Hechtia nivea I. Ramírez & C. F. Jiménez, 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 : 122-125

Hechtia nivea I. Ramírez & C. F. Jiménez , spec. nov. ( Figs. 3 , 5 , Table 2).

This new species is similar to Hechtia nuusaviorum in its inflorescence architecture and condensed, conical or cylindrical branches in both sexes; however the new species differ in that foliar blades are 21–39 x 1.3–2.9 cm (vs. 30–75 x 1.5–4.5 cm), densely white lepidote on both surfaces (vs. glabrous above and white lepidote abaxially); staminate inflorescences are denser, featuring ca. 12 branches in a rachis of 20 cm length (vs. 5 branches in the same length), branches 1.2–3 × 1–1.4 cm (vs. 4 cm long × 2.5 wide), primary bracts much longer than or equaling the branch length (vs. always shorter than the branches); pistillate inflorescences are denser with ca. 16 branches in 20 cm length (vs. ca. 5), primary bracts vary from shorter to longer than the branches (vs. always shorter), branches are cylindrical, and up to 2.4 cm long (vs. 3 cm long and spheroid), floral bracts are equaling the flower, petals green, ovary reddish, and stigma white (vs. floral bracts shorter than the petals, petals white, ovary and stigma white in H. nuusaviorum ).

TYPE:— MEXICO. Oaxaca: Municipio San Juan Bautista Cuicatlán, 4.10 km al S de San Pedro Nodón, camino de terracería hacia San Miguel Huautla , matorral crasicaule [unpaved road to San Miguel Huautla, shrubland with succulent elements], 17°46’32.2”N, 97°07’58.3”W, 1740 m elevation, 21 Marzo 2013, Ramírez, Jiménez & Flores 1826b ♀ (holotype CICY!; isotype MEXU!) .

Plants terrestrial or lithophytic, cespitose, when blooming 1–1.20 m tall, heliophilous. Rosettes 35–45 cm in diameter, 25–30 cm long, new rosettes originating from the base of the older ones. Leaves 60−70 per rosette, straight and ascending; sheaths oblong, 2.5–3 x (2.6–) 3.7–4.8 cm, basally entire, finely dentate toward the apex, white-yellowish adaxially and brownish abaxially when dry, sometimes with a darker brown distal area, glabrous on both surfaces; blades narrowly triangular, acuminate, pungent, 21–39 cm long, 1.3–2.9 cm wide at the base, 0.5–1.1 cm wide in the mid area, erect (central ones) to slightly recurved (outer ones), succulent, slightly concave, green, glabrous to sparsely white lepidote adaxially, white lepidote abaxially, margins spinose; spines usually retrorse, uncinate, 4–7 mm long, (0.8–)1.6–4.4(–5.1) cm apart, laxly arranged toward the apex, reddish. Inflorescence central (type SSP), one branched panicle in both sexes, erect.

Staminate inflorescence cylindrical, erect, 120–135 cm long; peduncle terete, 60−67 cm long, 0.9–1 cm in di- ameter at the base, ca. 3 times longer than the rosette, brown, glabrous, internodes 1.2–3.2 cm long; peduncle bracts with broadly triangular sheaths, the blades appressed to the peduncle, abruptly long (basal bracts) to shortly (upper ones) acuminate, 4–11 x 0.8–1 cm, entire, margins thin, brownish, glabrous, strongly nerved, the basal ones longer than internodes, the upper ones equaling the internodes; main axis 70–74 cm long, 0.4–0.5 cm in diameter, cylindrical, sulcate when dry, light brown, glabrous, internodes 1–1.5 cm long; primary bracts narrowly triangular, acuminate, 1.3–3.5 x 0.4–1(–1.3) cm, wider than the peduncle bracts and enclosing the base of the branches, entire, brownish, glabrous, strongly nerved, equaling or longer than the branches; branches 70−72 in number, ascendent or appresed, 1.2–3 cm long, 1–1.4 cm in diameter, sessile, with 30−70 flowers, densely arranged along the main axis, longer than the internodes, green; rachis hardly visible, cylindrical, green, smooth; floral bracts elliptic to broadly elliptic, 6.3–8 x 3.7–5.5 mm, concave, acute, strongly erose, light brown, longer than the sepals and petals, glabrous, 5−9 nerved. Flowers subsessile, erect, 5.5–6.7 mm long, 2.4–3.2 mm in diameter; pedicels terete, 1−2 mm long, 1−1.5 mm in diam- eter, glabrous; sepals usually 3, sometimes 4, oblong, 3.5–4 x 2.2–3 mm, concave, acute, stramineous, erose, glabrous, 5–7(–8) nerved; petals elliptic, 4–4.4 x 2.2–2.5 mm, rounded, cucullate, entire, white, glabrous, 7–9-nerved; stamens erect, adnate to the petals and to the pistillode base, barely protruding at anthesis; filaments narrowly triangular, 4–4.6 x 0.5–0.7 mm, white; anthers ovoid, 1.7–2.2 mm long, 0.7–1 mm in diameter, green; pistillode conical, 0.8−1 mm long, 1 mm in diameter, white, stigmatic lobes usually absent, when present ca. 0.2 mm long.

Pistillate inflorescence cylindrical, ca. 160 cm long, erect; peduncle cylindrical, 91–99 cm long, 0.8–0.9 cm in diameter at the base, much longer than the leaves, glaucous, green; peduncle bracts broadly triangular, abruptly long (basal ones) to shortly (upper ones) acuminate, appressed to the peduncle, 2.5–9.2 x 0.8–0.9 cm, entire, brownish, glabrous, strongly nerved, margins thin, the basal ones longer than the internodes, the upper ones equaling the internodes, internodes 1.2–3.2 cm long; main axis ca. 69 cm long, 0.4–0.5 cm in diameter at the base, cylindrical, sometimes flexuous, green, glabrous, internodes 1–3 cm long; primary bracts triangular, acuminate, 0.8–2.5 x 0.5–1 cm, light brown, glabrous, entire, strongly nerved, subequaling or shorter than the branches; branches ca. 44 in number, ascending or erect, 0.8–2.4 cm long, 0.7–1 cm in diameter, sessile, with 25−50 flowers, densely arranged; rachis not visible; floral bracts triangular ovate, 5.2–6.8 x 3.2–4 mm, concave, acute, strongly erose, brown, glabrous, ca. 7-nerved, longer than the sepals and petals. Flowers sessile, appressed to the rachis, (4.4–) 5.8–6.3 mm long, (2.4–) 3–3.3 mm in diameter; sepals deltoid, 3–3.4 x 2.6–3(–3.7) mm, acute, entire at the base, apically erose, brown, glabrous, ca. 5-nerved; petals triangular to triangular-ovate, 3–4.3 x 2–2.8 mm, acute, entire, green, glabrous, ca. 7-nerved; staminodes narrowly triangular, 1.1–2.4 mm long, 0.4–0.8 mm wide at the base, without vestigial anthers; filaments adnate to the bases of the petals and the ovary, green; stigmatic lobes short, slightly recurved, ca. 1.2 mm long, white; ovary superior, oblongoid, 2.5–3 mm long, 1.4–2 mm in diameter, green, placentation central. Fruits ellipsoid to broadly ellipsoid, sometimes asymmetrical, 6.3–8.9 mm long, 4–5.8 mm in diameter, brown; sepals, petals, staminodes and stigmatic lobes remaining in fruit; seeds variable in shape, generally ovate, rarely oblong, 3.4–4 x 1.3–2 mm, brown, with 2 wings, apical wing 0.3–0.5 mm long, basal wing 0.8–1.2 mm long.

Distribution and habitat:— Hechtia nivea is known from a restricted geographical area in the vicinity of the village of San Pedro Nodón. It grows as a lithophyte on vertical walls where rosettes resemble silver stars from afar. It also grows at the foothills in a general area of low caducifolious forest along with species of Agave Linnaeus (1753: 323) (Agavaceae) , Brahea Martius (1838: 243) (Arecaceae) , Cnidoscolus Pohl (1827: 56) (Euphorbiaceae) and Bursera Jacquin ex Linnaeus (1762: 471) (Burseraceae) , at elevations of about 1700 m. Hechtia nivea was collected in bloom during April 2013 and several plants of it are currently under cultivation.

Etymology: —The specific epithet refers to the white indumentum of the leaves lending the plant a snowy aspect.

Additional specimens examined (paratypes):— MEXICO. Oaxaca: Municipio San Juan Bautista Cuicatlán, 4.10 km al S de San Pedro Nodón, camino de terracería hacia San Miguel Huautla , matorral crasicaule, 17° 46’ 32.2” N, 97° 07’ 58.3” W, 1740 m elevation, 21 March 2013, Ramírez, Jiménez & Flores 1826a ♂ ( CICY!, MEXU!) , 1826c fruits ( CICY!, MEXU!, OAX!) .

& E. Ivón Ramírez; C. Prisciliano Flores).

Discussion: —The species was collected in the Sierras Centrales de Oaxaca physiogeographical province ( Fig. 3 ) and it can be recognized by the following combination of characters: rosettes are medium-sized with dense white lepidote leaves, branches of both sexes are reduced and short claviculate, pistillate flowers with green petals, the staminate ones with white petals. Hechtia nivea is compared with H. nuusaviorum ( Table 2), a morphologically similar species and also native from northwestern Oaxaca. Main differences include the smaller branches of H. nivea that are more densely packed on the rachis and the much narrower leaves with white lepidote indumentum above as opposed to the broad leaves of H. nuusaviorum which are glabrous above.

IUCN Conservation assessment: —Vulnerable (VU). Hechtia nivea meets criteria D2 of the IUCN (2001). 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 scattered and isolated on the slopes and tops of small hills where they are susceptible to fires and other anthropogenic disturbances.

Figures

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

FIGURE 5. Hechtia nivea. A. Plant with infructescence in habitat (indicated by an arrow) B. Staminate inflorescences at anthesis. C. Young infructescens. D. Staminate branches with flowers at anthesis. E. Pistillate branches with flowers at anthesis (Photographs A, B, D