Valerianapraecipitis (Caprifoliaceae), a species new to science and endemic to Central Chile

Abstract The species Valerianapraecipitis (Caprifoliaceae), new to science and endemic to the Ñuble Region, Central Chile, is formally described. Morphological data support its placement in a new species, clearly different from V.philippiana. A detailed description, insights about its habitat and ecology, distribution map and illustration are provided. A table of comparison is also given with the morphological characters discriminating V.praecipitis from V.philippiana. The species is assessed as Endangered (EN) under the IUCN categories.


Introduction
The Valerianaceae family was included in the Caprifoliaceae family by the Angiosperm Phylogeny Group III (APG III 2009). Although some authors continued using Valerianaceae for several years (e.g., Kutschker 2011), the family remained within the Caprifoliaceae in the APG IV (2016). Caprifoliaceae includes about 960 species in approximately 41 genera (Wang et al. 2020), having an almost cosmopolitan distribution, with centres of diversity in eastern North America and eastern Asia (Xu and Chang 2017).
Valeriana is one of the most diverse genera within the Caprifoliaceae, with a worldwide distribution, and centres of diversity in tropical areas of Central-America and to the south along the Andes mountains (Kutschker and Morrone 2012). In South-America, Valeriana species are present in Peru, Bolivia, Brazil, Chile and Argentina (Zuloaga et al. 2008). In Chile, Borsini (1966) described 42 species, while the most recent assessment identified 40 species in the Andes mountains of Chile and Argentina, between latitudes 33° and 56° S (Kutschker 2011). This area was identified as a centre of diversification of Valeriana species (Kutschker and Morrone 2012). In Chile 44 species are accepted, of which 18 are endemic, and interestingly, to date no introduced species has been found so far (Rodríguez et al. 2018). All species are herbaceous (Rodríguez et al. 2018) and many of them are distributed in high-altitude mountainous locations, usually above 1000 m elevation (e.g., V. stricta Clos, V. philippiana Briq.). They can also be restricted to dry soils (e.g., V. corynodes Borsini) or in permanently wet soils (e.g., V. fonckii Phil.). Recently, only one species new to science has been formally described, V. nahuelbutae Penneck. (Penneckamp 2020) and few new geographical locations have been found for other species (e.g., Kutschker 2011;Teillier et al. 2020). Furthermore, for most species little is known about their ecology or ethnobotany, and to this day, only one of the Chilean species have had formal conservation assessments completed according to the IUCN criteria (Valeriana senecioides Phil.; MMA 2021).
The Central Chilean Andes mountains are recognised as a centre for endemism in South-America (e.g., Villagrán and Hinojosa 1997;Arroyo et al. 2006). In addition, the Andean ranges of the Ñuble Region were declared as a Biosphere Reserve in 2011 (San Martín 2014;Fig. 1) and this area is of increasing interest since a new genus was recently described (Villarroel et al. 2021). However, several species in the region remain severely threatened (Hechenleitner et al. 2005). Intensive land-use changes due to human activities have affected vast extensions of almost all types of vegetation in Central Chile, including high-Andean habitats (Arroyo et al. 2006). In addition, global climate change is a serious threat to montane habitats that have reduced in size, are geographically isolated, and where the environmental conditions have changed significantly across small distances due to steep slopes (Báez et al. 2016).
In this manuscript we describe a species of Valeriana located in the Central Chilean Andes at around 36° S latitude and clearly distinguishable from other species by its remarkable silvery-green basal leaves. In the following sections, a detailed account on how the species was discovered is given as a formal description. In addition, a distribution map, insights about its habitat and ecology, conservation status, and illustrations are provided.

Herbarium and Fieldwork
During the austral spring-summer between 2015-2021 several botanical explorations were carried out in the Andean ranges within the locality of San Fabián de Alico, Punilla Province, Ñuble Region, Chile (Fig. 1), by means of rock-climbing in the Cordillera del Malalcura and Cuernos del Valiente and treks to Laguna del Florido. In addition, seven expeditions were made to Laguna Añil which fell within the scope of our research project entitled "Richness and distribution of the flora along an altitudinal gradient in Bullileo creek, Ñuble Region" (Villarroel 2019). During these excursions, a species of Valeriana that could not be assigned to any known species for Chile and Argentina was found. Its habitat and characters such as plant size and root system were observed and measured in the field.
Herbarium specimens were collected from Laguna Añil, and distributed to the herbaria of CONC, EIF, JBN and SGO (acronyms after Thiers 2016). As our preliminary observations of the plant and the key to Valeriana genus (Kutschker 2011) suggested similarities with Valeriana philippiana Briq., (e.g., basal leaves silvery-green colour and pinnatisect, terminal lobe size equal to bigger, fleshy texture, arranged in an imbricate rosette, fruits pubescent, pappus plumose), we examined the herbarium specimen at SGO to determine the morphological differences between both species. Also, online digital images of specimens available on CONC, E and US herbaria websites were studied, as well as literature (Borsini 1966;Kutschker 2008Kutschker , 2011. The taxonomic treatment was prepared after examining all available specimens.

Morphological analysis
The morphological study was based on observations and measurement of fresh and dried specimens. Detailed photographs of fresh material were taken in the field to document the overall plant morphology and especially the floral structure. In order to accurately describe the vegetative and reproductive morphology of the collected plants, dry and rehydrated specimens were dissected. Ovary, fruits, flowers and leaf details were photographed with a zoom lens and subsequently observed under a binocular microscope. Terminology for describing Valeriana plant parts followed Borsini (1966) and Kutschker (2008Kutschker ( , 2011.

Conservation status
The conservation status assessment of the species used the International Union for Conservation of Nature criteria (IUCN Standards and Petitions Committee 2019). The extent of occurrence (EOO) and area of occupancy (AOO) were calculated using GeoCat (Bachman et al. 2011).   (Fig. 2). Laguna Añil is the only site where herbarium specimens were collected.
Etymology. The specific epithet refers to cliff faces inhabited by these plants. The name means "Valeriana of cliffs" (latin praeceps = steep place, precipice, dangerous; genitive praecipitis).
Phenology. Flowering from November to December; fruiting from January to February.
Distribution and habitat. Endemic to the Andean ranges of the Ñuble Region, Chile (Fig. 1A, B). Specifically, 5 sites are known so far (Fig. 1C): Laguna Añil (1724 m elevation, 36°32'00.8"S, 71°23'36.1"W; 1650 m elevation, 36°32'2.28"S, 71°23'26.62"W); Cuernos del Valiente (1530 m elevation, 36°27'46.31"S, 71°29'14.41"W), Cordillera del Malalcura (1700 m elevation, 36°32'0.23"S, 71°30'7.59"W), Laguna del Florido (1980 m elevation, 36°30'55.07"S, 71°14'1.20"W), and the last at Laguna del Huemul (1970 m elevation, 36°52'40.11"S, 71°29'6.33"W, this locality was found by Eitel Thielemann). The maximum distance between the sites is 38 km. The species usually grows at high elevations (1530-1980 m), in crevices and small terraces of south, southeast and southwest facing cliffs (Fig. 5). Due to snow melting and low sun exposure, these sites remain humid during the dry season. Two closest weather stations, Punilla (840 m elevation) and Caracol (725 m elevation), indicate that the average annual temperature is 11.8 °C and the average total annual precipitation 2150 mm for the period 1965period -2012period (DGA 2018. Although at a lower elevation than V. praecipitis altitudinal range, a private pluviometer in the village of San Fabián de Alico (447 m elevation) recorded an annual average precipitation of 1399 mm for the period 2017-2020 (Covarrubias J.C., pers. comm.). In addition, to get a better impression of the local conditions during year 2020 temperature and humidity data loggers HOBO U23 Pro v2 (Onset Computer Corporation, Massachusetts, USA) registered an average annual temperature of 6.7 °C, with a minimum of -2.8 °C, a maximum of 24.1 °C, and an average humidity 60.12% at Laguna Añil; and an average annual temperature of 8.7 °C, with a minimum of -4.5 °C, a maximum of 24.9 °C, and an average humidity of 66.39 % in Cordillera del Malalcura. Conservation status. Valeriana praecipitis is assessed here as Endangered (EN) under the IUCN categories following criteria B2ab(iii). Criterion B2 was selected because its area of occupancy is < 500 km 2 (estimated at 20 km 2 ). Criterion "a" was selected because it is known to exist in two locations (Fig. 1C, north and south of Ñuble river). Criterion "b(iii)" was selected because there is a projected decline in the area, extent, and quality of habitat. High Andean plants are very sensitive to global warming, given that migration is limited by the lack of connectivity between summits and its reduced areas on the top, additionally, the 2010-2017 mega-drought in Central Chile, resulted in a significant reduction in precipitation and snow cover -the most severe during the last 1000 years -together with an increase in temperatures for the last decade (Garreaud et al. 2017;Cordero et al. 2019). One of the climate change model scenarios projects an increase of at least 1 °C of the mean temperature for the next 30 years, plus a decrease in winter precipitations of about 30% at the end of the century (Bozkurt et al. 2017). Valeriana praecipitis extent of occurrence is ~555 km 2 (Fig. 1B). The species is not present in any protected area in Chile, and it is not protected by law.

Discussion
Pollen evidence indicates that Valeriana is a Holarctic genus that might have arrived from the northern hemisphere, perhaps before the uplifting of the Andes during the Pleistocene (Kutschker and Morrone 2012). The authors found an endemism node area between latitudes 34° and 37° S, suggesting a diversification centre for Valeriana after a long period of isolation, caused by the Andes uplift. The same scenario might have occurred with other genera such as Berberis L., Ribes L., among others, indicating a complex centre of endemism of high conservation value (Moreira-Muñoz and Muñoz-Schick 2007). In the same way the genus Valeriana is key to understanding Andean biogeographic history (Kutschker and Morrone 2012), evolutionary processes that occurred in the area could have given rise to locally endemic species such as V. praecipitis, Rayenia malalcurensis and Viola chillanensis Phil. (Violaceae) (RBG Edinburgh 2021). The discovery of V. praecipitis in southern South-America follows the recent discovery of Rayenia malalcurensis, a newly described endemic genus and species found in the same area. As mentioned before, since the revision of Kutschker (2011), new locations and a new species were described. These discoveries suggest that both the region and the genus may reveal additional interesting botanic surprises. Although no genetic analysis was performed to determine its phylogenetic affinities, the comparison of morphological characteristics with its closest species shows notable differences in 11 out of 13 sets of characters (Table 1), in addition to a distance between their recorded distributions of approximately 410 km. The species is unmistakable, easy to recognize from other species in the area, especially in spring and summer due to its remarkable silvery-green basal leaves. However, it is difficult to find given the steepness of the sites where it occurs. Its extreme rarity and inaccessibility are undoubtedly the reasons why it has evaded discovery up until the present time.
In addition to consistent morphological differences, V. praecipitis stands out from other species of the genus due to its specific ecological habitat. Few other Valeriana species are able to grow abundantly in damp rock-cliffs at this high altitude, directly rooted in fissures or small soil pockets (e.g., V. chilensis Borsini in Chile or V. ruizlealii Borsini in Argentina). Rock-cliffs are challenging habitats with high erosion rates, limited soil depth and nutrients availability (Mathaux 2017;March-Salas et al. 2018). Mountain microclimatic conditions at high elevations are also severe due to high insolation and extreme low temperatures (Gale 1972). To adapt to these conditions, the species has a woody rhizome that can be more than 30 cm long and 5-20 mm in diameter, perhaps the largest of any Valeriana species. In addition, its deciduous leaves allow this species to avoid freezing temperatures and the presence of snow. These environmental conditions could have triggered the adaptation phenomenon mentioned above, and eventually speciation processes as suggested by Kutschker and Morrone (2012).
Little is known about rare and endangered species growing in the southern Andean cliff ecosystems, and many open questions remain. Future research needs to be done to identify morphological and physiological adaptations to grow under harsh soil and climatic conditions that could shed light on the future of Andean plant communities in the face of climate change. For instance, how new climatic scenarios could affect their area of occupancy? Are they able to migrate? Or more precisely, how extreme and persistent climatic conditions, like the ongoing mega-droughts, might affect the physiological performance of these species, perhaps pressing viable populations' threshold to the edge. The recent finding of V. praecipitis and Rayenia malalcurensis, in addition to other rare and endemic species, adds to the importance of monitoring and promoting the conservation of these species (Moreno-Gonzalez et al. 2019), especially those of Andean cliff ecosystems.  Borsini (1966) and Kutschker (2008Kutschker ( , 2011

mm long
Ellipsoid, 3-4 × 2 mm, pubescent; pappus plumose, bristles 11-13, 5-7 mm long V. praecipitis is not present in any public protected area in Chile (Fig. 1B). In 2011, the Andean and pre-Andean sectors of the Ñuble Region and north of the Biobío Region were declared a UNESCO World Biosphere Reserve (San Martín 2014). All the known subpopulations of V. praecipitis are found within this Biosphere Reserve, except the one located in the surroundings of Laguna Añil. However, although they are internationally recognized, Biosphere Reserves protection is not guaranteed by Chilean legislation. Actually, all sites are in privately owned lands with an overall low level of anthropic change. Without any formal protection, the area is highly susceptible to be affected by the construction of hydroelectric dams, mining industry, unregulated animal farming and unsustainable tourism. The high biodiversity levels of this area (e.g., Villarroel 2019), including the presence of narrow range and threatened species such as V. praecipitis and R. malalcurensis and the high degree of threat of the Andean region, should give priority to the conservation of Andean territory of the Ñuble Region. Such conservation priority is ever more urgent in the light of future increasing trends of more frequent and severe fires (e.g., McWethy et al. 2021).
Another threat specific to cliff vegetation is the possible impact that rock-climbing could cause. In Chile (and worldwide) rock-climbing is of increasing interest, attracting more people to the mountains (Bogges et al. 2021), and climbers and hiker's organizations are rightly asking for policy to change to allow for more open access to mountainous areas. However, with a greater number of people accessing mountain cliffs, the risk of negative human impacts would increase (Clark and Hessl 2015). So far, because of their remoteness and inaccessibility, Chilean cliff ecosystems have remained relatively unaltered by human impacts. The lack of access is not only due to a lack of trails, but also because many mountainous areas are privately owned. In the future, the major challenge will be to find the most effective strategy to conserve ecosystems, while maximizing the social benefits of access to mountains. by DAAD/BECAS Chile, 2014 (57144001) during early stages of the study design. We express our gratitude to the owners and administrators of the private sites where the plant was found, especially to Elías Acuña and Esau Marin. The authors would like to thank the curators of CONC, EIF, JBN, and SGO, especially Jimena Arriagada. We are indebted to Martin Gardner and Nicolás Lavandero for the support and revision of the manuscript. Thanks to Marco Duretto and an anonymous reviewer for their helpful suggestions during the reviewing process of this manuscript. We are grateful to Arón Cádiz-Véliz for the illustration of the species. Thank you so much to our field partners: Gonzalo Ossa, Eduardo Ponce, Rayen Neira and all members of the Bullileo Team.