Laelia, Lindley, 1831

Salazar, Gerardo A., Jiménez-Machorro, Rolando, Huerta, Héctor M. & Hágsater, Eric, 2014, A new species and a new natural hybrid of Laelia (Orchidaceae) from Oaxaca, Mexico, Phytotaxa 178 (1), pp. 161-170 : 167-168

Laelia × oaxacana Salazar & R.Jiménez , hybr. nat. nov.

Vegetatively similar to Laelia halbingeriana Salazar & Soto Arenas , differing in the distichous (vs. spiral) raceme and the proportionally narrower and more pointed sepals and petals.

Type:— MEXICO. Oaxaca. Barranca del Río Santo Domingo, muy al E de Tecomavaca , cerca de Buenos Aires (entre Coyula y el río Santo Domingo ), ca. 1,600–1,700 m elev., collected June 1986, flowered in cultivation 4 November 1991, Lau sub Hágsater 9539 (holotype AMO!, isotypes MEXU!, SERO!) .

Epiphytic herb vegetatively similar to L. halbingeriana (see above). Inflorescence 80−135 cm long, from the mature pseudobulb, apical, erect-arcuate, racemose, long-pedunculate; peduncle 65–110 cm long, 5−6 mm in diameter, subterete, without basal spathe but provided with strict, tubular, scarious, obtuse to acute bracts 6−10 cm long, which cover most part of the internodes; raceme 15−30 cm long, with 4−9 flowers, these simultaneous and arranged distichously, floral bracts 4.2−7 cm long, up to 1.5 cm wide, sheathing the ovaries, scarious at anthesis, whitish but often suffused and dotted with brown, oblong-elliptic, acute to acuminate, margins involute. Flowers showy, resupinate, odourless, sepals and petals rose-lilac, labellum deep magenta with the centre yellow and provided with radiating dark purple veins, column green with purple lines and dots; dorsal sepal 5.8−7.3 × 1−1.3 cm, lanceolate, acute, margins somewhat recurved and slightly waved; lateral sepals 5.5−7 × 1−1.2 cm, obliquely lanceolate, acute, margins slightly waved; petals 5.7−7.2 × 1.2−1.8 cm, obliquely oblong-lanceolate, acute, spreading and oriented in a vertical plane, margins slightly waved;. labellum 4−4.8 cm total length, 2.6−4 cm wide across the lateral lobes, adnate to the base of the column for ca. 3 mm, arcuate, deeply three-lobed; lateral lobes 2.5−3 × 1.3−1.6 cm, vertical at each side of the column and touching each other above it in natural position, obliquely ovate, rounded, undulate, when spread out without distinct sinuses separating them from the mid-lobe; mid-lobe 1.6−2.1 × 1.6−2.3 cm, obovate to obcordate, rounded to shallowly emarginated at apex, mucronulate, margins waved; callus consisting of an oblong thickening bearing 3 low keels running from the base of the labellum to the basal one-third of the mid-lobe, where they are slightly more prominent (1−1.5 mm tall); column 2−2.6 cm long, 6.5−7 mm wide near the apex, oblong, slightly arching, trigonous, ventrally concave, apex three-toothed with the central tooth more prominent and somewhat incurved over the anther, base provided with an excavation (cuniculus) that penetrates the apex of the ovary for ca. 3 mm but lacks nectar; anther ca. 4.5 × 3.5 mm, ventral, sub-quadrate, slightly bilobed; rostellum retrorse, rounded, provided on the internal surface with a lunate viscarium; pollinarium ca. 3.5 mm long and wide, with 8 laterally compressed, obliquely ovate, yellow pollinia arranged in two rows; pollinia with yellow granular caudicles; ovary 3.7−5 cm long, 4−5 mm in diameter near the apex, sub-terete, twisted, provided with three smooth longitudinal ribs above the basal one-third. Capsule not seen.

Distribution and ecology:—Known only from the Sierra Madre Oriental in northern Oaxaca ( Fig. 4 ). Epiphytic, in an ecocline of tropical deciduous/semideciduous forest and oak forest at 1,100 −1,700 m elevation.

Etymology:—This natural hybrid swarm is named after the Mexican state of Oaxaca.

Phenology:—Plants in bloom have been observed in the field in late October and early November, and from September to December in cultivation.

Conservation status:—So far this natural hybrid has only been recorded from the surroundings of the village of Coyula, in northern Oaxaca, in which L. halbingeriana and L. anceps coexist. The hybrids seem to represent an unusual, local phenomenon that, if required, could be easily replicated ex situ. Therefore, we do not consider it as a conservation concern.

Discussion:—At first glance, L. × oaxacana looks like a plant of L. halbingeriana bearing an inflorescence of L. anceps by virtue of the distichous arrangement of the flowers in the raceme, instead of the spiral raceme of L. halbingeriana . The spreading petals oriented vertically are similar to those of L. anceps (although proportionately narrower; Fig. 2 G−H), in contrast with the distinctly arcuate petals of L. halbingeriana , which are oriented horizontally ( Fig. 2 D ). The stout plants with two-leaved pseudobulbs and the proportionately narrower, waved sepals and petals easily allow for the separation of hybrid specimens from L. anceps .

Figures

FIGURE 2. Taxa of Laelia discussed in the text.A–C. Laelia superbiens (Chiapas, Miller s.n., AMO).A. Flower. B. Close-up of labellum and column. C. Ventral view of column apex. D–F. Laelia halbingeriana (Oaxaca; D–E from Salazar et al. 6695; F from Jones s.n.). D. Flower. E. Close-up of labellum and column. F. Ventral view of the column apex. G. Flowers of Laelia anceps (Oaxaca, Salazar et al. 6685). H. Flower of Laelia ×oaxacana (Oaxaca, Lau sub Hágsater 9359). Photographers: Eric Hágsater (A, B); Edward W. Greenwood (C, F); Gerardo A. Salazar (D, E, G); Rolando Jiménez-Machorro (H).

FIGURE 4. Distribution of Laelia anceps, L. halbingeriana, L. superbiens and L. ×oaxacana. Symbols indicate point locality records of each species; colours indicate potential distribution areas according to the best models obtained with GARP (see text).