Trichocline minuana (Compositae, Mutisieae), a new species endemic to the Pampas in Southern Brazil and Uruguay

A new species of the genus Trichocline is described. Trichocline minuana is restricted to the state of Rio Grande do Sul, Brazil and northern Uruguay, where is found in lowland pampean grasslands, generally associated to rocky and dry soils. The main characters that distinguish this species from the other sympatric and morphologically close species T. humilis and T. incana are the presence of a small scape and strongly pinnatisect leaves that have lobes with acute apex, and a large, lanceolate terminal lobe. This study provides a detailed description of the species, information about distribution, conservation status assessment and information about its ecological aspects.


Introduction
The genus Trichocline Cass. (Asteraceae, Compositae) belongs to the tribe Mutisieae, and is nested in the Gerbera-Complex in a South American endemic clade which also contains the genera Lulia Zardini and Brachyclados D.Don. There are approximately 23 described species of this genus and they are distributed into two main centers of diversity (Zardini 1975); one is along the Andes from southern Peru to southern Patagonia and the other is in the Southern Brazilian Plateau and Pampean Biogeographic Province (Cabrera & Willink 1973) in Uruguay, Northeasteran Argentina and Rio Grande do Sul state in Brazil.
Some of the species frequently present a wide range distribution, along the highland grasslands in Brazil and in the Andes in Argentina, but others are rare and restricted (Zardini 1975). Ten species are distributed along the Southern Brazilian Plateau, from the highland grasslands with Araucaria Forests to the lowland grasslands and coastal Plain in Southern Brazil and Uruguay. All the species are perennial herbs, and the habit can vary from caulescent herbs with alternate leaves and axillary scapes to acaulescent herbs with rosette leaves and terminal scapes. The genus presents conspicuous monocephalous capitula with colorful bilabiate florets, where the rays have a long abaxial lobe.
Rodriguésia 71: e02202018. 2020 One of the main morphological characters that distinguishes Trichocline from the other genera of the Gerbera-Complex are the presence of staminodes in the ray florets and a cypsela that is truncate at the apex, with long and claviform twin hairs covering the whole extension (Zardini 1975;Katinas et al. 2008).
During systematic studies of the tribe Mutiseae, led by the first author, we found a new species occurring in rocky soils along lowland grassland vegetation of the Pampa Phytogeographic Region, in Southern Brazil and Uruguay. We provide a taxonomic description, illustrations, conservation status assessment, and a distribution map.

Materials and Methods
We have conducted fieldtrips to the locations where the species was collected, and revised the The morphological nomenclature followed Beentje (2010) and the measurements were taken from dried herbarium samples. General information about the taxon's distribution, habitat and phenology was taken from herbarium sheets and observations in the field.
The conservation status assessment was based on IUCN (2016) criteria, and area of occupancy and extent of occurrence were calculated with Kew's Geospatial Conservation Assessment Tool -GeoCAT (<http://geocat.kew.org>). Figs. 1; 2 The new species is morphologically close to T. humilis Less. and T. incana Cass., and they are sympatric. The morphological differences between the new taxon and T. humilis are the strongly pinnatisect leaves with large and lanceolate lateral and terminal lobes, often forming secondary lobes (vs. entire or pinnatisect, with small and rounded lateral and terminal lobes), lobes with acute apex (vs. rounded apex), terminal lobe large and lanceolate (vs. small, rounded not conspicuous terminal lobe) and tomentose indument in the involucral bracts and scape (vs. glabrous or glabrescent). The short scape of T. minuana is also observed in T. humilis, however it is less frequent in this species. Moreover, the new taxon can be distinguished from T. incana by the short scapes (vs. long scapes), involucre bracts with brownish margins (vs. greenish margins) and the presence of a large lanceolate terminal lobe in the leaves (vs. short lanceolate terminal lobe).
The species was named after the South American native group Minuanos, which were spread throughout the Pampean region in southern Brazil and Uruguay.