Hechtia flexilifolia I. Ramírez & Carnevali, 2014

Morillo, Ivón Ramírez, Jiménez, Carlos F., Fernández-Concha, Germán Carnevali & Pinzón, Juan P., 2014, Three new species and growth patterns in Hechtia (Bromeliaceae: Hechtioideae), Phytotaxa 178 (2), pp. 113-127 : 116-117

Hechtia flexilifolia I. Ramírez & Carnevali , spec. nov. ( Figs. 2 , 3 ).

This new species is characterized by an unique combination of characters: leaves numerous, (20–) 30–40 in number, proportionally long, narrow, flexible, margins densely spinose, abaxial epidermis glossy and wrinkled, shedding when dry, staminate inflorescence a 1–2 times divided panicle, with a long peduncle, branches at first secund, then horizontal, branches densely flowered, cylindrical, rachis green, sulcate, sterile bases of branches bracteate, petals white.

TYPE:— MEXICO. Oaxaca : Distrito de Tlaxiaco, Municipio Santiago Yosondúa, ca. 4 km después de Santiago de Yosondúa , rumbo a Yerba Santa , en las cascadas, riscos en bosque de pino-encino con algunos elementos mesófilos [ca. 4 km beyond Santiago de Yosondúa, toward Yerba Santa, by the waterfalls, cliffs with pine-oak forest with some mesophyll elements], 16° 50’ 43” N, 97° 34’ 52” W, 1990 m elevation, 1 July 2013, Ramírez & Carnevali 1868 ♂ (holotype CICY (x7)!; isotypes MEXU!, OAX!, SEL!, US!) .

Plants lithophytic, forming a hemispherical rosette, 20–25 cm long, 50–55 cm in diameter. Leaves (20–) 30–40 in number, erect, becoming slightly reflexed, flexible; sheaths broadly oblong, 3–4 x 5.5–6.5 cm, glabrous, drying whiteyellowish at the base, dark brown, densely white lepidote and dentate close to the blade; blades sublinear triangular, acute, pungent, 12–60(–100) cm long, 1.5–2.5(–3) cm wide at the base, apical half reflexed, succulent, flexible, Ushaped in cross section, dark green, densely white lepidote abaxially, adaxially corrugated, covered by a thin, white layer (probably the cuticle) that peels off easily, especially when dry, margins spinose, white-yellowish; spines antrorse, ca. 2 mm long decreasing to ca. 1mm long at the apex, 1–1.5 cm apart. Inflorescence central, emerging from the center of a newly-forming rosette (type SPFP), erect.

Staminate inflorescence one to twice-branched panicle, ellipsoid, erect or arcuate (only seen in cultivation), sometimes a few primary branches produce a secondary short branch at their base, 2.10–2.70 m long; peduncle terete, 92–97 cm long, 0.8–1.2 cm in diameter, green, longer than the leaves, internodes (2.3–) 3.7–4.7 cm long; peduncle bracts narrowly triangular, long acuminate, (1.8–) 2.7–19.2 cm long, 1.8–2.4 cm wide at the base, entire to finely serrate, sheaths and blades well differentiated, the basal ones recurved, those at the base with the blades ca. 4 times longer than their sheaths, the apical ones erect, with blades and sheaths the same length; main axis 1.2–1.8 m long, 0.5–0.9 cm in diameter, green, 2–3 times longer than the leaves and ca. 2 times longer than the peduncle, internodes 1.3–3 cm long; primary bracts broadly triangular, acuminate, 0.5–1.8 x 0.3–1.6 cm, thin and brittle, yellowish to light brown, glabrescent, strongly nerved, clasping the peduncle of the branch but shorter than it, peduncle bracteate; branches (52–) 77–81 in number, forming a 45° angle with the main axis then arching and subspreading to pendulous, 4.7–28 cm long, each with 31–250 flowers, apices of the branches (at least in cultivation) do not develop and remain light brown, with abortive floral buds; rachis 1–3 mm in diameter, flattened at the base, strongly sulcate, sterile bases of branches bracteate, light green in the first order branches (1–) 2–3.5 cm long, in the second order branches (0.9–) 1.5 cm long; floral bracts lanceolate, acute, 2.2–4.3 x 1–2 mm, erose to strongly erose, hyaline, yellowish, glabrous, 3–5 nerved, verrucose close to the central nerve. Flowers pedicellate, verticillate, 4–5.7 mm long; pedicels obconical, 1–1.4 mm long, green; sepals free, ovate, acute, 2–2.4 x 1.2–1.6 mm, entire, light brown, glabrous, 1–3-nerved; petals free, elliptic to broadly elliptic, acute to rounded, 2.4–3.5 x 1.4–2.3 mm, entire, white, glabrous, 5-nerved, arranged so as o seemingly form a three-pointed star in anthesis; stamens 1.7–3.1 mm long, 3 opposed to the sepals, three to the petals; filaments narrowly triangular, flat in cross section, 1.5–2.7 x 0.4 mm, white; anthers elliptic, 1–1.4 x 0.3–0.5 mm, dorsifixed; pistillode conical, ca. 0.3 mm long, sometimes inconspicuous, stigmatic blades inconspicuous.

Pistillate inflorescence (known and described based on photographs in habitat and on a dry infructescence, an once-branched panicle, cylindrical, erect, 1.4–1.5 m long; peduncle terete, 50–60 cm long, 0.8–1.2 cm in diameter, internodes 1.9–4.1 cm long; peduncle bracts similar with those of the staminate inflorescence; main axis 50–60 cm long, ca. 0.4 cm in diameter, internodes 0.5–2 cm long; primary bracts broadly triangular, acuminate, 1.1–1.2 x 0.6–0.7 cm, thin and brittle, margins entire and undulate, drying pale brown, glabrous, multinerved, enclosing the sterile bases of branches, shorter than or equaling the peduncle of the branch; branches (11–) 14–18 in number, 0.5–1 cm long stipitate, spreading to ascending, 4–10.5 cm long, 45–120 flowered; rachis 2–2.5 mm in diameter, flattened at the base of the branches, slightly sulcate, drying dark brown; floral bracts ovate, acute, 2–3 x 1.5–2 mm, hyaline, yellowish, glabrous, 1-nerved. Flowers known and described based on the remaining structures on the fruit, subsessile, verticillate, densely grouped; pedicel obconical, 1–2 mm long, 0.5–1 mm in diameter, drying dark brown; sepals free, ovate, acute, 1.5–2.2 x 1.3–1.6 mm, entire, light brown, glabrous, 1-nerved; petals triangular, acute, 2.5–2.8 x 1–1.3 mm, entire, color unknown, 3-nerved; staminodes narrowly triangular, 1–1.4 x 0.3–0.5 mm; ovary unknown. Fruits narrowly ovoid, 5–6 mm long, 2 mm in diameter, dark brown with black spots, glabrous; sepals, petals, staminodes, and stigmatic lobes remaining on the capsule upon maturity; seeds 1–2 in number per locule, fusiform, 3.7–4.9 mm long, 0.6–1 mm in diameter, apical wing 0.6–1 mm long, basal wing 1–1.2 mm long.

Distribution and habitat:— Hechtia flexilifolia is known from a restricted geographical area near the village of Yosondúa, where it grows in close sympatry with H. nuusaviorum Espejo & López-Ferr. in Espejo et al. (2007b: 98). There it grows as a lithophyte on steep or vertical rock walls, at an elevation of ca. 1970 m, surrounded by humid forest. Most collections have been made from around the Yosondúa waterfalls, a well-known touristic site.

Etymology: —The specific epithet refers to the flexible foliar blades, an unique feature in the genus in Oaxaca since the rest of the species have succulent, rigid, inflexible leaves.

Additional specimens examined (paratypes):— MEXICO. Oaxaca: Distrito de Tlaxiaco, Municipio Santiago Yosondúa, de la desviación a Yerba Santa hacia la desviación a El Vergel , 16° 50’ 43” N, 97° 34’ 52” W, 1992 m elevation, 11 Noviembre 2005, Carnevali et al. 7136 fruits ( CICY (x2)!); ca. 4 km después de Santiago de Yosondúa , rumbo a Yerba Santa, en las cascadas, riscos en bosque de pino-encino con algunos elementos mesófilos [ca. 4 km beyond Santiago de Yosondúa, toward Yerba Santa, by the waterfalls, cliffs with pine-oak forest with some mesophyll elements], 16° 50’ 43” N, 97° 34’ 52” W, 1990 m elevation, 24 Julio 2009, Ramírez & Carnevali 1745 ♂ ( CICY!, ENCB!) .

Discussion: —The species has been collected in the Mixteca Alta region near the limits with the Cordillera Costera Sur phytogeographical province ( Cervantes-Zamora et al. 1990, Fig. 3 ), in the western area of the Mexican State of Oaxaca. It grows sympatrically with Hechtia nuusaviorum , a species well characterized by its glomerule-like pistillate inflorescence branches, and wider, more succulent foliar blades. In the field both species are readily recognized by leaf width and texture. Hechtia flexilifolia has narrower foliar blades that are white lepidote abaxially whereas the adaxial surface looks wrinkled. When the leaf blades dry, a thin layer from the adaxial epidermis peels off, apparently the cuticle because we did not observe foliar trichomes on the adaxial surface. This species is well characterized by its densely flowered spikes of both staminate and pistillate flowers. Plants were collected in fruit and cultivated but only staminate plants bloomed in 2009 and again in 2013. However, no pistillate plants produced inflorescences during eight years of cultivation. A recent trip to the type locality (2012) revealed small rosettes not ready to bloom and no recent evidence of previous flowering. However, vegetative features and staminate flower characteristics are sufficient to propose this species as new. A population of Hechtia occurring along the Oaxaca-Puerto Escondido road (Ramírez & Carnevali 1881, CICY, separated by ca. 90 km SE in straight line) strongly resembles H. flexilifolia in rosette features and the staminate inflorescence, but in this population some branches produced two small additional spikes at the base. Besides this, everything else is exactly the same. The problem of assuming this as the same species is that in some groups of Hechtia male flowers and inflorescences are extremely similar whereas pistillate inflorescences are strikingly different. As we are not sure if this is the case, we will await further evidence before we refer this population to any Hechtia species.

IUCN Conservation assessment: —Vulnerable (VU). Hechtia flexilifolia meets criteria D2 of the IUCN (2010). The species is known from an area of less than 2 km 2 within which it occurs only at a handful of small sites. Albeit local populations of the species can be rich in individuals and are often inaccessible, they are widely dispersed and isolated on the slopes and cliffs of the mountainous landscape.

Figures

FIGURE 2. Hechtia flexilifolia. Staminate plant. A. Part of rosette and peduncle. B. Inflorescence originates in a young rosette (pattern SPFP). C. Branches of the inflorescences are initially pendulous. D. Flowers at anthesis. E. Branches. (Photographs by Ivón Ramírez)

FIGURE 3. Geographical distribution of the three new species: Hechtia flexilifolia, H. huamelulaensis, and H. nivea.