Senecio scapioides (Compositae: Senecioneae: Senecioniinae): a new species from the Departamento de Boyacá, in Andean Colombia

Routine use of the virtual herbarium of the collections in COL (Instituto de Ciencias Naturales de la Universidad Nacional de Colombia) revealed the presence of an as yet undescribed species of Senecio amongst the material of Senecio adglacialis and S. leucanthemoides. Following subsequent herbarium studies and fieldwork, Senecio scapioides (Compositae: Senecioneae: Senecioniinae), from the Departamento de Boyacá, in Andean Colombia, was recognised and is described and illustrated; it is compared with S. adglacialis and S. leucanthemoides. Notes on its distribution and habitat, conservation status, phenology, and etymology are also provided, and the distribution of the three species mapped.


Introduction
In 2015, one of the authors (DJNH) reassessed the status of the Compositae in published Floras, checklists and available related databases. During that exercise, the available database for the checklist of the Colombian Flora (Bernal et al. 2015) was reassessed for its completeness (of both genera and species), for the Compositae. At that time, 230 genera (together with 7 splits from Vernonia Schreb.), including 1274 species, this represented 523 endemic species (41.1% of the total of Compositae), and equivalent to 5.6% of the Flora's angiosperm total. However, a significant number of taxa (both genera and species) were missing from the database; this re-assessment was put on hold until mid-2017. Whilst the number of genera remains the same (with some added and others deleted), the current estimates are 1260 species (excluding purely cultivated species), including 582 endemics (46.3%).
In 2016, the Royal Botanic Gardens, Kew, became a partner in a joint programme, Colombia Bio (Colombia BIO 2016), established by ColCiencias (the Colombian Administrative Department of Science, Technology and Innovation), and aimed at increasing knowledge of Colombia's biodiversity. This partnership involves the Instituto de Investigación de Recursos Biológicos Alexander von Humboldt (FMB = Herbario Federico Medem Bogotá), and the Universidad Pedagógica y Technológia de Colombia; Kew's involvement is funded in part by the British Council (via BEIS = Department for Business, Energy & Industrial Strategy, UK). As a subset of Colombia BIO, Boyacá Bio is a regional programme which Kew has become directly involved with. The intention is to provide checklists of some of the more important families of flowering plants (Araceae, Leguminosae, Myrtaceae) where Kew has some expertise, and often in collaboration with Colombian researchers, for the Departamento de Boyacá. The experience of one author (DJNH) in creating annotated systematic checklists (see Hind 2011, for an unpublished version of one for Bolivia), was then used to create a similar style of preliminary checklist of the Compositae for the Departamento de Boyacá, Colombia, en route to a full draft list of the Compositae of Colombia, supplementing the published Catálogo (Bernal et al. 2016a, b).
Whilst the second author (DJNH) constructed the Compositae checklist for the Departamento, constant checks were made against the virtual herbarium of the Instituto de Ciencias Naturales de la Universidad Nacional de Colombia (= COL). These were primarily concerned with a visual confirmation that the determinations of the material were correct, as well as supplying supplementary information to be used in the checklist (e.g. altitude of collections, habit and habitat, and flowering time). At present, following the second author's listing, there are 23 native or native and naturalised genera from the tribe Senecioneae present in Colombia However, it was during that process that it became clear that within Senecio some imaged collections did not belong to the taxa to which they had been determined. Most of the senecios in Boyacá are high altitude species (3,000 -5,000 m, rarely down to 2,000 m) and, excluding the weedy S. vulgaris L. (which is only present in its discoid form in Colombiae.g. Cuatrecasas 13658, Díaz-Piedrahíta et al. 958, Knoth 3379, Velasco 184), 75% of them possess radiate capitula, together with one variety of S. comosus Sch.Bip.; half of the radiate species have yellow ray limbs, the others purple or carmine-coloured. All of the discoid-headed taxa possess yellow corollas. Material determined as S. leucanthemoides Cuatrec., other than the type collection, Cuatrecasas et al. 12050 (and the contemporaneous Cuatrecasas et al. 12055), was clearly not conspecific. In addition, material determined as S. adglacialis Cuatrec. was clearly not that species, but appeared identical to that mis-determined under S. leucanthemoides together with one additional sheet under the easily-recognised S. formosus Kunth. This unmatched material is of a distinctive rhizomatous perennial herb with entire to sparsely serrate sessile leaves and solitary, scapiform radiate capitula, with yellow ray limbs.

Description
RECOGNITION. In habit, leaf shape and yellow radiate capitula Senecio scapioides resembles S. adglacialis but the new species differs in having a densely arachnoid indumentum and in being sericeous pubescent on its stems, abaxial leaf surface and involucre (vs sparsely arachnoid and sericeous pubescent), generally longer glandular trichomes (1.       of occupancy is (348 km 2 ) within the threshold for Endangered in criterion B2. The number and size of the populations is not well-known, and the species could not be accurately assessed based on its population size and decline. Nevertheless, the modern threats to habitat of livestock grazing and frequent fires, as well as climate warming and drying in the northern Andes (Vásquez et al. 2015;IPCC 2014), and more than a third of the Páramos de Boyacá now destroyed, mainly due to the introduction of grasslands and crops (Moreno et al. 2016), mean that the species habitat is in continuous decline. Therefore, following the criteria established by the IUCN (2013) Fig. 1A, 3B, C), yellow radiate capitula similar in size and shape (Fig. 3D, E), and staminodes present in the fertile ray florets (Fig. 2E). Although most of the collections studied of the new species have been previously identified as Senecio leucanthemoides and/or S. adglacialis, this is understandable, because both species have yellow radiate capitula and grow in areas of páramo (Fig. 3). Both J. Cuatrecasas and S. Díaz-Piedrahita, renowned American synantherologists, saw material of the undescribed species but did not describe it.
Senecio adglacialis does not grow sympatrically with S. scapioides, since no material of the new species has been found from the superpáramo vegetation of the Sierra Nevada del Cocuy (Map 1). This Sierra has a high percentage of endemics within the Colombian Cordillera Oriental and several senecios are endemic to the Sierra (e.g. S. cocuyanus Cuatrec., S. supremus Cuatrec. and S. pascuiandinus Cuatrec.) (Cleef 1981; M i r a n d a -E s q u i v e l e t a l . 2 0 0 2 ) . O t h er w i s e , S. leucanthemoides is only known from the type locality  Table 1. (continued) in the páramo of Almorzadero (Departamento de Santander) (Map 1), a humid shrubby páramo at 3800 m elevation, and represents the northernmost distribution for this group of rhizomatous, scapiform species with yellow radiate capitula. A table of comparison of selected characters amongst Senecio scapioides and these closest relatives is provided in Table 1.
The radiate capitula with the two types of yellow floret noted in the new species also resembles Senecio funckii, a species restricted to two disjunct localities in the Venezuelan Sierra Nevada de Merida and in the Colombian Sierra Nevada de Santa Marta (Ávila et al. in Bernal et al. 2015;Hokche et al. 2008) (Map 1). Nevertheless, the indumentum, habit and leaf type of S. funckii are distinctly different, being glabrate, suffrutescent with erect branches, no rhizome, an inflorescence leafy throughout, with flat leaves possessing doubly dentate margins, while S. scapioides and its morphological and geographical relatives, are perennial herbs with a basal rhizomatous stem, their basal leaves rosettiform, the inflorescences scapiform and the leaf margins always revolute, crenate, and completely covered with an arachnoid and sericeous indumentum ( Fig. 1A; 2A, B; 3B, C). licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/ licenses/by/4.0/.