A new species of Symplocos (Symplocaceae) from southern Ecuador

Abstract A new species from Ecuador, Symplocos limonensis, is here described and illustrated. It resembles Symplocos clethrifolia but differs by having larger leaves with evident (i.e., not concealed) areoles on lower surface, sessile inflorescences, smaller white corollas, and fewer stamens. The species is only known from three collections in the Andean forests of Morona-Santiago Province in southern Ecuador.


Introduction
Th e genus Symplocos Jacq. is represented in Ecuador by ca. 33 species (Ståhl 2010a), the majority of which occur in Andean forests at 2500-3500 m elevation (Ståhl 1995). Th irteen of the species are country endemics (Barriga 2011) and have been described in the last 25 years, signifi cantly increasing the knowledge of this still poorly known genus. In his treatment of the Symplocaceae for the Flora of Ecuador series, Ståhl (1991) described several new species of Symplocos, especially from southern Ecuador. One of these, S. clethrifolia Ståhl, was based on fi ve collections, one of which (Ulloa 487) was indicated to deviate from the remaining four in fl oral and leaf features. Th is collection was provisionally treated under S. clethrifolia until more material could help elucidate its taxonomic status.

Materials and methods
Recent examination of the Symplocos collections in Ecuadorian herbaria revealed additional gatherings from the same general area that have led us to conclude that the Ulloa collection, along with some new ones, belong to a previously undescribed species, which is described here. Acronyms of the herbaria follow Th iers (2015).
Speciemens Etymology. Th e name of the species refers to the town of Limón, offi cially known as General Leonidas Plaza Gutiérrez. Th e road leading from the Andean town of Gualaceo to Limón, situated at 1400 m altitude on the east Andean slopes, has long been considered an important locality for botanical exploration where many new species have been found.
Distribution and conservation status. Th e species is known solely from three collections made in disturbed upper Andean forests and scrub páramo on the highest point of the Gualaceo-Limón-Macas road in Morona-Santiago Province of southern Ecuador. Th e area of occupancy (AOO) of the species is less than 20 km 2 and falls within the "Área de Conservación Municipal Tinajillas-Río Gualaceño," a locally managed reserve; however, the category of protection is of lesser status than that of a National Park. Since 2000, we have searched for additional plants but could not locate any, fi nding only one population of Symplocos quitensis Brand (1901: 76), a very different species with a wide Andean distribution. Th e road was poorly maintained and treacherous until recently, but has now been considerably widened in the process of being paved, and consequently the natural vegetation alongside is heavily destroyed. Ongoing wood extraction for charcoal production, expansion of areas under cultivation, and mining activities for clay, gravel, and metals are threats to the natural habitats in this region. Given current knowledge, we assign a provisional IUCN conservation status of Endangered (IUCN 2014) to this species.
Discussion. Symplocos limonensis resembles S. clethrifolia Ståhl and S. golondrinae Ståhl by having leaves with conspicuous venation, the veins of the lower side being prominent and verrucose and those on the upper side impressed. It diff ers from S. clethrifolia, which also is restricted to southern Ecuador (but from other localities), by having larger leaves (up to 13.5 vs. 9.5 cm) with evident (i.e., not concealed) venation areoles abaxially (vs. densely ferrugineous-velutinous with matted hairs concealing areoles), sessile infl orescences (vs. pedunculate), smaller (5-6 vs. c. 8 mm long), white (vs. red to pink) corollas, and fewer stamens (40-50 vs. 60-70). From S. golondrinae it diff ers by the larger size of leaves and fl owers, with the leaves being coriaceous (vs. cartilaginous), long-villous abaxially (vs. sparsely strigose) and having longer (1-1.5 vs. < 1 cm) petioles, and by having a densely villous fl ower disk (vs. glabrous). Moreover, S. golondrinae occurs in northwestern Ecuador, on the opposite side of the Andes.
Symplocos quitensis has been collected in the same area of the new species, but it is readily distinguished from both S. limonensis and S. clethrifolia by the densely hispid branchlets, smaller (up to 6.5 × 4 cm), membranaceous leaves, and pinkish fl owers borne in short racemes.
In the most recent key to Andean Symplocos (Ståhl 2010a), S. limonensis keys to S. clethrifolia (albeit with the infl orescence pedunculate) or to S. robusta Ståhl. Th e latter species is known only from Bolivia and diff ers from S. limonensis in, e.g., its larger (to 14.5 × 8.5 cm), longer-petiolate (to 2 cm) leaves, more numerous fl owers (up to 20) per infl orescence, and strigose corollas (vs. glabrous).
Symplocos limonensis has fl owers with 5 to 7 petals, but being notoriously instable in many species of Symplocos, and often not studied, the number of petals may show to be of little taxonomic signifi cance.
In the key to infrageneric taxa of the genus (Fritsch et al. 2008), Symplocos limonensis falls into the tropical American clade Symplocos subg. Symplocos sect. Symplocos having exerted, monodelphous stamens adnate to the corolla beyond its base, and the fi laments fl attened and constricted apically.