Polascontria

Cruz-Zamora, Yuridia, Cruz-García, Felipe, Orozco-Arroyo, Gregorio, Reyes-Santiago, Jerónimo, Martínez-Castilla, León P., Wegier, Ana & Vázquez-Santana, Sonia, 2017, × Polascontria (Cactaceae), a nothogenus that represents the gene flow between Escontria and Polaskia, Phytotaxa 295 (2), pp. 141-158 : 151-155

× Polascontria . Y. Cruz & S. Vázquez, nothogen. nov. ( Polaskia × Escontria )

Generitype: —× Polascontria huajuapensis Y.Cruz & S.Vázquez. ( Fig. 6 ).

Diagnosis: —Tree with many branches; trunk brown, short but well defined, with deciduos spines when old, branches of first order erect parallel to each other, or arched at the base, olive green when young and pale green when old; forming a compact coup; ribs slightly triangular in transverse section of branches, areoles elliptic to circular, with some central and one radial spines, all gray and acicular, rigid, unequal in length. Flowers, produced only at apices of the branches, one per areole, hermaphrodite and diurnal, with all tepals extended; external perianth segments green and internal creamy, complete extended during anthesis, pericarpel with broad but short bracts with marginal and triangular papiraceous tissue and with spines in the axile; stamens numerous, included, filaments white, anthers yellowish; long style; stigma multilobate whitish yellow; nectar sweet and copious chamber, ovary inferous. Fruit is globular, brownish red in peel and pulp, sweet and edible; with translucent and papiraceous broad and short bracts with axile and setaceous and rigid spines, deciduous at maturity. Seeds ovoid, black; testa rugose and cuticle striate. A few fruits contain aborted seeds.

× Polascontria huajuapensis Y. Cruz & S. Vázquez , sp. nov. ( Polaskia chichipe × Escontria chiotilla )

Type: — MEXICO. Oaxaca: Mpio. Huajuapan de León localidad Corral de Piedra (N 17º 45.155´W 097º 44.73´, N 17º 44.947´W 097º 44.458´, and N 17º 45.114´W 097º 44.732´), 1680 MSL, 04 March 2002. Rosas López & Cruz- Zamora 1 (holotype: voucher 1025387, MEXU!). ( Figs. 6−8 ).

Diagnosis: — Planta arborescens 3–5 m alta; rami cylindrici 2.0– 2.5 m longi 24.5–30.0 cm diametro, supra areolas; spinae radiales inaequales; spina centralis 1, 3.7 cm longa; flos 6.5–7.0 cm longus, 4.5 cm latus, pericarpellum bracteis et areolis; fructus globosus, 3–6 cm diametro, spinis 3–4 mm longis, bracteae breves et latae, 12 mm latae et 2.4 mm altae; semina 1.2–1.5 mm longa, 0.8–1.0 mm lata.

Description: — Plants 3–5 m tall, branched; trunk brown, 40–60 cm high, with deciduos spines when old; branches of first order erect and parallel, or arched at the base, up to 2.5 m in width, pale-green (young branches olive-green), forming a compact coup; ribs 6–8, slightly triangular in transverse section of branches; areoles elliptic to circular 0.8–1.3 cm wide, with distance between each other of about 6.6 cm; radial spines 7–10, gray, acicular, rigid, unequal in length (the longest is 6.9 cm), deciduous at maturity; central spine 1 per areole, 29.9–37.71 mm long and 14.5–14.8 mm in diameter, rigid and acicular; slightly yellowish when young, grayish at maturity. Flowers only at the end of the branches, one per areole, bisexual and diurnal, with all tepals extended, 29.9 mm long and 14.8 mm in diameter (at anthesis); 16–18 external perianth segments green, the internal creamy, completly extended during the anthesis, pericarpels with broad but short bracts with marginal and triangular papiraceous tissue and with axillar spines; stamens many, with filaments white, and anthers yellowish; style 1; stigmatic lobes 6–8, whitish-yellow; nectar sweet and copious chamber: ovary inferous, 5–6 mm long and 5 mm in diameter. Fruit globular, brownish-red in peel and pulp, sweet and edible; 3–5 cm long, with translucent and papiraceous broad and short bracts with axilar and setaceous and rigid spines, largest, 3.0–4.0 mm long, deciduous at maturity. Seeds with 1.2–1.5 mm long and 0.8–1.0 mm in diameter, ovoid, black; testa rugose and cuticle striate, a few fruits contain unfertilized ovules and small aborted seeds without embryo or neither endosperm and with abnormal testa with irregular striations on lateral regions of seeds.

Etymology:— The generic epiteth “ Polascontria ” refer to both Polaskia and Escontria genera name. The specific epithet makes reference to the place where the hybrid was found (Huajuapan de León, Oaxaca).

Distribution and ecology:— This new nothospecies is only known from the type locality (Mixteca Baja), close to Huajuapan de León Oaxaca, a semiarid area of Mexico. Especially in the Tehuacán-Cuicatlán Valley (S-Mexico) there is the highest species richness of Pachycereeae and the highest number of endemic species of Cactaceae ( Gibson & Nobel 1986) . Plants of × Polascontria huajuapensis are low in number and grow sympatrically with its parents P. chichipe , and E. chiotilla .

Phenology:— Flowering time is from February to June, while fruiting stage is March− July. The pollination (by bees and hummingbirds) is diurnal. Pollinators are the same of the parents, suggesting that there are not any spatial barriers to pollen flow among individuals of parents and × Polascontria huajuapensis in which blooming periods overlap in all sympatric population.

Vernacular name and uses:— In la Mixteca Baja, Oaxaca, are almost unknown by native people, but some persons could named them with the same common name to those of P. chichipe as “chichipe ”,“chichituna” or inclusively with those fruits of E. chiotilla as “jiotilla”, “quiotilla”, “chiotilla ”. The fruits are sweet and edible.

Taxonomic notes:— × Polascontria huajuapensis belongs to the subfamily Cactoideae , tribe Pachycereeae , subtribe Stenocereinae (Cruz-Zamora 2002) , the latter close to subtribe Pachycereinae ( Arias et al. 1997, Cornejo & Simpson 1997, Anderson 2001). Stenocereinae includes taxa with triterpenes pigmented cells in funicule and silica bodies, while Pachycereinae have alkaloids or calcium oxalate crystals and the funicule lacks of pigment cells ( Gibson & Horak 1978). The new hybrid evolved throw intergeneric hybridization.

Figures

FIGURE 6. Illustration of ×Polascontria huajuapensis. A. Plant habit. B. Branch. C. Branch in cross section. D. Areole. E. Bracts with areoles on fruits. F. Floral dissection. G. Flower (apical view). H. Bud flower with bracts. I. Fruit [drawing (from herbarium specimens: Cruz-González 1 (MEXU), vouchers 1025386, 1025387 1040183 (MEXU), and photographs by the authors)].

FIGURE 7. Specimen of ×Polascontria huajuapensis (holotype: voucher 1025387, MEXU).

FIGURE 8. Photos of ×Polascontria huajuapensis (voucher 1040183, MEXU).