Populus primaveralepensis A.Vázquez, Muñiz-Castro & Zuno, 2019

Vázquez-García, J. Antonio, Muñiz-Castro, Miguel Ángel, González, Rosa Elena Martínez-, Nieves-Hernández, Gregorio, Pulido-Ávila, María Guadalupe, Hernández-Vera, Gerardo & Delgadillo, Osvaldo Zuno, 2019, Populus primaveralepensis sp. nov. (Salicaceae, Malpighiales), a new species of white poplar from the Bosque La Primavera Biosphere Reserve in western Mexico, European Journal of Taxonomy 498, pp. 1-16 : 5-12

Populus primaveralepensis A.Vázquez, Muñiz-Castro & Zuno sp. nov.

urn:lsid:ipni.org:names:77194127-1

Figs 1–4

Differential diagnosis

Populus primaveralepensis sp. nov. is morphologically close to P. luziarum , but it differs from the latter in possessing various qualitative and quantitative characters, such as having taller trees with nonsoboliferous habit, branching angle of ca 45º with white and ringed bark, and leaves with higher blade to petiole ratio (large leaves with petioles 2.9–3.9 vs 5.4–6 cm long, leaf blades frequently elliptic or ovate to widely ovate vs widely ovate to ovate-deltoid, 17–18.5 vs 15.5–16 cm long, inflorescences dense vs sparse, and shorter capsules, 1.0–1.8 vs 2.0– 2.5 mm ( Table 1 ).

Type material

Holotype

MEXICO • fr; Jalisco, Tala, along Río La Lobera, Llano Grande , Reserva de La Biosfera Bosque La Primavera ; 20.6° N, 103.6° W; 1604 m a.s.l.; 4 Mar. 2013; J. Antonio Vázquez-García, Padilla-Lepe, and Zuno-Delgadillo 10005 leg.; montane cloud forest relict; IBUG.

Isotypes

MEXICO • Same data as for the holotype; K, MEXU, MO, ZEA .

Etymology

The epithet honors the collective conservation accomplishments at Bosque La Primavera for its twelfth anniversary as a MaB–UNESCO Biosphere Reserve as well as the biologist Jesús Padilla Lepe, a young and enthusiastic botanical explorer graduated from the Universidad de Guadalajara who discovered the species.

Other material examined

MEXICO – Jalisco • ♀ fl buds; Municipio Arenal, Bosque La Primavera , 1.5 km S of Fraccionamiento El Roble; 20°41′48.00″ N, 103°37′49.71″ W; 1330 m a.s.l.; 25 Oct. 2009; M. Harker et al. 4045 leg.; IBUG • st; Municipio Tala, Bosque La Primavera, Llano Grande ; 20°39′27″ N, 103°37′39″ W; 1604 m a.s.l.; 8 Feb. 2012; Padilla-Lepe and Zuno-Delgadillo s.n. leg.; IBUG • ♂ fl; Tala, Arroyo La Lobera ; 20°39′27.5″ N, 103°37′42.2″ W; 1640 m a.s.l.; 5 Nov. 2017; J. Padilla-Lepe, O. Ibarrarán-Madrigal, and J. J. Padilla-García 252a leg.; IBUG • ♀ fl, fr; same collection data as for preceding, J. Padilla- Lepe, O. Ibarrarán-Madrigal, and J. J. Padilla-García 252b leg.; IBUG • ♂ fl; Acequia, in the SE margin of the town of Tala, intersection at El Álamo, 1 km before the Higher Technological Institute of Tala ; 20°38′33.56″ N, 103°41′52.18″ W; 1332 m a.s.l.; 18 Aug. 2013; Vázquez-García et al. 10106b leg.; IBUG • ♀ fl, fr; same collection data as for preceding; Vázquez-García et al. 10106c leg.; IBUG • ♂; same collection data as for preceding; 2 Oct. 2017; Vázquez-García and Padilla-Lepe 10150 leg.; IBUG • ♀ fl, fr; same collection data as for preceding; Vázquez-García and Padilla-Lepe 10151 leg.; IBUG • ♂ fl; Municipio de Tala, Arroyo La Lobera 3.5 km E del Macrolibramiento ; 20°39′18.64″ N, 103°38′56.54″ W; 1427 m a.s.l.; 31 Oct. 2017; H. Luquín-Sánchez and G. Nieves-Hernández s.n. leg.; IBUG • ♀ fl, fr; same collection data as for preceding; 20°39′17.28″ N, 103°39′7.25″ W; 1439 m a.s.l.; H. Luquín-Sánchez and G. Nieves-Hernández s.n. leg.; IBUG .

Description

Trees 5–30 m tall; trunk 0.3–1.2 m in diameter at breast height, branched or single stemmed; spreading exclusively by seeds (non-soboliferous); bark smooth and whitish at sapling stage, and upper branches occasionally becoming shallowly furrowed and never tessellated. Petioles 2.0–4.2(5.4) cm long, flattened near the leaf union, densely pubescent. Leaf blades (7.0)9.3–18.5 × (4.5)7–10.2–(14.3) cm, elliptic to ovate to widely ovate, rounded to subcordate at the base and acute at the apex, abaxially and densely pubescent throughout. Bud of the male inflorescence 5–7 × 2–3 mm, bright reddish brown, glabrescent, with 6 scales. Male ament 10–70 × 10–25 mm, cylindrical, pendulous and curved, with densely arranged flowers; rachis 1.0– 1.5 mm thick, creamy to white, brown when it dries, glabrous; pedicels 0.5–1.5 mm long, greenish; bracteoles 2.5–3.7 × 1.7 mm, ovate, with margin entire and ciliate, unlobed, dentate at the apex, reddish brown. Staminate flowers 48–50, 1.5–2.2 mm long, pedicellate; pedicels 0.3–0.5 mm long; floral disc 1.0– 1.2 in diameter, meniscoid, shallow cup, shaped to patelliform, oblique, creamy, brown yellowish when it dries; stamens 6–12, free; filaments 0.5–0.7 mm long, glabrous; anthers 0.6–1.5 × 0.5–0.8 mm, pale yellow, basifix and oblong, longitudinal dehiscence, with tecae 0.6–1.5 × 0.2–0.3 mm. Bud of the female inflorescence 6–15 × 3–5 mm; scales 6–7, 1–5 × 2–6 mm, brown reddish, glabrescent. Female ament 40–80 mm, cylindrical, dense; rachis 1.0– 1.5 mm width; pedicels 0.5–1.5 mm long, greenish-yellow color, brown when it dries, sparsely ciliate; bracteoles 2–3 × 1–2 mm, narrowly ovate to elliptic to broadly spathulate, with margin sparsely denticulate to entire, non-lobed, ciliate, caducous, greenish yellow at anthesis, brown-reddish when it dries. Pistillate flowers 30–80, 1.0– 1.5 mm long, glabrous; pedicel 0.5–1.0 mm; floral disc 1.2–1.8 mm in diameter, ciathiform, scarcely ciliated; ovary inferior, pisiform, pubescent to glabrescent; styles 0.5–2.0 mm long, each branched into curved stigmas. Infrutescence 20–80 × 10–20 mm; rachis 1.0– 1.5 mm thick, brown and glabrate; peduncle 1.0– 1.2 mm long; brown and glabrate; bracteoles 3.5–4.0 × 1.2–1.8 mm, narrowly ovate to elliptic to broadly spathulate, margin sparsely denticulate to entire, non-lobed, ciliate, caducous, greenish yellow at anthesis, brown-reddish when it dries; capsules 30–80, 1.0–1.8 × 0.6–0.9 mm, bivalved, closed, narrowly ovoid, pubescence translucent; seeds 1–3 per capsule, 0.3–0.7 × 0.2–0.4 mm, creamy yellowish or reddish brown; pappus 4–6 mm long, yellowish brown or white.

Distribution, habitat and phenology

Western Mexico: State of Jalisco, Bosque La Primavera Biosphere Reserve, along the tributaries of Río La Lobera and Río Caliente, in the municipalities of Tala and Arenal, respectively ( Fig. 5 ).

The relict gallery cloud forest includes Clethra rosei Britton ( Clethraceae Klotzsch ), Ficus insipida Willd. ( Moraceae Gaudich. ), Ilex dugesii Fernald ( Aquifoliaceae Bercht. & J.Presl ), Morella cerifera (L.) Small ( Myricaceae Rich. ex Kunth ), Persea hintonii C.K. Allen ( Lauraceae Juss. ), Prunus serotina subsp. capuli (Cav.) McVaugh ( Rosaceae Juss. ), Quercus magnoliifolia Née and Quercus gentryi C.H.Muller ( Fagaceae Dumort. ), and Salix taxifolia Kunth ( Salicaceae Mirb. ) ( Table 1 ). The flowering occurs from August to November, the fruiting from October to November, and deciduous foliage can be observed during winter, from January to early March.

Taxonomic remarks

Because of its bifacial leaves, broad ciliate bracts; persistent, entire and oblique disk, two carpels, and 4–6 seeds, P. primaveralepensis sp. nov. falls within P. sect. Populus , the most speciose section of the genus (13 species); it belongs to P. subsect. Tomentosae, a subsection consisting of white poplars with abaxially pubescent leaves ( Eckenwalder 1977a, 1977b). Populus primaveralepensis sp. nov. is morphologically close to P. luziarum in having abaxially tomentose leaves and buds; however, it differs from the latter in having a taller habit (25–30 vs 15–20 m), a different type of spread (exclusively by seeds vs both by seeds and by means of root-borne sucker shoots), branches white and ringed vs brown and not ringed, branching angle (usually ca 45 vs> 75º), longer large-sized leaves with shorter petioles, elliptic to ovate to widely ovate vs widely ovate to ovate-deltoid, rounded to subcordate at the base vs obtuse to rounded to subcordate, and acute at the apex vs rounded, acute to shortly apiculate ( Table 1 ). Additionally, P. primaveralepensis sp. nov. differs from P. luziarum in terms of its phenology, losing leaves during winter vs autumn.

Ethnobotany

The species is locally known as “álamo”. There is no available information on the use of the species in Jalisco; however, sometimes it is kept as a shade tree for cows. Like other species in the genus Populus , P. primaveralepensis sp. nov. is a potential source of cellulose fibers, and can be used as an ornamental tree, or for restoration of watersheds in central Jalisco.

Conservation status

Populus primaveralepensis sp. nov. consists of four small and restricted subpopulations: (1) a single tree in a water spring of a tributary of Río Caliente, Arenal, Bosque La Primavera (20°41′48.00″ N, 103°37′49.71″ W); (2) a second and largest population (ca 100 trees), located at Llano Grande, Tala, along the Lobera River in Bosque La Primavera (20°39′27.5″ N, 103°37′42.2″ W); (3) eight trees including some old-growth forms in Tala, along the road to the Instituto Tecnológico Superior de Tala (20°38′33.56″ N, 103°41′52.18″ W), the older trees, ca 1 m in diameter, are ca 80 years old; (4) two additional trees, nearly 2 km east of the “Macrolibramiento” highway of the Guadalajara metropolis, along Río La Lobera (20°39′18.64″ N, 103°38′56.54″ W, male tree; 20°39′17.28″ N, 103°39′7.25″ W, female tree).

The known Extent of Occurrence (EOO) of P. primaveralepensis sp. nov. is ca 97.88 km 2, but from this area, only an Area of Occupancy (AOO) of ca 48.29 km 2 is represented by its habitat (relict gallery cloud forests in humid ravines); the rest is occupied by human settlements (Tala city and La Primavera town), country roads, highways, agriculture, and pasturelands, even inside the BLPBR. Hence, according with IUCN Red List criteria B1ab(iii) ( IUCN 2012), P. primaveralepensis sp. nov. should be categorized as Critically Endangered, an addition to the flora of conservation concern at BLPBR ( Table 2 ), because it has an EOO <100 km 2, very small and restricted subpopulations which are severely fragmented; there are less than 120 individuals known, and there is a continuing observed and projected decline in the area and quality of its habitat (relict gallery cloud forest).

Populus primaveralepensis sp. nov. is extremely rare, thus it should be protected immediately. It is important to disseminate this case and alert the general public that the fragmentation of habitats (mainly road expansion) represents a great threat for these fragile relict ecosystems, which have harboured numerous species for over one hundred millennia ( Mahood 1980).

Figures

Fig. 1. Populus primaveralepensis A.Vázquez, Muñiz-Castro & Zuno sp. nov. A–E, I–K. Vázquez- García et al. 10106c leg., IBUG. F–H. Vázquez-García et al. 10106b leg., IBUG. A. Variability of leaves. B. Leaf bud. C. Branch with female inflorescence. D–E. Early and late state of inflorescence. F–G. Late and early male inflorescence. H. Male flower. I. Infrutescence with pappus. J. Capsule complete and in half, with pappus. K. Developing gynoecium. Illustrations: E. E. Vázquez-Verdejo.

Fig. 2. Populus primaveralepensis A.Vázquez, Muñiz-Castro & Zuno sp. nov. Tree showing its habit and bark. J. Padilla Lepe, standing next to the tree; photograph: O. Ibarrarán.

Fig. 3. Populus primaveralepensis A.Vázquez, Muñiz-Castro & Zuno sp. nov., male individual, Vázquez-García et al. 10106b leg., IBUG. A–B. Two views of same branch with inflorescence past anthesis. C. Inflorescence at anthesis. D. Branch showing leaf variability and venation. Photographs: A. Vázquez.

Fig. 4. Populus primaveralepensis A.Vázquez, Muñiz-Castro & Zuno sp. nov., female individual, Vázquez-García et al. 10106c leg., IBUG. A. Inflorescence at anthesis. B. Inflorescence past anthesis. C. Developing infrutescence. D. Trunk. E. Branch with leaves and dehiscing capsules, showing the whitish pappus of seeds. Photographs: A. Vázquez.

Fig. 5. Maps. A. Distribution of P. primaveralepensis A.Vázquez, Muñiz-Castro & Zuno sp. nov. and related species of Populus L. in western Mexico. B. Distribution of the species of Populus in Jalisco with a close up for P. luziarum A.Vázquez, Muñiz-Castro & Padilla-Lepe and P. primaveralepensis sp. nov.