Xochiquetzallia magnifolia García-Mend. & J.Gut., sp. nov. Figure 1.

Type:— MEXICO: Oaxaca, distrito de Tlaxiaco: municipio de San Juan Teita, 2 km S de San Juan Teita, 1,358 m, 17°5’6.2’’N, 97°24’37.5’’W, 9 July 2017, A. García-Mendoza et al. 11165 (holotype: MEXU, isotypes: to be distributed).

Diagnosis: — Xochiquetzallia magnifolia is characterized by having 1–2 leaves, 45–100 × 0.5–0.8 cm, teretes; scape 30–60 cm long, (7–)12–25 flowers per umbel; flowers erect, subcampanulate, pale to intense violet, externally with a brownish central longitudinal stripe with reddish edges; tepals 1.2–1.5 × 0.3–0.6 cm, elliptical, 3 longitudinal veins, central, acute apex, papillose, slightly reflexed; and style 7–9 mm long, inclined.

Perennial geophytic herbs, 30–60 cm tall. Corms 2–3 × 2–3 cm, subglobose, neck 2–4 cm long; brown external cataphylls, yellowish-brown internals, with longitudinal fibers. Leaves 1–2, 45–100 × 0.5–0.8 cm, teretes, with a longitudinal groove, acute apex, glabrous to sparsely papillate at the base, variously recurved when young, later semiprostrate, green, somewhat pruinose, when fresh with a spongy consistency. Inflorescence umbellate, scapes 1–2 per plant, 30–60 cm long, terete; spathe bracts 4–6 × 1–2 mm, narrowly triangular, bracteoles one per flower. Flowers (7–)12–25, on pedicels (3.5–) 5–6.5 cm long, erect, subcampanulate, pale to intense violet, externally with a brownish central longitudinal stripe with reddish edges; perianth tube 2–4 mm long, 6 tepals in two series, the external ones 1.2–1.5 × 0.3–0.6 cm, the internal ones slightly shorter and narrower, narrowly elliptic, with 3 longitudinal, central veins, acute apex, papillose, slightly reflexed in anthesis; stamens 6, free, filaments 5–7 mm long, adnate to the neck of the tube, broader toward the base, whitish to pale violet, anthers ca. 2 × 1 mm, basifixed, yellow, ovary 4–6 × 2–3 mm, ellipsoid, adnate to perigonium, pale green, style 7–9 mm long, inclined, whitish, stigma entire, papillose. Fruits, capsules 10 × 7–8 mm, subglobose, brown. Seeds 2–3 × 2–3 mm, compressed, irregular, black.

Distribution and habitat:— Xochiquetzallia magnifolia is known only from one locality in the upper basin of the Verde River, Tlaxiaco District, Oaxaca. It grows on open and sunny slopes, on gypsic soils, at altitudes from 1340–1400 m, on sites with a xerophilous scrub and associated with Agave gypsicola García-Mend. & D. Sandoval in García-Mendoza et al. (2019: 6), Bletia mixtecana Salazar & C. Chávez in Salazar et al. (2016: 120), Bouteloua elata Reeder & Reeder (1963: 215), Brahea dulcis (Kunth) Mart. in Martius (1838: 244), Cephalocereus parvispinus Arias, Tapia & Guzmán (2019: 150), Cnidoscolus angustidens Torr. (1859: 198), Mixtecalia teitaensis Redonda-Mart., García-Mend. & D.Sandoval in García-Mendoza et al. (2020: 128), Muhlenbergia emersleyi Vasey (1892: 66), Pinguicula heterophylla Benth. in Bentham (1839: 70), Polanisia uniglandulosa (Cav.) DC. in De Candolle (1824: 242) and Viguiera dentata (Cav.) Spreng. in Sprengel (1826: 615).

Phenology:—Flowering from October to December, and fruiting from December to January.

Etymology:—The specific epithet refers to the large and robust leaves, which are the longest and with the greatest diameter in the genus to date.

Common names:—The new taxon is known as cebollín or cebolla de zopilote (chives or buzzard´s onion) (nduva ndiki loti, Mixtec).

Additional specimens examined (paratypes):— MEXICO. Oaxaca: Distrito de Tlaxiaco, municipio de San Juan Teita, cerro SE de San Juan Teita, 1,352 m, 17°5’29.2’’N, 97°24’35.7’’W, 24 October 2017, A. García-Mendoza et al. 11100 (MEXU!); 2 km S de San Juan Teita, 1358 m, 17°5’6.2’’N, 97°24’37.5’’W, 9 December 2017, A. GarcíaMendoza et al. 11166 (MEXU!); Ibid., A. García-Mendoza et al. 11177 (MEXU!); barranca du´ma xuteku (cola de la barranca viva, tail of the living canyon), 1 km E de San Juan Teita, 1389 m, 17°4’52.55’’N, 97°24’23.60’’W, 9 August 2019, A. García-Mendoza et al. 11446 (MEXU!); paraje Totocaha (arriba del cerro La Campana, above La Campana hill), 3 km S de San Juan Teita, 1,511 m, 17°4’17.9’’N, 97°24’41.4’’W, 29 January 2020, A. García-Mendoza et al. 11506 (MEXU!); paraje Xe kava (al pie de la peña, at the foot of the boulder), 1 km SE de San Juan Teita, 1342 m, 17°5’24’’N, 97°24’36.7’’W, 27 March 2018, A. López Santiago et al. 23 (MEXU!).

Conservation status:— Xochiquetzallia magnifolia is a microendemic species known only from the type locality. According to the risk categories of the IUCN (2017), it’s range is approximately 25 km 2, with a locally abundant population, but it is restricted to gypsum soils and threatened with extinction in the face of future events caused by human activity. It is proposed that it is considered in the category of vulnerable (VU).

Taxonomic comments:— Xochiquetzallia magnifolia presents unique characters in the genus, including leaf size, scape, flowers, number of flowers per umbel, and the inclined style (Figure 2). According to Lenz (1971) and Gutiérrez & Terrazas (2020), the morphologically closest species is X. hannibalii (L.W.Lenz) J.Gut. in Gutiérrez & Terrazas (2020: 45), from which it differs based on the characteristics indicated in Table 1. The description of this species broadens the distribution of the genus toward southeastern Mexico (Figure 3). In addition, X. magnifolia is located outside the Balsas basin (Morrone 2017) since it is restricted to the Verde River Basin in the Mexican State of Oaxaca (Figure 3). The gypsum scrub on which it develops is unique in the state, occurs in a small area, and supports numerous endemic species, some of which have been recently published as Agave gypsicola, Bletia mixtecana, Cephalocereus parvispinus, and Mixtecalia teitaensis, and others are in the process of being described.