Habenaria yookuaaensis Mejía-Marín, Espejo, López-Ferr. & R. Jiménez, 2017

Mejía-Marín, María Isabel, Espejo-Serna, Adolfo, López-Ferrari, Ana Rosa & Jiménez-Machorro, Rolando, 2017, Habenaria yookuaaensis (Orchidaceae: Orchidioideae), a new species from Oaxaca, Mexico, Phytotaxa 292 (1), pp. 74-78 : 74-78

Habenaria yookuaaensis Mejía-Marín, Espejo, López-Ferr. & R. Jiménez , sp. nov. ( Figs. 1 , 2 )

Similar to Habenaria brevilabiata Richard & Galeotti (1845: 29) , but habit terrestrial, with flowers white-greenish, petals oblong-falcate, and lip acuminate, with two triangular divaricate basal auricles.

Type:— MEXICO. Oaxaca: distrito de Jamiltepec, municipio de San Juan Colorado, Santa María Nutío, en la ribera del río Poza del Cuate, 16° 29’ 23.4’’ N, 97° 54’ 19.5’’ W, bosque de galería, 291 m, 11 September 2012, M. I. Mejía -Marín 95, A. Espejo, A. R. LópezFerrari, M. I. Verona -Trejo, I. N. Gómez -Escamilla y E. Mejía -Marín (holotype UAMIZ!, isotype AMO!).

Plants 35–42 cm tall including the inflorescence, terrestrial, erect, glabrous. Roots thin, ca. 2 mm diameter. Tuberoid not seen. Leaves 8–11, polystichous, sheathing, the larger ones in the middle of the stem, the lower ones reduced to sheaths, 0.5–10 cm long, 1.5–2 cm wide, with the blades 0.5–10 cm long, 1.5–2 cm wide, elliptic to narrowly elliptic, membranous, acute to acuminate, attenuate at the base, entire, glabrous, 3 veined. Inflorescence 8–15 cm long, terminal, racemose, cylindrical, rachis slightly keeled, green; floral bracts 1–2 cm long, 0.2–0.5 cm wide, lanceolate, acuminate, attenuate at the base, entire, those of the basal flowers slightly larger than the ovary, and those of the upper flowers shorter than the ovary, 3–5 veined. Flowers 2–3 cm long, ca. 1.2 cm wide, ascendant, white-greenish, 12–18 per inflorescence; ovary 1.5–1.6 cm long, 1.7–1.9 mm diameter, pedicelllate, erect, arcuate, terete, slightly verrucose, 6-ribbed; dorsal sepal 5–7 mm long, 4.5–5 mm wide, green, widely ovoid to orbicular, erect, concave, forming a helmet over the column, obtuse to rounded at the apex, margin minutely papillose; lateral sepals 5–9 mm long, 3–4 mm wide, green, obliquely elliptic-lanceolate, acute to rounded, 3 veined; petals white with the margin light green, oblong-falcate, 3–5 mm long, 1.5–3 mm wide, entire, obtuse, 2 veined (the upper vein bifurcate near the base); lip 7– 7.5 mm long, 1–1.7 mm wide, white with the apex light green, linear-oblong, acute to acuminate, with two basal, short, triangular, divaricate auricles ca. 1 mm long, ca. 0.5 mm wide; spur 20–22 mm long, 1–1.5 mm wide, white, longer than ovary, pendulous to reflexed, slightly dilated and flattened at the apical portion; column 1.5–2.7 mm long, 1–1.7 mm wide, white-greenish, oblong to rectangular, slightly arcuate in lateral view, truncate to emarginate at the apex; stelidia ca. 1 mm long, ca. 1 mm wide, short, subquadrate, verrucose; rostellum ca. 1 mm high, thick, deltoid; stigmatic processes 0.7–1.5 mm long, 0.7–1 mm wide, green, short, subquadrate, thick; anther bilocular, the anther cells parallel, oblique, elliptic, each one extending in a divaricate straight channel, ca. 5.4 mm long; pollinia ca. 2 mm long, reddish, elliptic, oblique; viscidia brown, hemispherical, in the apex of the anther channel. Fruit and seeds not seen.

Etymology:—The specific epithet refers to the name of San Juan Colorado, place where was found the new taxon, and derives from the Mixtec word “yo’o kua’a” formed by the terms “yo’o” (bejucos, lianas) and “kuaa’a” (rojo, colorado), and means “lugar de tierra colorada” (place of red soil).

Distribution and Habitat:— Habenaria yookuaaensis is known until now from two localities in the state of Oaxaca. The plants are very scarce and grow between rocks, on moist soils rich in organic matter, under the shade of the trees on the riverbanks. It flowers in September.

Additional specimens examined (paratypes):— MEXICO. Oaxaca: municipality of La Compañía, km 14.6 Río de la Y road, 1850 m, in shade on limestone, 26 August 1986, pressed 01 September 1986, Greenwood & Suárez 285 (AMO).

Comments:—The new taxon belongs to the complex of Habenaria brevilabiata Richard & Galeotti (1845: 29) , H. virens Richard & Galeotti (1845: 29) , H. odontopetala Reichenbach (1844: 7) , H. strictissima Reichenbach (1844: 7) , and H. acalcarata Espejo-Serna & López-Ferrari (1993: 249) , characterized by the presence of a widened lip, with basal triangular, divaricate auricles or lobes, and entire petals. However H. yookuaaensis is distinguished by its flowers white-greenish with the petals oblong-falcate. The most similar species, H. brevilabiata , is an epiphyte (vs. terrestrial), 20–30 cm tall (vs. 35–42 cm) and has flowers yellowish-green (vs. greenish-white). The plants of H. virens are larger (more than 50 cm vs. 35–42 cm tall), with numerous flowers (20–30 vs. 12–18), and a reflexed lip with two divergent triangular lobes and the spur curved and directed upwards. In the case of H. odontopetala the plants are higher (50–60 vs. 35–42 cm), and the petals are tridentate (vs. obtuse). H. strictissima has more than 30 flowers densely disposed (vs. 12–18 laxly disposed), the lip triangular-oblong (vs. linear-oblong) and the petals subquadrate (vs. oblong-falcate). Finally, in H. acalcarata the flowers, 40–80 per inflorescence (vs. 12–18), are smaller (8–9 vs. 15–16 mm), and without spur. A detailed comparison between these taxa is presented in Table 1.

Figures

FIGURE 1. Habenaria yookuaaensis Mejía-Marín, Espejo, López-Ferr., & R. Jiménez.A. Habit. B. Inflorescence. C. Flowers

FIGURE 2. Habenaria yookuaaensis Mejía-Marín, Espejo, López-Ferr., & R. Jiménez. A. Habit. B. Inflorescence. C. Flower, frontal view. D. Flower, lateral view. E. Dissected flower. F. Column, frontal view. G. Column, lateral view. H. Pollinia. I. Floral bract. Figure elaborated by Rolando Jiménez Machorro based in the specimen Greenwood & Suárez 285.