Stenocereus pruinosus (Otto ex Pfeiff.) Buxb., Botanische Studien

Alvarado-Sizzo, Hernán, Casas, Alejandro, Parra, Fabiola, Arreola-Nava, Hilda Julieta, Terrazas, Teresa & Sánchez, Cristian, 2018, Species delimitation in the Stenocereus griseus (Cactaceae) species complex reveals a new species, S. huastecorum, PLoS ONE (e 0190385) 13 (1), pp. 1-25 : 17-18

Stenocereus pruinosus (Otto ex Pfeiff.) Buxb., Botanische Studien 12:101. 1961 [ 61].

[urn:lsid:ipni.org:names:244646–2:1.3]. Type. México, cultivated in Berlin Botanical Garden, (unknown).

Neotype (designated here): México, Oaxaca, Municipio de Santiago Huaucuclilla, 10.5 km sobre la terracería Huaucuclilla-Tlalixtlahuaca. 17˚ 29 0 046 N, 97˚ 03 0 115 W. Vegetación: Bosque tropical caducifolio. Plantas arborescentes, hasta 4 metros de alto, ramificación basítona, ápice pruinoso. Flores blancas con una franja roja hacia el ápice, tubulares. 10-Marzo-2007, D. A. Aquino García con S. Arias ( MEXU 1272791).

Additional observed specimens: Table D in S 3 Appendix.

Candelabraform tree, 2–5 m tall; trunk 30–60 cm tall and 15–20 cm width; second and even third order branching, spreading, forming a wide canopy, branches up to 4 m long and 10–15 cm width, grayish green to glaucous; mucilage cavities not evident in branch transverse sections; ribs 6 to 8, acute in transverse section, straight to slightly sinuated in longitudinal section, 20–30 mm tall by 20–30 mm wide at the base; areolas 10–40 mm apart each, round to obovate (scutelliform), 70–80 mm long and wide, with numerous light-colored trichomes; radial spines 7–9, subulated, divergent, 5–30 mm long, white with yellowish base when young, grayish when mature; up to 4 central spines, subulated, robust, up to 40 mm long, white when young, grayish at maturity; subapical or lateral flowers, night anthesis remaining opened until the next day morning, infundibuliform, 8–9.5 cm long and 4.5–6.7 cm wide at anthesis; pericarpel ovoid, green with brownish hues, 15–25 mm long and 12–15 mm wide, covered with slightly prominent podaria, imbricated, with triangular scales about 1 mm long and 2 mm wide at the base, greenish, few trichomes, yellowish white; receptacular tube 18–25 mm long, podaria with decurrent scales, oblong, apex obtuse to spatulate, mucronate, about 5–7 mm wide; outer perianth segments narrow obovate, apex round to acute, mucronate, 15–20 mm long and about 13 mm wide, green with brownish margins; inner segments oblong to spatulate, entire margin, 2–4 cm long and 1.5 cm wide, white to pinkish-white; stamina included, numerous, arranged in verticillate series; basifix anthers, yellowish, style 35–45 mm long and 2 mm wide, yellowish white; stigma lobules 8–10, 4–7 mm long, yellowish white; nectar chamber semi-closed by the lower filaments curvature, 10–15 mm long and 5 mm wide, striated walls; ovary about 10 mm long and 5.8 mm wide; fruit ovoid, dehiscent when ripe, 60.2–120 mm in polar diameter by 55–81 mm in equatorial diameter [ 64], green to purple, covered by areolas with numerous setose spines, about 15 mm long, white, deciduous at maturity, sweet flesh, yellow, orange, red or purple; widely ovoid, black seeds 1.9–2.8 mm long by 1.4–2.1 mm wide.

Common name: "Pitayo", "Pitayo de octubre".

Phenology: flowers during spring (March to May), fruits from April to June with a second reproductive peak between August and October.

Habitat: xerophitic scrubland and tropical deciduous forest, from 300 to 1650 meters above sea level. Grows alongside with &scontria chiotilla, Myrtillocactus geometrizans , and Prosopis sp.

Discussion: Pfeiffer described &chinocactus pruinosus from cultivated plants in Berlin Botanical Garden. According to Stafleu and Cowan [ 62] Pfeiffer’s vouchers were deposited in the KASSEL herbarium, whose collection was destroyed during World War II. Lemaireocereus longispinus type, according to Britton & Rose [ 65] was cultivated in the New York Botanical Garden but now is no longer present.

Distribution: endemic to Mexico, in the states of Guerrero, Oaxaca, and Puebla.