Praxelis minima A. Teles & P.L. Viana, 2016

Teles, Aristônio M., Viana, Pedro L. & Esteves, Roberto L., 2016, Taxonomic novelties in Praxelis (Asteraceae, Eupatorieae): a new species and a new combination, Phytotaxa 278 (1), pp. 48-54 : 49-53

Praxelis minima A. Teles & P.L. Viana , sp. nov. ( Figs. 1 , 2 , and 3)

The new species differs from Praxelis kleinioides ( Kunth 1820: 128) Schultz-Bipontinus (1866: 254) in its erect stem, petiolate leaves, peduncles 0.5–3.8 cm long, involucre 4–5 mm long, involucral bracts 13, florets ca. 22 per capitulum, and corolla ca. 2 mm long (vs. stem prostrate, leaves sessile, peduncles 5–10 cm long, involucre 7–10 mm long, involucral bracts ca. 22, florets 25–30 per capitulum, and corolla 5–5.5 mm long).

Type:— BRAZIL. Minas Gerais: Aiurouca, Parque Estadual do Papagaio, subida para o Pico do Papagaio, saindo do Retiro dos Pedros, 22°02 ′ S, 44°39 ′ W, 1900 m, 12 March 2008, P. L. Viana 3923, N. F. O. Mota, L. A. Echternacht, L. V. C. Silva & G. M. Maciel (holotype BHCB, isotypes K, UFG, US).

Annual herbs, 5.5–8.5 cm tall. Stem erect, terete, simple, hirsute, trichomes eglandular, leafy throughout. Leaves opposite-decussate, petiolate, petiole 1–3 mm long; blade 4–11 mm long, 1–5 mm wide, ovate to lanceolate, apex acute, base attenuate, decurrent, penninerved, secondary veins inconspicuous, hirsute on both sides, trichomes eglandular, whole margins serrate, revolute. Capitula homogamous, discoid, pedunculate, solitary, terminal or axillary; peduncles 0.5–3.8 cm long, hirsute, bracteolate; bracteoles linear, ca. 2 mm long; involucre campanulate, 4–5 mm long, 3–4 mm diam.; involucral bracts 13, 3–4-seriate, imbricate, series decreasing in size towards base, scarious, outer bracts (first series) 2–3 × 0.8–1 mm lanceolate, apex acuminate, middle bracts (second series) 3–3.5 × 1–1.2 mm, oblanceolate, apex acute, inner bracts (third and fourth series) ca. 5 × 1.7 mm, oblanceolate, apex acute, 3–7-veined, all deciduous, burgundy-coloured (in fresh material); receptacle conical, foveate. Florets perfect, ca. 22, corolla ca. 2 mm long, funnelform, 5-lobate, lobes 0.5 mm long, papillose, lavander; filaments with anther collar basally dilated (balusterform), anthers ca. 0.8 mm long, inserted, base obtuse, apical anther appendage ca. 0.1 mm long, oblong; style 2.1–3 mm long, branches 1–1.5 mm long, apex obtuse, densely papillose, base cylindrical, glabrous. Cypselae (immature) ca. 2 mm long, flattened, 4-ribbed, setuliferous, ribs ciliate; carpopodium distinct, broad, asymmetrical; pappus 1–2 mm long, barbellate bristles ca. 20, 1-seriate, persistent.

Distribution and Ecology:— This new species is so far known only from the Parque Estadual da Serra do Papagaio, in Aiurouca and Baependi municipalities, Minas Gerais State, Brazil ( Fig. 3 ) ( Table 1). This conservation area is situated in the Serra Mantiqueira range, and protects important remnants of Atlantic Rain Forest and highland grasslands, locally referred to as campos de altitude. The species was collected growing on granite rock outcrops, forming clumps among mosses and other annual plants ( Fig. 2 ), on a mountain summit, at 1.900 –2.050 MASL

Conservation Status:— The only known collections of Praxelis minima were collected in the surroundings of the Papagaio peak, with an area of occupancy estimated to be less than 10 km 2. According to IUCN Red list categories and criteria ( IUCN 2016), this species should be evaluated as Critically Endangered (criterion B, subcriteria B1 and B2, and criterion D).

Phenology:— Flowering specimens were collected in March and April.

Etymology:— The specific epithet is an allusion to the minuscule size of the species, an impressive characteristic that is infrequent in the genus.

Additional specimens examined (paratypes):— BRAZIL. Minas Gerais: Baependi, Serra do Papagaio State Park, Pico do Papagaio, 22°02 ′ 38 ″ S, 44°38 ′ 33 ″ W, 2.050 m, 8 April 2016, J.G.F. Mendonça, E. Landroz, L. Sandanha, A. Dale & F. Villela 218 (CESJ, UFG).

Discussion:— Praxelis minima attracts the attention by its minute size, and appears to be related to P. kleinioides , but the latter shows some differences like greater height, stem prostrate, leaves sessile, and peduncles, involucre, and corolla larger than in P. minima , besides more numerous involucral bracts and florets.

Praxelis decumbens (Gardner) A. Teles & R. Esteves , comb. nov. Chromolaena decumbens Gardner (1846: 466) . Eupatorium decumbens (Gardner) Baker (1876: 344) .

Type:— BRAZIL. Minas Gerais: dry hills near Morro Velho, September 1840, Gardner 4754/3 (holotype BM barcode BM 000541018).

Distribution:— Endemic to Brazil, found in the Minas Gerais and São Paulo States (BFG 2015) ( Table 1).

Discussion:— This species was described by Gardner (1846: 466) in the genus Chromolaena . However, Baker (1876: 344) included it in Eupatorium sect. Praxelis (Cassini) Benth. ex Baker. In fact this species has a conic receptacle and a strongly asymmetrical carpopodium, which are the characters of Praxelis . The position of this species in Chromolaena as originally proposed by Gardner (1846) and accepted by King & Robinson (1970) was probably because this species has apparently persistent involucral bracts. Nonetheless, Chromolaena is characterized by a flat or almost flat receptacle, and a symmetrical carpopodium. Although deciduous involucral bracts is a character of the subtribe Praxelinae , it is possible to find species of Praxelis with persistent involucral bracts as in P. sanctopaulensis . On the basis of these morphological characters we propose here a new combination in Praxelis , as suggested by Nakajima (2000) and Esteves (2001).

Currently fifteen species of Praxelis are known to occur in Brazil as shown in Table 1. With a new species described here and a combination proposed the number of species of Praxelis in the world increased to nineteen, and they can be distinguished from the other species in the Minas Gerais State based on the key provided below.

Figures

FIGURE 1. Praxelis minima. A. Habit. B. Capitulum. C. Receptacle. D. Floret. E. Stamen. F. Style. (All illustrations made from the holotype. Drawings by Belkiss Alméri).

FIGURE 2. Praxelis minima in nature. A. Habit. B. Habitat. C. Some specimens showing the diminutive size of this new species. (Photos by Pedro Viana).

FIGURE 3. Distribution of Praxelis minima.