Paepalanthus altamirensis, Tissot-Squalli, Mara L. & Sauthier, Luana J., 2017

Tissot-Squalli, Mara L. & Sauthier, Luana J., 2017, Paepalanthus altamirensis, a new species of Paepalanthus subg. Platycaulon (Eriocaulaceae) from Brazil, Phytotaxa 299 (2), pp. 252-260 : 253-254

Paepalanthus altamirensis Tissot-Sq. & Sauthier sp. nov. ( Figs. 1–4 )

Type: — BRAZIL, Minas Gerais, Nova União, Altamira, Mutuca de Cima, Serra do Cipó, ( SAD 69): 19°29’17’’S, 43°34’22’’W ± 4 km, 16 November 2013, Tissot-Squalli s.n. (holotype HUI 3881!, isotypes HUI, BHCB, SPF, B).

Diagnosis:— Paepalanthus altamirensis differs from other taxa by the following set of features: red coloration on the foliar base, leaf indumentum persistent with long trichomes, leaf superficial waxes absent, undulations on abaxial leaf surface, leaf hypodermis with at least two layers of cells, vascular bundles in the pith on the scape, and external involucral bracts white.

Perennial herbs, 5–30 cm long. Rosette usually with rhizome. Stem vertical, 2.7–5.5 cm thick and 1.9–5.3 cm long, diameter consistent as the plant is growing. Leaves flat, chartaceous, acuminate to acute; linear, 8.8–17.7 cm long, 0.4–1.5 cm wide at the base and 0.3–0.9 cm wide in the middle; relative length 19.6–35.8, leaf base at least twice as wide as the middle region; without superficial wax; undulated on abaxial surface; stomatic area of the hydathode glabrous; leaf indumentum usually persistent on adaxial and abaxial surfaces, but glabrous or scarcely pilose at the apex, mainly on adaxial surface; indumentum on leaf margins persistent or deciduous, with trichome basal cells persistent and clearly visible, trichomes long and usually upright with more than 3 cells; adaxial surface of foliar base red; membrane at the margin of leaves absent; collenchyma along the leaf margin present; hypodermis present at the adaxial side of the mesophyll, with at least 2 layers of cells; remnants of vascular bundles at the base of the rosette deciduous. Inflorescences are capitula arranged from 2–9 in a single row at branched scarcely pilose scapes; scapes 12–20 cm long, 1.14 times the length of the leaves; vascular bundles in one or more rings around the pith; some vascular bundles in the pith and also in the cortex; number of scapes during a flowering season 1–22; sheath present, chartaceous, green, glabrous, almost one third of the leaf length, margin smooth, without cilia, straight and truncate, “U”–shaped from lateral view; involucral bracts glabrous on the dorsal face; external involucral bracts lanceolate to ovate, strongly acuminate or caudate, white, as long as or longer than the capitulum, surpassing the internal involucral bracts; internal involucral bracts lanceolate to ovate, obtuse to acute, green to dark brown. Flowers 3-merous; floral bracts lanceolate to ovate, obtuse to acute, ciliated; sepals of pistillate flowers 2–3.2 mm long, ciliate toward the apex, otherwise glabrous; petals of pistillate flowers 0.2–2.8 mm long, ciliate toward the apex and on the lateral margins; pistil 0.1–2.2 mm long; stigmatic branches bifid; sepals of staminate flowers 0.8–2.8 mm long, ciliate toward the apex, otherwise glabrous; stamens 0.7–2.7 mm long.

Etymology:— This species is named after the locality where it was found.

Distribution, Habitat and Conservation:— Paepalanthus altamirensis is known only from Serra do Cipó in Brazil, forming a single population growing over rocky soil dominated by an assemblage of grasses belonging to the genera Andropogon Linnaeus (1753: 1045) , Axonopus Palisot de Beauvois (1812: 12) , Panicum Linnaeus (1753: 55) and Paspalum Linnaeus (1759: 855) , among others. In addition to species of Eriocaulaceae , species of Poaceae Barnhart (1895: 7) , Velloziaceae Agardh (1858: 55) , Cyperaceae Jussieu (1789: 26) and Xyridaceae Agardh (1823: 158) are also representative of this landscape. Other populations of P. altamirensis were not found after searches at several sites of potential occurrence in the Serra do Cipó and in nearby areas around the municipalities of Serro, Milho Verde, Diamantina, Conselheiro da Mata, Datas, São Gonçalo do Rio das Pedras and Itabira, among others, where several other species of Eriocaulaceae can be found. The number of mature individuals, counted in 2013, is low, with fewer than 50 plants found. The occurrence area of the new species is less than 100 km 2 and its occupancy area is less than 10 km 2. It is possible the species could become extinct within a very short time, because of the effects of human activities where it occurs, such as fire and cattle grazing. In addition, Serra do Cipó is a very popular tourist destination; there are hostels nearby and the area is used for camping. Because of this, P. altamirensis can be ranked as critically endangered (CR) in accordance with the IUCN (2016) criteria (B1a,b + B2a,b).

Morphological comments:— Given the transversal orientation of capitula on the scape, we place P. altamirensis in P. sect. Divisi. This species is similar to some other species of this section, but can be differentiated by vegetative and reproductive features, such as the white bracts (rare in P. subg. Platycaulon , which usually has brown bracts), the red adaxial surface of the foliar base (the leaf base is usually green in P. subg. Platycaulon ), undulations in the leaves surface (which may be visible or not in P. subg. Platycaulon ), the disposition and presence of vascular bundles in the scape pith (these features are variable in the subgenus), the presence of leaf hypodermis (the hypodermis can be absent, 1-layered or 2-layered or variable in some species), the presence of collenchyma along the leaf margin (which can be absent in several species) and the persistent indumentum on leaves.

The red color on the foliar base is a good starting point for identification of the new species. According to Tissot-Squalli (1997a), only six species of P. subg. Platycaulon present this character, including P. corymbosus ( Bongard 1831: 629) Kunth (1841: 509) , P. laxifolius Körnicke (1863: 395) , P. moedensis Silveira (1928: 134) , P. spixianus Martius (1835: 14) , P. trichopetalum Körnicke (1863: 399) and P. vellozioides Körnicke (1863: 401) . Paepalanthus laxifolius is a caulescent plant and cannot be confused with P. altamirensis , which has a rosette habit with a short rhizome. Detailed morphological comparison of these species is listed in Table 1.

Some characters are variable in P. altamirensis . Young plants usually have smaller leaves compared to older plants, and the indumentum is persistent in young individuals but deciduous, especially at the apex and on leaf margins, in older plants. These features may be associated with the environment where the species occur. In young plants, the density of indumentum may increase survival in dry areas, as the trichomes help minimize water loss and exposure to ultraviolet radiation ( Levin 1973).

The red color and the width of the foliar base in the new species are also variable. In older plants the foliar base is at least twice as wide as the middle region, whereas in younger plants they are the same width. In older individuals, the red color is markedly noticeable in expanded leaves, but in young leaves, in the central region of rosette, this coloration is often lighter in tone. For identification, fully expanded leaves from the base of the rosette should be examined, since in these the red color is most clearly visible.

Paepalanthus altamirensis has a sweet smelling of its rhizome. This was noticed in the field. However, after specimens were dried, this feature was lost. Further phytochemical research of this scent may be warranted, as many compounds of pharmaceutical interest have been found in Paepalanthus ( Vilegas et al. 1998, Vilegas et al. 1999, Zanutto 2013).

Figures

FIGURE 1. Paepalanthus altamirensis, (A) inflorescences; (B) habitat in the type locality near Nova União Minas Gerais; (C) habit at the same site; (D) young inflorescences and indumentum of adaxial leaf surfaces; (E) red color on the adaxial surface of the leaf base; and (F) undulation and pubescence of abaxial surface. Photos A–D by M.L. Tissot-Squalli and E–F by L.J. Sauthier.

FIGURE 2. Paepalanthus altamirensis. Vegetative and reproductive characteristics. (A) apex of the leaf; (B) foliar base; (C) partial capitula; (D) scape with the organization of partial capitula; (E) sheath and (F) habit. Illustration by L. Sauthier.

FIGURE 3. Paepalanthus altamirensis. Floral structures. (A) external involucral bract; (B, C) internal involucral bracts, (C) internal involucral bract from the more internal series; (D) floral bract of staminate flower; (E) floral bract of pistillate flower; (F) sepal of pistillate flower; (G) petal of pistillate flower; (H) sepal of staminate flower; (I) pistil with stigma and appendices; (J) staminate flower with anthers and nectaries. Illustrations by L. Sauthier.

FIGURE 4. Anatomy of Paepalanthus altamirensis. (A) Leaf margin in transverse section, adaxial side up; (B) Scape in transverse section. Abbreviations: Ep Epidermis, Hy Hypodermis, Co Collenchyma, Pa Parenchyma, VS Vascular Sheath, X Xylem, P Phloem, Sc Sclerenchyma, VB Vascular Bundles.