Paepalanthus paganuccii Giul. & M. J. G. Andrade 2022, sp. nov.
Creators: name: Andrade, Maria José Gomes De
name: Trovó, Marcelo
name: Rocha, Lamarck
name: Giulietti, Ana Maria
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Poales
Eriocaulaceae
Paepalanthus
Paepalanthus paganuccii

description: 1. Paepalanthus paganuccii Giul. & M.J.G. Andrade, sp. nov. (Figures 2C–E, 3, 4A–K, 5A–I).
Type:— BRAZIL. Bahia: Município de Pilão Arcado, Barra do Iuiu, 10°07’09”S, 42°51’15”W, 436 m alt., 07 September 2005 (fl., fr.), L. P. Queiroz et al. 10917 (holotype: HUEFS [101058]!).
Diagnosis:— Paepalanthus paganuccii resembles P. sessiliflorus, sharing with it the general habit consisting of an elongated stem, the lack of scapes and spathes, two series of involucral bracts, trimerous flowers, and floral bract pilose at apex. Paepalanthus paganuccii is mainly distinguished by its being robust with 4.5–7.0 cm long tall (vs. 0.6–1.6 (–3.0 cm long); leaves usually senescent at the lower parts of the stem with persistent leaf sheaths (vs. persistent leaves along the entire stem), erect to patent, 8–10 mm long, acuminate apex (vs. recurved, 3–5 mm long, acute to obtuse apex), differentiated into sheath and blade (vs. undifferentiated); apical leaves surpassing the flowers by two times or more the floral disc size (vs. apical leaves surpassing the flowers slightly or one time the floral disc); involucral bracts lanceolate (external series) to obovate-elliptic (inner series), apex acute (vs. involucral bracts narrowly-oblong, apex cuspidate; floral bracts spathulate (vs. oblong to linear); seed coat tuberculate-striate (vs. seed coat reticulate).
Description:— Annual caulescent herb, 4.5–7.0 cm tall., roots brown. Stem erect, branched at the distal parts, leaves spirally arranged along the stem, persistent from middle to the apex and usually deciduous from the middle to base with persistent sheaths. Leaves lanceolate, erect to patent, membranous to chartaceous, 8–10 × 0.2–0.3 mm, apex acuminate, sheath abruptly detached from the limb, ca. 0.8 mm wide, ciliate along the margin from the middle toward the limb base, trichomes long (ca. 1.2 mm long), filamentous, 3–4-celled, basal and collar cells bulging, distal cells with short tuberculate wall; the uppermost leaves subtending the capitulum, about two times longer than the floral disc. Scape and spathe absent. Each capitulum terminating an abbreviated leafy branch, sessile, hemispherical, ca. 2 mm diam., receptacle densely long-villous with erect white trichomes, ca. 1.3 mm long. Involucral bracts in 2 series, ca. 6 bracts in each series, bracts of the outer series ca. 1.6 × 0.5 mm, lanceolate, apex acute, glabrous, bracts of the inner series ca. 1.4 × 0.8 mm, obovate-elliptic, apex acute, glabrous. Floral bracts spathulate, ca. 1.6 × 0.4 mm, apex round, long-ciliate in the upper part, filamentous trichomes (ca. 0.4 mm long), uniseriate, 4–5-celled, apex acute, slightly shorter than staminate flowers and with the size of the pistillate flowers. Flowers trimerous. Staminate flowers ca. 2 mm long; pedicel ca. 0.6 mm long; sepals spathulate-obovate, concave, fused at base, ca. 0.7 mm long, apex round or emarginate, white-cilliate, with short trichomes; anthophore ca. 0.5 mm long, corolla campanulate, shortly lobed, involute after anthesis, glabrous, overtopping the calyx due to the anthophore; stamens 3, exserted, filaments filiform, adnate to corolla, 2-thecous, 4-sporangiate, anthers dorsifixed; carpellodes 3, reduced. Pistillate flowers, ca. 1.4 mm long, pedicel ca. 0.6 mm long; sepals linear-spathulate, concave, free, ca. 0.8 mm long, apex rounded, glabrous, becoming rigid and revolute during the fruit development; petals 3, free, flat, linear-spathulate, ca. 0.8 mm long, loosely ciliate at the rounded apex; gynoecium ca. 1.0 mm long, 3-locular ovary, ca. 0.4 mm long, styles united in column ca. 0.6 mm long, stigmatic branches united, short stigmas, caducous during fruiting, nectariferous branches lacking. Fruit a capsule, released from the capitulum with the erect petals still connected at the top by the ciliate margin, through the elevation of the fruit associated with the pression of the rigid and revolute sepals. Seed obovate, ca. 0.4 mm long, seed coat with primary sculpture with a tuberculate-striate pattern, with tubercule organized in rows. This pattern is probably associate to a presence of an almost intact periclinal wall when the seed is liberated.
Distribution, Habitat, and Conservation:— The type of Paepalanthus paganuccii was collected in the Caatinga of western Bahia, forming a dense population over seasonally humid sandy soils in a temporary lagoon in the São Francisco riverbanks (400 m high). Other disjunct populations were found in sandy areas of the Cerrado in Maranhão, and Tocantins (Figure 3), but further detailed botanical expeditions and careful analysis of herbarium specimens may reveal a more continuous distribution.
Paepalanthus paganuccii has EOO = 118,138.378 km 2, and A00 = 16.000 km 2. Its populations are threatened by disturbance and change of the water regime near the São Francisco River as well as increasing disturbance and clearing of vast tracts of the Cerrado of Maranhão and Tocantins for agrobusiness. Apart from the population found within the Parque Nacional da Chapada das Mesas (Silva 903), the other populations are currently under threat. According IUCN (2019) criteria B1(bii,iv) and B2 (b,iii,iv), we consider the species should be treated as Endangered (EN).
Etymology:— The epithet honours Prof. Dr. Luciano Paganucci de Queiroz from the Universidade Estadual de Feira de Santana, Bahia, Brazil, for collecting the holotype and specially for his relevant contributions to the botanical studies of the Brazilian Semiarid region.
Comments:— Paepalanthus paganuccii differs from the majority of the Eriocaulaceae by lacking one of the family’s main diagnostic characters, the presence of scapes and spathes. In this species the sessile capitulum terminates a short leafy branch, resembling the two species of P. subg. Thelxinoë. The flowers in the new species are however trimerous instead of dimerous, being therefore morphologically more related to P. sessiliflorus, its sister species (Figure 1). Paepalanthus paganuccii is provisionally placed in P. ser. Leptocephali, which also comprises P. sessiliflorus and P. polytrichoides, both also annual herbs, with the seeds with a similar dispersal mechanism (Figures 2–5).
Among the Paepalanthus species with trimerous flowers, P. paganuccii is morphologically most related to P. sessiliflorus, and the differences between both species are detailed in the diagnosis and in Table 2 and illustrated in Figures 4–5. The specimens which have been included as paratypes were not examined in the phylogeny, nor were their seeds examined under SEM. However, they display other morphological characters, which is in accord with those found in P. paganuccii, even though some specimens may have leaves that are persistent along the stem, when juvenile (see Harley 56669 from Tocantins). Another aspect, which distinguishes between the two species in their distribution. While P. paganuccii is limited to a few populations within the Caatinga and Cerrado, P. sessiliflorus occurs in the Atlantic dunes and campo rupestre of the Chapada Diamantina in Bahia, with a heterotypic variety in northern South America (Figure 3).
Additional material examined:— BRAZIL. Bahia: Gentio do Ouro, estrada de Gentio do Ouro para XiqueXique (BA-160/BR-330), ca. 20 km de Xique-Xique, 11°07’04”S, 42°44’14”W, 03 May 2014, C. M. Siniscalchi et al. 471 (HUEFS, SPF). Maranhão: Carolina, Rodovia MA-010, Serra do Portal da Chapada, solo arenoso na base dos paredões de arenito, em áreas sombreadas, 296 m, 07°11’12”S, 47°25’22”W, 19 May 2012, C. Silva et al. 903 (HUEFS). Tocantins: Miracema do Tocantins, Rodovia TO-010, para a cidade de Lagedo e Palmas, ca. 9 km da cidade, paredão úmido na beira da estrada, 263 m, 09°37’48”S, 48°25’04”W, 01 February 2012, R. M. Harley et al. 56669 (HUEFS).
description: Published as part of Andrade, Maria José Gomes De, Trovó, Marcelo, Rocha, Lamarck & Giulietti, Ana Maria, 2022, Paepalanthus (Eriocaulaceae) without scapes and spathes, a survey with the description of a new species, pp. 135-152 in Phytotaxa 560 (2) on pages 140-143, DOI: 10.11646/phytotaxa.560.2.1, http://zenodo.org/record/7040562