Paepalanthus irwinii Trovo & Echtern. 2022, sp. nov.
Creators: name: Trovó, Marcelo
name: Echternacht, Lívia
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Poales
Eriocaulaceae
Paepalanthus
Paepalanthus irwinii

description: Paepalanthus irwinii Trovó & Echtern. sp. nov.
urn:lsid:ipni.org:names:77302849-1
Figs 4–5, 7A
Diagnosis
Differs from Paepalanthus acanthophyllus by being a more gracile plant with shorter, linear leaves, shorter and narrower reproductive axis, shorter, linear to narrowly lanceolate axis bracts, fewer scapes per plant, capitula usually narrower, and petals of the pistillate flower with obtuse to mucronate apex.
Etymology
The epithet “ irwinii ” honors Howard Samuel Irwin, the coordinator of the Planalto Expeditions Program, which collected over 225 000 specimens and over 30 000 numbers in Central Brazil by 1972 (NYBG 2021). The Eriocaulaceae set of specimens from the “Planalto Expeditions” is precious, encompassing many type specimens.
Material examined
Type BRAZIL • Goiás, Alto Paraíso de Goiás, Parque Nacional da Chapada dos Veadeiros, GO 239, entre Alto Paraíso de Goiás e São Jorge; 14°0ʹ5ʹʹ S, 47°43ʹ48ʹʹW; 14 Nov. 2017; M.L.O. Trovó et al. 706; holotype: RB [RB1405241]; isotypes: CEN [CEN112954], OUPR.
Paratypes BRAZIL • Goiás, Alto Paraíso de Goiás; 9 May 1987; N.L. Menezes 1217; RB, SPF • same locality as for preceding; 20 May 1994; M. Aparecida-da-Silva et al. 1921; RB, SPF • same locality as for preceding; 27 Apr. 2009; D. Cardoso et al. 2600; HUEFS, RB • same locality as for preceding; 22 Mar. 2012; M. Watanabe et al. 227; RB, SPF.
Description
Herbs perennial, solitary or forming small clumps of ramets, 45.0−60.0 cm tall; rhizome short, erect, usually sprouting; rosette stem short, ca 0.5−1.5 cm long. Leaves usually deciduous in fertile specimens, membranaceous to chartaceous, linear, greenish, flat, patent to recurved, 1.0−3.0 × 0.1−0.2 cm,glabrescent on both surfaces, margins with long, sparse trichomes, apex acute. Reproductive axis erect, 30.0−45.0 cm long, ca 0.3 cm diameter, glabrous; all axis bracts with similar shape, amplexicaul, chartaceous, linear to narrowly lanceolate, patent to recurved, 0.5−1.5 × 0.1−0.3 cm, apex acute, usually entirely glabrous, the younger with long trichomes towards the margin. Spathes 3.5−4.5 mm long, glabrous, apex acute. Scapes 5−25, arranged at the reproductive axis apex, 12.0−28.0 cm long, glabrous or rarely with sparse trichomes. Capitula 0.5−0.9 mm diam., hemispherical to spherical, whitish; involucral bracts in 2−4 series, dark castaneous, deltate, ca 2.5 mm long, glabrous or rarely with sparse trichomes abaxially, sparsely ciliate, apex obtuse. Flowers dimerous, ca 80 per capitulum, disposed in concentric rings; floral bracts linear to narrowly oblanceolate, castaneous with central whitish stripe, flat, 1.5−2.0 mm long, mostly glabrous or sparsely pilose distally on the abaxial surface, margin ciliate toward the acute apex, glabrescent. Staminate flowers ca 3.5 mm long; pedicel with ca 0.5 mm long; sepals free, narrowly obovate, castaneous with central whitish stripe, ca 2.5 mm long, mostly glabrous or sparsely pilose distally on the abaxial surface, densely ciliate toward the acute apex, glabrescent; anthophore fleshy, elongated, ca 1.5 mm long; petals fused into a tube, whitish, membranaceous, ca 0.5 mm long; stamens ca 0.8 mm long, cream-colored; carpellodes 3, papillose. Pistillate flowers ca 2.5 mm long, sessile or subsessile; sepals free, dolabriform, whitish, ca 2.0 mm long, densely pilose abaxially, densely ciliate toward the obtuse apex, glabrescent; petals free, dolabriform, whitish, ca 1.5 mm long, sparsely pilose abaxially, ciliate toward the obtuse to mucronate apex, glabrescent; gynoecium 2.5 mm long, stigmatic branches bifid at the apex, twice as long as the nectariferous branches, staminodes not seen. Fruit a loculicidal capsule. Seeds ellipsoid, reddish.
Distribution, habitat, and conservation
Populations of Paepalanthus irwinii sp. nov. with ca 10−75 flowering individuals were frequently found in the Chapada dos Veadeiros National Park. Different from most of the endemic species of Eriocaulaceae to the area, which are locally restricted, the species is distributed from the Rio Preto Valley in the vicinity of São Jorge village to the Pouso Alto Region. Populations occur in different phytophysiognomies, from open fields to rupestrian savannahs, but the individuals grow only over shallow, usually wet, rocky soils. It is also worth mentioning that many individuals were seen in flower after a severe fire event in 2017. Based on the IUCN (2019) distribution criteria, EN: B1ab (i,ii,iii,iv), and its occurrence inside a National Conservation Unit, the species should be considered Vulnerable.
Notes
Paepalanthus irwinii sp. nov. belongs to Paepalanthus sect. Diphyomene Ruhland, one of the few categories of Paepalanthus mostly diversified in the Chapada dos Veadeiros Region (Trovó & Sano 2010; Trovó et al. 2013). The species is morphologically most similar to P. acanthophyllus due to its general habit, deciduous leaves, patent and spiny axis bracts, and the shape and color of the capitula and involucral bracts. Paepalanthus irwinii is distinguished by being a more gracile plant up to 60 cm tall (vs up to 120 cm); with shorter and narrower, linear leaves, 1.0−3.0 × 0.1−0.2 cm (vs lanceolate, 3.5−8.0 × 0.3−0.7 cm); shorter and narrower reproductive axis, ca 45.0 cm tall and 0.3 cm diam. (vs longer and wider, ca 100.0 cm tall and 0.6 cm diam.); linear to narrowly lanceolate axis bracts, 0.5−1.5 × 0.1−0.3 cm (vs lanceolate, 1.0−5.5 × 0.8−1.2 cm); up to 25 scapes per plant (vs up to 80 scapes per plant); narrower capitula, ca 0.9 cm diam. (vs wider, ca 1.5 cm diam.); and the petals of the pistillate flower with obtuse to mucronate apex (vs petals of the pistillate flower with obtuse to rounded apex). Although sympatric, these species grow in different habitats and flower at different times. While P. irwinii occurs over shallow, rocky soils, P. acanthophyllus occurs over a more consolidated argillaceous soil. Individuals of the new species are usually seen in flower and fruit from November to May, while P. acanthophyllus is usually fertile from April to August.
description: Published as part of Trovó, Marcelo & Echternacht, Lívia, 2022, The Paepalanthoideae (Eriocaulaceae) of the Chapada dos Veadeiros National Park, Brazil: taxonomic novelties, identification key, and illustrated list of species, pp. 58-93 in European Journal of Taxonomy 834 on pages 65-68, DOI: 10.5852/ejt.2022.834.1899, http://zenodo.org/record/6981051