Plantago bradei Pilger (1949: 568)

Hassemer, Gustavo, 2017, Reestablishment of Plantago bradei (Plantaginaceae), an overlooked narrowly endemic species from Serra do Caparaó, eastern Brazil, and range extension of P. guilleminiana, Phytotaxa 296 (3), pp. 253-264 : 254-259

Plantago bradei Pilger (1949: 568)

Lectotype (designated by Rahn 1974: 104, 166):— BRAZIL. MINAS GERAIS: Alto Caparaó: Serra do Caparaó, Pico do Cristal , 2700 m, 24 September 1941, A. C. Brade 17007 (B-100294735–image! [ Fig. 1 ]).

Description: —Single-rosette herbs, up to 26 cm tall, perennial. Taproot thickened, up to 10 cm long and to 1.5 cm wide; numerous unthickened cord-like secondary roots also present. Caudex generally inconspicuous, with negligible longitudinal growth, up to 2.6 cm wide, with a crown of conspicuous (up to 1.6 cm) orange-coloured trichomes at its apex. Leaves 2.4–12.8 × 0.7–1.6 cm, coriaceous, 3- to 5-veined, densely covered with trichomes on both faces, which produce a shiny appearance; petiole indistinct from the elliptic-lanceolate blade; apex acuminate; margin sparsely denticulate. Trichomes on leaves silvery, appressed, filiform, terete, with inconspicuous cellular articulations, very slender throughout their entire length and not gradually tapering towards the apex. Plant not blackening when drying. Inflorescences 5.9–25.2 cm long. Scape 3.9–12.1 cm long, cylindrical, with longitudinal grooves, densely pilose; trichomes on scape silvery, variously directed, filiform, terete, with inconspicuous cellular articulations, very slender throughout their entire length and not gradually tapering towards the apex. Spike 2.0– 13.1 cm long, usually approximately equal to the length of the scape (except in dwarf plants, where it normally has half the length of the scape), cylindrical, multi-flowered, flowers much more densely distributed than most other species in Plantago section Virginica Barnéoud (1845: 7) , but still a little less densely distributed in the lower part of the spike, as is the norm in this section. Bracts narrowly triangular, 2.7–3.2 × 1.1–1.2 mm; apex acuminate; margin densely ciliate; keel densely pilose; dorsal face glabrous (except along the keel), rugose; ventral face glabrous, shiny. Flowers hermaphrodite. Anterior sepals elliptic, 2.4–2.7 × 0.9–1.1 mm; apex acute; margin glabrescent; keel darker and thicker than the rather hyaline wings; keel rugose on the dorsal face, pilose in the distal half; keel glabrous and shiny on the ventral face. Posterior sepals ovate, 2.8–3.1 × 1.6–1.9 mm; apex acute; margin glabrous; keel darker and thicker than the rather hyaline wings; dorsal face glabrous, rugose along the keel; ventral face glabrous, shiny along the keel. Corolla actinomorphic, glabrous; lobes patent, 1.4–1.7 × 1.0 mm, ovate, apex mucronate. Stamens 4; anthers 1.2 × 1.0 mm, light purple when fresh. Ovary with 3 ovules. Mature fruits and seeds not seen.

Etymology: —The name honours the German botanist Alexander Curt Brade (1881–1971), who collected the type of this species.

Illustrations and photographs: — Figs. 1 , 2 and 3A ; Figs. A–B in de Paula-Souza and Souza (2002) (sub P. commersoniana ).

Phenology: —Flowering from September to February. Fruiting unknown.

Distribution and habitat: —This species is restricted to rocky, shallow grasslands in the high areas (above 2300 m elevation) of Serra do Caparaó, a prominent mountainous area located between eastern Minas Gerais and southwestern Espírito Santo states, eastern Brazil ( Figs. 4 and 5 ).

Conservation status: —This species is to be considered critically endangered (CR–B2a,b[iii]) according to the IUCN (2012, 2016) criteria, because it only occurs in one locality and, although located within an environmental protection area (Parque Nacional do Caparaó) it could still be threatened as these plants occur very close to camping areas and trails where there is intense tourist visitation.

Notes: — Plantago bradei was described in Pilger (1949) as a narrowly endemic species from Serra do Caparaó, with a remarkable combination of silvery lanceolate leaves and 3-ovuled ovaries. Twenty-five years later, in his treatment of Plantago section Virginica, Rahn (1974) typified the name P. bradei (apparently unintentionally, as he used “type” instead of “ lectotype, here designated” used when lectotypifying other names) and reduced it to a synonym of P. commersoniana , on the grounds that the only difference he could find between the two species would be the number of ovules (three in P. bradei , 1–2 in P. commersoniana ), which according to him could be variable in other species of Plantago within this section. Rahn’s new definition of P. commersoniana included, therefore, plants with very variable morphology (ranging from linear to elliptic-lanceolate leaves, and rather lax to densely packed spikes) and a remarkable disjunct distribution ( Fig. 5 ).

The examination of herbarium specimens of these plants from Serra do Caparaó ( P. bradei ), in addition to field work there and in most other areas where P. commersoniana has been recorded has evidenced that there are considerable morphological differences between the population from Serra do Caparaó ( P. bradei ) and all other populations of P. commersoniana ( Fig. 6 ; Fig. 44 in Rahn 1974; Fig. 3A–H in Hassemer et al. 2014; Fig. 5A in Hassemer 2016) ( Tab. 1). The principal characters distinguishing these two species are the leaves (elliptic-lanceolate and coriaceous in P. bradei , linear and papiraceous in P. commersoniana ), the inflorescences (densely packed in P. bradei , rather lax in P. commersoniana ) and the number of ovules (three in P. bradei , 1–2 in P. commersoniana ). In addition to that, the caudex in P. bradei is much wider and more robust than in P. commersoniana , which is a remarkably slender and fragile species. Plantago bradei also has some morphological similarities with P. rahniana ( Fig. 1 in Hassemer et al. 2014; Fig. 5C in Hassemer 2016) ( Tab. 1), which was itself only recently segregated from the P. commersoniana complex.

Perhaps even more important than these morphological differences, which are particularly striking when living plants are compared, the distribution gap between the area of occurrence of P. bradei and the nearest known population of P. commersoniana (in Guarapuava municipality, Paraná state, southern Brazil) is impressive, ca. 1150 km. Suitable habitats for both species do exist between these areas, e.g. in Serra do Itatiaia (high mountains between western Rio de Janeiro and southern Minas Gerais states); however, neither species has ever been collected there, despite being a botanically well-known and well-sampled area. Based on that, it is evident that there is no gene flow occurring between these populations, even if that would be possible in the first place. It is important to remark that species of Plantago do not have specialised seed dispersal mechanisms, and as a consequence Plantago populations are generally highly aggregated and have low gene flux with other populations. These facts reinforce the morphological evidence presented, in supporting the recognition of P. bradei .

Since there is no overlapping of the taxonomically-relevant characters distinguishing P. bradei from P. commersoniana ( Tab. 1), and because only one population of P. bradei is known to exist, and only very few collections of this species are available (see below), it seems unnecessary to apply morphometric analyses to separate these two species. In any case, the considerable morphological differences between these species and their completely different distributions are enough to justify their segregation, in line with the current taxonomy of Plantago section Virginica ( Rahn 1974, Hassemer et al. 2015, Hassemer 2016).

I have not been able to see mature fruits or seeds of P. bradei , as neither did Pilger (1949) nor Rahn (1974), who only saw the type of this species. Furthermore, de Paula-Souza and Souza (2002) do not include the seeds of this species in their morphological description and illustrations. I expect that the recognition of this species will bolster the taxonomic and conservation interest in P. bradei , therefore increasing the scientific knowledge on this rare and remarkable species, and also stimulate more studies of the flora of Serra do Caparaó, a geologically and biologically unique and interesting area.

Additional specimens examined: — BRAZIL. ESPÍRITO SANTO: Dores do Rio Preto: Parque Nacional do Caparaó, entre Arrozal e Morro do Tesouro , campo de altitude, 18 February 2000, J. de Paula-Souza et al. 3098 (ESA-64290– image!; MBM-244533!) ; MINAS GERAIS: Alto Caparaó: Parque Nacional do Caparaó, caminho entre Tronqueira (1970 m) e o Pico da Bandeira (2890 m), campo de altitude, 2 September 1996, V. C. Souza et al. 12183 (ESA-37391–image!) ; Parque Nacional do Caparaó, trilha para o Pico da Bandeira , próximo à casa de pedra, campo de altitude, 1790–2400 m, 12 February 1998, J. de Paula-Souza et al. 2131 (ESA-61835–image!) ; Parque Nacional do Caparaó, trilha de Tronqueira ao Pico da Bandeira , 9 March 2010, J. M. da Silva & J. Cordeiro 7646 (MBM-359625!) ; Parque Nacional do Caparaó, trilha para o Pico da Bandeira , ca. 4 km da Tronqueira, 20°25’15” S, 41°48’16” W, 22 September 2012, A. V. Scatigna & M. Monge 262 (UEC-180606–image!) ; Serra do Caparaó , 20°25.306’ S, 41°48.704’ W, 2368 m, 2 November 2015, G. Hassemer et al. 826 ( ASE!; B!; C!; FT!; FURB!; VIES!; W!; WELT!) .

Figures

FIGURE 1. Lectotype of Plantago bradei (A.C. Brade 17007, B-100294735). Available online from: http://herbarium.bgbm.org/object/ B100294735.

FIGURE 2. A and B: Plantago bradei in its natural environment in Serra do Caparaó.

FIGURE 3. A: Population of Plantago bradei in high-elevation grasslands in Serra do Caparaó. B: Population of Plantago guilleminiana in a semi-shaded area in Serra do Caparaó.

FIGURE 4. Overview of Serra do Caparaó. A: Rock outcrops area. B: Environment aspect close to the summits (high-elevation grasslands).

FIGURE 5. Distribution map of Plantago commersoniana (purple dots) and other species that were segregated from it since Rahn (1974): P. bradei, and also the location of the new records of P. guilleminiana in Serra do Caparaó (green star); P. hatschbachiana (red diamonds); and P. rahniana (yellow triangles).

FIGURE 6. Plantago commersoniana in Parque Salto del Penitente, Lavalleja, southern Uruguay. A: Aspect of plant. B: Detail of inflorescence. Photographs by Eduardo Marchesi, November 2015.