taxonID	type	description	language	source
03AEDA29FFD9F164998FFA9713D13EDD.taxon	diagnosis	Grindelia rheophila differs from all other congeners by the combination of linear-elliptic leaves (40 – 142 × 4 – 14 mm) and the co-occurrence of 11 – 12 deciduous hemipaleaceous (0 – 3) and bristle (9 – 12) pappus elements (3.3 – 5.1 mm long).	en	Fernandes, Fernando, Büneker, Henrique Mallmann, Iganci, João, Souza-Chies, Tatiana Teixeira De, Heiden, Gustavo (2025): Grindelia rheophila (Asteraceae, Astereae): A new species and a river-borne exception in a genus shaped by Deserts. Phytotaxa 720 (1): 35-45, DOI: 10.11646/phytotaxa.720.1.3, URL: https://doi.org/10.11646/phytotaxa.720.1.3
03AEDA29FFD9F164998FFA9713D13EDD.taxon	materials_examined	Type: — BRAZIL. Rio Grande do Sul: Quevedos, Usina do Rio Toropi, sobre rochedos junto ao rio, 29 ° 23 ’ 16 ” S 54 ° 01 ’ 19 ” W, 221 m [inferred coordinates and elevation], 15 September 2007, R. A. Wasum 4157 (holotype ECT 10031, isotype BHCB 114548; HUCS 31755!; ICN 167643!; JOI 11252; UFP 65452).	en	Fernandes, Fernando, Büneker, Henrique Mallmann, Iganci, João, Souza-Chies, Tatiana Teixeira De, Heiden, Gustavo (2025): Grindelia rheophila (Asteraceae, Astereae): A new species and a river-borne exception in a genus shaped by Deserts. Phytotaxa 720 (1): 35-45, DOI: 10.11646/phytotaxa.720.1.3, URL: https://doi.org/10.11646/phytotaxa.720.1.3
03AEDA29FFD9F164998FFA9713D13EDD.taxon	description	Shrubs, saxicolous, 0.35 – 1 m tall, sympodial, virgate. Stems erect or rarely decumbent, cylindrical, vinaceous to green, with light brown bark, smooth and slightly striate, sparsely pubescent, glabrous at maturity, trichomes glandular; internodes in upper vegetative and flowering branches 5 – 20 mm long. Leaves 40 – 142 × 4 – 14 mm, alternate, light green, concolorous, sessile, entire; blade papery, linear-elliptic; base tapering; apex acute; margin serrate with uncinate teeth, not revolute; venation pinnate; indumentum sparsely pubescent, trichomes glandular or rarely normal. Bracts 31 – 112 × 3 – 12 mm, alternate, light green, concolorous, sessile, entire; blade papery, linear-elliptic; base tapering; apex acute; margin serrate with uncinate teeth, not revolute; venation pinnate; indumentum sparsely pubescent, trichomes glandular or rarely normal. Bracteoles 10 – 45 × 3 – 8.5 mm, alternate, light green, concolorous, sessile, entire; blade papery, linear-elliptic to oblong or lanceolate near the capitulum; base tapering; apex acute; margin serrate with uncinate teeth, not revolute; venation pinnate; indumentum sparsely pubescent, trichomes glandular or rarely normal; as they ascend, the bracteoles become progressively smaller and more similar in appearance to the outer phyllaries. Capitulum solitary; involucre 8 – 10 × 9 – 20 mm, 4 – 5 - seriate. Phyllaries 68 – 81. Outer phyllaries 7 – 8 × 1 – 1.5 mm, light green and sometimes vinaceous at the apex, linear-lanceolate, papery; base decurrent, adpressed; midportion patent; apex long attenuated, supinate; margin smooth; indumentum sparsely pubescent with glandular trichomes. Second series 7 – 8 × 1.1 – 2.0 mm, light green and sometimes vinaceous at the apex, linear-lanceolate, papery; base decurrent, adpressed; midportion patent; apex long attenuated, supinate; margin smooth; indumentum sparsely pubescent with glandular trichomes. Intermediate series 7 – 8 × 1.5 – 2.1 mm, light green to light green and stramineous on the margins, sometimes vinaceous at the apex, lanceolate, papery; base decurrent, adpressed; midportion patent; apex long attenuated to attenuate, supinate; margin smooth; indumentum sparsely pubescent with glandular trichomes. Inner phyllaries 6 – 9 × 1.7 – 2 mm, light green to stramineous on the margins, lanceolate to elliptic, papery; base decurrent, adpressed; apex attenuated; margin smooth; indumentum sparsely pubescent with glandular trichomes. Receptacle slightly convex. Ray florets 15 – 24, pistillate, ligulate, corolla yellow; tube 4 – 6.1 × 0.4 – 0.8 mm, sparsely pubescent with glandular trichomes; throat puberulous with glandular trichomes; limb elliptic, 14 – 25 × 3 – 3.2 mm; apex acute; puberulent to glabrous, trichomes glandular when present. Ovary ovoid to ovoid-cylindrical, 1.6 – 1.9 × 0.9 – 1.1 mm; puberulent to glabrous, trichomes glandular when present. Style 3.8 – 8 mm long; style arms 0.4 – 1 mm long, apex sparsely pubescent. Disc florets 128 – 211, perfect; corolla yellow; tube 5.3 – 7.3 × 1 – 1.7 mm, sparsely pubescent with glandular trichomes, when present; throat puberulous with glandular trichomes, when present; lobes puberulent to glabrous, glandular trichomes when present. Anthers 2.3 – 4.3 mm long, light yellow. Ovary 1.1 – 1.9 × 0.6 – 1.2 mm, ovoid to cylindrical; sparsely pubescent to glabrous, trichomes glandular when present; style 5.4 – 10.9 mm long; style arms 1.8 – 2 mm long, apex sparsely pubescent. Cypselae 2 – 3 × 1 – 1.2 mm, brown, laterally flattened, glabrous, apex truncate. Pappus hemipaleaceous, 3.3 – 5.1 mm long, 11 – 12 pappus elements; 0 – 3 scale; 9 – 12 bristles, deciduous.	en	Fernandes, Fernando, Büneker, Henrique Mallmann, Iganci, João, Souza-Chies, Tatiana Teixeira De, Heiden, Gustavo (2025): Grindelia rheophila (Asteraceae, Astereae): A new species and a river-borne exception in a genus shaped by Deserts. Phytotaxa 720 (1): 35-45, DOI: 10.11646/phytotaxa.720.1.3, URL: https://doi.org/10.11646/phytotaxa.720.1.3
03AEDA29FFD9F164998FFA9713D13EDD.taxon	distribution	Distribution and Habitat: — Localities of G. rheophila were found in the municipalities of Jari, Júlio de Castilhos, Quevedos and São Martinho da Serra, in Rio Grande do Sul state, Southern Brazil (Figure 3). The new species is saxicolous and grows along the edge of the South Brazilian plateau in the northern headquarters of the Ibicuí river basin tributaries at an elevation of approximately 219 to 401 meters above sea level. Two populations are found along the bedrock margins of the rapids of the Toropi river, which marks the natural border between the municipalities of Jari, Júlio de Castilhos and Quevedos, while the second record comes from Cachoeira do Moinho, a waterfall of the Itaimbé creek, which is a tributary of the Ibicuí-Mirim river in São Martinho da Serra municipality. Grindelia rheophila is always associated with rheophilic environments in the river’s flood-prone margins (Figure 3). It occurs together with other typically rheophytic species endemic to the area, often growing among populations of Dyckia strehliana (Bromeliaceae).	en	Fernandes, Fernando, Büneker, Henrique Mallmann, Iganci, João, Souza-Chies, Tatiana Teixeira De, Heiden, Gustavo (2025): Grindelia rheophila (Asteraceae, Astereae): A new species and a river-borne exception in a genus shaped by Deserts. Phytotaxa 720 (1): 35-45, DOI: 10.11646/phytotaxa.720.1.3, URL: https://doi.org/10.11646/phytotaxa.720.1.3
03AEDA29FFD9F164998FFA9713D13EDD.taxon	conservation	Preliminary Conservation Status: — Grindelia rheophila is classified as Critically Endangered (CR) following the IUCN (2024) Red List assessment criteria: A 2 ac + 3 c + 4 ac; B 1 ab (i, ii, iii, iv) c (iii). This classification is based on the species’ extremely limited geographic distribution, with an Extent of Occurrence (EOO) of 43.8 km ² and an Area of Occupancy (AOO) of 16 km ², calculated from the actual area where individuals were observed. These spatial metrics were obtained through analysis using GeoCAT (Bachman et al. 2011), which showed the species occurs in a highly fragmented and degraded habitat. All applicable IUCN criteria (A – D) were evaluated; criterion E was not applied due to insufficient data for quantitative extinction risk analysis. The species is known from only three isolated populations. Its largest population, in the Toropi River, is under a strong influence from a dam (PCH Quebra Dentes), located approximately 110 meters away, which compromises habitat quality. Additionally, recent and future floods, intensified by climate change, have the potential to decimate these already fragile populations (Garssen et al. 2015, 2017). The species has a reduced EOO, and its AOO is only 6 km ² above the threshold that would also classify it as Critically Endangered (CR) under criterion B 2 a, b (i, ii, iii, iv), c (iii), indicating that this parameter is already at the maximum risk threshold before extinction. Grindelia rheophila exhibits typical adaptations of rheophytes, with its growth form and leaves shaped by hydrodynamics being the main characteristics (Imaichi & Kato 1997). The species was found exclusively in these environments, highlighting its vulnerability to disturbances in water regimes and the pressures from human activities and climate change. The Toropi river and the Itaimbé creek are tributaries of the Ibicuí river, which was affected by the extreme weather event that occurred in Rio Grande do Sul state in May 2024, which caused unprecedented social and ecological damage across Rio Grande do Sul, impacting 95 % of the state’s municipalities (Pillar & Overbeck 2024). Although the most severe impacts were recorded in the Taquari-Antas and Jacuí basins, flooding also disrupted ecosystems along the Toropi River and other watercourses (Rio Grande do Sul 2024). Such extreme events, which are becoming increasingly frequent, pose a threat to riparian environments and may endanger plant species that grow in these habitats, such as G. rheophila. Given the increasing frequency of such extreme weather events, the conservation of G. rheophila requires urgent attention, including enhanced habitat protection, continuous monitoring of population dynamics in the face of climate change and seed collection for ex situ conservation. Previous research in the region (Marchiori et al. 2014) provided recommendations during the licensing process of the Quebra Dentes Hydroelectric Power Plant, which were successfully implemented. Following these suggestions, an area with a palm grove of the endangered Butia witeckii and Trithrinax brasiliensis Martius (1844: 44) located near the project was transformed into a conservation area, ensuring protection for the native species occurring there. However, changes in the hydrological regime caused by upstream damming may still be negatively affecting rheophytic communities contiguous to the conservation area, where the G. rheophila populations are found.	en	Fernandes, Fernando, Büneker, Henrique Mallmann, Iganci, João, Souza-Chies, Tatiana Teixeira De, Heiden, Gustavo (2025): Grindelia rheophila (Asteraceae, Astereae): A new species and a river-borne exception in a genus shaped by Deserts. Phytotaxa 720 (1): 35-45, DOI: 10.11646/phytotaxa.720.1.3, URL: https://doi.org/10.11646/phytotaxa.720.1.3
03AEDA29FFD9F164998FFA9713D13EDD.taxon	etymology	Etymology: — The specific epithet refers to the rheophilic habitat of the new species and the morphological adaptations specialized for this environment.	en	Fernandes, Fernando, Büneker, Henrique Mallmann, Iganci, João, Souza-Chies, Tatiana Teixeira De, Heiden, Gustavo (2025): Grindelia rheophila (Asteraceae, Astereae): A new species and a river-borne exception in a genus shaped by Deserts. Phytotaxa 720 (1): 35-45, DOI: 10.11646/phytotaxa.720.1.3, URL: https://doi.org/10.11646/phytotaxa.720.1.3
03AEDA29FFD9F164998FFA9713D13EDD.taxon	biology_ecology	Phenology: — Flowering specimens were collected in nature from September and October. Under cultivation in the rocky garden of the Colégio Politécnico of the Federal University of Santa Maria, two specimens of G. rheophila produced their first buds in August and flowered up to June.	en	Fernandes, Fernando, Büneker, Henrique Mallmann, Iganci, João, Souza-Chies, Tatiana Teixeira De, Heiden, Gustavo (2025): Grindelia rheophila (Asteraceae, Astereae): A new species and a river-borne exception in a genus shaped by Deserts. Phytotaxa 720 (1): 35-45, DOI: 10.11646/phytotaxa.720.1.3, URL: https://doi.org/10.11646/phytotaxa.720.1.3
03AEDA29FFD9F164998FFA9713D13EDD.taxon	discussion	Notes: — The new species was assigned to Grindelia because it exhibits all the diagnostic traits of the genus described by Nesom & Robinson (2007), such as glutinous leaves, capitula with campanulate involucres, bracts arranged in multiple series (4 – 5) with sclerified bases, thick-walled cypselae, and a pappus composed of few deciduous elements (11 – 12). Grindelia rheophila was previously identified as G. scorzonerifolia Hooker & Arnott (1836: 45) or G. buphthalmoides Candolle (1836: 16). However, G. buphthalmoides has oblanceolate leaves (vs. linear-elliptic) and only bristle pappus elements (vs. bristles and some hemipaleaceous ones). On the other hand, G. scorzonerifolia is a prostrate or decumbent shrub (vs. erect, sometimes decumbent), with narrowly elliptical leaves that are lobed, pinnatifid, or pinnatisect (vs. entire linear-elliptic), and has 4 – 7 pappus bristles (vs. 11 – 12 elements, including some hemipaleaceous ones). The new species also superficially resembles G. pulchella Dunal (1819: 51), which also has linear-elliptic leaves, but differs by its smaller leaf size (23 – 51 × 2 – 4 mm vs. 40 – 110 × 4 – 13 mm) and by having only 6 – 9 bristly pappus elements (vs. bristles and some hemipaleaceous ones).	en	Fernandes, Fernando, Büneker, Henrique Mallmann, Iganci, João, Souza-Chies, Tatiana Teixeira De, Heiden, Gustavo (2025): Grindelia rheophila (Asteraceae, Astereae): A new species and a river-borne exception in a genus shaped by Deserts. Phytotaxa 720 (1): 35-45, DOI: 10.11646/phytotaxa.720.1.3, URL: https://doi.org/10.11646/phytotaxa.720.1.3
03AEDA29FFD9F164998FFA9713D13EDD.taxon	materials_examined	Additional specimens examined (paratypes): — BRAZIL. Rio Grande do Sul: Jari, Estrada para Quevedos, campo pedregoso nas margens do rio Toropi; decomposição de basalto, 12 September 2002, S. Bordignon s. n. (UNILASALLE 2308). Júlio de Castilhos & Quevedos, saxícola em ambas as margens do rio Toropi, próximo à antiga Usina de Quebra Dentes, 29 ° 23 ’ 23.1 ” S, 54 ° 01 ’ 07.8 ” W, seedling obtained on 19 September 2012, flowering and herborized on 24 August 2016 from specimen cultivated in Santa Maria, H. M. Büneker 98, R. C. Pontes & L. Witeck (ECT!, ICN!). São Martinho da Serra, 1 m de altura, capítulos de cor amarela, em paredão ao lado da Cachoeira do Moinho, 18 de outubro de 2015, 29 ° 31 ’ 32 ” S, 53 ° 52 ’ 26 ” W, L. Lemer & G. A. Orso 41 (HDCF 7364 digital image!).	en	Fernandes, Fernando, Büneker, Henrique Mallmann, Iganci, João, Souza-Chies, Tatiana Teixeira De, Heiden, Gustavo (2025): Grindelia rheophila (Asteraceae, Astereae): A new species and a river-borne exception in a genus shaped by Deserts. Phytotaxa 720 (1): 35-45, DOI: 10.11646/phytotaxa.720.1.3, URL: https://doi.org/10.11646/phytotaxa.720.1.3
