Magnolia weerakitana Archila, A.Vázquez & Tribouillier, 2022

Vázquez-García, J. Antonio, Tribouillier-Navas, Erick, Archila, Fredy, Aguilar, Rudy Eduardo & Shalisko, Viacheslav, 2022, Two new species of Magnolia (Magnoliaceae) from Alta Verapaz and Quiché, Guatemala, Phytotaxa 559 (1), pp. 35-44 : 39-40

Magnolia weerakitana Archila, A.Vázquez & Tribouillier sp. nov. ( Figs. 3–4 ).

Type:— GUATEMALA. Alta Verapaz: municipality of Cobán, 1300 m, 15°27’51.92”N, 90°22’27.64”W, gallery forest, with Alnus acuminata Kunth (1817: 20) , Juglans olanchana Standl. & L.O. Williams (1950: 76) , Magnolia tribouillierana and Psidium guajava Linnaeus (1753: 470) ; 7 Mar 2021, Archila & Tribouillier MG-090 (holotype: BIGU! ; isotypes: AGUAT!, BIGU!, IBUG!) .

Magnolia weerakitana belongs to M. sect. Magnolia and is similar to M. montebelloensis , but it differs from the latter in having glabrous peduncles vs. pubescent; number of spathaceous bracts 2 vs. 3; flower diameter 15.0–17.0 vs. 11.0– 11.8 cm; more numerous stamens 90.0–100.0 vs. (53.0–)60.0–66.0(–85.0); more numerous petals 8–10 vs. 6; larger sepals 6.2–7.2 × 4.0–4.8 vs. 4.2–4.3 × 2.7–2.8; larger petals 6.5–7.0 × 3.5 vs. 4.4–5.4 × 2.0– 2.7 cm; larger and glabrous fruits 6.0–8.0 × 3.0 cm vs. (3.5–)5.4–6.3 × 2.5–2.7(–3.4) cm, and glabrescent to pubescent; more numerous carpels 40.0–42.0 vs. (22.0–)24.0–34.0(–35.0). The species is also similar to M. yoroconte , but it differs from the latter in having larger flowers 15.0–17.0 vs. 6.0–10.0 cm; more numerous petals 8–10 vs. 6; size of external petals 6.5–7.0 × 3.5 vs. 3.0 × 2.0 cm; and larger fruits of 6.0–8.0 × 3.0 vs. 4.0–6.0 × 2.0–4.0 cm ( Table 2 ).

Evergreen trees, 16.0–23.0 m high, 80.0–90.0 cm DBH, branches glabrous, warty; bud scales small, glabrous, sometimes slightly and inconspicuously pubescent apically; petioles 2.2–2.5 × 0.2–0.3 cm, glabrous; leaf blades 15.0–17.0 × 6.2–7.0 cm, obovoid to elliptic, with obtuse to acute apex, base shortly narrow, glabrous in both surfaces including in tender leaves, with 10–15 veins at each side; flowers 15.0–17.0 cm in diameter; spathaceous bracts 2 per flower, 4.0– 4.6(–5.5) cm, glabrous adaxially, abaxially glabrous at the base but pubescent from the middle part (yellowish golden trichomes) to apex (yellowish amber trichomes); floral peduncles 5.0–8.0 × 0.8–1.2 cm, glabrous, warty; sepals 3–4, 6.2–7.2 × 4.0– 4.8 cm, markedly reflexed, widely elliptic, concave, with orbicular to retuse apex; petals 8–10, white, outer petals 6.5–7.0 × 3.5 cm with 1.3 cm wide base, narrowly obovoid, obtuse apex, inner petals 4.4–7.2 × 2.2–3.5 cm, from elliptic-obovoid to obovoid and spathulate; staminophore red-purple 1.0–1.3 × 0.8–1.1 cm; stamens 90–100, 1.5–1.7 × 0.3–0.4 cm; gynoecium 2.7–3.0 × 1.5–1.8 cm, globose, whitish green, glabrous; fruit a polyfollicle, 6.0–8.0 × 2.9–3.1 cm, oblong, glabrous, greenish when immature, turning purple when ripe, follicles 40–42, 2.7–3.0 × 1.4–1.5 cm, styles 0.8 cm, geniculate, stiff.

Distribution, phenology and ecology:— Endemic to the municipality of Cobán, Alta Verapaz Department, Guatemala. Known so far from the banks of the Cahabón River, approximately 1300 m. Flowering March–June, fruiting June–August.

Etymology: — Honouring Weerakit Harnpariphan, “the magnolia guardian”, a distinguished horticulturist, in recognition of his devotion and contribution to Magnolia ex-situ conservation.

Conservation status: —A strictly endemic species with extremely narrow known distribution. Considered critically endangered (CR) following the D criterion of IUCN (2019) because the number of surviving mature individuals in the unique known locality is one, the other two known individuals have not survived after discovery. The extent of occurrence is the minimum possible, whereas the known area of occupancy was estimated as 4 km ² using the IUCN recommended grid cell, the decline was inferred both in the area of occupancy and the habitat because nearby forests were cut down during land-use change and urbanization; in this way, the species may fulfil also the criteria B1ab(iii) and B2ab(ii) for critically endangered species. The species is not protected by the Guatemalan system of protected areas ( CONAP 2011).

Other specimens examined:— GUATEMALA. Alta Verapaz: municipality of Cobán , 1300 m, 15°27’51”N, 90°22’27”W, 2 April 2021 Tribouillier & Archila MG-091, MG-092, MG-093 ( BIGU) , 7 May 2021 Tribouillier & Archila MG-094, MG-095 ( BIGU) , 7 May 2021 Tribouillier & Archila MG-096, MG-097 ( AGUAT) .

Figures

FIGURE 3. of Magnolia weerakitana. A. Flower. B. Holotype at BIGU, C. Fruit Photographs: A & C. by Javier Archila; B. by Mario Véliz.

FIGURE 4. Distribution of Magnolia quichensis, M. weerakitana and other Magnolia species from the centre of Magnolia endemism in the Guatemalan north-west-arc.