Lepanthes marielana N.Gutiérrez, J.S.Moreno & S.Vieira-Uribe

Morales, Nicolás Gutiérrez, Vieira-Uribe, Sebastián & Moreno, Juan Sebastián, 2021, Lepanthes marielana (Orchidaceae, Pleurothallidinae), a new species from the eastern Andes in Colombia, Phytotaxa 484 (1), pp. 113-120 : 116-117

Lepanthes marielana N.Gutiérrez, J.S.Moreno & S.Vieira-Uribe , sp nov. ( Figs. 1 , 2 , 5C )

Type:— COLOMBIA, Santander: La Belleza, 2380 m. July 2018. M. Calderón H 156, N. Gutiérrez (holotype: JBB!). Lepanthes marielana is most similar to Lepanthes clausa Luer & Escobar (1985: 728) but can be distinguished by the echinate floral bracts, the non-resupinate, light yellow flowers with a central claret blotch, the blades of the lip subfalcate with the apices surrounding the apex of the column and by the lip appendix subtriangular to oblong.

Plant small, epiphytic, caespitose, occasionally prolific; roots slender, flexuous, to 0.6 mm in diameter. Ramicaul slender, erect, 1.4–2.7 cm long, enclosed by 3–5 minutely ciliate, acuminate lepanthiform sheaths. Leaves, sub-erect, broadly elliptical, coriaceous, obtuse, 0.9–1.6 × 0.6–1.1 cm, the apex minutely emarginate with a central mucro, the base cuneate into a petiole ca. 2 mm long. Inflorescence a slender, erect to sub-erect, successively few-flowered raceme, 2–4 cm long; floral bracts echinate, acuminate, ca. 1 mm long, pedicels 1.5 mm long. Ovary shallowly costate, 0.7–1.0 mm long. Flowers non-resupinate, light yellow with a central claret blotch almost covering the dorsal sepal, the petals suffused with claret along the internal margins, the lip and anther cap white suffused with claret marginally. Sepals completely spread, ovate, acuminate to caudate, dorsal sepal slightly concave, adaxially carinate, 3.5–4 × 2.4 mm, 3-veined, connate to the lateral sepals for ca. 2.3 mm, lateral sepals oblique, 2-veined, connate ca. 1.9 mm into an ovate, bifid lamina, 3.5 × 2.7 mm. Petals transversely bilobed, pubescent, 2.8 × 0.7 mm, the lobes subequal, narrowly triangular, subfalcate, subacute, attenuate, the apex incurved, the upper lobe slightly wider and shorter. Lip bilaminate, the blades ovate to elliptical, subfalcate, minutely pubescent, attenuate, 1 mm long, the rounded apices ciliate, the connectives ca. 0.5 mm long, cuneate, minutely pubescent, the body rectangular when expanded, adnate to the base of the column; the appendix subtriangular to oblong, ciliate, completely appressed on the stigmatic fluid. Column terete, 1 mm long, the anther dorsal and the stigma apical. Anther cap cordate, ca. 0.7 mm long. Pollinia yellow, two, pyriform, 0.5 mm long.

Additional material examined: — COLOMBIA, Santander: Municipality of La Belleza , 2380 m. January 2020. M. Calderón H 193, N. Gutiérrez, J. de Jesus (paratype: JBB!) .

Eponymy: —Named in honor of the memory of the first author’s maternal grandmother, Mariela Caro de Morales (1924-2018) ( Fig. 3 ), who managed the land where the new species was found and agreed to preserve it as a natural reserve. This species is an acknowledgment of her love and dedication as the head of her family.

Distribution & Ecology: — Lepanthes marielana is known from a single locality in the western slope of the eastern Andes of Colombia, inhabiting a tropical mountain forest fragment in a small canyon with steep walls and difficult access along the “Peñabonita” river ( Fig. 4 ). The plants were found growing epiphytic ca. 1.5 m above the ground, in aggregated clusters separated by several meters. The new species shares the habitat with other orchid species such as Masdevallia platyglossa Reichenbach (1886: 552) , Stelis lagarantha Luer & Escobar (2016: 203) and Oliveriana ortizii Fernández (1969: 86) . In the same forest relict, the richness of Andinia subgen. Brachycladium (Luer) Karremans & Vieira-Uribe in Wilson et al. (2017: 123) species is remarkable, with ten different species, including the recently described Andinia auriculipetala Vieira-Uribe & Gutiérrez (2020: 1) . Individuals from the same locality show some variation in characters like the shape of the leaves (broadly elliptical to elliptical), and color of the blades of the lip (from white to burgundy). Specimens cultivated in greenhouse conditions did not produce capsules without hand pollination.

Discussion: — Lepanthes marielana is most similar to L. clausa and L. cucullata Luer & Escobar (1994: 89) , both Colombian endemics from the eastern Andes. The vegetative features are similar, sharing features such as the inflorescence surpassing the broadly elliptical leaves, small successive flowers and numerous capsules. The dorsal sepal is more or less concave, the petals are transversely bilobed, with subequal lobes, pubescent in some degree, as so the blades of the lip. Lepanthes clausa has similarly shaped sepals and a ciliate appendix that lies in contact with the stigma, an unusual feature noted by Luer (2012). Lepanthes marielana differs from that species in the echinate floral bracts (vs. glabrous), the non-resupinate flowers, light yellow with a central claret blotch (vs. flowers resupinate, red), the upper lobe of the petals narrowly triangular, subacute (vs. oblong, rounded), the lip proportionally smaller when compared to the petals, the blades of the lip ovate to elliptical, subfalcate, with the apices surrounding the apex of the column (vs. narrowly ovate, with the apices surpassing by far the apex of the column) and by the lip appendix subtriangular to oblong (vs. appendix oblong, thick, with a sessile, orbicular apical segment). Lepanthes cucullata shares the echinate floral bracts of L. marielana and the elliptical to ovate blades of the lip, but the flowers are cleistogamous, the dorsal sepal is deeply concave, the lateral sepals are free, with margins subdenticulate, the petals have oblong lobes (vs. narrowly triangular), with rounded ends (vs. subacute), the apices of the blades of the lip are incurved under the column (vs. apices surrounding the apex of the column), the appendix is minutely bilobed and it does not touch the stigma (vs. subtriangular to oblong, completely appressed on the stigmatic fluid) and the ovary is echinate (vs. smooth).

Flower resupination (from the Latin resupinus) is traditionally defined as the torsion of the flower buds, so that the labellum assumes the lowermost position of the perianth in an opening flower ( Ames 1938, Arditti 2003). Luer (1996) suggests Lepanthes flowers are “strictly speaking” non-resupinate, as there is no rotation of the flower buds. But instead, the flowers of Lepanthes bend to one side, due to the partial torsion of the ovary or peduncle, and the final orientation of the lip in its natural position depends also on the orientation of the plant (erect to pendent) together with the orientation of the inflorescence. In L. clausa and L. cucullata , the resupinated flowers are carried in a loose, horizontal inflorescence, bending to one side due to a partial torsion of the ovary, with the lip in the lowermost portion of the flower. Conversely, in L. marielana , the erect to sub erect inflorescences bear non-resupinate flowers with, neither the ovary or the peduncle twisted at all.

Figures

FIGURE 1. Illustration of Lepanthes marielana. A. Habit. B. Flower. C. Dissected perianth. D. Lip and column lateral view. E. Lip ventral view. F. Anther cap and pollinarium.

FIGURE 2. Photographs of Lepanthes marielana. A. Frontal view. B. Lateral view. C. Habitat and plant in-situ.

FIGURE 3. Mariela Caro de Morales (1924–2018).

FIGURE 4. Landscape view of the small canyon where Lepanthes marielana was found. Photograph by N. Gutiérrez Morales.

FIGURE 5. Comparison with the most similar species.A.Lepanthes clausa. B. Lepanthes cucullata. C. Lepanthes marielana. Photographs by J. S. Moreno (B) and S. Vieira-Uribe (A, C)