Lepanthes microprosartima Tobar & M.J.Gavil., 2021

Suarez, Francisco Tobar, Lopez, Maria Fernanda, Gavilanes, Maria Jose, Monteros, Marco Federico, Garcia, Tatiana Santander & Graham, Catherine Helen, 2021, Three new endemic species of Lepanthes (Orchidaceae, Pleurothallidinae) from the highlands of Ecuador, PhytoKeys 180, pp. 111-132 : 111

2. Lepanthes microprosartima Tobar & M.J.Gavil. sp. nov.

Figs 6 , 7 , 8a

Diagnosis.

Similar in habit to Lepanthes obandoi Tobar & M.F. López, but distinguished by the inflorescence shorter than the leaf (vs. Inflorescence longer than) and petals with unequal triangular lobes (vs. lobes lanceolate-oblong, subequal). Lepanthes mirador Luer & Hirtz is also similar, differing from it in the superposed, arcuate secondary stems (vs. secondary stems erect, not superposed), leaf light green on the underside (vs. dark purple underside), and the tiny, oblong-lanceolate appendix (vs. appendix oblong with bilobed apex).

Type.

Ecuador. Pichincha, Nono, Yanacocha Reserve , masked trogon path, 0.122416°N, - 78.590283°W, 3530 m, 25 Nov 2018, Tobar & Angulo 3357 (holotype: QCA-spirit; isotypes: QCNE, HPUCESI-spirit) .

Terrestrial, caespitose, prolific herbs up to 40 cm in height. Roots flexuous, cylindrical, pink with yellow apex. Ramicauls arcuate, new stems arise from the apex of the old ones superposed, 4.1-25.0 × 0.2-0.3 cm long, with 4-16 internodes, covered completely by lepanthiform sheaths, these light brown, 0.3-2.9 cm long, the ostium microscopically muricate, acuminate. Leaves arcuate, 7.5-9.4 × 1.1-2.2 cm, blades oblong-ovate, light to dark green, minutely serrate along the margin, long-acuminate apically, base cuneate, contracted into a petiole 4-7 mm long. Inflorescence one per stem, shorter than the leaf, 2.5-6 cm long, borne on the underside of the leaf, racemose; peduncle filiform, 2 mm long, ca. 0.5 mm in diameter, surrounded by a basal bract. Floral bracts 2 mm long, papiraceous, obliquely infundibuliform, glabrous and long-apiculate. Ovary 3.2 mm long, obpyramidal, with irregular keels. Flowers ca. 4.5 × 13 mm; sepals entirely yellow, petals yellow with edges slightly suffused with red or pink; lip yellow with the base and edges of the blades red or pink; column pink or purple and anther purple with two yellow spots at the base. Sepals with minutely denticulate margins, dorsal sepal 6 × 4.5 mm, broadly ovate-triangular, minutely denticulate, shortly acuminate, 3-veined; lateral sepals 7 × 2.4 mm long, connate to their middle, obliquely ovate with divergent acute-acuminate apex, 2-veined. Petals ca. 3 × 1.4 mm long, 1-veined, minutely pubescent, transversely bilobed, the upper lobe narrowly triangular with revolute margins, the lower lobe smaller, broadly triangular, obtuse. Lip bi-laminate, the blades minutely pubescent, ovate, rounded, close to each other in their proximal part and divergent at the apex, ca. 1.4 × 1.2 mm; connective short, deeply cuneate, the base of the lip connate with the base of the column, sinuous, obtuse; appendix tiny, oblong-lanceolate, pubescent at the apex. Column slightly arcuate, slightly broadened apically, somewhat compressed dorsoventrally, ca. 1.2 × 0.8 mm; clinandrium covering the lower half of the anther. Anther dorsal, stigma ventral, horseshoe-shaped. Rostellum minutely triangular, yellow. Capsule ovoid 6-ribed ca. 4 × 6 mm, with persistent perianth. Capsule ellipsoid, 6-ribed.

Other specimens examined.

Paratypes Ecuador. Pichincha, Nono, Reserva Verdecocha, Verdecocha : Transecto de Aves y Conservacion en Reserva Verdecocha , - 0.118420°N, - 78.597470°W, 3400 m, 06 Feb 2018, Tobar, Santander & Hipo 3130 (QCA); Nono, Yanacocha Reserve , sendero hacia la Reserva Verdecocha 500 metros al suroeste de los bebederos de colibríes, 0.118420°N, - 78.597470°W, 3810 m, 07 May 2018, Tobar 3359 (QCA) .

Distribution and habitat.

This species is endemic to the Yanacocha and Verdecocha reserves on the western slopes of Volcán Pichincha (Fig. 4 ), where it is found growing from 3200 to 3800 m in evergreen montane forest (BsAn03) according to Ministerio del Ambiente del Ecuador (2013). Lepanthes microprosartima grows terrestrially on the edges of the trails of both reserves and shares the habitat with other species such as L. mucronata Lindl., L. bibalbis Luer & Sijm and L. dunstervilleorum Foldats, as well as Stelis laevigata (Lindl.) Pridgeon & M.W.Chase, Stelis pusilla Kunth, Masdevallia laevis Lindl. and Platystele stonyx Luer. Unlike other terrestrial species of Lepanthes that grow on roadside embankments with greater availability of light, this species can also thrive within the forest in dense shade.

Phenology.

The species was collected in flower in November, February and May, which suggests that flowering occurs throughout the rainy season, from October to the end of May.

Etymology.

From the Greek μικρό, small and προσάρτημα, appendix, in reference to the tiny appendix of this species.

Preliminary conservation status.

Only three collecting sites have been found during three years of monitoring at two locations: Yanacocha and Verdecocha reserves (Fig. 9 ), and around 40 mature individuals are known, which suggests that it is a rare species. This orchid is mainly terrestrial, and has not been found growing in other trails of the reserve or in nearby areas, the extent of occurrence calculate for the specie is <100 km2 and area of occupancy is 8 km2, Based on the available information, this species is preliminarily assessed as Critically Endangered (CR) B1a+2a given that the known population are restricted to a small area in the western slopes of Pichincha Volcano, representing one location (sensu IUCN 2012), and the number of known mature individuals is fewer than 250.

Discussion.

The closest species are Lepanthes mirador (Fig. 8a ) from north-east Ecuador and Central Cordillera of Colombia, and L. tungurahuae Luer & Hirtz (Fig. 8c ) from central Ecuador, but is easily distinguished from both by the overlapping secondary stems. Lepanthes microprosartima also differs from L. mirador in the light green leaves and oblong-lanceolate appendix (vs. leaves dark purple in the abaxial surface and appendix oblong, with a bilobed apical segment). From L. tungurahuae the new species is distinguished by the oblong leaves (vs. ovate elliptical), the petal lobes revolute, marked with red at the edges (vs. not revolute and marked with red at the base) and the blades of the labellum ovate (vs. blades narrowing oblong-ovate). In habit it also resembles L. obandoi from the north east of Ecuador, but the new species has an inflorescence shorter than the leaf (vs. longer than the leaf.), and the petals have triangular, unequal lobes (vs. lobes subequal, lanceolate-oblong).

Figures

Figure 4. Geographical distribution of the three new species of Lepanthes microprsartima Tobar & M. J. Gavil. (black hexagon, three collections), Lepanthes caranqui Tobar & Monteros (black triangle, two collections) and Lepanthes oro-lojaensis Tobar & M. F. Lopez (black pentagon, one collection).

Figure 6. Lepanthes microprosartima A habit B flower C dissected sepal and petals D dorsal view of the spread-out lip whitout the column E lateral view of the ovary, and lip F lateral view of the ovary and column G ventral view of the column showing the horse-shaped stigma Drawn by M. Gavilanes from the plant that served as type (Tobar et al. 3357).

Figure 7. Lepanthes microprosartima A plant growing in its natural habitat B front view of the flower C lateral view of the lip showing the apendix D detail of the fruit E lateral view of the petal showing the revolute apex F detail of the leaf margin, minutely denticulate G anther dorsal view H anther ventral view I polinarium. Photograph by Francisco Tobar from the plant that served as type (Tobar et al. 3357).

Figure 8. Comparison with the most similar species to Lepanthes microprosartima Tobar & M. J. Gavil. A Lepanthes microprosartima B Lepanthes mirador C Lepanthes tungurahuae. Photographs A, B by F. Tobar and C A. Hirtz.

Figure 9. Natural habitat of Lepanthes microprosartima in the western slopes of Pichincha volcano A Yanacocha reserve B Verdecocha reserve.