Magnolia faustinomirandae A.Vázquez (2013: 463)

Vázquez-García, J. Antonio, Tribouillier-Navas, Erick, Archila, Fredy, Véliz, Mario, Peña, A. Salome Ortega & Shalisko, Viacheslav, 2021, Three new species of Magnolia (Magnoliaceae) endemic to the north-wet-arc in the Maya Highlands of Guatemala, Phytotaxa 529 (1), pp. 57-70 : 66-68

Magnolia faustinomirandae A.Vázquez (2013: 463) ( Fig. 5 ).

Type:— MÉXICO. Chiapas: 5 km south-east of Jitotol along the road to Bochil , Municipality Jitotol , open forest with Pinus , Quercus , Nyssa , Liquidambar and Brunellia, 1600 m , 9 Jan 1981 (fr), Breedlove 49350 (holotype: CAS!, 2 sheets; isotypes: CH! MEXU!).

Magnolia faustinomirandae belongs to the Magnolia sect. Magnolia and has been previously confirmed only from populations in cloud forests near the type locality but not verified in situ for the last four decades. Based on morphology and supported by shared climate (similar rainfall and temperature regimes), M. faustinomirandae is here confirmed from several populations in Quiché, Guatemala. Despite differences in the underlying geology between these disjunct populations (ca. 247 km apart), magnolias are not lithophytes, but rather rely on soil quality. Additionally, M. faustinomirandae shares with M. mayae a similar biogeographical niche, the former occurring within 124 km of radius and the latter within 104 km of radius, the two geographically converging at the Maya Highlands in Quiché, Guatemala, where they are only 7 km apart and diverging in the Tierras Altas de Chiapas (Morrone 2017) where they are 66 km apart. However, the two species differ in leaf morphology and habitat, M. mayae much larger (nearly twice as long) in rainforest (760–1350 m), whereas M. faustinomirandae occurs in open cloud forests (1400–1700 m) often composed of pines and oaks. Furthermore, the distribution of these three species could in part be explained by bird dispersal, since tucaneta esmeralda ( Aulacorhynchus prasinus ) and motmot have been observed to disperse Magnolia seeds (F.Archila, unpubl.) and they also occur in the upper Mesaoamerican region (https://ebird.org/home).

Trees 5.0–23.0 m tall, 40.0–50.0 cm DBH; terminal twigs 0.5–0.8 × 0.4–0.5; petioles 1.5–3.0 cm, thickened at the base; leaves (10.0–)12.0–25.0 × (5.0–)7.0–12.0 cm, obovate to elliptic, rarely lanceolate, 10–14 pair of veins; peduncles densely yellowish pilose; flowers 9–14 cm in diam., spathaceaous bracts 2, 4.0–5.1 × 4.1–5.3 cm; peduncle 1.5–3.4(–4.5) × (0.5–) 0.6–0.7 cm; sepals 3, strongly reflexed and concave, soon becoming dark brown and contrasting with the creamy white petals; petals (5–)6, broadly to narrowly obovate, strongly concave, creamy white, with a lemony fragrance; stamens ca. 100–120 (estimated from staminal scars); gynoecium rhomboid, glabrescent, stigmas curved outward (1.8–)2.2–2.5 × (1.0–) 1.2–1.3 cm; polyfollicle obongoid 5.0–6.5 × 2.5–3.0 cm, carpels 36–40; seeds (1–)2 per carpel, becoming black after drying.

Magnolia faustinomirandae shares with Magnolia pugana (Iltis & Vázquez 1994: 14) Vázquez & Carvajal (2002:137) the shape of fruit and a similar number of carpels, but it differs in having leaf apex subacuminate vs. acute, peduncles densely hairy vs. glabrous, petals (5–)6 vs. (6–)7, stigmas curved outward vs. almost uncurled, sepals soon becoming dark brown and contrasting with the creamy white petals vs. fading pale brown all together with the creamy white petals, gynoecium glabrescent vs. glabrous. Magnolia faustinomirandae was formerly treated as M. aff. yoroconte (Vázquez-García 1990, 1994). However, it differs from M. yoroconte in being a smaller tree, up to 23.0 m vs. up to 42.0 m, and having larger leaves (10.0–)12.0–25.0 × (5.0–)7.0–12.0 vs. 12.0 × 5.0 cm, sepals soon becoming dark brown contrasting much from petals vs. white at anthesis, gynoecium rhomboid, glabrescent, yellowish pubescent at the lower third of its length vs. oblongoid, pubescent at the base only, stigmas curved outward, conspicuous vs. straight, less conspicuous, and a fewer carpels 36–40 vs. 40–50. Specimens from Los Tuxtlas, México, are excluded. Distribution, phenology and ecology:— Disjunct but endemic to the Maya Highlands (1400-1700 m), the northern populations in Jitotol, Chiapas, and the southern populations in Quiché, in open cloud forest with Pinus , Quercus , Liquidambar styraciflua , Nyssa sylvatica and Brunellia mexicana , flowering March–June, fruiting January.

Eponymy, ethnobotany and conservation:— Magnolia faustinomirandae was named in honour of Professor Faustino Miranda , who devoted his life to botany, studying algae and the flora and vegetation of Chiapas. There is no use recorded for this species in Chiapas, México, but in Guatemala it is a first-quality wood, locally known as corazón negro (black heart). The species is critically endangered, perhaps extinct in the type locality because no other collections from that area are known. The precise location and legal protection of populations of this species are urgently needed. In Guatemala its major threat is use as timber.

Other specimens examined:— MÉXICO. Chiapas: La Cumbre, km 65, Jitotol, 26 Apr 1964 (just past fl), MacDougall s.n. (MEXU); few miles beyond Bojil [Bochil] toward Pueblo Nuevo, within 100 yards beyond the 65 km post on that road, 4 Aug 1964 (sterile), McDaniel s.n., 26491-PI 302799 (grown at NA from cuttings grafted on M. virginiana × M. grandiflora understock); 29 Jun 1973 (fl), Meyer & Eisenbeiss s.n. (NA, 3 sheets including two black and white photographs and a separate colour slide). GUATEMALA. El Quiché: Chajul, Encuentros Amacchel, 15°41´N, 91°01´W, 1550 m, 11 Jan 2019 (fl), Tribouillier & Archila MG-076 (BIGU); 15 Feb 2019 (fl, fr), Tribouillier & Archila MG-077, MG-078 (BIGU, IBUG); 7 Mar 2019 (fr), Tribouillier & Archila MG-079, MG-080 (BIGU, AGUAT); 10 Jan 2020 (fl), Tribouillier & Archila MG-081, MG-082 (BIGU); 10 Jan 2020 (fl, fr), Tribouillier & Archila MG-083, MG-084, MG-085, MG-086 (BIGU, IBUG); Chajul, Finca La Perla, 15°36´N, 91°06´W, 1700 m, 25 Oct 2010 (fr), Tribouillier ET-465 (BIGU). Specimens from Los Tuxtlas, Mexico, were excluded because they have fewer carpels and smaller fruits, and future work may indicate that these populations represent a taxon separate from M. faustinomirandae .

Notes:— Magnolias of Guatemala display a pattern mostly associated with the north-wet-arc ( Wendt 1987), and two thirds of the Guatemalan magnolias are endémic except for three shared with México: M. faustinonomirandae , M. mayae and M. montebelloensis . Two are shared with El Salvador and/or Honduras: M. hondurensis and M. yoroconte ; the magnolias of Belize are still poorly understood ( Fig. 1.1 ).

Two centres of Magnoliaceae diversity and endemism occur in Guatemala and contribute to the high endemism of the country ( Veliz et al. 2014, Archila et al. 2018), suggesting at first a pattern of sympatric speciation: one centre in the Maya Highlands of Huehuetenango-Quiché and another in the Verapaces region, possibly associated with areas of higher rainfall as suggested by Gentry (1988) but separated along a gradient of decreasing rainfall from west to east and by the dryer Chixoy watershed. Magnolia montebelloensis and M. javieri are the only species shared by the two areas ( Fig. 1.2 ).

Two of the species, M. ottoi and M. steyermarkii , belong to a different clade in M. sect. Talauma . These two species are allopatric, each confined to a different department ( Fig. 1.3 ). Within the Huehuetenango-Quiché region five species of Magnolia sect. Magnolia co-occurr: M. mayae ecologically adapted to lowlands in the lower montane rainforest (700–1350 m), whereas M. faustinomirandae , M. javieri , M. montebelloensis and M. veliziana occur in open cloud forest mixed with pine and oak at higher elevation (1400–1700 m) ( Fig. 1.4 ). Within the Verapaces region, six species of M. sect. Magnolia co-occur: M. archilana , M. guatemalensis , M. javieri , M. oscarrodrigoi , M. poqomchi and M. tribouillieriana ( Fig. 1.5 ). The eastern part of Guatemala has two species, M. yoroconte and M. hondurensis , representing a marginal distribution of species mostly distributed in El Salvador and/or Honduras ( Fig. 1.6 ).

Figures

FIGURE 1. Distribution of Magnoliaceae in Guatemala.Map A shows the full set of known Magnoliaceae localities for species occurring in Guatemala and extent rectangles for five closeup maps B–F; maps B, D, E represent Magnolia localities for species from section Magnolia, including close up to the North-Wet-Arc (B), to the zone of Huehuetenango and western Quiché (D); to Alta Verapaz, Baja Verapaz and eastern Quiché (E); map C is a closeup to the localities for species from section Talauma; map F is a closeup to the known confirmed localities of M. hondurensis and M. yoroconte.

FIGURE 5. Magnolia faustinomirandae. A-B. Flower at male phase. C. Isolated trees. D. Mature polyfollicles. E. Dehiscing fruit. F. Seeds, fruit after dehiscence. Photographs by E. Tribouillier.