Paepalanthus salimenae Cabrini & Trovó, 2024

Cabrini, Mylena, Lira, Catarina, Suyama, Yoshihisa, Takahashi, Daiki, Ishikawa, Naoko, Paglia, Isis & Trovó, Marcelo, 2024, Genomic and morphological data reveal a critically endangered new species from the Atlantic Forest, Paepalanthus salimenae (Eriocaulaceae), Phytotaxa 655 (2), pp. 173-186 : 178-181

Paepalanthus salimenae Cabrini & Trovó sp. nov. Figs. 3 , 4

Diagnosis:— Paepalanthus salimenae is morphologically closely related to Paepalanthus calvus , differing by its narrower leaves with persistent trichomes on both surfaces, longer trichomes on the spathes and scapes, involucral bracts with trichomes and an acute apex, and floral bracts and sepals that are adaxially pilose from the middle to the apex.

Type:— BRAZIL. Minas Gerais, Juiz de Fora, Torreões , Próximo à estrada de Toledos, -21.789783, -43.592153, 7 May 2023, M.D. Cabrini 14, M. Trovó, I. Paglia, W. Picanço, F.R.G. Salimena, J.L.L. Castro (holotype RB; isotypes B, NY, SPF) .

Herbs 29–43.5 cm tall. Stem branched with conspicuous caudex. Leaves arranged in rosette, deciduous at the base, membranaceous to chartaceous, linear to lanceolate, flat to recurved, 5.5–13.5 × 0.4–0.7 cm, green with whitish indumentum, striated, adaxial surface with uniseriate trichomes, abaxial surface with conspicuous uniseriate trichomes along the striations, margin ciliate, apex acute. Spathes 5.2–11.5 cm long, dorsally striated with long uniseriate trichomes along the striations, apex acute, oblique opening, greenish to paleaceous. Scapes 1–5, terminal, 26–31.5 cm long, multicostate, covered with trichomes along the ribs. Capitula 8.5–11.5 mm diam., hemispherical to spherical, whitish; involucral bracts in 3–4 series, brown, 2–3.5 mm long, adaxial surface densely pilose, margin densely ciliate, ovate, apex acute. Flowers trimerous, ca. 450 per capitulum, the staminate ones ca. 15x more numerous than the pistillate ones; floral bracts spathulate to linear, greenish when young to brown when senescent, 2–3 mm long, abaxially pilose from the middle to the obtuse apex, tufted, ciliate. Staminate flowers 2–3 mm long, pedicel 0.3–0.5 mm long; sepals fused at the base, obovate, brown from the middle to the apex, light brown at the base, 2–2.6 mm long, abaxial surface sparsely pilose, margin sparsely ciliate, apex acute, tufted; petals fused into a tube 2–2.5 mm long, colorless, hyaline, membranaceous; carpellodes 3, colorless to brown. Pistillate flowers 2–2.5 mm long, pedicel 0.5–0.8 mm long; sepals fused at the base, obovate, light brown to brown at the apex, 1.5–2 mm long, abaxial surface sparsely pilose, margin sparsely ciliate, apex obtuse, tufted; petals ca. 2 mm long, narrowly trullate, colorless at the middle, brownish to brown at the base and apex, abaxial surface sparsely pilose, apex acute, tufted; gynoecium 1.5–2 mm long, stigmatic branches bifid at the apex, 3x longer than the nectariferous branches. Fruits are loculicidal capsules released by the recurved sepals. Seeds 1–1.5 mm long, ovate, reddish brown.

Etymology: —The epithet “ salimenae ” is dedicated to our friend and enthusiastic botanist, Dr. Fátima R.G. Salimena, in recognition of her great efforts towards the conservation of the habitats where the new species occurs.

Distribution and Habitat: — Paepalanthus salimenae is a microendemic species restricted to Juiz de Fora municipality, in the state of Minas Gerais ( Fig. 4 ). The two known subpopulations of this species are restricted to isolated patches of quartzitic sandy soil in campos rupestres, at elevations ranging from 703 to 788 m a.s.l. ( Figs. 1 , 4A–F ).

Taxonomic Notes: — Paepalanthus salimenae is placed in P. ser. Paepalanthus . The species is morphologically distinct from P. calvus , the most similar species, due to the narrower leaves (0.4–0.7 vs. 1–1.5 cm wide), smaller leaves and spathes (5.5–13.5 and 5.2–11.5 vs. 16–23 and 16-23 cm long, respectively), leaves, spathes, and scapes with persistent trichomes (vs. glabrescent), and shorter scapes (26–31.5 vs. 50–70 cm long). The new species also presents narrower capitula (8.5–11.5 vs. 14–16 mm diam.), the involucral bracts are brown (vs. dark-brown), with trichomes (vs. glabrous), margin densely ciliate (vs. ciliate), and apex acute (vs. obtuse). The floral bracts in the new species are spathulate to linear (vs. oblong), the sepals are obovate (vs. spathulate), with abaxial surface sparsely pilose (vs. densely pilose), and the stigmatic branches are 3x longer than the nectariferous branches (vs. 2x longer). It is also worth mentioning that the new species is restricted to lower sites (700–800 m a.s.l.) of white sand soils, while P. calvus occurs in higher elevations (1.370 –1.950 m a.s.l.) over more argillaceous soils.

Paepalanthus capixaba Trovó et al. (2016: 84) , a species described from Espírito Santo state and occurring in similar habitat, shares similarities with P. salimenae . The new species described here can be distinguished from P. capixaba by the presence of stem branched with conspicuous caudex (vs. absent), shorter leaves and spathes (5.5–13.5 and 5.2–11.5 vs. 7–25 and 7–14 cm long, respectively). The new species also presents a higher number of flowers, ca. 450 in total (vs. ca. 60). Its involucral bracts are brown (vs. cream-colored to golden), with trichomes densely pilose (vs. pubescent), margin densely ciliate (vs. ciliate toward the apex) and acute apex (vs. obtuse to mucronate). The floral bracts are spathulate to linear (vs. oblong), with apex obtuse (vs. mucronate), while the sepals’ apex pilosity is tufted (vs. not tufted), the sepals abaxial surface are sparsely pilose (vs. pubescent), and the stigmatic branches are bifid at 1/3 of the length (vs. bifid at 1/10 of the length). Additionally, these two species have allopatric distributions, with populations approximately 300 km apart.

Paratypes: BRAZIL. Minas Gerais: Juiz de Fora, Toledos , 23 November 1991, M.C. Brügger & al. s.n. (CESJ 26124!, RB 781584 !) ; 29 November 1998, A.N. Caifafa & G.L. Soares s.n. ( CESJ 30513 !). BRAZIL. Minas Gerais: Juiz de Fora , Pires, 6 April 2023, A.R. Carnevalli & al. 18 ( CESJ 77558 !) ; -21.969158, -43.576473, 7 May 2023, M.D. Cabrini & al. 15 ( RB, SPF) .

Conservation status and threats: Paepalanthus salimenae is suggested as a Critically Endangered (CR) species, according to IUCN criteria B1ab(iii) + B2ab(iii) +D. The subpopulations face a high threat due to their AOO of less than 10 km ² (8 km ²), and they were found only in two private properties, including a mining company’s land ( Fig. 1A,B ). This species is likely undergoing a decline in AOO, and population size due to mining activities.

Habitat destruction and fragmentation are significant threats to a species’ genetic diversity ( Ouborg et al. 2006, Exposito-Alonso et al. 2022). Fragmentation can, in particular, diminish plant fitness and increase its vulnerability to extinction by reducing populations to smaller, isolated groups ( Oostermeijer et al. 2003, Ouborg et al. 2003). Additionally, unforeseen events, such as environmental stochasticity, fires, droughts, or anthropogenic impacts, can further exacerbate the risk of population extinction ( Lande 1998, Lienert 2004, Heinken & Weber 2013). Numerous studies have demonstrated the significant impact of anthropogenic damage on habitat, genetic diversity, and species survival ( Ledig 1992, Tilman & Lehman 2001, Le Stradic et al. 2018, Phair et al. 2020). These findings emphasize the need for further studies on the conservation of species inhabiting these areas, including P. salimenae .

Given the limited number of known subpopulations inhabiting this fragile habitat occurring in private properties— a grassland used for pasture and a mining company land—urgent conservation actions are needed to protect Paepalanthus salimenae . Based on the data obtained, we propose the inclusion of P. salimenae on the red list of Brazil and Minas Gerais State flora for legal protection. Recognizing each subpopulation as a distinct unit for conservation and management is crucial, requiring equal attention to both in situ and ex situ conservation strategies.

Figures

FIGURE 1. Distribution map of Paepalanthus calvus and Paepalanthus sp. nov.; boundaries, topography, and the estimated species’ area of occurrence. Locality abbreviations: CJ—Campos do Jordão; CJI—Pindamonhangaba; PQ—Delfim Moreira; ITA—Itamonte; EX—Extrema; MP—Minduri; IBI—Ibitipoca; PD—Caeté; JF—Toledos, Juiz de Fora; JFP—Pires, Juiz de Fora.

FIGURE 3. Paepalanthus salimenae Cabrini & Trovó sp. nov. A. Habitat. B. Leaf detail. C. Scapes and spathes detail. D. Capitulum detail. E. Involucral bract abaxial surface. F. Floral bract abaxial surface. G. Staminate flower. H. Staminate flower, evidencing the opened corolla and the nectariferous carpellodes. I. Pistillate flower. J. Gynoecium.

FIGURE 4. Habitat and habit of Paepalanthus salimenae Cabrini & Trovó sp. nov. A. Overview of the occurrence area in Juiz de Fora (Pires), with sand mining activity noted. B and C. Habitat detail in Juiz de Fora (Pires). D. Habitat detail in Juiz de Fora (Toledos). E. Clump of rosettes. F. Rosette and caudex detail. G. Leaf detail. H. Capitulum detail, lateral view. I. Capitulum detail, bottom view.