Results

Plant material.- Specimens collected in 1994 are deposited in the collections of the Herbario de Botánica Económica del Ecuador QUSF. Flowers are preserved in 75% ethanol with glicerine. Living individuals were found and examined at the type locality in 2015 and 2016, but no specimens were collected, and photographs were taken in-situ. Research on the material lead to the knowledge that it belonged to a new species.

Study area.- The only known population of the new species was discovered close to Quito, in the sourthern valley of Los Chillos near Pita river.

Figure 1 Pleurothallis quitu-cara. A, habit. B, disected flower. C, flower close-up. D, dorsal view of the lip, flattened (left), with normal bent apex (right). E, lip close up showing with portruding abaxial callus (Illustration: Luis Baquero). 

Pleurothallis quitu-cara Carrera & Baquero, sp. nov. (Figure 1-3).

TYPE: Ecuador. Provincia de Pichincha: Valle de los Chillos, Río, -0.436431°S, -78.4118900°W, 2980 m, April 10th, 1994, V. Zak 6543 (holotype: 2380 QUSF).

Diagnosis: Pleurothallis quitu-cara is similar to P. corysta Luer, from which it differs in the rectangular lip with an elliptical small glenion with an elevated center at the base, a minutely pubescent, protruding callus and the apex of the lip bent upwards versus the erect, subovate, without an obvious glenion and an elevated line on the disc and the apex of the lip not bent in P. corysta (Figure 3).

Plant medium in size, epiphytic or terrestrial, caespitose, with slender roots. Ramicauls stout and glandular, pendent to horizontal, 25-35 cm long, with three, 8-10 cm long, tubular sheaths. Leaf horizontal to pendent, coriaceous, oblong, slightly undulated, leaf-margins slightly deflexed, 13-20 × 6-8 cm, base sub sessile, cordate to deeply cordate, apex rostrate and acute. Inflorescence a fascicle of 1-4 medium sized simultaneous flowers subtended by a spathe 1 cm long, peduncles 10-12 mm long withing the spathe; floral bracts 4.5-6.0 mm long; pedicel 7.0-8.5 mm long; ovary smooth, six-ridged, 5.0-5.5 mm long. Dorsal sepal deeply concave, ovate, acute, 19 × 12 mm, 7 veined, sulphur-coloured (xanthic above and below) or sulphur coloured with 7 sanguine color veins (non xanthic above, below without colored veins). Lateral sepals connate into a side-decurved, lanceolate, acute synsepal, 16 × 8 mm, 6 veined, yellow-sulphur coloured, powdered with sanguine color glands (non-xanthic form with more obvious). Petals pubescent, deeply decurved below the lip, crescent shaped, subacute, 10.0 × 1.8 mm, colored as the dorsal sepal. Lip oblong, 6.8 × 4.1 mm, sides bent downwards, papillose, apex obtuse, apiculate, bent upwards, with a small swollen callus underneath, pubescent at the margins, the base truncate with a small elliptical glenion with an elevated center, the quadrangular disc convex, minutely pubescent, lemon- coloured above, milk-white color at the base suffused with leather-yellow in xanthic form, lemon-coloured suffused with a sanguine color above, milk-white color at the base, suffused with leather-yellow in the middle and suffused with sanguine color below in non xanthic form. Column stout, 2.5 mm long, 2.3 mm wide, foot thick, rostellum and bilobed stigma apical. Pollinia 2, yellow.

Eponymy: Honoring Quitu-Cara, the indigenous group which originally inhabited Quito and the valley near Quito, where the known population of the new species persists.

Distribution and habitat: Pleurothallis quitu-cara has been found only at one locality in the Hoya de Guayllabamba, valley of Los Chillos, on the canyon of the River Pita (Figure 4). A population of approximately 50 plants of Pleurothallis quitu-cara grows at the type locality. Two color forms, a xanthic and a non- xanthic form, coexist (Figure 2B). It is not clear if the species is always represented by this two colour forms, or other phenotypes could be found somewhere else. Nevertheless, no other populations of the species are known by the authors at the moment, which does not necessarily mean P. quitu-cara is restricted to this single population. More exploration is needed to confirm if this original population is the only one known for the species. This finding confirms that, even so close to Quito, the capital of a well explored country, when it comes to orchids, a new species of orchid can still be found anywhere.

Conservation status and extinction risk: The type locality of Pleurothallis quitu-cara is located in one of the most populated valleys of the northern Andes, Los Chillos. Habitat destruction in Los Chillos is extensive, mostly produced by expansion of the agricultural frontier focused on monocultures, especially for the floral industry, and expansion of the urban frontier. The few remnants of natural ecosystems in Los Chillos are found in ravines, gorges and protective forests, although most of them are in precarious state of conservation. Unfortunately, the area is not under any type of formal protection. Exploration of additional surrounding canyons and surrounding areas is needed to confirm how restricted is the distribution of this new species. Urgent conservation actions are needed in order to preserve the known population of P. quitu-cara and other species that are restricted to the particular ecosystem. We are unaware of the presence of this new species in ex situ situations. However, it is important to remember that in situ conservation actions should lead the way to preserve biodiversity, while ex situ management by itself is only complementary and alone has little conservation impacts (^{Wilson et al. 2016}).

Figure 2 Photos of Pleurothallis quitu-cara. A, leaf with a inflorescence with succesive flowers; 1 = callus at the abaxial surface of the lip; 2 = apex of the lip bented upwards. B, two color forms, non xanthic form at the left and xanthic form at the right. C, petals notably crossed below the lip (Photos: Kilian Zuchan, Luis Baquero). 

Discussion

In its general shape of the flower, P. quitu-cara reminds some other species and species- complex of Pleurothallis; P. corysta, P. adonis Luer, P. linguifera Lindl., P. grandiflora Lindl., P. jupiter Luer and P. sarcochila Garay (Table 1). It is most similar to P. corysta but, the size of the flowers, the pubescent, slim petals and the shape of the lip are totally different among the two species (Figure 3). Two distinctive traits are present in P. quitu-cara lip; an elevated, microscopically pubescent, and quadrangular disc, and a small, protruding callus at the upward bent apex of the lip. Considering that the final portion of the lip bents upwards, the protrusion in the apex of the lip is most conspicuous and might have something to do with pollinator attraction. Pleurothallis corysta, on the other hand, has a similar growing habit to the new species and a swollen apex of the central vein at the apex of the lip, also similar to P. quitu-cara although the shape of the petals, the glabrous flowers and the absence of an obvious glenion separates it from P. quitu-cara (Figure 1, 2A, 3).

Figure 3 Comparison between Pleurothallis corysta Luer and Pleurothallis quitu-cara. A, P. corysta (left) and P. quitu-cara (right). B-C, P. corysta in situ (habit and flower). Photo by Martín Carrera (A) and Luis E. Baquero (B-C). 

Figure 4 Collection location of Pleurothallis quitu-cara (red star) in the gorge of “Río Pita” in “Valle de los Chillos” near Quito (Map: Emilia Peñaherrera).