Passiflora zapalinamensis Kuethe, Encina & Cruz-Anaya, 2022

Kuethe, J. R., Encina-Domínguez, Juan A. & Cruz-Anaya, Arturo, 2022, Passiflora zapalinamensis, a new species of supersect. Bryonioides (Passifloraceae) from northeast Mexico, Phytotaxa 560 (1), pp. 104-112 : 105-110

Passiflora zapalinamensis Kuethe, Encina & Cruz-Anaya , sp. nov. ( Figs. 1–4 ).

Type: ― MEXICO. Coahuila: Municipality of Saltillo, Sierra de Zapalinamé , 4.47 km south-west of the community Cuauhtémoc , primary pine forest with Pinus arizonica and Pinus cembroides , 25°16’38.59”N, 100°54’10.39”W, 2,465 m, 6 October 2017, J.A. Encina et al. 6127 (holotype ANSM!) .

Diagnosis: ― Passiflora zapalinamensis resembles P. exsudans Zucc. and P. bryonioides Kunth , but it differs by having opposite to subopposite petiolar glands without uncinate trichomes, shorter petioles and peduncles, usually solitary (rarely in pairs) inflorescence, smaller fruit, red stems and relatively smaller stipules and leaves that are consistently obtuse to rounded at apex.

Description: ―Climbing vine, (0.7–)1.0–3.0 m long with several slender stems from a central root, pubescent to uncinate trichomes, juvenile leaves more densely tomentose to pilose. Stems terete, often a distinct red colour, sparsely hirsute with 0.8 mm long clear trichomes. Stipules 4–6 mm long, about 2–3 mm wide, ovate-auriculate to caudate with a 2 mm elongated point, light green, margins entire, with few trichomes along the margins; petioles 2.5–3 cm long, often reddish like stems, hirsute, bearing two glands about 5–6 mm the distance from the base, the nectaries positioned subopposite to alternate, never perfectly opposite, the distance of difference from opposite 0.5–1.0 mm, widely obovoid to depressed obovoid, sessile but narrowed at base, about 1.0– 1.2 mm long, 0.9–1.0 mm wide at apex, green; leaves prominently 3-lobed, occasionally very shallowly 5-lobed, green, 5.5–7.0 cm long, 7–9 cm wide, lobes deeply incised and near perpendicular, distance of incision about 1.5–1.7 cm from base of the blade, sinus about 75°–80°, when 4th and 5th lobe present those borne obtusely from the base of the lateral lobes about 2 cm the distance from the base of the blade and no longer than 1.5 cm, base broadly cordate to shallowly and squarely cordate, the lobes ovate-oblong, consistently obtuse to rounded at apex or occasionally softly acute, the lobes slightly narrowed at base, margins of central lobe entire, margins of lateral lobes widely serrate in the proximal half, with 4 narrow teeth per side; laminar nectaries mostly absent, when present then arranged in two opposite pairs on the margins of the central lobe, obscure, 0.5–0.6 mm in diameter, ca. 1–2 mm from the margin, slightly raised and discoid, green. Peduncles 3.0– 3.5 cm long, solitary or rarely arranged in pairs, bearing bracts close to the base of the flowers; bracts very small, 1.0– 1.5 mm long, linear-triangular to capillary. Flower buds green, widely ovoid to widely ellipsoid, obtuse, rounded, hirsute; flowers 1.9–2.6 cm in diameter, subpendent to borne sublaterally, always facing slightly downwards, with a slight sweet scent; hypanthium 6–8 mm in diameter, about 3–4 mm high; sepals 9–10 mm long, 5–5.5 mm wide, ovate-oblong, rounded at apex, not corniculate, greenish and hirsute abaxially, white and glabrous adaxially; petals 5–6 mm long, 3.5–4 mm wide, ovate and acute apically, white, membranous to quickly shriveled; coronal filaments in 1 series, 6–7 mm long, white with 2–3 purplish bands, the bands very rarely somewhat indistinct and merging with each other, most often the apical 2 bands are merged; operculum 2.0– 2.2 mm long, whitish green with purplish in upper half; limen whitish green; ovary 2.4–2.5 mm long, 2.0– 2.1 mm wide, narrow ellipsoid, glabrous. Fruit 2.4–3.2 cm long, 2.2–3.1 cm in diameter, widely obovoid, bluish black or dark purplish black; seeds reticulate, 5–5.2 mm long, 4.0– 4.5 mm wide.

The species described here belongs to supersect. Bryonioides (Harms) J.M. MacDougal & Feuillet (2003: 34) , a group comprising ca. 18–19 species ( MacDougal 1994) with a distribution that is concentrated throughout Mexico, the south-western United States and Guatemala. This group, often referred to as the “hooked trichomed group” in older works ( MacDougal 1994), is readily recognized by its uncinate to pilose foliar vestiture, conspicuous stipules, biglandular petioles, distinctive floral structure and semi-annual habit ( MacDougal 1994, MacDougal 2001, LozadaPérez & Gutiérrez 2016). Many of these species are well adapted to the seasonal dry temperate forests of their native range, and their stems frequently sprout again from their roots each seasonal cycle ( MacDougal 1994). Although this group contains several variable species complexes throughout its wide distribution, the species described and illustrated here was collected from a geographically isolated region and cannot be confidently identified with any of the known species within the supersection.

Phenology and ecology: ― Passiflora zapalinamensis was collected in flower from June to July, which in its native habitat corresponds with the short (but often intense) rainy season. Fruits have been collected between August and November and turn dark purple upon reaching maturity. It has been observed as the host plant of the butterfly Dione moneta poeyii Butler (1873: 227) , which consumes the leaves at the larval stage.

Etymology: ―The specific epithet is dedicated to the overarching mountain range of the type locality, the Sierra de Zapalinamé in Coahuila, Mexico.

Distribution and habitat:— The species occurs in scattered populations, in canyons and hillsides in northerncentral Mexico. Here, the species can be found at altitudes between 2,400 to 2,800 m.s.m.l. in a semi-dry, shrub forested region within the greater Sierra de Zapalinamé, where the species was first identified as new and according to Encina-Domínguez et al. (2016) this mountain is located in the transition zone between two regions, the Sierra Madre Oriental (mountain region) and the Mexican High Plateau (xeric region).

The Gran Sierra Plegada subprovince, potentially the extent of the distribution of P. zapalinamensis , stretches the states of Nuevo León and Coahuila in northeastern Mexico and is part of the Sierra Madre Oriental. The region of Cuauhtémoc and Sierra Hermosa where this species is found, is a small relief composed of hills, valleys and plains just southeast of the city Saltillo in the state of Coahuila ( Figure 3 ). The pinyon pine forest associated with Chaparral ( Encina-Domínguez et al. 2019). This relatively small region has a curious biogeographical composition, as it is located within the desert climate of the Chihuahuan Desert Region but is supported by the El Salado Hydrological Region ( SPP 1983 ). The infiltration of the water to the subsoil is intense, allowing the formation of springs at the foot of the mountain range that supports the growth of xeric forests in this otherwise dry desert area ( SPP 1983 ).

The most notable populations of P. zapalinamensis were cited in a small region between the national route RT 57 in the south portion of Sierra de Zapalinamé, also close to the intermontane villages called “ ejidos ” of the Sierra Hermosa and Cuauhtémoc ( Figure 3 ), where it was found growing under a canopy of pine forest and chaparral vegetation ( Encina-Domínguez et al. 2019) at elevations between 2,400 and 2,800 m. Its ecological association is with pine trees of Pinus cembroides Zucc. (1832: 392) , also P. arizonica Engelm. (1878: 260) and P. greggii Engelm. ex Parl. (1868: 396) . In the shrub layer, Quercus microphylla Née (1801: 264) , Cercocarpus montanus Raf. (1832: 146) and Agave gentryi Ullrich (1990: 190) are common, with scattered individuals of Arbutus xalapensis Kunth (1818: 279) and Prunus serotina Ehrh. (1783: 285) ( Encina-Domínguez et al. 2016). This region is geologically composed of Jurassic limestones (Kuethe, pers. obs.), which may indicate this species grows only on the more alkaline soils. Other populations have been identified from herbarium and georeferenced photographs indicating a presence of this species throughout the northern extend of the Sierra Madre Oriental covering portions of the Nuevo León, San Luis Potosí and Tamaulipas states. A southern metapopulation has been identified in Guanajuato state north of León along the RT 87, and in the Victoria region west of the township of Xichú.

Conservation:— To date, the new species was found at a few localities in the southeast of the Sierra de Zapalinamé and across the Sierra Madre Oriental. According to the GeoCAT algorithm ( Bachman et al. 2011) based on the extent of occurrence (EOO) and the area of occupancy (AOO), the EOO is 76,545 km 2 and AOO is 68 km 2. If an official IUCN analysis were to be carried out, P. zapalinamensis is likely to be placed in the conservation status as endangered (EN), criterion B2ab (iii) ( IUCN 2017). It is, therefore, considered to be facing a high risk of extinction in the wild.

Unfortunately, semi-dry shrubby vegetation is a very fragile habitat which is particularly vulnerable to bush fires. According to the Sierra Hermosa National Park website (www.inafed.gob.mx), this mountain is a natural protected area, enacted by the government of the state of Coahuila since 1996 ( Anonymous 1996), with the intention of preventing damage to the range and generating recovery and restoration actions for the natural processes. This decree, albeit more focused on the water supply from the springs rather than the biological heritage, will help to prevent degradation of the area due to unsustainable farming or forest clearing. Unfortunately, the other locations where P. zapalinamensis has been identified are not part of any protectorate scheme, hence the longevity and sustainability of these outlaying populations are much more fragile.

Additional specimens examined:— MEXICO. Coahuila: Municipality of Saltillo, Sierra de Zapalinamé, Cañón de las Norias , 25°15’37.66’’N, 100°52’25.36’’W, 2880, July 2017, J. A . Encina et al. 6282 ( ANSM!) ; Coahuila, Puerto de Chapultepec , 25°13’59.30’’N, 101°0’50.36’’W, 2425 m, June 2018, J. A . Encina et al. 6605 ( ANSM!) ; Coahuila – Saltillo, Sierra Catana , 40 km SW de Saltillo, 25.25000°, -101.20000°, 2700 m, 29 July 1992, J. A . Villarreal with M. A . Carranza & H . Nieto 6462 ( MEXU!) ; Guanajuato, El Cocotero, 30 km W de Xichu , 2300 m, 21°18’45”N, 100°07’59”W, López & Ventura 7290 ( IEB) ; Guanajuato, Victoria, Alrededores de San Agustín , 2400 m, 21°18’00”N, 100°09’36”W, 11 August 1991, J . Rzedowski 50861 ( IEB) ; Guanajuato, Victoria, El Sauz de la Higuera , 2100 m, 16 October 1987, R . Santillán 503 ( MEXU!) ; Nuevo León, Cieneguillas, puerto de Sta. Ana cerca de Galeana , June 1934, C. H. & M. T . Mueller s.n. ( MEXU!) ; Nuevo León, S and SE-facing slope, E of Ranchito La Serradero, E of Cieneguillas, Mun. Galeana , 8400 ft, 24°56’09”N, 100°13’39”W, 01 October 1979, J. M . MacDougal & J . Miley 472 ( DUKE) ; Nuevo León, near Ojo de Agua at the foot of Cerro Potosi , 1980 m, 12 July 1945, A. J . Sharp 45697 ( MEXU!) ; Tamaulipas, Bustamante. 3 km al W de Bustamante , 1900 m, 28 May 1976, F . González Medrano et al. FGM9259 ( MEXU!) .

Photographic material examined:— MEXICO. Coahuila: Municipality of Saltillo, Sierra de Zapalinamé, Puerto de Chapultepec , 25°14’46.6’’N, 100°54’07.9’’W, June 2018, A. Cruz-Anaya (https://www.inaturalist.org/ observations/118659196) ; Sierra de Zapalinamé, ejido Cuauhtémoc , 25°17’21.4’’N 100°55’06.1’’W, June 2018, L. Jiménez Hernández (https://www.inaturalist.org/observations/57808180) ; Fagáceas del Noreste , 25°14’53.5”N 100°54’34.4”W, July 2016, O. A. Sánchez Flores (https://www.inaturalist.org/observations/4282218) ; Guanajuato, Victoria , 21°15’53.1”N 100°07’56.1”W, October 2018, E. Mendiola González (https://www.inaturalist.org/ observations/21440726) .

Figures

FIGURE 1. Passiflora zapalinamensis sp. nov. (A-D) featuring important morphological detail.A) Flower in detail. B) Leaf in detail, note the rounded apices of the leaves. C) The alternately placed petiolar nectary glands. D) The immature fruit. E) Type location of Passiflora zapalinamensis featuring the semi-dry, shrub forested region of the greater Sierra de Zapalinamé All pictures taken by Arturo Cruz Anaya in the Sierra de Zapalinamé.

FIGURE 2. Type (ANSM 6127) of Passiflora zapalinamensis. Collected by Juan A. Encina, 2017.

FIGURE 3. Distribution of Passiflora zapalinamensis within the Sierra Zapalinamé, southeast Coahuila, Mexico.

FIGURE 4. Distribution and allopatry of the Passiflora exsudans complex within Mexico. Blue) Passiflora zapalinamensis; Green) Passiflora hispidula; Red) Passiflora exsudans.