Introduction

With more than 1,100 species, Lepanthes Sw. is one of the Noetropical genera in the Orchidaceae with most accepted species together with Stelis Sw. (^{Karremans 2016}). New species are being discovered frequently (^{Jørgensen & Leon-Yanez 1999}, Karremans 2016, ^{Moreno et al. 2017}, ^{Pupulin & Bogarin 2012}). Some species in the genus show a wide distribution range while others are endemic to restricted localities (^{Baquero 2018}, Moreno et al. 2017). Species of Lepanthes are recognized by the ramicauls enclosed by commonly ciliated lepanthiform sheaths, the petals transversely bilobed or trilobed, and a complex lip that has a body which connects to a pair of blades which frequently cover the column (^{Luer 1996}). At the base of the lip a small structure, present in most of the species in the genus, is called the appendix (Luer 1996). The shape, size, and position of the appendix has been traditionally used as a morphological trait which helps to distinguish among different species in the genus, and its importance in Lepanthes pollination has been confirmed by ^{Blanco and Barboza (2005}). Nevertheless, other characteristics, like the number of lobes in the petals and the shape of the lip, can also help to distinguish among species in Lepanthes.

Based on the number of petals and lip’s lobes, some species of Lepanthes have received suggestive names, like Lepanthes pentoxys Luer, Lepanthes hexapus Luer & Escobar, Lepanthes heptapus Luer & Escobar and Lepanthes octopus Luer & Escobar with five, six, seven and eight filaments and lobes respectively (^{Dodson 2004}, ^{Luer & Thoerle 2012}, Luer 1996).

A rich species area of Lepanthes is located in Carchi province, Ecuador, very close to the limit with Imbabura and Esmeraldas provinces. In this region, a new species has been discovered. It is described and compared here with an informal group of species within the genus, that shares similar morphological characteristics, both in the plants and flowers (^{Luer 1996}).

Lepanthes tetrapus Baquero & J.S.Moreno, sp. nov.

(Figure 1-4).

TYPE: Ecuador. Carchi: north-west of Lita, 0°55’ 24.42.0”N 78°30’12.28”W, 754 m, 08.03.2017, L. Baquero et al. LB 3112 (holotype, QCNE).

Diagnosis: Lepanthes tetrapus is vegetatively and floraly similar to L. hexapus, from which it differs by the petals with two curved, filiform lobes instead of three.

Figure 1 Lepanthes tetrapus Baquero & J.S.Moreno. A. Plant and Habit. B. Flower view in – position. C. Flower dissected. D. Column and lip detail. E. Lip detail. F. Pollinarium. Line-draw by Juan Sebastián Moreno. 

Figure 2 Lepanthes tetrapus Baquero & J.S.Moreno. A. Plant with flower in situ. B. Frontal view of the flower and comparison with biohazard international symbol. C. Close-up of the Lip and petals. D. Lateral view of the flower. Photos by Luis E. Baquero. 

Epiphytic, caespitose, erect to suberect herb. Roots flexuous, to 0.5 mm in diameter. Ramicauls erect, 4.0-9.0 mm long, enclosed by 3-5 minutely ciliate, keeled, lepanthiform sheaths, the ostia minutely ciliate, ovate, acuminate and slightly dilated. Leaves erect, coriaceous, elliptic-ovate, subacute, light green, prominently reticulated along the veins, veined in purple, 1.0-3.0 × 0.6-1.0 cm, the base cuneate into a petiole 1 mm long. Inflorescence a congested, distichous, glabrous, successively flowered raceme, developed above the leaf, shorter or as long as the leaves, up to 1.8 cm long; peduncle terete, 0.6 cm long. Floral bracts acute, 0.8 mm long. Pedicels 1.5 mm long, persistent. Ovary to 1 mm long, glabrous. Sepals yellowish green suffused with brown-red towards the center, spiculate at the abaxial side of the veins. Dorsal sepal free, obovate, obtuse, acuminate, slightly concave, 3-veined, 3.0-3.3 × 1.5-1.7 mm, the margins minutely denticulate. Lateral sepals obovate, acuminate, slightly concave, 2-veined, 3.0-3.3 × 1.5-1.6 mm, connate for 0.5 mm. Petals yellow, darker towards the apex, transversely bilobed, filiform, 2.5 × 0.5 mm, the lobes equal in size and shape, falcate- oblong with the apex rounded, minutely pubescent, ciliate along the margins. Lip purple, orange towards the margin, bilaminate, the blades narrowly ovate to elliptic-oblong, the apex long pubescent, curved towards the column, 2.5-2.7 mm long, ciliate along the margins; the connectives cuneate, oblong, the body thick, densely pubescent, rounded, connate to the middle of the column; the appendix conspicuous, thick, pubescent, ovoid, bilobulate at the apex. Column cylindric, to 1.5 mm long, the anther and the stigma apical. Pollinia two, ovoid, basally filiform. Anther cap, magenta, obovate.

Figure 3 Comparison of Lepanthes tetrapus Baquero & J.S.Moreno and two similar species. A. Lepanthes tetrapus Baquero & J.S.Moreno. B. Lepanthes hexapus Luer & Escobar. C. Lepanthes aguirrei Luer. Photos by Luis E. Baquero (A-B) and Sebastián Vieira-Uribe (C). 

Etymology: From Greek “four-footed” due to the four filiform lobes of the petals.

Lepanthes tetrapus is very similar in habit and flowers to L. hexapus and L. aguirrei Luer (Figure 3). Both species, L. hexapus and L. aguirrei, have erect leaves with purple reticulations, the inflorescence shorter than the leaf, flowers with essentially free sepals and trifurcate petals, and plants which are small for the genus. Nevertheless, the two species differ in the size of the plants (taller in L. aguirrei, with ramicauls reaching 4.5 cm vs. 2 cm long in L. hexapus) and the apex of the sepals, which is stoutly caudate in L. aguirrei and acute in L. hexapus. Lepanthes tetrapus is similar to both species, sharing all the characteristics mentioned above except for the two filiform lobes of each petal instead of three. Due to the characteristic shape of the petal lobes and the apex of the lip, this species has been known so far as the “biohazard” Lepanthes, due to the remarkable similarity with the international alert symbol (Figure 2). This similarity might visually help to immediately distinguish L. tetrapus from any other species in the genus.

Distribution and ecology: This species is known from a low elevation cloud-forest close to Lita, where it is fairly common. Another locality is known for the species in the province of Esmeraldas. It is found growing with several other species of Lepanthes including L. filamentosa Luer & Hirtz, L. saltatrix Luer & Hirtz, L. tentaculata Luer & Hirtz, L. scrotifera Luer & Hirtz and L. bibarbullata Luer. Lepanthes tetrapus grows significantly lower in elevation than L. hexapus and has not been observed at elevations higher than 800 m (Figure 4).

A specific locality for Lepanthes bibarbullata Luer. This species was originally described without a known locality from a specimen obtained from J&L Orchids (Luer 2002). It is here recorded for the first time with a known locality.

Lepanthes bibarbullata^{Luer, Monogr. Syst. Bot. Missouri Bot. Gard. 88: 87, f. 310. 2002}.

TYPE: Ecuador. Without locality: cultivated by J&L Orchids 799-593, Easton, CT, Nov 2000, C. Luer 19440 (holotype, MO).

Specimen studied: Ecuador. Carchi: north-west of Lita, 0°55’24.42.0”N 78°30’12.28”W, 754 m, 08.03.2017, L. Baquero et al. LB 3113 (QCNE) (Figure 4A).

Figure 4 Lepanthes bibarbullata Luer and some sympatric species in the genus. A. Lepanthes bibarbullata Luer. B. Lepanthes tetrapus Baquero & J.S.Moreno. C. Lepanthes saltatrix Luer & Hirtz. D. Lepanthes tentaculata Luer & Hirtz. E. Lepanthes filamentosa Luer & Hirtz. Photos by Luis E. Baquero.