Recent field research on the eastern slopes of the Andes resulted in the discovery of a new species of Bomarea from the Cerro Candelaria Reserve in the Tungurahua province of Ecuador. Bomarea pastazensis is the second smallest species in the genus and differs from the smallest by the presence of glutinous trichomes on the ovary, glabrous sepals, and greenish-yellow petals with purple spots. Based on IUCN guidelines, a preliminary conservation status is assigned as Vulnerable (VU).

Recientes investigaciones de campo en las estribaciones orientales de los Andes dieron como resultado el descubrimiento de una nueva especie de Bomarea en la Reserva Cerro Candelaria en la provincia de Tungurahua en Ecuador. Bomarea pastazensis es la segunda especie más pequeña del género y se diferencia por la presencia de tricomas glutinosos en el ovario, sépalos glabros y pétalos verdes con amarillo y manchas moradas. Con base en los lineamientos de la IUCN, se le asigna un estado preliminar de conservación de Vulnerable (VU).

Alstroemeriaceae, Andes, Bomarea, Ecuador, endemism, taxonomy

There are more than 100 species of Bomarea Mirb. in South America (Hofreiter 2006) and 39 species in Ecuador (Harling and Neuendorf 2003). The description of Bomarea pastazensis brings the total diversity to 40 species in Ecuador. The most recent monograph of Bomarea was provided by Hofreiter and Tillich (2002) and included an updated classification system based on Baker (1888) that recognized the following four subgenera: Baccata Hofr., Bomarea Baker, Sphaerine (Herb.) Baker, and Wichuraea (M. Roemer) Baker. More recently, molecular phylogenetic studies have failed to support the monophyly of these subgenera (Alzate et al. 2008b; Tribble et al. 2022), suggesting that many of the morphological characters that previously defined infrageneric classification are homoplastic or have evolved convergently. Alzate et al. (2008b) showed that traditionally recognized subgeneric ranks proposed by Baker (1888) and Hofreiter and Tillich (2002) are polyphyletic. Tribble et al. (2022) described three main clades within Bomarea, but no updated classification system has yet been proposed. In the present study we recognize the lack of strongly supported subgeneric ranks (Alzate et al. 2008b; Tribble et al. 2022) and discuss the traditional subgenus that most resembles Bomarea pastazensis.

Bomarea pastazensis most closely resembles the morphologies associated with the subgenus Sphaerine because of the following characters (Hofreiter 2005): erect or hanging habit [mostly non-twining except for B. coccinea (Ruiz & Pav.) Baker] (Fig. 1E), resupinate leaves (Figs 1D, 2E), and inferior ovaries (Figs 1A–C, 2A). Recent molecular work suggests that Sphaerine is non-monophyletic and some morphological characteristics of this group are likely adaptations to environmental conditions (Alzate et al. 2008b; Tribble et al. 2022). The subgenus Sphaerine ranges from the northern Andes of Colombia and Venezuela to Bolivia. In Ecuador, the subgenus is distributed mainly on the eastern Andean slopes. A detailed taxonomic history and overview of Sphaerine was provided by Hofreiter (2006), including updated circumscriptions and two new species. The addition of Bomarea pastazensis brings the total diversity of subgenus Sphaerine to 13 species.

Figure 1. 

Some species of Ecuadorian Bomarea subgenus Sphaerine A Bomarea brachysepala B Bomarea distichifolia C Bomarea hieronymi D resupinate leaf (rotated petiole indicated with white arrow) of Bomarea hieronymi E terrestrial habit (non-twining) of Bomarea hieronymi. Photos A, B by N. Exe, C–E by J.L. Clark (J.L. Clark 17350).

Figure 2. 

Bomarea pastazensis A lateral view of flower B front view of flower featuring mature androecium C mature gynoecium D petal E adaxial leaf surface F mature flowers with foliage G habitat H tuberous roots. Photos A by J.L. Clark (J.L. Clark 14839), B–H by N. Exe (N. Exe et al. 2).

Ecuador is the center of diversity for Bomarea (Hofreiter and Tillich 2002; Harling and Neuendorf 2003; Hofreiter 2005; Hofreiter and Rodríguez 2006; Alzate et al. 2008a), which is supported by the presence of 40 of the 120+ currently known species. The other species of Bomarea subgenus Sphaerine occurring in Ecuador (Hofreiter 2005; Hofreiter and Rodríguez 2006) are: B. brachysepala Benth. (Fig. 1A), B. distichifolia (Ruiz & Pav.) Baker (Fig. 1B), B. hieronymi Pax (Fig. 1), B. linifolia (Kunth) Baker, and B. nervosa (Herb.) Baker.

The Cerro Candelaria Reserve, owned by the Ecuadorian NGO Fundación EcoMinga, is within the upper Pastaza watershed, an area recently documented for high-levels of local endemism because of the presence of microclimates created by Amazon-Andean airflow currents and the irregular topography (Jost 2004). The Cerro Candelaria Reserve comprises 2800+ hectares, ranging in altitude from 1700 to 3860 m (Reyes-Puig et al. 2013). The private reserve is located within the Llanganates-Sangay corridor, which facilitates a protected corridor for biodiversity between the Llanganates and Sangay National Parks (Fig. 3).

Figure 3. 

Distribution map of Bomarea pastazensis. Red dots indicate collections or observations.

Plants were photographed and collected during three separate field expeditions to the Cerro Candelaria Reserve by Clark in 2016 (Clark 2016), Exe and Johnson in January 2022, and Exe, Johnson, and Fierro-Minda in November 2022. Specimens were deposited at Pontificia Universidad Católica del Ecuador (QCA), Marie Selby Botanical Gardens (SEL), and Universidad de Guayaquil (GUAY). Digital images were taken of live specimens in the field using an Olympus TG5 and 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, herbarium specimens, and digital images using the program ImageJ (Schneider et al. 2012).

We assessed the extinction risk of Bomarea pastazensis following the IUCN Red List Categories and Criteria (IUCN 2012) and guidelines of the IUCN Standards and Petitions Committee (2022). We considered observations, collection localities, and population estimate from fieldwork. Species extent of occurrence (EOO) and area of occupancy (AOO) were calculated using GeoCAT (Bachman et al. 2011) with the default setting of 2 km² grid.

Some botanical terminology has been used inconsistently in previous descriptions of Bomarea, and other terminology is specific to Bomarea. Here, we clarify our use of potentially confusing terms to ensure that our definitions are unambiguous while linking the description to other literature. Botanical glossaries usually refer to sepals as the outer whorl of the perianth and petals as the inner whorl of the perianth (e.g., Harris and Harris 2006; Pell and Angell 2016). In contrast, ‘tepal’ is used when describing cases where the outer and inner perianth whorls are identical or when perianth whorls are not readily differentiated. Some Bomarea taxonomists use the terms inner and outer tepals in their descriptions of the perianth (Hofreiter 2005; 2006; Hofreiter and Rodríguez 2006) and others use the terms sepals and petals (Harling and Neuendorf 2003). The description of Bomarea pastazensis uses sepals and petals to provide greater specificity because the two perianth layers are easily differentiated. Furthermore, we use the terms adaxial and abaxial following the definition of these terms to refer to the portion of the leaf facing towards or away from, respectively, the structure-bearing organ (the stem) during development (Eckel 2011). When referring to the surface of resupinate leaves (rotating 180 degrees) of Bomarea pastazensis, abaxial is the upper surface of the leaf, and adaxial is the lower surface of the leaf, terminology that is consistent with other Bomarea descriptions (Hofreiter and Lyshede 2006). Following Hofreiter (2005), we use the term “claw” to refer to the horn-like thickened sepal apex in many Bomarea species.

We thank the Ministry of the Environment of Ecuador for providing permits for specimen collection and transportation (Research permit Aves y Conservación N° 007-2018-IC-FLO-FAU and mobilization permit Aves y Conservación 005-FLO-2019-DPAP-MA). We thank Lucely L. Vilca Bustameante (Instituto Nacional de Investigación en Glaciares y Ecosistemas de Montaña, Cusco, Peru) for sharing her field images of Bomarea pumila (Fig. 5). We are grateful to Guillermo Peña for assisting with the expedition and collection of specimens, as well as providing supplemental locality information. We thank the Science Collections Digitisation Project at the Royal Botanic Gardens, Kew for facilitating an image of the syntype for Bomarea pumila (Fig. 5). We are grateful to Alan W. Meerow and an anonymous reviewer for providing helpful feedback on an earlier version of the manuscript.