one of the authors (Leccinum J. García-Morales).

Distribution and ecology: ― Magnolia alejandrae has a narrow distribution in the Sierra Madre Oriental (central western Tamaulipas State), being known from three populations occurring in two municipalities (Victoria and Jaumave), at 1500‒1600 m, where the plants grow in cloud forest or humid pine-oak forests.

Phenology: ―Flowering April‒May, fruiting August‒September.

Conservation status: ―On the basis of the IUCN Red List criteria ( IUCN 2014) and the available data, we can apply the criteria B and C. The two populations of Magnolia alejandrae consist of less than 500 individuals, so by the application of criterion Ba the species can be considered as Critically Endangered (CR). The AOO is less than 1 km 2, so according to criterion C, M. alejandrae is an Endangered (EN) species. Adopting maximum parsimony ( IUCN 2014), we here assess M. alejandrae as Critically Endangered (CR).

Taxonomic notes: ― Magnolia alejandrae is similar to M. nuevoloeonensis , M. rzedowskiana and M. vovidesii , from which it differs in the diameter of its flowers, colour of the petal blotch, number of stamens, size of fruits and number of carpels ( Table 1).

Additional specimens examined: ― MÉXICO. Tamaulipas: Municipio de Jaumave Los Farallones , ca. 6 km N Rancho El Molino, 1600 m bosque mesófilo de montaña, 1 May 2016, García-Morales 5448 ( ITCV) ; Municipio de Victoria, Rancho El Molino , 1500 m, 29 March 2009, García-Morales 858 ( ITCV) ; Rancho El Molino , 1500 m, 10 May 2009, García-Morales 1211 ( ITCV) ; Rancho El Molino , 1500 m, 14 May 2010, García-Morales 1779 ( ITCV) ; Rancho El Molino , 1500 m, 01 August 2013, García-Morales 2303 ( ITCV) .

Figures

FIGURE 1. Magnolia alejandrae: A. Tree. B. Bark. C. Leaves and flower. D. Gynoecium and stamens. E. Flower bracts. F. Fruit.

FIGURE 2. Holotype of Magnolia alejandrae (ITCV!). A. Leaves. B. Flower.