A new species of Saracha (Solanaceae) from the Central Andes of Peru

Abstract Saracha andina Rob. Fernandez, I. Revilla & E. Pariente, sp. nov. (Solanaceae), a new species endemic to the central Andes of Peru, is described here. The new species differs from other species of Saracha Ruiz & Pav. by the combination of small and coriaceous leaves and clearly tubular flowers. A summary of the taxonomic history of the genus Saracha, an identification key for its species and a phylogenetic analysis of this genus and related genera are provided.


Introduction
The genus Saracha Ruiz & Pav. (Solanaceae) comprises two species of sometimes armed shrubs and small trees, with subcoriaceous to coriaceous leaves, pendant campanulate to tubular flowers, and fruits that blacken when mature. The species are distributed from Venezuela to Bolivia from 2200 to 4500 m.a.s.l. (Alvarez 1996, Smith andBaum 2006). Some authors have postulated that the flowers of Saracha are entomophilous (Cocucci 1999, Knapp 2010, but field observations indicate that at least one species, S. quitensis (Hook.) Miers, is pollinated by hummingbirds (Alvarez 1996, Tinoco et al. 2009.
Despite its small size, Saracha presents a complex taxonomic history. In 1794, Ruiz and Pavón established the genus Saracha in their Florae Peruvianae et Chilensis Prodromus, without describing any species or designating any type specimen. They presented only the generic description and an illustration. However, both match Saracha punctata Ruiz & Pav., which was described in the second volume of the Flora Peruviana et Chilensis (Ruiz and Pavón 1799). Therefore, according to Art. 40.3 of the International Code of Nomenclature (McNeill et al. 2012), Saracha punctata should be considered as the type species of the genus, as previously indicated by other authors (Gentry 1974, Miers 1853, Morton 1938. In the second volume, Ruiz and Pavón (1799) also described four new species, Saracha biflora Ruiz & Pav., Saracha contorta Ruiz & Pav., Saracha dentata Ruiz & Pav. and Saracha procumbens (Cav.) Ruiz & Pav., the latter four are now unanimously considered within the genus Jaltomata Schltdl. (Benítez 1976, D´Arcy et al. 1993, Gentry 1973, Mione and Yacher 2005, Mione et al. 2001, Mione et al. 2016. Years later, Miers (1848) identified two groups within Saracha, one comprising shrub and tree species with campanulate flowers and the other comprising herbaceous species with rotate flowers. In 1848, he created a new genus (Poecilochroma Miers) for the first group, using Saracha punctata as the type. He described five new species of Poecilochroma, and transferred Lycium quitense Hook. to Poecilochroma quitensis (Hook.) Miers. For the second group, Miers (1849) created an amended description of Saracha, together with the description of ten new species and a list of previously published species.
Due to the type chosen for Poecilochroma, Miers had created a superfluous genus which therefore had to be rejected (Art. 52.1 of the International Code of Nomenclature; McNeill et al. 2012). In subsequent work, Miers (1853) identified his error and transferred of all recognized species in Poecilochroma to Saracha. Nevertheless, the problematic circumscriptions of the genera Saracha and Poecilochroma sensu Miers (1848Miers ( , 1849 were widely used in subsequent studies (Dunal 1852, Benítez 1974, Macbride 1962, Miers 1849-1857, Walpers 1852-1853, Wettstein 1895, although these circumscriptions were disputed by some authors (Macbride 1930, 1962, Morton 1938. The nomenclatural confusion was clarified by Gentry (1973), who restored the genus Jaltomata, corresponding to Saracha sensu Miers (1849). Further, Gentry (1974) discussed the typification of Saracha and reduced Poecilochroma to a synonym. These new re-circumscriptions of the genera Saracha and Jaltomata have been accepted and continue to be used in treatments of Solanaceae (Alvarez 1996, D´Arcy 1979, Hun-ziker 2001. Currently, the names registered in Saracha, most of which were published by Miers (1849Miers ( , 1853 and Bitter (1913Bitter ( , 1921Bitter ( , 1922Bitter ( , 1924aBitter ( , 1924b, have become synonyms of the two accepted species of Saracha or transferred to Jaltomata (Alvarez 1996. The most recent treatment of Saracha (Alvarez 1996) recognized only two species, S. punctata and S. quitensis, although the former is divided among three subspecies.
Recent phylogenetic studies have clarified the evolutionary history of Saracha. The genus falls within the fleshy-fruited subfamily Solanoideae, but is distantly related to Jaltomata (Olmstead et al. 1999(Olmstead et al. , 2008. Indeed, the closest relatives to Saracha belong to the genera Acnistus Schott, Dunalia Kunth, Eriolarynx (Hunz.) Hunz., Iochroma Benth. and Vassobia Rusby. Together, these six genera comprise the subtribe Iochrominae (Miers) Hunz., which along with the subtribes Physalinae (Miers) Hunz. and Withaninae Bohs & Olmstead form the tribe Physaleae sensu Olmstead et al. (1999Olmstead et al. ( , 2008. Saracha species do not form a monophyletic group due to the nested placement of Dunalia solanacea Kunth, a species which differs dramatically in form from Saracha Baum 2006, Cueva et al. 2015). Nonetheless, like Saracha, D. solanacea is restricted to the Andes and produces black fruits (unlike the remaining species of Iochrominae).
During botanical collections carried out in the Department of Ayacucho as part of the "Inventario Nacional Forestal-Ecozona Sierra" in 2015, individuals were collected with clear affinities to the genus Saracha. After molecular phylogenetic analysis and the review of additional material across Peru, these individuals have been recognized as a distinct undescribed species. In this article, we provide a complete description of this new species, along with ecological information and a revised identification key for the genus.

Methods
The description was made through examination of herbarium specimens deposited in COLO, F, HSP, MO, MOL and USM (acronyms according to the Index Herbariorum, http://sweetgum.nybg.org/science/ih/), and notes taken during the study of individuals in the field. Conservation status was assigned using IUCN criteria (2012), combining field information, bibliographic data on habitat and geographic distribution based on herbarium specimens.

Saracha andina
Distribution and habitat. Saracha andina is a shrub endemic to the scrub and relict forests in the central Andes of Peru (Depts. Ayacucho, Huancavelica and Lima) at over 3500 to 4000 m in elevation (Fig. 2). Saracha andina grows in stony areas, on slight to moderate slopes, and near creeks. Populations of this species in the Ayacucho region have been recorded to occur in relict forest with a maximum height from 4 to 5 meters dominated by Polylepis microphylla (Wedd.) Bitter and accompanied by Escallonia myrtilloides L.f., sharing the understory with Berberis lutea Ruiz & Pav. and Hesperomeles obtusifolia (Pers.) Lindl.
Ecology. Flowering and fruiting from June to September. Characteristics of the flower suggest pollination by hummingbirds (Faegri and van der Pijil 1979). In the forest where S. andina was collected, we observed hummingbirds such as Metallura phoebe and Oreotrochilus estella, common species in relict forests of "Queñuales" (Servat at al. 2002). These birds may be pollinators of this new species.
Common name and uses. In Pachaca (Dept. Ayacucho) it is commonly known as "checc-ches" in where the native people mention that strong and straight branches had been used for yarning wool (pers. comm.).
Conservation status. According to the IUCN Red List Categories (IUCN 2012), S. andina is classified as Endangered [EN (B1biii)]. The extent of occupancy is estimated to be less than 1,000 sqkm. Furthermore, no population of S. andina currently grows in any protected area and the relict forests where it lives have been reduced as result of increasing anthropogenic pressure. In this context, S. andina populations are highly susceptible to processes of fragmentation and degradation in short term.  Discussion. Saracha andina differs from other species of the genus in its small oblong to broadly elliptic leaves 12-27 × 6-14 mm with inconspicuous nerves and tubular flowers 33.5-35 mm long. In contrast, S. punctata has elliptic leaves 20-150 × 8-60 mm and widely campanulate flowers, and S. quitensis has shorter tubular to infundibuliform flowers 12-26 mm long (Figure 3). Among other members of the subtribe Iochrominae sensu Olmstead et al. (1999Olmstead et al. ( , 2008, S. andina is perhaps most easily confused with species of Dunalia, many of which have tubular flowers of similar length and the plants are spiny (see discussion in D'Arcy and Smith 1987). Nonetheless, species of Dunalia have a diagnostic pair of appendages on either side of the filament base ("stapet") (Hunziker 1960(Hunziker , 2001, and sometimes the leaves clustered on short shoots but they lack the conspicuous coriaceous leaves of Saracha. Key to the species of Saracha, expanded from Alvarez (1996)  The maximum likelihood phylogenetic analysis places S. andina together with the other members of Saracha with high bootstrap support (91%, Figure 4). As in previous analyses Baum 2006, Cueva et al. 2015), Saracha is allied with Dunalia, Eriolaryx and Vassobia, all of which are distributed principally in the Andes of South America. Dunalia solanacea remains nested within Saracha, a placement supported by its black fruits, which are present in Saracha but absent in other Dunalia species (Smith and Baum 2006). Overall, these molecular results are consistent with the placement of S. andina in the genus Saracha.