Magnolia montebelloensis A.Vázquez & Pérez-Farr., 2017

Vázquez-García, J. Antonio, Pérez-Farrera, Miguel Ángel, Gómez-Domínguez, Héctor, Muñiz-Castro, Miguel Ángel & Sahagún-Godínez, Eduardo, 2017, Magnolia montebelloensis, a new species in section Magnolia from Lagunas de Montebello National Park, Chiapas, México, with a key to Magnoliaceae of Chiapas, Phytotaxa 328 (2), pp. 101-114 : 104-111

Magnolia montebelloensis A.Vázquez & Pérez-Farr. , sp. nov. ( Figs. 1–4 )

Type:— MEXICO. Chiapas: Municipio La Trinitaria , km 4, road from Tsikaw [Tziscao] to Colonia Cuauhtémoc, Paraje Dos Lagos, 16°05’32.7” N, 91°38’12.9” W, 1452 m, 26 Oct 2013, in cloud forest, Vázquez-García 10109 (fl, fl bud, fr) (holotype: IBUG!; isotypes BIGU!, CR!, HEM!, MEXU!) .

Magnolia montebelloensis is similar to M. poasana from Costa Rica in having fruits of similar size with somewhat beaked carpels. However, it differs from the latter in height, 12–16(–24) vs. 25–30 m, distal twig internodes pubescent to glabrescent vs. glabrous, stipules pubescent vs. glabrous, three densely hairy spathaceous bracts vs. two and glabrous, length of the largest peduncular internode 1.0–1.5 vs 3.0–4.0 cm, number of stamens (53–)60–66(–85) vs. 50–52(–54), and carpels pubescent vs. glabrous.

Evergreen trees, 12–16(–24) m tall, 20–35 cm dbh; twigs 0.6–0.9 cm width; twig internodes 1.0–1.6 × 0.6–8.0 cm, lenticellate, terminal internodes glabrescent to densely shiny, yellowish pubescent; petioles (2.3–)3.2–3.4(–4.0) × (0.2–) 0.3–0.4 cm, glabrous, without stipular scars; stipules free from the petiole, 7.0–11.1 × 1.2 cm, pinkish, densely pubescent; early leaf buds 0.5–1.1 cm, densely pubescent, leaves oblong lanceolate (9.0–)15.3–20.2(–22.2) × (3.5–) 6.6–8.5(–10.8) cm, adaxially and abaxially glabrous; largest peduncular internodes 1.0– 1.5 cm long; flower buds ovoid to oblongoid, consisting of three spathaceous, densely hirsute bracts, with long golden-yellowish hairs, the outermost bract often glabrescent; flowers terminal, solitary, 11 cm in diam., creamy white; sepals 3, 4.2–4.3 × 2.7–2.8 cm, greenish; petals 6, outer ones 5.3–5.4 × 2.6–2.7 cm, obovate, gradually narrowed toward the base, creamy white; inner petals 4.4–4.5 × 2.0– 2.3 cm, obovate, creamy white, fragrant; staminophore (0.65–)0.80–0.90 × 0.60–0.80 cm, reddish; stamens(53–)60–66(–85), laminar, creamy yellowish, reddish at base, the connective obtuse to acute, strongly arched; stigmas 0.3–0.4 cm, curled and filiform, beaked, mostly persistent, tan to brownish; fruit oblongoid (3.5–)5.4– 6.3 × 2.5–2.7(–3.4) cm, yellowish to reddish, glabrescent to pubescent; carpels (22–)24–34(–35), acute at the apex and with curled, persistent stigmas, the beaks 0.4–0.5 cm, pubescent to glabrescent; seeds 1–2 per carpel, 0.9–1.0 × 0.8 cm, scarlet red.

Eponymy: — This species is named after the Lagunas de Montebello National Park, the type locality.

Distribution and habitat: — Endemic to the Lagunas de Montebello Region, Municipality of La Trinitaria, in eastern Chiapas, Mexico, in the physiographic province Sierras de Chiapas y Guatemala, subprovince Altos de Chiapas (INEGI 2004), ( Fig. 1 , Table 2). Only known from five solitary trees on roadsides at the edge of pasturelands on gentle slopes between Tziscao and Colonia Cuauhtémoc and from another collection locality at Cinco Lagos, at 1300–1600 m. According to data from the meteorological station in Tziscao (16.1° N, 91.63° W; 1475 m) the mean annual temperature is 17.3° C, mean annual precipitation 2279 mm and mean annual evaporation 948 mm. The climate of the region is humid temperate with a long cool summer and abundant rains, which is referred to as (Cb(m)(f)ig), according to García & CONABIO (1998) and García (2004). More than 10.2% of precipitation falls during the winter. The climate is isothermal (less than 5° C of annual oscillation of monthly mean temperatures) of a Ganges type. The region is covered by a Lower Cretaceous limestone that gave rise to the formation of a karstic lake complex of more than 50 lakes, which includes solution lakes with dolines ( Hutchinson 1957), uvalas and poljes ( Alcocer et al. 2016). The dominant soil types on the M. montebelloensis location records are luvisol profondic-humic, umbrisol humicendoleptic and infertile luvisol cromic-dystric, with intermediate texture ( INEGI 2013).

Magnolia montebelloensis is said to be a rare species that is found scattered in the forest (pers. comm., Joel Hernández-Morales from Ejido Tziscao, 26 October 2013). This species inhabits the Chiapas Montane Forests ecoregion ( Olson et al. 2001), in montane rain forest (sensu Breedlove 1981), subtropical wet forest (sensu Holdridge 1967) or bosque mesófilo de montaña (sensu Rzedowski 1978), growing with Malmea sp. , Parathesis belizensis, Podocarpus matudae, Liquidambar styraciflua , Cornus sp. , and Saurauia sp. It is to be expected on the Guatemalan side and the Maya Mountains in Belize.

None of the other seven Magnolia species in Chiapas has the same elevational range as M. montebelloensis except for M. faustinomirandae ( Table 2), but the latter receives less annual precipitation (1705–1918 vs. 2295–2754 mm). Los Altos de Chiapas Mountain (the central Chiapas Highlands; 1600–2884 m) has served as a partial geo-ecological barrier between both species ( Fig. 1 ), contributing to the observed allopatric pattern. The isolation of these two species generated by this mountain chain should have been greater during the long cool periods of Pleistocene glaciations, since these two species are likely more sensitive to frost than Magnolia sharpii , which is the species best adapted to the colder climatic regime of the highest mountains of the central Chiapas Highlands ( Fig. 1 , Table 2).

There are two Magnolia species in section Magnolia that are geographically close to M. montebelloensis : Magnolia mayae and M. sharpii , but the habitat conditions that both face are different to those of M. montebelloensis . Magnolia mayae prefers the warmer and wetter Lacandonian tropical rainforest conditions, unlike the cooler habitat of M. montebelloensis ( Table 2), and competes with tall tropical rainforest trees, which are absent in the montane forests of M. montebelloensis . Magnolia sharpii prefers colder and less rainy conditions ( Table 2), where night frosts are frequent from December to April ( Wolf 2005), whereas the Montebello Lakes region has no frosts ( Ramírez-Marcial et al. 2010).

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Phenology:— Flowering April–June, occasional flowers throughout the year; fruiting September–November.

Ethnobotany: — No uses have been recorded for this species, which is locally known as “tajchack” (in the Tzeltal language).

Conservation status: — Trees are being spared because they are considered rare. The assigned category of this species is critically endangered (CR). Despite the legal protection afforded to the Lagunas de Montebello National Park (LMNP), global warming, frequent severe fires, high incidence of tropical insect pests and agricultural expansion are seriously threatening this species with extinction. Conservation status of Magnolia montebelloensis was evaluated using the B1ab(ii,iii) and B2ab(iii) criteria of the IUCN Red List Categories and Criteria ( IUCN 2012).

B1a: The known extent of occurrence (EOO) for this species was determined using a combined technique of areographic analysis ( Rapoport & Monjeau 2001) and the minimum convex polygon method ( IUCN 2012), the latter traced around the circular buffer areas that surround the record points of the species, for which radii were equal to the average of the minimum distances between pairs of record points of the species (mean propinquity index). The EOO of M. montebelloensis was estimated as an area of approximately 49.5 km 2. The area of extent of occurrence of M. montebelloensis is severely fragmented by agricultural and pasture lands, human settlements and high frequency of wildfires outside and even inside the Lagunas de Montebello National Park. An example was the severe fires (canopy fires) of 1998 that damaged 50% of the National Park area and deforested about 30% of the land ( CONANP 2006, March & Flamenco, 1996). Many remnant individuals of its population are found as isolated trees in a matrix of pasturelands and croplands. Another threat to M. montebelloensis is the increase in the use and pollution of water resources of the Montebello Lakes, due to increased human population in the vicinity and wastewater discharges from the city of Comitán into Río Grande, which discharges into Lake Tepancoapan, the largest of the Montebello Lakes ( CONANP 2007). Magnolia montebelloensis is highly dependent upon the quantity and quality of the water in the lakes.

B1b(ii, iii): The extent and quality of the montane rain forest of the LMNP region, the habitat of M. montebelloensis , has been reduced continuously since 1970. That year the National Park had 71.98% of its forest in good condition ( CONANP 2007). By 1993, 61.39% of the park had been reduced to disturbed or fragmented cloud forests and 10% of disturbed or fragmented temperate forests, with only 264 ha in good condition ( SARH 1994). By 1995 the transformed or disturbed areas covered more than 50% of the total area and by 2005 only 4707 ha of a total of 6425 ha were forest area, and of these 44% was disturbed or secondary growth forests.

B2ab(iii): The area of known occupancy (AOO) of the species was estimated to measure approximately 8.7 km 2 because the EOO polygon has more than 80% of its area occupied by agricultural and pasturelands, human settlements and lakes. Only approximately 42% (20.7 km 2) of the EOO is inside the “protected” LMNP, of this ca. 3.5 km 2 are lakes, 10.2 km 2 agriculture or pastures and 0.8 km 2 human settlements, resulting in only 6.2 km 2 of “protected” montane forest habitat for M. montebelloensis . Outside the protected LMNP, the situation is even worse, and only small fragments of secondary montane forest remain, which in total cover no more than 2.5 km 2. The total known AOO of M. montebelloensis is approximately 8.7 km 2.

All magnolias of Chiapas are narrow endemics, mostly confined to Chiapas, except for M. mayae , which is found in both sides of the Mexican-Guatemalan border, and M. zamudioi , which also is found in eastern Oaxaca ( Fig. 1 , Tables 2 and 3). Six (75%) out of the eight species of Magnolia from Chiapas are critically endangered ( Table 3), and the other two are endangered. There are three Chiapan Magnolia species that are highly restricted, M. montebelloensis , M. faustinomirandae and an unnamed species from the Tacaná volcano ( Fig. 1 , Table 3), all of them matching the critically endangered category of the IUCN Red List.

Half of the Chiapan magnolias occur in protected natural areas, and thus immediate action is suggested to protect the other four species, M. faustinomirandae , M. mayae , M. sharpii and M. zamudioi ( Table 3). Seven out of the eight Magnolia species (88%) are not found in ex-situ collections despite being endangered or critically endangered ( Table 3).

In recent decades, in the face of the partial collapse of the traditional agricultural economy and the absence of alternatives in Chiapas, the rural population has elected to ensure their survival in the short term rather than adopting strategies for long-term development ( Peláez-Herreros 2012). This means that the rural human populations of Chiapas still need to make intensive use of their natural resources, such as logging for wood, firewood and charcoal for their basic needs ( Ghilardi et al. 2007, Baroody 2013) or convert land to extensive agriculture or pasturelands ( Castillo-Santiago et al. 2007). As long as the causes of lags in sustainable development and economic deficiencies remain in rural areas of Chiapas, it will be difficult to stop or reverse deforestation, and this will keep the species of Magnolia in critical danger of extinction.

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Additional specimens examined:— MEXICO. Chiapas: Municipio La Trinitaria, Lago Tziscao on the border with Guatemala , 30 mi E of La Trinitaria , 4500 ft [ca. 1372 m], 14 Apr 1965 (fl bud, fl), Breedlove 9743 ( CAS) ; La Trinitaria, Lago Tsiskaw on the Guatemala border, 30 mi E of La Trinitaria , 4500 ft [ca. 1372 m], 27 May 1965 (fl, young gynoecium), Breedlove 1066 ( CAS) ; La Trinitaria, E of Laguna Tziscao, Monte Bello National Park , 16 Nov 1972 (fl bud, fr), 1300 m, Breedlove & Dressler, 29606 ( CAS) ; La Trinitaria, E of Laguna Tziscao, Monte Bello National Park , 23 Jan 1973 (fl bud, fr), 1300 m, Breedlove & Smith 32252 ( CAS) ; La Trinitaria, Laguna Tziscao, Monte Bello National Park , 1300 m, 13 May 1973 (fl, young gynoecium), Breedlove 35173 ( CHIP) ; La Trinitaria, Laguna Tziscao, Monte Bello National Park , 1300 m, 13 May 1973 (sterile), Breedlove 35273 ( CAS, CHIP) ; La Trinitaria, near Cinco Lagos, Lagos de Monte Bello National Park , 1372 m, 5 Oct 1981 (fr), Breedlove 53334 ( CAS) ; La Trinitaria, Col. Cuauhtémoc, N side of the road, 10 Jun 1984 (fl bud, fl), Méndez G. (Alush Shilon Ton) 7656 ( CHIP) ; La Trinitaria, Cinco Lagunas, Lagos de Monte Bello National Park , 1600 m, 24 May 1988 (sterile), Breedlove 68649 ( CAS) ; La Trinitaria, E of Laguna Tziscao, Monte Bello National Park, 6 Jul 1988 (sterile), Vázquez-García et al. 4645 ( WIS) ; La Trinitaria, Ejido Tziscao, 16°05’11.8”N, 91°38’58.6W ”, 1465 m, 26 Oct 2013 (fr), Vázquez-García et al. 10107 ( BIGU, CR, HEM, IBUG, MEXU) ; La Trinitaria, km 3, Tziscao to Benito Juárez , 16°05’21”N, 91°38’34.9”W, 1455 m, 26 Oct 2013 (fl bud, fr), Vázquez-García et al. 10108 ( BIGU, CR, HEM, IBUG, MEXU) .

Figures

FIGURE 1. Distribution of Magnolia montebelloensis and other species of Magnolia from Chiapas and Oaxaca (Mexico) and Guatemala. Section Magnolia: red solid circles: M. montebelloensis; solid black squares: M. sharpii; solid black triangles: M. mayae; solid white rhombuses: unnamed Magnolia; solid white triangles: M. faustinomirandae; pentagons: M. zamudioi; crosses: M. guatemalensis Donnell Smith (1909: 253); section Talauma: solid white squares: M. lacandonica; stars: M. perezfarrerae; solid black rhombus: M. steyermarkii Vázquez (Váquez-García et al., 2012c: 122).

FIGURE 2. Magnolia montebelloensis. A. Tree, standing at the base Miguel Muñiz & Antonio Vázquez. B. Stipule on late leaf bud. C. Leaves. D. Flower bud with spathaceous bract and early axillary leaf buds. E–F. Flowers forced open with and without stamens, respectively. G. Flower after male phase. H. Developing gynoecium, with axillary leaf buds. I. Developing fruit. Photographs by Antonio Vázquez, A–C & I from Vázquez-García et al. 10107; & D–H, from the holotype.

FIGURE 3. Magnolia montebelloensis. A–F. Fruit maturation to dehiscence. G–H. Carpels removed to show morphological variability. I. Fruits on the ground. Photographs by Antonio Vázquez, A & E–I from Vázquez-García et al. 10108; B–D from Vázquez-García et al. 10107.

FIGURE 4. Magnolia montebelloensis.A. Flower after male phase.B. Flower manually forced open with stamens removed.C. Flower bud with densely hirsute spathaceous bract and early vegetative buds. D. Leaf stipule in late vegetative bud. E. Gynoecium with early axillary leaf buds and terminal internode; sepals, petals and stamens removed. F. Developing fruit. G–H. Fruits during dehiscence. Illustration by Esaú Vázquez-Verdejo. A–C & E from the holotype. D, F–G from Vázquez-García et al. 10107; H from Vázquez-García et al. 10108.