﻿Monopyleglutinosa (Gesneriaceae), a new species from the western slopes of the Ecuadorian Andes

﻿Abstract Exploratory field expeditions to the western slopes of the Ecuadorian Andes resulted in the discovery of a new species of Monopyle (Gesneriaceae). Monopyleglutinosa J.L.Clark & Keene, sp. nov. is described as a narrow endemic from lowland forests along the border of the Reserva Ecológica Los Illinizas in the Province of Cotopaxi. The new species is unique for the presence of glutinous or sticky trichomes on the calyx lobes and outer surface of the inferior ovary. Based on IUCN guidelines, a preliminary conservation status is assigned as Critically Endangered (CR).


Introduction
The flowering plant family Gesneriaceae is in the order Lamiales and comprises 3400+ species in 150+ genera (Weber 2004;Weber et al. 2013). The family is divided into three strongly-supported monophyletic subfamilies (Ogutcen et al. 2021) and seven tribes (Weber et al. 2013(Weber et al. , 2020. The majority of New World members are in the subfamily Gesnerioideae and are represented by 1200+ species and 77 genera . Monopyle Moritz ex Benth. & Hook.f. is classified in the tribe Gesnerieae and subtribe Gloxiniinae (Weber et al. 2013(Weber et al. , 2020. Monopyle is a genus of terrestrial understory or epiphytic herbs distributed from Guatemala to northern South America. There are 11 described species of Monopyle in Ecuador (Keene 2013). The genus currently comprises 22 recognized species ). The addition of Monopyle glutinosa brings the total species diversity to 23. The actual number of species is probably double what is currently recognized, based on preliminary estimates from ongoing monographic work by Keene (2013). Additionally, recent exploratory expeditions have yielded numerous new or undescribed species poorly represented in herbaria. Here, we describe a new species that was collected in 2022 during a research expedition to the western Andean foothills.
Monopyle is morphologically complex and has had little attention since Morton's monographic revision (Morton 1945). The genus is traditionally characterized by strongly anisophyllous opposite leaves, campanulate corollas, and the presence of uncinate trichomes (Keene 2013). Additional diagnostic characters that define Monopyle include variably swollen internodes, a nodal ridge, and the presence of an osmophore (floral fragrance gland) at the base of the corolla. Many Monopyle species are presumably local endemics and appear to be restricted to a specific watershed. Narrow distributions are likely the result of the minute seeds limited by a splash-cup seed dispersal mechanism.

Materials and methods
Plants were vouchered and photographed during a 2022 field expedition to Ecuador (Clark 2022). Specimens were deposited at the Pontificia Universidad Católica del Ecuador (QCA), Marie Selby Botanical Gardens (SEL), United States National Herbarium (US), New York Botanical Garden (NY), and Missouri Botanical Garden (MO). Digital images were taken of live specimens in the field using a Nikon D100 DSLR with a Nikon 105 mm lens and a Nikon SB-29s ring flash. Morphological observations and measurements were made from live collections, alcohol-preserved material, and digital images using the program ImageJ (https://imagej.nih.gov/ij/).
We assessed the extinction risk of Monopyle glutinosa following the IUCN Red List Categories and Criteria (2022) and guidelines of the IUCN Standards and Petitions Committee (2022). We considered observations, collection localities and population estimates from fieldwork. Species extent of occurrence (EOO) and area of occupancy (AOO) were calculated using GeoCAT (Bachman et al. 2011; http://geocat.kew.org/) with the default setting of 2 km 2 grid. Diagnosis. Similar to Monopyle ecuadorensis, differing in larger calyx lobes that reach 1.5 cm in length (vs. 0.5-1.0 cm long in M. ecuadorensis), larger campanulate corolla tube that exceeds 3.0 cm in length (vs. corolla tube less than 3 cm in M. ecuadorensis), and a uniformly dark purple corolla tube (vs. broad range of corolla tube colors from uniformly white to white suffused with blue in M. ecuadorensis).
Phenology. Flowering in March. Fruits not observed. Etymology. The trichomes on the calyx lobes and inferior ovary allow the flower to cling to an upside-down finger (Fig. 1C). This specific epithet reflects the sticky trichomes on the outer surface of the inferior ovary and calyx lobes.

Distribution and preliminary assessment of conservation status.
Monopyle glutinosa is endemic to the western Andean slopes of Ecuador. The three known collections are located in the buffer zone and the southern region of Reserva Ecológica Los Illinizas, from disturbed primary forests. GeoCAT calculated the following values for EOO = 46.31 km 2 and AOO = 12 km 2 . Based on the available information and according to the IUCN Red List Criteria and Guidelines (IUCN 2022; IUCN Standards and Petitions Committee 2022), M. glutinosa is preliminarily assessed as Critically Endangered (CR, B1a,biii), based on its limited geographic range (EOO < 100 km 2 ) and the uncertain future of habitat conservation of western Andean forests as exemplified by the deforestation for agriculture throughout the buffer zone and inside the park.
Comments. Monopyle glutinosa differs from all other Monopyle by the presence of sticky glandular trichomes intermixed with similarly-sized uncinate trichomes on the outer surface of the inferior ovary and calyx lobes. Monopyle glutinosa and M. ecuadorensis share a similar terrestrial dorsiventral habit with a terminal inflorescence, swollen regions along the stem between nodes (Fig. 2C), and similar shapes of calyx and corolla. The inflorescence on M. glutinosa has shorter peduncles and appears more compact (< 10 cm). The inflorescence on M. ecuadorensis has more inflorescence branching and appears broader from longer peduncles, often exceeding 10 cm in length and width (Fig. 2D). The campanulate flowers and broadly ovate calyx lobes are similar to M. ecuadorensis. The campanulate corolla tube in M. glutinosa exceeds 3 cm (Fig. 1A), in contrast to the smaller corolla tube in M. ecuadorensis that rarely exceeds 3 cm in length ( Fig. 2A) and 1 cm in width (Fig. 2B). The broadly ovate calyx lobes with acuminate, reflexed apices are longer (ca. 1.5 cm long) in M. glutinosa (Fig. 1B) relative to the shorter (ca. 0.5-1.0 cm long) calyx lobes in M. ecuadorensis (Fig. 2B). Corolla tube coloration ranges in M. ecuadorensis from uniformly white to white suffused with blue ( Fig. 2A). In contrast, the corolla tube of M. glutinosa is uniformly dark purple (Fig. 1A). Monopyle ecuadorensis is distributed throughout western Ecuador (usually above 1200 meters). In contrast, M. glutinosa is locally endemic and restricted to altitudes below 1200 meters.