Penstemon dugesii Pérez-Calix & Zacarías, 2020

Zacarías-Correa, Ana Gabriela, Pérez-Calix, Emmanuel & Samain, Marie-Stéphanie, 2020, Penstemon dugesii (Plantaginaceae), a new species from Guanajuato, Mexico, Phytotaxa 447 (3), pp. 209-215 : 210-213

Penstemon dugesii Pérez-Calix & Zacarías , sp. nov., Figs. 1 – 3

Perennial herb, morphologically similar to P. coriaceus , differing its habit (perennial herb vs. subshrub), the stems in the basal portion of the inflorescence (brownish and smooth vs. gray to black and strongly scarred), the length of the internodes (1.5–3.8 cm vs. 0.5–1.5 cm), the width of the basal leaves (1.8–3.5 cm vs. 1.3–1.5 cm) and inflorescence leaves (0.9–1.5 cm vs. 0.7–1 cm), the texture of the leaves (foliaceous vs. leathery), longer peduncles of the cyme (1–2.5 vs. 0.4–1 cm long), and longer corolla (3.5–4 cm vs. 2.6–3 cm long).

TYPE: — MEXICO. Guanajuato, municipality Guanajuato: Cañada de La Virgen, 2351 m, 21°10’07.1”N, 101°12‘08.3“W, 29 July 2017, E. Pérez 6689 (holotype IEB!, isotypes MEXU!, SLPM!).

Perennial herb with basal woody stem, prostrate, decumbent, 0.5–1.5 m high, branched from the base, stem green or reddish in the young branches and inflorescence, brown in the basal part of the plant, puberulent in two longitudinal lines. Leaves opposite, internodal length 1.5–3.8 cm, subpetiolate, elliptic, spatulate to elliptic-spatulate, basal leaves 4–8 × 1.8–3.5 cm, inflorescence leaves 2–3.5 × 9– 1.5 cm, axillary fascicles of smaller leaves evident, apex obtuse, base cuneate-decurrent to shortly attenuated-decurrent, margin entire, occasionally with scattered teeth, barely evident in the upper middle part, midvein protruding abaxially, two pairs of lateral veins obscurely evident, glabrous, resinousdotted, texture foliaceous. Inflorescence an apical panicle, cymose branches 6, opposite, flowers 1–3 per individual cyme, peduncles of the cyme 1–2.5 cm long, puberulent. Flowers pentamerous, pedicels 0.3–0.8 cm long, pubescent, non-glandular. Lobes of the calyx 5, briefly adnate at the base, elliptic, apex acute, 5.5–6 × 3.5–4 mm, puberulent (scattered glandular hairs). Corolla tubular, purple red, in anthesis 3.5–4 cm long, tube 3.2–3.3 cm long, puberulent externally; upper lip bilobed, 5–6 mm long, lobes oblong; lower lip 3-lobed, 4–6 mm long, lobes oblong. Stamens exerted, didynamous, long pair 4–4.7 cm long, short pair 3.5–4cm long; staminode 3–3.5 cm long, apically pubescent; anthers peltate-explanate after dehiscence, 0.2–0.3 cm long. Style 3.1–3.5 cm long. Capsule 0.9–1.2 cm long. Seeds angled, 3–3.5 mm long, brown.

Distribution and habitat: —This species is known only from two localities within the mountain range called Sierra de Santa Rosa, in the municipality of Guanajuato ( Cañada de La Virgen and El Ciervo). The Sierra de Santa Rosa is part of the Mexican Central Plateau province, which is geologically formed by sedimentary rocks of detritic materials and igneous rocks in the form of basalts, ignimbrites, rhyolites, andesites and tuffs, dating from the Quaternary ( Anonymous 1980). The main vegetation type of this mountain range is Quercus forest. Penstemon dugesii grows on rocky slopes, in humid areas of oak forest, at elevations of 2400–2650 m.

Phenology: —It has been collected in flower from July to August.

Etymology: —The name of the species honors Alfred Auguste Dalsescantz Dugès (1826–1910), French doctor and zoologist who lived and worked for more than 50 years in the city of Guanajuato. He became interested in the flora of the region and, between 1865 and 1900, collected plant specimens that were studied by Asa Gray and Sereno Watson, amongst others. Additionally, he founded a herbarium in the city of Guanajuato, of which the surviving part is to be found in the Alfredo Dugès Museum at the University of Guanajuato ( Rzedowski et al. 2009).

Conservation: —According to the criteria and categories of IUCN (2012), Penstemon dugesii should be classified as Vulnerable (VUD1 + 2), due to the estimated population size which has less than 1000 mature individuals, an area of occupancy less than 20 km 2, and its only two known localities.

Additional material examined of Penstemon dugesii : — MEXICO. Guanajuato, municipality Guanajuato: Cañada de la Virgen (antigua carretera Guanajuato – Dolores Hidalgo), 7 September 1993, E. Pérez Calix & H. Díaz 2786 ( IEB!) ; Cañada de la Virgen, Agua Sabrosa , 10 August 1997, J. Martínez-Cruz 456 ( MEXU!) ; El Ciervo , 21 October 1997, J. Martínez-Cruz 750 ( MEXU!) .

Material examined of Penstemon coriaceus : — MEXICO. Aguascalientes, municipality Aguascalientes: eastern slopes of Cerro de los Gallos (ca. 15 miles south of Aguascalientes), about 3 miles W of hacienda Las Rosas, without date, R. McVaugh 17100 ( MEXU!) ; municipality Calvillo : 0.5 km al W de la barranca El Pilar, 13 September 2012, M. López 139 ( HUAA!) ; 1 km al SW de la barranca El Pilar , 13 September 2012, M. López 147 ( HUAA!) ; cañada a 6.8 km al N de El Temazcal , 20 November 2013, M. López 1050 ( HUAA!) ; Sierra del Laurel, near the Jalisco-Aguascalientes border, ca. 10 miles SE of Calvillo, without date, R. McVaugh 18444 ( MEXU!). Durango, municipality Pánuco de Coronado : Sierra de Los Altares de José Ángel Parra , 13 September 2018, A.G. Zacarías et al. 197 ( CIIDIR!, IEB!). Guanajuato, municipality Ocampo : 4–6 km al S de Santa Bárbara, 29 July 1996, E. Pérez Calix 3380 ( IEB!) ; sierra de Jacales , al S de Ocampo, 12 July 2000, E. Carranza 6099 ( IEB!) ; municipality San Felipe: Sierra del Cubo, aprox. 3 km al E de El Cubo , 25 July 2012, S. Zamudio-R. 15723 ( IEB!). San Luis Potosí, municipality San Luis Potosí: ca. 13 miles SW of San Luis Potosí in high peak North of highway, 28 July 1958, R.M. Straw 1437 ( MEXU!) ; Canyon on W side of highest ridge of Cerro El Potosí, South of city of San Luis Potosí, 30 April 1980, T. Wendt 249 ( MEXU!) ; Cerro el Potosí, ladera W, 2 km SE de La Amapola, 20 June 2017, E. Pérez Calix 6646 ( IEB!). Zacatecas, municipality Río Grande: 2 miles N of Fresnillo near tropic of Cancer , on mountain west of highway, 11 August 1958, R.M. Straw 1699 ( MEXU!) .

Figures

FIGURE 1. Penstemon dugesii Pérez-Calix & Zacarías, sp. nov. A) habit; B) detail of leaf margin; C) flower in front view; D) dissection of the flower; E) stamen apex; F) fruit; G) seed. Drawn by Alfonso Barbosa based on E. Pérez 6689.

FIGURE 2. Variation in the morphology of the leaves and dissection of the corolla of Penstemon coriaceus (A, B) and Penstemon dugesii (C, D). Drawn by Alfonso Barbosa based on E. Pérez Calix 6646 and 6689, respectively.

FIGURE 3. Holotype of Penstemon dugesii (A) and herbarium sheet of Penstemon coriaceus (B).