Paepalanthus argyrotrychus F.N. Costa, Andrino & Echtern., 2016

Costa, Fabiane Nepomuceno, Andrino, Caroline Oliveira, Trovó, Marcelo, Echternacht, Livia & Sano, Paulo Takeo, 2016, Three new micro-endemic species of Paepalanthus (Paepalanthoideae, Eriocaulaceae) from Serra do Ambrósio, Minas Gerais, Brazil, Phytotaxa 247 (2), pp. 118-126 : 119-122

Paepalanthus argyrotrychus F.N. Costa, Andrino & Echtern. , sp. nov. ( Figs. 1A–E , 2B , 4 )

Type:— BRAZIL. Minas Gerais: Rio Vermelho, Serra do Ambrósio, Vargem do Anjo, próximo à comunidade de Pedra Menina, 1334 m elev., 18°08’02.4”S, 43°01’02.3”W, 26 June 2012, F. N. Costa, A. B. Sampaio, R. Ramos & S. N. Fonseca 1542 (holotype DIAM!, isotypes B!, SPF!)

Paepalanthus argyrotrychus is characterized by its densely sericeous indumentum on both surface of leaves and spathes, sparsely villous or more frequently glabrous and golden-colored scapes, and brown involucral bracts.

Perennial herbs. Rhizome thickened or not, 1–10 cm long. Leaves rosulate, flat to reflexed, light green to silvery, chartaceous, lanceolate, 6.0–14.0 × 0.3–0.7 cm, adaxial surface sericeous, abaxial surface densely sericeous, margin pilose, apex mucronate. Spathes appressed to the scapes, chartaceous, 6–12 cm long, densely sericeous, margin ciliate, apex acute. Scapes ca. 3–22 per rosette, golden, 22–28 cm long, multicostate, sparsely villous to glabrous. Capitula hemispheric, 1.0– 1.5 cm diam. Involucral bracts in 4–5 series, brown, ovate, ca. 2.0–3.0 × 1.5–2.0 mm, glabrous on adaxial surface, lanose to glabrescent abaxially, margin ciliate, apex obtuse. Flowers 3-merous, ca. 120 per capitula: 2× more staminate than pistillate. Floral bracts dark brown to cream-colored, lanceolate to oblanceolate, ca. 4 mm long, glabrous on both surfaces, margin ciliate, tufted at the acute apex. Staminate flowers ca. 3 mm long, excluding the pedicel; pedicel ca. 1 mm long, with long and numerous trichomes; sepals free to fused up to the middle, membranaceous, lanceolate, ca. 3 mm long, glabrous on both surfaces, margin ciliate; corolla tubular, membranaceous, cream, hyaline, glabrous; stamens ca. 2.5–4.0 mm long, anthers cream; pistillodes 3, papillose. Pistillate flowers ca. 2.0– 4.5 mm long, excluding the pedicel; pedicel ca. 0.2–0.5 mm long, with long and numerous trichomes; sepals fused at the base, membranaceous, cream, lanceolate, ca. 2.0–4.0 mm long, glabrous on both surfaces, margin ciliate towards the obtuse apex; petals membranaceous, hyaline, lanceolate, ca. 2.0–4.0 mm long, glabrous on both surfaces, margin ciliate; gynoecium ca. 3 mm long, stigmatic branches bifid at the apex, 1× longer than the nectariferous branches; staminodes 3, scale-like. Seeds reddish to brown, rounded, striate.

Etymology:— The epithet “ argyrotrychus ” refers to the silvery appearance of the leaves with sericeous indument.

Distribution and habitat: — Paepalanthus argyrotrychus is known from only one locality in Rio Vermelho municipality, at the top of a mountain locally known as Espigão do Meio, in Serra do Ambrósio. Paepalanthus argyrotrychus is terrestrial and occurs in open areas, in Campos Rupestres between 900 to 1330 meters of elevation, growing over white, coarse, sandy to gravelly, quartzitic soil ( Figs. 2A and 4 ).

Conservation: —This species is known from only two subpopulations and the area of occupancy is eight km 2. The subpopulations are not included in any protected area. Due to its very narrow distribution and proximity to mining sites for sand extraction, the species is considered critically endangered (CR), fulfilling criteria B2ab (i, ii, iii, iv, v) and C2a (i) ( IUCN 2011).

Discussion: — Paepalanthus argyrotrychus is morphologically similar to P. farinaceus , which is another new species described here, and P. albo-tomentosus Herzog (1924: 83) . From all the other Paepalanthus species it can be easily differentiated by its light green to silver leaves and spathes due to the presence of sericeous indument with white trichomes, golden and frequently glabrous scapes, and brown and abaxially glabrous involucral bracts. The silvery color of leaves and spathes contrasts strongly with the usual golden and brown colors of scapes and involucral bracts, respectively (see Fig. 2B ). Paepalanthus albo-tomentosus also shows this contrast of color between leaves and spathes vs. scapes and involucral bracts; however, its vestiture is densely tomentose (vs. sericeous), including the involucral bracts (vs. glabrous). Paepalanthus argyrotrychus and P. farinaceus have a similar general habit, with sericeous leaves, but the former can be easily distinguished by its light green to silvery leaves (vs. whitish), golden and glabrous scapes (vs. whitish and sericeous to glabrescent), and brown involucral bracts, which are glabrous abaxially (vs. stramineous to cream and sericeous abaxially). Paepalanthus argyrotrychus and P. farinaceus are sympatric on the Serra do Ambrósio; Paepalanthus albo-tomentosus is known only from Serra das Almas (Brumado municipality, Bahia), ca. 500 km N from Serra do Ambrósio.

The flowering period probably extends from June to October, the period when specimens were collected with flower and fruit. The sepals are fused at the base and possibly play a role in ejecting the fruit from the inflorescence in wind dispersal, as described by Hensold (1988) and Trovó & Stützel (2011).

Additional specimens examined (paratypes): — BRAZIL. Minas Gerais: Rio Vermelho, Fazenda Vargem do Anjo, Espigão do Meio , October 1984, E. Isejima , R. Mello-Silva , J. R. Pirani & M. Meguro CFCR 5469 ( SPF) ; Fazenda Vargem do Anjo, Morro Espigão do Meio , June 1991, R. Mello Silva, M. L. F. Salatino, A. Salatino & P. Affonso 421 ( SPF) ; Serra do Ambrósio, Espigão do Meio , August 1985, R. Mello Silva CFCR 7884 ( SPF, MBM) ; Pedra Menina, Serra do Ambrósio, extração de areia da Várzea do Anjo , 898 m elev., 18˚07’55.74” S, 43˚02’23.07” W, July 2013, R. R. Silva, S. N. Fonseca & S. R. Silva 97 ( DIAM) .

Figures

FIGURE 1. Paepalanthus argyrotrychus F.N. Costa, Andrino & Echtern. A. Habit. B. Capitulum with flowers at anthesis. C. Involucral bract, abaxial surface. D. Pistillate flower. E. Staminate flower. Paepalanthus farinaceus F.N. Costa, Andrino & Trovó. F. Habit. G. Capitulum with flowers at anthesis. H. Involucral bract, abaxial surface. Paepalanthus velutiphyllus F.N. Costa, Andrino & Sano. I. Habit. J. Leaf, adaxial surface. (Drawn from the holotypes).

FIGURE 2. A. Top of the mountain Espigão do Meio, in Serra do Ambrósio. B. Habit of Paepalanthus argyrotrychus F.N. Costa,Andrino & Echtern. C. Habit of Paepalanthus farinaceus F.N. Costa, Andrino & Trovó. (Photos by F.N. Costa).

FIGURE 4. Map showing the distributions of three new species.