Paepalanthus aleurophyllus Trovó, 2013

Trovó, M., Echternacht, L., Sano, P. T. & Costa, F. N., 2013, Paepalanthus aleurophyllus, a new species of Eriocaulaceae from Minas Gerais, Brazil, Blumea 58 (1), pp. 77-79 : 77-79

Paepalanthus aleurophyllus Trovó , sp. nov. — Fig. 1

Typus: V. C. Souza 8400 , P. H. Miyagi , J.P. Souza (holo SPF; iso B, ESA, HUEFS, NY, P, UB, UFMG), Brazil, Minas Gerais, Santo Antônio do Itambé , “Início da estrada para o pico do Itambé. 800–1200 msm.”, 12 Mar. 1995 .

Etymology. The epithet ‘ aleurophyllus ’ alludes to the floury appearance of the leaves, due to its short and dolabriform to fusiform trichomes, which are unusual in Paepalanthus .

Herbs. Stem short, not thickened, 1–2 cm long. Rhizome absent. Leaves arranged in a rosette, flat, lanceolate, chartaceous, 5–9.5 by 0.4–0.7 cm long, green, abaxial surface glabrous with conspicuous venation, adaxial surface with short (c. 0.15–0.30 mm long), basally attached dolabriform to fusiform trichomes, margins densely ciliate, apex acute. Spathes chartaceous, 1–3 cm long, with short fusiform trichomes, apex acute, oblique opened. Scapes free, c. 6–30 per plant, arranged in a seemingly axillary position, 4.5–11.5 cm long, multicostate, with short, fusiform to filamentous trichomes between the ribs. Capitula 0.5–1 cm diam, brown involucre, white disc. Involucral bracts in 2–4 series, ovate, c. 3 mm long, brown, pilose to glabrescent on abaxial surface, ciliate to glabrescent toward the acute to mucronate apex. Flowers 3-merous, c. 40 per capitula: 30 staminate flowers, 10 pistillate flowers. Floral bracts oblong, c. 3 mm long, glabrous on both surfaces, ciliate toward the acute apex, brown. Staminate flowers c. 4 mm long; pedicel c. 0.5 mm long, with long, filamentous trichomes; sepals fused at the base, obovate, c. 3 mm long, pilose on abaxial surface apex to glabrescent, ciliate toward the obtuse apex, stramineous to dark brown; corolla tubular, glabrous, membranaceous, cream, unlobed; stamens c. 2 mm long, adnate at base to the corolla, anthers cream; pistillodes 3, elongated, papillose.

© 2013 Naturalis Biodiversity Center

Pistillate flowers c. 4 mm long, sessile; sepals fused at base, oblong to oblanceolate, c. 4 mm long, stramineous to brown, pilose on abaxial surface apex to glabrescent, ciliate toward the obtuse apex, thickening during fruit maturation; petals membranaceous, oblong to navicular, c. 3 mm long, stramineous to cream, hyaline to opaque, pilose on abaxial surface apex to glabrescent, ciliate toward the obtuse apex; gynoecium c. 3 mm long at anthesis, stigmatic branches shortly bifid at the apex, twice longer than the nectariferous branches; staminodes 3, scale-like. Fruit a loculicidal capsule.

d

Distribution & Conservation — Paepalanthus aleurophyllus is known from a few populations occurring in Santo Antônio do Itambé (Minas Gerais). These populations are restricted to a mountain known as Pico do Itambé, in the Espinhaço Range. This mountain, which is a conservation unit, hosts many endemic species of Eriocaulaceae . Trovó et al. (2011) described Paepalanthus hirtellus Trovó, Echtern. & Sano , restricted to the Pico do Itambé State Park. Silveira (1928) described various species found only in this area or also in adjacent mountains between the Pico do Itambé and the Chapada do Couto in Minas Gerais. As the region has been poorly collected, it is possible that these species are distributed more widely than currently known.

Paepalanthus aleurophyllus occurs on slopes of Pico do Itambé, which is on the boundary of the Atlantic Forest and Cerrado biomes. Nowadays, the natural habitats of the surroundings of Pico do Itambé State Park are quite fragmented, mainly because of agriculture and pasture, and the forested areas are limited to small remnants and river banks. Considering its narrow distribution, the species is endangered according to criteria B1, B2a i, and B2a of the IUCN (2011).

Habitat & Ecology — The species grows in shady places, on riparian understories. According to the herbarium sheets, individuals occupy humid, argillaceous soils. This is not very common within Paepalanthus , as most of the species occur in drier soils in open areas. The flowering period probably extends from the beginning of February to May. The species was found with fully developed flowers and fruits between March and April, coinciding with the end of the rainy period.

Morphological affinities — We place P. aleurophyllus in Paepalanthus subg. Paepalanthus due to its simple scapes, trimerous flowers, staminate flowers with glabrous corolla, and capsular fruits.A more precise placement within Ruhland (1903) classification leads to Paepalanthus ser. Paepalanthus , as the species has leaves disposed in rosette and scapes in a seemingly axillary position. Recent phylogenetic studies indicated that P. ser. Paepalanthus is polyphyletic ( Andrade et al. 2010, Trovó et al. 2013). We decided, however, to provisionally include the species into this category until a more stable classification is available.

The ciliate leaves with dolabriform to fusiform trichomes on the adaxial surface, conferring a farinaceous appearance, the conspicuous venation on the abaxial surface, and the trichomes between the scape ribs are a very rare character set within Paepalanthus . Jointly with the general habit of the species and some floral features, such as the obtuse sepals of the staminate flower, they are unique attributes to distinguish P. aleurophyllus as a new taxon. Among the congeneric species, P. aleurophyllus is morphologically similar to P. diplobetor Ruhland and P. ciliolatus Ruhland , both species also belonging to Paepalanthus ser. Paepalanthus .

Paepalanthus aleurophyllus and P. diplobetor have approximately the same general habit, given by the length of leaves and scapes (c. 3.5–9.5 cm and c. 4.5–11.5 cm, respectively), have lanceolate and pilose leaves, pilose spathes c. 1–3 cm, and brown involucral bracts. In addition to the diagnostic characters, P. aleurophyllus can be differentiated by its longer leaves of 5–9.5 cm (vs 3–5.5 cm), pubescent with trichomes shorter than 1 mm long (vs lanose with trichomes up to 5 mm long), spathes pilose as the leaves (vs lanose spathes), multicostate scapes (vs tricostate) and wider capitula of 0.5–1 cm (vs 0.4–0.5 cm). The species are allopatric, as P. diplobetor presents a southern distribution, occurring on ferruginous campos rupestres, in the Quadrilátero Ferrífero (Minas Gerais).

Another species similar to P. aleurophyllus is P. ciliolatus , also from the Quadrilátero Ferrífero. Morphological affinities are the pilose and ciliate leaves of c. 5–13 cm, the pilose scapes and spathes, and the brown involucral bracts. However, P. aleurophyllus has lanceolate, short-ciliate leaves (vs linear, long-ciliate), scapes of shorter length (4.5–11.5 cm vs 10–35 cm), and shorter spathes (1–3 cm vs 4–7 cm).

Additional specimens examined. BRAZIL, Minas Gerais, Santo Antônio do Itambé , G . Hatschbach 27512 ( RFA), 9 Sept. 1972; A. M . Giulietti CFCR 7787 , N. L . Menezes, M . Meguro ( SPF), 1 Apr. 1985 .

Note — Paepalanthus aleurophyllus is distinguished from other Paepalanthus by its densely ciliate leaves with dolabriform to fusiform trichomes on the adaxial surface, conspicuous venation on the abaxial leaf surface, and its trichomes between the scape ribs. The general habit and floral features, such as the obtuse sepals of the staminate flowers are also useful for its identification.

Figures

Fig. 1 Paepalanthus aleurophyllus Trovó. a. Habit; b. two forms of leaf hairs, on the left, a dolabriform trichome, on the right, a fusiform trichome; c. adaxial leaf surface detailing the floury indument; d. scape detailing the trichomes between the ribs; e. capitula detail; f. involucral bract abaxial surface; g. floral bract abaxial surface; h. staminate flower; i. staminate flower with sepals and pedicel removed, and opened corolla; j. pistillate flower; k. gynoecium with seeds released (Souza et al. 8400, SPF).