Opuntia hyptiacantha F.A.C. Weber (1898: 894)

Neotype (designated by Scheinvar et al. 2010: 287): — MEXICO. San Luis Potosí, 13 Km northwest of San Luis Potosí, 01 May 1973, Sánchez-Mejorada 1734 (MEXU!).

Description:— Plant 2.0– 2.5 m high tree (Fig. 15A). Defined trunk, 35 cm in diameter, slightly grayish scaly bark with light brown tones (Fig. 15B). Glabrous epidermis (Fig. 18C). Elliptical to oval cladodes, 32–40 cm long x 14–24 cm wide and 2–3 cm thick, green in color, covered with a light layer of wax (Fig. 16A). Areolas arranged in 12–13 series, 3.6 cm spacing between series, 3.4 cm spacing between elliptical areolas, 0.4 × 0.3 cm, short black trichomes, (Fig. 16B). Very small and scarce yellow glochids, arranged at the top of the areola. 0–9 white spines, yellowish apex, rigid, generally erect and diffuse, some of which are generally adpressed at the edge, unequal in length, 0.3–2.1 cm, the lower part of the cladode has no spines (Fig. 16C). Juvenile cladodes with prominent tubers, areolas with short brown to black trichomes, some reddish white bristle hairs, erect subulate green leaves, with reddish apex (Fig. 15C). Acute flower buds, reddish perianth segments with accumulated apex, elliptical pericarpel, slightly elevated tubers, areolas with short brown trichomes, brown glochids and areolas with brown bristles (Fig. 16D and 16E). Yellow flowers (Fig. 16F), 6.0–7.0 cm long, elliptical pericarp, ca. 3.4 × 2.3 cm, areolas arranged in 5–6 series, 0.66 cm spacing between them, with crass basal scale, outer segments of the perianth with obovate form, mucroned apex, smooth yellow edges, with medium greenish striation, reddish apex, oblanceolated inner segments, emarginated apex, yellow with reddish apical part, upper edges slightly dentate, stamens 1/3 of the length of the perianth, reddish and yellow filaments, yellow anthers, cuneiform style, ca. 1.9 cm long, light green, usually eight green papillary lobes of stigma, ca. 0.5 cm long, with medium white pink striation (Fig. 17B). Red elliptical fruits (Fig. 17C), 5.0– 6.5 cm long, sunken floral striated scar, large and circular to elliptical areolas, (Fig. 17E), arranged in 4–5 series, 1 cm spacing from each other and 0.7 cm between series, long black trichomes, some spines, short yellow glochids, juicy and sweet pink red funicles (Fig. 17D). Lenticular seed with irregular lateral aril, lateral trhead-micropilar region, micropilum and funiculus included (Fig. 17F).

Micromorphology:— Thornswith lignified epidermal cells 98.35 ± 1.40 × 23.64 ± 1.10 μm in the distal part (Fig. 18B), 61.22 ± 1.30 × 12.04 ± 1.40 μm, continuous epidermal cells and rough texture, in the middle part (Fig. 18A). Glabrous epidermis, irregular epidermal cells (Fig. 18C) and paracytic stomas (Fig. 18D). Polyhedron-shaped pollen grain hexagonal, pantoaperturate (Fig. 18E), 111.16 ± 1.40 μm in diameter, 8432.28 μm ² in area, 10.10 ± 1.90 μm distance between each distal opening (pores), with a diameter of 22.50 ± 1.50 μm, 15–17 pores with walls of 1.85 ± 0.14 μm width and wart (Fig. 18F).

Vernacular names:— Nopal cascarón, tuna mansa, tuna corriente and Tuna chaveña (see e.g., Bravo-Hollis 1978, Anderson 2001, Scheinvar 2004).

Phenology:— Opuntia hyptiacantha blooms from March–April, whereas fruiting time if June–July.

Habitat and distribution:— Endemic to Mexico, it is known in the states of Aguascalientes, Ciudad de México, Guanajuato, Hidalgo, Jalisco, México, Oaxaca, Puebla, Querétaro, San Luis Potosí, Tlaxcala and Zacatecas (see e.g., Arias et al. 1997, Guzmán et al. 2003, Scheinvar 2004, Scheinvar et al. 2010, Arias et al. 2012, Hernández et al. 2014) (Fig. 2). It grows in xerophytic scrub (Rzedowski 1978).