Paepalanthus canastrensis Silveira 1928

Paepalanthus canastrensis Silveira (1928a: 228). (Figs. 3–5) Diagnosis: — Paepalanthus canastrensis differs from P. versatilis by the brown to dark brown external involucral bracts, at least one third shorter than the capitulum high (× stramineous to light brown, as long as the capitulum or almost its high) and by the remnants of vascular bundles deciduous or absent in straw fibers (× persistent, castaneous fibers). From P. aulociliatus, it differs by the non-ciliated staminate flower tube (× ciliated), internal involucral bracts ovate (× orbiculate) and by the linear to lanceolate leaves (× narrow-triangular). Type: — BRAZIL. Minas Gerais: In campis arenosis siceisque in Serra da Canastra. April 1925, A.A. Silveira 745 (Lectotype designated here: R barcode R000139231a!, isotype R barcode R000139231!). Perennial herb, 11.5–38.6 cm high, habit in rosette, stem vertical, internodes shorter than 0.5 cm, remnants of vascular bundles deciduous or absent in straw fibers.Leaves 8.2–31.7 × 0.4–2.3 cm, spirallate, flat, linear to lanceolate, leathering, with or without superficial wax, glabrous; apex cuspidate, acute to attenuate, glabrous below the hydathodes area; margins ciliated with long deciduous cilia; leaf base with a paler color, membrane absent. Spathe membranaceous, almost transparent to green, very short and inconspicuous with 0.5–1 cm long, ciliated, truncate. Scapes 8–37.8 cm long, glabrous to scarcely pilose, branched, grouping free capitula. External involucral bracts lanceolate to ovate, at least one third shorter than the internal involucral bracts, dorsally glabrous to pilose with a dense to scarcely persistent indumentum, obtuse to acute, brown to dark brown. Internal involucral bracts lanceolate to ovate, dorsally glabrous to pilose with a dense or scarcely persistent indumentum, obtuse to acute, brown to dark brown. Flowers trimerous. Staminate flower 2–4 mm long; floral bracts 2–4 mm long, lanceolate to ovate, dorsally glabrous but densely pilose towards the apex with subclavate trichomes, obtuse to acute; sepals 1.2–4 mm long, obovate, connate until the middle or up the basal one third, obtuse to acute; floral tube not ciliated, hyaline. Pistillate flower 1.8–4.5 mm long, pedicellate; floral bracts 1.7–4.5 mm long, lanceolate, dorsally glabrous but densely pilose towards the apex with subclavate trichomes, obtuse to acute; sepals 2–4.5 mm long, oblanceolate, connate at the base, obtuse to acute; petals of pistillate flowers 1.1–3.5 mm long, oblanceolate to obovate, obtuse to acute; gynoecium with nectariferous branches shorter than the stigmatic branches. Fruit loculicidal capsule. Seeds 1.5–1.6 mm, reddish brown, tegument forming white appendages after hydration. Habitat, distribution and conservation: — Paepalanthus canastrensis has the widest distribution among the species evaluated, sympatric to most of them, occurring in the Chapadão do Diamante and Chapadão do Zagaia, with some records in the Serra do Cemitério and Serra da Canastra (Figs. 2, 5). Recent field expeditions were able to record the species outside of the Serra da Canastra region, in the adjacent mountain Serra da Pimenta, expanding the distribution of the species, which until then was considered endemic to this region. The species inhabits sandy dry soil to temporarily wet organic soils. The main threat observed for P. canastrensis is the fire (Fig. 15), which mainly affects the survival of young individuals. It is a constant threat factor, which can fluctuate with greater or lesser intensity in different regions, with a low average recurrence of fires in populations. Some already inactive quartzite mining degradation processes can occasionally be found in the region. Paepalanthus canastrensis has an AOO of 104 km 2 and EOO of 1,904 km 2 (Fig. 14), which indicates a conservation status of Endangered (EN), according to the criteria B1ab(iii)+2ab(iii). Morphologic comments: — Silveira (1928a) has described two P. subg. Platycaulon species from Serra da Canastra, P. canastrensis and P. gustavii Silveira (1928a: 227). Analysis of the type materials of these species shows that the most significant difference between them is the pilosity in the involucral bracts. Silveira (1928a) mentioned this difference. The involucral bracts of P. gustavii were described as pubescent and becoming glabrous (dorso pubescents demum glabrescentes), while in P. canastrensis, they all are externally pubescent (omnes extus pubescentes). In addition, the type of P. canastrensis is a more robust plant than the type of P. gustavii. However, due the lack of more distinctive evidence, P. gustavii was considered a synonym of P. canastrensis (Tissot-Squalli 1997a, 1997b). Recent field expeditions to the Serra da Canastra were able to register specimens from the same population at different times. They revealed plants with involucral bracts densely pilose to scarcely pilose after and during the dry season (Figs. 3 h-j; 4b,c,o,p,b’,c’,o’,p’). This particularity was observed in the Serra Brava Mountain (Fig. 2d), one of the many mountains in the Serra da Canastra, where the same population englobes these two conditions of pilosity on the involucral bracts. Neighbor populations of Serra Brava show mainly scarcely pilose involucral bracts to plants which are almost glabrous. We concluded these differences in pilosity as a morphologic variation of the same species. The Serra Brava has dry sandy soil, which does not accumulate water during the rainy season. As for the neighboring populations, the substrate has an organic composition and water-holding capacity (Fig. 2c). Álvaro da Silveira mentioned both the dry and humid conditions for P. canastrensis. In the herbarium, the habitat description points to a dry substrate (in campis arenosis siceisque), whereas in Floralia Mountium (Silveira 1928a) it is described as humid (in campis arenosis humidisque). The Serra da Canastra covers a wide range of environments (Fig. 2) and it is possible that Álvaro da Silveira observed the species in both conditions. Thus, the variation in trichome density may be linked to a natural strategy to reduce dehydration and reflect the ultraviolet irradiation (Karabourniotis 2020; Wang et al. 2021). The width variation of leaves in P. canastrensis is also quite significant. The variation ranges from leaves as narrow as 0.5 cm, linear in shape (Fig. 3b), to lanceolate measuring over 2 cm (Fig. 3c, d). Most of the records of the linear morphotype lack original coordinates, but based on the habitat and locality descriptions in the herbaria, we suspect that these plants are restrict to the Chapadão do Diamante, whereas the lanceolate morphotype are distributed throughout the Serra da Canastra. Apart from the differences in leaf shape and width, the linear morphotype exhibits glabrous involucral bracts (Fig. 4 a-c) and fewer capitula per scape compared to the lanceolate morphotype (Fig. 3h), while both pistillate and staminate flowers remain identical (Fig. 4). Nomenclatural notes: —The examined material indicated by Silveira (1928) consists of two sheets and a photograph. Álvaro da Silveira had a different system for storing his collection, where all the specimens under the same label were kept together in an envelope with a single label (Lazzari 2000). During the process of incorporation into Museum Nacional Herbarium (R), the photographed specimen apparently did not receive the original label, but rather a photocopied one. Here, we designate the material in better conservation (R barcode R000139231a) as the lectotype in a second step of lectotypification, as it is not possible to definitively recognize the specimen photographed by Silveira. Additional specimens examined: — BRAZIL. Minas Gerais: São Roque de Minas, Parque Nacional da Serra da Canastra, estrada para Sacramento, próximo a muro de pedra ao lado direito da estrada e a manilha de água, 30 March 2013, L.M. Borges 1039 et al. (SPF, RB); Morro ca. 2 km da sede administrativa, 20º15’36’’S 46º25’26’’W, elev. 1342 m, 23 June 2001, N.M. Castro 17 et al. (SPF, HUFU image); Serra Brava, 1480 m, 02 October 1999, F.N. Costa 121 et al. (SPF, HUIRB); Nascente do rio São Francisco, 20 November 2002, F.C. Duarte 104 et al. (HUFU image); Estrada São Roque-Sacramento, campo limpo após Curral de Pedras, 22 November 1998, M.A. Farinaccio 201A et al. (SPF, HUIRB); Estrada entre São Roque e a nascente do Rio São Francisco, 20º15’03’’S 46º26’05’’W, 31 May 2014, M.S. Freitas 31 et al. (HUFU image); Percurso entre a Portaria 2 [São João Batista da Canastra] e a nascente do Rio São Francisco, próximo à parte alta da Casca d’Anta, 20º16’49’’S 46º31’16’’W, elev. 1353 m, 29 May 2014, L. Echternacht 2473 et al. (HUFU image); Estrada para Sacramento, próximo ao vale da nascente do rio São Francisco, 17 April 1994, J.N. Nakajima 274 et al. (SPF, HUFU image); 2 km da sede administrativa, estrada para Sacramento, 15 October 1994, J.N. Nakajima 517 et al. (SPF, HUFU image); Estrada para Sacramento, morro após o vale do rio São Francisco, 18 March 1995, J.N. Nakajima 802 et al. (SPF, HUFU image); Colina próxima à sede, lado esquerdo da estrada, 20 February 1994, R. Romero 629 & J.N. Nakajima (HUFU image); Estrada para cachoeira Casca d’Anta, 24 February 1994, R. Romero 728 & J.N. Nakajima (SPF, HUFU image); Primeiro morro próximo à sede, 26 June 1994, R. Romero 1020 & J.N. Nakajima (HUFU image); 19 km da sede administrativa, estrada São Roque-Sacramento, 28 June 1994, R. Romero 1071 & J.N. Nakajima (SPF, HUFU image); 1 km após torre de observação, estrada para Sacramento, 23 Aug 1994, R. Romero 1159 et al. (SPF, HUFU image); Morro próximo à sede administrativa, 10 January 1995, R. Romero 1653 et al. (SPF, HUFU image); 17 March 1995, R. Romero 1946 et al. (SPF, HUFU image); 15 July 1995, R. Romero 2375 et al. (SPF, HUFU image); Estrada São Roque-Sacramento, 3 km da sede administrativa, 15 July 1995, R. Romero 2403 et al. (SPF, HUFU image); Morro do Careca, 20 Januar