Paepalanthus mellosilvae Trovo. A. Habit 2021, sp. nov.
Creators: name: Trovó, Marcelo
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Poales
Eriocaulaceae
Paepalanthus
Paepalanthus mellosilvae

description: Paepalanthus mellosilvae Trovó, sp. nov. Fig. 1.
Paepalanthus mellosilvae differs from Paepalanthus harmsii Ruhland (1903: 216) by the presence of a rhizome, narrower leaves, more numerous scapes, narrower capitula, sparsely pilose involucral bracts, and obdeltate floral bracts. The pilosity of the floral parts are also rather different, being usually more densely pilose on the abaxial surface and margins of the petals and sepals of P. mellosilvae.
Type:— BRAZIL. Minas Gerais: São Tomé das Letras, Pico do Gavião, contrafortes sudoeste. Mata Nebular. 21 o 37’S 44 o 55W. Elev. 1400m, 22 February 1999, R. Mello-Silva & al. 1620 (holotype, RB! [600436]; isotypes BHCB!, HUEFS! [83902], K!, NY!, SP!, SPF! [135081]).
Herbs, solitary, 25.0−35.0 cm tall; rhizome present, shortly elongated, aerial stem short ca. 1.5 cm long. Leaves persistent even when dry, chartaceous, lanceolate, multi-nerved, patent to recurved, rosulate, 12.0−16.0 × 0.5−1.0 cm, mostly glabrous with very sparse long trichomes, apex acute. Spathes 4.0− 5.5 cm long, greenish, mostly glabrous with very sparse long trichomes, apex acute. Scapes 80−130, arranged in subsequent terminal cohorts of 5−8 units, 20.0−27.0 cm long, mostly glabrous with very sparse trichomes on the distal part. Capitula 3.5−6.0 mm diam., usually hemispherical, whitish to ochraceous; involucral bracts in 2−4 series, stramineous to light-castaneous, external just slightly surpassing the floral disc, usually oblong with acute apex, internal deltate to obdeltate with obtuse apex, flat to navicular, ca. 2.0 mm long, sparsely pilose with ciliate margin, glabrescent when older; receptacle flat with long trichomes. Flowers trimerous, ca. 50 per capitulum; floral bracts obdeltate with obtuse to mucronate apex, flat to slightly navicular, ca. 2.0 mm long, densely pilose distally, densely ciliate toward the margin. Staminate flowers ca. 3.5 mm long; pedicel ca. 0.5 mm long; sepals fused at the base, obovate, flat to navicular, castaneous, ca. 2.5 mm long, pilose distally, margin ciliate toward the apex, apex obtuse to rounded; anthophore fleshy, elongated; corolla fused into a tube, whitish, membranaceous, ca. 1.0 mm long; stamens ca. 1.5 mm long; carpellodes 3, papillose. Pistillate flower ca. 2.0 mm long, sessile to sub sessile; sepals fused at the very base, narrowly oblong, castaneous, ca. 3.0 mm long, pilose distally, margin ciliate toward the apex, apex obtuse to acute; petals linear to narrowly oblong, whitish, ca. 2.5 mm long, sparsely pilose distally, margin sparsely ciliate toward the apex, apex acute to obtuse; gynoecium ca. 3.5 mm long, stigmatic branches bifid at the apex, 3 × longer than the nectariferous branches. Fruits a loculicidal capsule. Seeds elliptical, reddish.
Etymology: —The epithet “ mellosilvae ” is a tribute to Prof. Dr. Renato de Mello-Silva, who collected a very complete set of specimens of this new species, which was selected as the type collection. Renato was a tenacious botanist, an inspiring professor, and a good friend.
Distribution, Habitat, and Conservation: — Paepalanthus mellosilvae is known from a single locality within the Mantiqueira Range in Minas Gerais, Brazil. From the collection label, discussions with the first collector of the type specimens, and photos posted on popular social media, it is clear that the species forms small, dense populations growing along trails in shaded areas of cloud forests, sometimes exposed to sunlight. However, according to Prof. Dr. Renato de Mello-Silva, the surrounding area of the populations from São Tomé das Letras municipality is under intense quartzitic mining activity. Considering the few known populations, and the absence of populations in conservation units, the species is suggested here as critically endangered according to the IUCN (2019) distribution criteria B1B2ab(i, ii, iii, iv).
Comments:— Paepalanthus mellosilvae is provisionally placed in P. subg. Paepalanthus Ruhland (1903: 122) in Ruhland’s (1903) classification system due to its unicapitulate scapes, involucral bracts adaxially glabrous, trimerous flowers, and capsulate fruits. This placement is not definitive within the classification system and may need further adjustments when a much-needed revised classification system is available (Andrade et al. 2010, Trovó et al. 2013, Andrino et al. 2020). The species is placed along with P. harmsii, P. acuminatus Ruhland (1903: 217), and P. leiseringii Ruhland (1903: 216), which were previously described in P. subg. Xeractis Koernicke (1863: 336) and later transferred to P. subg. Paepalanthus (Hensold 1988). Paepalanthus harmsii and P. acuminatus emerged as sister species, nested within a clade of species mostly occurring in the Mantiqueira Range (Andrino et al. 2020). Based on the morphological similarities and the geographical distribution of these species, I suspect that P. mellosilvae may be related to this clade.
The morphologically most similar species to Paepalanthus mellosilvae is P. harmsii, which also occurs in the Mantiqueira Range, being restricted to Ibitipoca State Park and Serra Negra, two localities at approximately 100 km far from the occurrence site of P. mellosilvae. Both species share the robust habit, the stramineous to light castaneous involucral bracts just slightly surpassing the floral disc, and the shaded habitat. Paepalanthus mellosilvae is mainly distinguished by its rhizome present (vs. usually absent), narrower leaves (0.5−1.0 vs. 0.7−2.7 cm wide), more numerous scapes (80−130 vs. 15−50), narrower capitula (3.5−6.0 vs. 7.0−12.0 mm diam.), sparsely pilose involucral bracts (vs. tomentose) and obdeltate floral bracts (vs. linear). The outer involucral bracts of P. harmsii are also useful for distinction, as they are frequently greenish, while in P. mellosilvae they are stramineous to light-castaneous in all series. Additionally, the pilosity of the floral parts are also rather different in these species, being usually more densely pilose on the abaxial surface and margins of petals and sepals in P. mellosilvae when compared to P. harmsii.
Finally, Paepalanthus mellosilvae also resembles P. macaheensis Koernicke (1871: 311) and an unidentified collection from Santa Rita do Jacutinga in Minas Gerais state. Paepalanthus macaheensis is a more gracile species with usually elongated stem, being also easily differentiated by its densely packed capitula with castaneous involucral bracts shorter than the floral disc, and gynoecium with stigmatic branches only slightly longer than the nectariferous branches. At first glance, the unidentified specimens L. Krieger s.n. (CESJ 8900, RB 806590, SPF 151271) from Santa Rita do Jacutinga (Minas Gerais) are morphologically similar to P. mellosilvae, being relatively smaller and more glabrous. However, the brow and ovate, glabrous involucral bracts, and especially the linear floral bracts with sparse trichomes are much too different to be included in the morphological variation of P. mellosilvae. Additional specimens of this taxon would be worth analyzing to assure its identity.
description: Published as part of Trovó, Marcelo, 2021, Paepalanthus mellosilvae (Eriocaulaceae), a new species from the Mantiqueira Range in Minas Gerais, Brazil, pp. 248-252 in Phytotaxa 500 (3) on pages 249-251, DOI: 10.11646/phytotaxa.500.3.9, http://zenodo.org/record/5424642