Lepanthes leimebambana B.T.Larsen, Salas Guerr. & Dignum, 2018

Larsen, Bruno, Guerrero, Marcos Salas & Dignum, Johannes H. M., 2018, Two new peruvian species of Lepanthes (Orchidaceae) with a unique column morphology, Phytotaxa 373 (4), pp. 291-296 : 294-295

Lepanthes leimebambana B.T.Larsen, Salas Guerr. & Dignum , sp. nov. ( Figs. 2 , 3B , 4 )

Type:— PERU. Amazonas: Prov. Chachapoyas, Dist. Leimebamba, Laurel-Cordillera de Yasgolga, 2800 m, 20 October 2016, Salas, Dignum et al. 116 (holotype: USM).

This species is similar to other small species of Lepanthes with a successively flowered, flexuous distichous raceme, but it is easily distinguished by the combination of flowers with shallowly concave dorsal sepals and the conspicuous, glabrous, ovate apex on the dorsal part of the column.

Epiphytic, sympodial, caespitose herbs up to 7 cm tall. Roots to 1 mm in diameter. Ramicauls erect, 2–4 cm long, enclosed by 3–7 microscopically scabrous lepanthiform sheaths with a dilated, minutely ciliate ostia, Leaves erect, ovate, obtuse 2–3 X 1.0– 1.5 cm, the base cuneate into a petiole 1 mm long. Inflorescence a progressively lengthening, successively flowered, flexuous, distichous raceme, up to 5 cm long including the filiform peduncle 2 cm long; floral bracts 1.5 mm long; pedicels 4 mm long; ovary 1 mm long with erose ribs. Sepals pale yellow, diffusely suffused with light red along the veins, the margins and the carinate veins denticulate, the dorsal sepal ovate, acuminate, shallowly concave, long-acuminate 6.7 X 2.9 mm, 3-veined, connate to the lateral sepals for 1 mm, the lateral sepals narrowly ovate-triangular, acute, long-acuminate, 7.1 X 3.8 mm, connate 1.5 mm, 2-veined. Petals pale yellow, suffused with red along their inner margin and apices, minutely pubescent, margins microscopically ciliate, transversely bilobed 0.7 X 4.2 mm, lobes subequal, upper lobe oblong with the end rounded, lower lobe slightly narrower, acute. Lip purple, bilaminate, blades oblong, glabrous, external margins lightly revolute, 1.0 X 0.5 mm, margins minutely ciliate, bases obliquely truncate, apices round, long-ciliate, connectives cuneate, body connate to the column above the base, sinus obtuse with a narrowly linear, acuminate appendix. Column purple, 1.5 X 0.5 mm, dorsal part with a conspicuous, glabrous, ovate, convex, angled apex, 1.2 X 0.9 mm, from below the middle of the column, with an inconspicuous, smooth, lightly depressed centrally triangular crest along the middle, the sides projecting 0.2 mm, the margins lightly revolute forcing the blades of the lip to bend outwards at the end of the connectives, the base rounded, the apex drawn into a truncate beak with the anther apical, the stigma ventral. Anther cap pyriform, located at the apex of the column. Pollinia 2, narrowly obpyriform, attenuate at the base, on a subquadrate viscidium. Capsule not seen.

Etymology:— Named in reference to the only known locality of the species in Leimebamba, Peru, where the type specimen was collected.

Distribution and habitat:— Peru, only know from a single collection from the eastern Leimebamba, near El Laurel, halfway to the Valley of Los Chilchos. Epiphytic in humid forest, at 2800 m elevation.

Phenology:— Recorded to flower in October.

Conservation Status:— Evaluated as data deficient (DD), according to the IUCN (2001) classification.

Comments:— This is the second species in the genus from Peru with a large, helm-like apex on the back of the column. Lepanthes leimebambana is characterised by the slender ramicauls (to 4 cm long), elliptical leaves, 2–3 cm long and a progressively lengthening, successively flowered, flexuous, distichous raceme. The sepals are ovate, long-acuminate with the margins and the carinate veins denticulate. The petals are transversely bilobed, with unequal lobes. Although L. leimebambana is distinct, it is morphologically similar to L. dignumii . In both species the lip is bilaminate with the lobes poorly developed into blades with rounded, long ciliate apices in L. leimebambana vs. truncate, long ciliate in L. dignumii . The appendix of the lip is in both species narrowly linear. The dorsal part of the column of L. leimebambana has an ovate, glabrous conspicuous helm-like apex vs. obovate in L. dignumii .

Figures

FIGURE 2. Lepanthes leimebambana B.T.Larsen, Salas Guerr. & Dignum.A. Habit. B. Peduncle with flower bract and pedicel. C. Flower. D. Dissected flower. E. Column, lip and ovary, lateral. F. Column and lip, dorsal view. G. Lip, dorsal view. H. Column, dorsal view. I. Anther cap and pollinia. Drawn from the holotype by Bruno Larsen.

FIGURE 3. A. Lepanthes dignumii. B. Lepanthes leimebambana (photographs by M. Salas Guerrero).

FIGURE 4. Lepanthes leimebambana at the type locality in Leimebamba, Peru (photograph by M. Salas Guerrero).