A new species of Epidendrum L. (Orchidaceae) of pendulous habit from Peru

Abstract A new species of Epidendrum L. from northern Peru is described, illustrated, and compared with related species. This new species belongs to the Laxicaule Group and shares morphological characteristics with Epidendrumlaxicaule D.E. Benn & Christenson but differs in the shape and length of the dorsal sepal; the shape of the petals and the lip, ribs position of the lip, shape of the vesicle formed between the ovary and the column as well as the section of the stem.


Introduction
The genus Epidendrum Linnaeus (1763: 1347) are terrestrial, epiphytic and lithophytic plants that occur in different types of vegetation ranging from tropical forests, coastal dunes and scrubs to Andean paramos (Hágsater and Soto 2005;Chase et al. 2015). The genus ranks as one of the most diverse among Neotropical orchids, with around 2400 species (Hágsater et al. 2016), 1500 of them being recently treated and illustrated in the Icones Orchidacearum series (Hágsater and Salazar 1993;Hágsater et al. 1999;Hágsater and Sánchez 2001, 2004, 2006, 2007, 2008, 2009, 2010, 2013, 2015a, 2015bHágsater and Santiago 2018a, 2018b, 2020a, 2020b, 2021. Though there have been many attempts to separate Epidendrum into various genera (Hágsater 1985;Hágsater and Soto 2005), it has been argued that it is best left as a single large genus reflecting its monophyly, as revealed by molecular studies (Hágsater and Soto 2005;Granados et al. 2020). Groups of species within Epidendrum can be cohesively aggregated based on vegetative and floral characteristics, which are also supported by molecular information. As this work is in progress, no formal sub-generic classification has been proposed to date, based on the informal groups recognized in current taxonomic practice (Hágsater 1985;Hágsater and Huayta 2018). This is the case of the Laxicaule group, endemic to Peru, which is characterized by the pendulous, monopodial habit, with sub-apical branching, the laterally compressed to ancipitous stems, the relatively short leaves, the short racemose, few-flowered inflorescences, the large flowers and the lip with prominent ribs (Hágsater and Huayta 2018). Presently, there are only two species in the group: Epidendrum laxicaule D.E. Benn & Christenson and E. megalopentadactylum Hágsater & Huayta (Hágsater and Huayta 2018) found in central Peru. Here we are describing, illustrating and representing with photographs a new species of Epidendrum, E. lufinorum Ocupa & Hágsater, as well as photographs of the related species and two undescribed species. A table is provided with the characteristics that distinguish the three species of the Laxicaule Group for which information is available.

Material and methods
A living plant in flower of the new species was collected in March 2016 during a botanical expedition to Cerro Parcos in the department of Cajamarca, northeastern Peru. The photographs were taken in situ using a Canon Rebel T3 camera equipped with a Canon EF-S 18-55mm f/3.5-5.6 lens and were later used for preparing the line drawing and figures. Fresh flowers were preserved in 70% ethanol and 1% glycerol. The single collected plant was dried to make a herbarium specimen, which was afterwards deposited in the Herbarium Truxillense (HUT, acronym following Thiers 2021, updated continuously), Trujillo, Peru.
In order to determine the taxonomic status of the collected specimen, we examined all relevant Epidendrum material from USM and MOL (acronym following Thiers 2021, updated continuously), because both herbaria have a large collection of Epidendrum species. The original descriptions from holotypes of related species (Bennett and Christenson 1998;Hágsater and Santiago 2018a) were consulted and compared. Additionally, some online resources including the scans of relevant type specimens were accessed such as the JSTOR Global Plants web portal (https://plants.jstor.org). A distribution map of the proposed new species and related species, was prepared using the software QGIS 3.10 (QGIS Development Team 2020). The holotype specimen was collected under the research permit for the project "Estudios Taxonómicos Selectos de la Flora del Norte del Perú" with Resolution N° 247 -2016 -SERFOR/DGGSPFFS and the extension Resol. 430-2017. 3.2 × 0.6 cm) which is oblong-oblanceolate (vs. narrowly oblanceolate), with an obtuse apex (vs. acute), the linear and obtuse petals (vs. narrowly linear-lanceolate and acuminate), lip transversely cordate (vs. transverse), disc with 5 parallel and central ribs (vs. 5 parallel ribs projecting distally), a gibbous vesicle (vs. globose) and the stem section terete (vs. elliptic).
Distribution, habitat and comments on the conservation of the species. This species is currently known only from the type locality in the northern zone of Peru, near the base of the hill known locally as Cerro Parcos, in the village of Villa Rica, San José de Lourdes district (Fig. 3). The habitat of Epidendrum lufinorum is within an area with high agricultural activity such as the cultivation of Coffea arabica L. (Rubiaceae Juss.). No more individuals of this species were found in the surrounding areas, but a fertile individual (holotype) and some other small specimens growing as epiphytes on the trunks of C. arabica plants, occasionally sharing the same phorophyte with other orchid species such as Gongora aromatica Rchb.f., Masdevallia glandulosa Königer, Stenia calceolaris (Garay) Dodson & D.E.Benn. and Telipogon astroglossus Rchb.f., which would support the hypothesis of a possible adaptation of this species to anthropized environments. However, its habitat continues to be fragmented as a consequence of tree felling, the expansion of agricultural crops and practices such as pruning and clearing coffee trees of epiphytic plants. The latter is a very common practice among the local population, as a way to maintain optimal conditions for the efficient production of coffee beans, however, it threatens the presence of the few individuals of E. lufinorum that may be growing.
Most of the coffee crops were located near secondary forest patches with some individuals of trees as Cedrela odorata L., Delostoma integrifolium D.Don, Erythrina edulis Triana ex Micheli and Vochysia vismiifolia Spruce ex Warm.
Phenology. Epidendrum lufinorum was observed flowering in April, at the end of the rainy season in that region.
Notes on Laxicaule Group. The combination of a monopodial pendulous habit, linear leaves, an apical inflorescence with few flowers, and a lip with a prominent ribbed disc places the new species in the informal Laxicaule Group.
There are two species in the group, both presently known from Peru: Epidendrum laxicaule and E. megalopentadactylum (Hágsater and Huayta 2018) reported in Junin and Pasco, respectively (Fig. 4A, B).  Among the two species belonging to the Laxicaule group, Epidendrum lufinorum is most similar to E. laxicaule, from which it differs in the shape and length of the dorsal sepal; the shape of the petals and the lip, disc ribs position of the lip; shape of the vesicle formed between the ovary and the column as well as the section of the stem. E. lufinorum is easily distinguished from the other species of the Laxicaule group by the characteristics indicated in the Table 1. It is worth mentioning that the type specimen of E. lufinorum we collected is a plant consisting of a flowering primary stem, with a new secondary branch clearly visible in its early stage of development (Fig. 2B).
In May 2015, a specimen of another species, Epidendrum aff. laxicaule sp. nov., was found growing as an epiphyte in a montane forest in the western part of Amazonas department in northern Peru, in the Cajaruro district of Utcubamba province, at an elevation of 1685 m. It was observed and validated with photographs ( Fig. 5A, B, C) by Luis Pillaca and shows vegetative and morphological characteristics similar to those of E. laxicaule and E. lufinorum. However, it has flat and thick, narrow leaves, a much more prominent vesicle at the apex of the ovary and the narrower lip with three parallel and central ribs. Pillaca indicates that the area where the specimen was found has been destroyed due to agricultural encroachment.
A year later, in the same department, but in the province of Bagua, district of Aramango, a specimen of an additional species, Epidendrum aff. megalopentadactylum sp. nov., was found as part of the private collection of Ricardo Saens Saavedra †. This specimen observed and photographed (Fig. 5 D, E) by Luis Ocupa, presents morphological characteristics similar to E. megalopentadactylum, such as pendulous plants with flat leaves, conduplicate at the base, strongly laterally compressed and ancipitous stems and an entire lip, but is distinguished by the presence of a vesicle and the lip without ribs.