Paepalanthus magnus L. H. Rocha, Gonella & Andrino, 2024

Rocha, Luiz Henrique, Gonella, Paulo Minatel & Oliveira Andrino, Caroline, 2024, A missing piece is found: a new species of Paepalanthus (Poales, Eriocaulaceae) and the puzzling relations of the campos rupestres mountaintop floras of eastern Minas Gerais, Brazil, PhytoKeys 242, pp. 317-332 : 317-332

Paepalanthus magnus L. H. Rocha, Gonella & Andrino sp. nov.

Fig. 1 , 2 , 3 , 4 , 5

Type.

Brazil. Minas Gerais: Conselheiro Pena, Serra do Padre Ângelo , Serra do Pinhão , Pico do Pinhão , 19 ° 15 ' 21 " S, 41 ° 34 ' 57.24 " W, 1500 m elev., fl. & fr., 18 Apr 2022, P. M. Gonella, L. H. Rocha, D. R. Couto, D. P. Cordeiro & E. C. Ribeiro 3402 (holotype: UB; isotype: SPF) .

Diagnosis.

The new species is most similar to Paepalanthus regelianus Körn. , with which it shares the pilose abaxial surface of the leaves. However, P. regelianus presents scapes that are about twice as long as the leaves and tomentose (vs. scapes at least 3 times longer than the leaves, and glabrous in P. magnus ) and involucral bracts with a glabrous abaxial surface and ciliated margin (vs. pilose in P. magnus ). Furthermore, the spathes of P. regelianus are shorter than its leaves, approximately half as long as the leaves (vs. spathes about as long as the leaves), present uniformly distributed trichomes (vs. along longitudinal nerves), and possess a short opening, no longer than 1 cm long (vs. opening distinctly longer, 2.5–6.0 cm long).

Description.

Terricolous or rupicolous perennial herb, 55.0– 94.5 cm high. Roots fibrous. Caudex present. Stem aerial, elongate, erect, thick, surrounded by marcescent leaves, 6.5–35.0 cm long. Leaves rosulate, 14.3–27.0 × 0.4–1.6 cm, linear-lanceolate, green, abaxial surface with trichomes ca. 4 mm long along the marked nerves, adaxial surface smooth and glabrous, margins ciliate, apex acute, mucronate. Inflorescences solitary per subtending leaf, axillary. Spathes 13.0–24.0 cm long, chartaceous, cylindrical, closed, abaxial surface pilose along the marked nerves (striate), adaxial (internal) surface glabrous, obliquely opened, opening 2.5–6.0 cm long, margin ciliate, apex acuminate. Scapes 50.0–89.0 cm long, 1–21 per plant (rosette), 5 - costate, erect, glabrous, green to golden, free. Capitula 5.0–15.0 mm diam., white. Involucral bracts in 7–9 series, ca. 1.7–3.8 × 1.3–2.1 mm, ovate, castaneous, margin ciliate, abaxially pubescent, shorter than the flowers. Floral bracts ca. 3.5 mm long, linear-lanceolate, pigmented, densely pilose in the apical half with uniseriate trichomes ca. 2 mm long, margin ciliate. Flowers 3 - merous, diclinous, arranged in concentric circles without clear organization. Staminate flowers ca. 3.5 mm long; pedicels ca. 1 mm long, pilose, with trichomes 2–2.5 mm long; sepals ca. 2.5–3 × 1 mm, oblanceolate, united in the base to up to 1 / 3 of length, castaneous with pigmentation concentrated in the center and becoming more translucent towards the margins, abaxial surface densely pilose in the apical 2 / 3, trichomes reducing in size towards the apex, adaxial surface glabrous, margin ciliate, apex acuminate; corolla tubular, ca. 2.5 mm long, free lobes ca. 0.3 mm long, entirely glabrous, hyaline; stamens epipetalous, filament ca. 1.5 mm long, anther dorsifixed, ca. 0.3 mm long; pistillodes papillose, ca. 1 mm long. Pistillate flowers ca. 4.5 mm long; pedicel ca. 0.5 mm long, densely pilose with long trichomes; sepals ca. 3.5 mm long, oblong, united only at the very base, castaneous with apex more strongly pigmented, adaxial surface glabrous, abaxial surface with apex slightly pilose, margin ciliate, apex acuminate-truncate; petals ca. 3 mm long, hyaline, base slightly pigmented, narrow obovate, free, adaxial surface pilose, abaxial surface glabrous, margin ciliate, apex acute; gynoecium with stigmatic and nectariferous branches emerging at the same height in the column, stigmatic branches ca. 1 mm long, apex bifid, nectariferous branches ca. 0.7 mm long, apex papillose, ovary ca. 1 mm diam, ovoid; Seed ca. 0.76 × 0.60 mm ovoid to ellipsoid, reddish, hilum acute, micropile obtuse, with numerous appendices with truncate apex along the periclinal walls.

Etymology.

The epithet “ magnus ” derives from the Latin “ great ”, “ large ”. This epithet was selected to denote the characteristic of the species being large in size, contrasting with the majority of Eriocaulaceae species found in the region where it occurs but also a reference to its larger size compared to its putative closest taxa.

Distribution and habitat.

Paepalanthus magnus is a microendemic species, found only at the top plateau of Pico do Pinhão (1540 m a. s. l.), one of the highest peaks of Serra do Padre Ângelo, a mountain complex located in the municipality of Conselheiro Pena, eastern Minas Gerais, southeastern Brazil (Fig. 4 ). The species was found at elevations above 1500 m a. s. l., forming a population of no more than 100 individuals growing directly on sandy soil among grasses or between large blocks of quartzitic rock, exposed to direct sunlight, in campos rupestres vegetation (Fig. 2 A, B ).

Pico do Pinhão is part of the northern massif of SPA, the Serra do Pinhão, whose culminating point is Pico do Sossego (1605 m), to the northwest of Pico do Pinhão. Expeditions to the former failed to find new populations of the species, which were also not found in the other higher peaks of the region, such as Pico da Bela Adormecida (also known as Padre Ângelo; 1550 m) and Pico da Aliança (1430 m), reinforcing the microendemic character of the species. At Pico do Pinhão, the campos rupestres are found at elevations above 1300 m. They are surrounded by a matrix of the Montane Seasonal Forest, which harbors the last individuals of the northernmost population of the endangered gymnosperm Araucaria angustifolia (Bertol.) Kuntze ( Moura 1975) , locally known as “ pinhão ” hence the name of the Serra. Such forest matrix, however, is severely degraded and is still subject to fires for land clearing and pasture formation (Fig. 5 ), as well as by the presence of cattle. The surrounding area is also severely invaded by alien species, especially the fern Pteridium aquilinum (L.) Kuhn ( Dennstaedtiaceae ) and molasses grass Melinis minutiflora P. Beauv. ( Poaceae ).

Phenology.

Specimens were collected with flowers and fruits in April, which is by the end of the rainy season. The presence of old inflorescences with viable fruits, however, suggests that the flowering may occur since the beginning of the rainy season, which in the region starts in October / November.

Conservation status.

Preliminarily assessed as Critically Endangered – CR B 1 ab (iii) + B 2 ab (iii). The species is known from a single location in an area that is not protected, and which is subject to several ongoing threats to the quality of the habitat, such as deforestation, the presence of cattle, recurrent use of fires, and the presence of invasive species. Furthermore, species restricted to mountaintop habitats are especially vulnerable to the effects of climate change, especially intense droughts that may cause increased mortality (already observed in other taxa in the region) or intense rainfalls, which may cause landslides (already reported in the SPA following intense rainfall in the 2021 / 2022 rainy season). Arson fires are especially recurrent in the southwest of Serra do Pinhão (Fig. 5 A ) and are used by local farmers to renovate pastures and clear land for coffee and Eucalyptus plantations. These fires, however, often escape to native vegetation, causing the observed reduction of forest remnants and the intensification of invasion by the aforementioned alien species. The last of these intense fire events was in 2020 (Fig. 5 B ), also the year of another intense fire affecting the Pico da Bela Adormecida and its species ( Andrino and Gonella 2021; Gonella et al. 2022; Andrino et al. 2024).

Since the species is known from a single location, it has an estimated AOO of 4 km 2, and it does not have an associated EOO polygon, which, combined with the small population size and the listed ongoing threats, allow us to project a continuing decline in the quality of the habitat. Therefore, we suggest that the species should be declared Critically Endangered under the IUCN (2012) criteria. This preliminary assessment will be submitted to the Brazilian Flora authority of the IUCN Red List, coordinated by Centro Nacional de Conservação da Flora (CNCFlora), for validation.

Additional specimen examined (paratype).

Brazil. Minas Gerais: Conselheiro Pena, Serra do Padre Ângelo , complexo Serra do Pinhão , Pico do Pinhão , 18 Apr 2022, D. R. Couto, P. M. Gonella, D. P. Cordeiro & L. H. Rocha-Pinto 6286 ( MBML) .

Figures

Figure 1. Paepalanthus magnus A habit B leaf apex C spathe, detail of the opening D capitula in dorsal (left) and ventral (right) view E involucral bract F floral bract G staminate flower in lateral view H staminate flower with sectioned corolla, exposing the stamens and pistillodes I pistillate flower in lateral view J pistillate flower with petals and sepals distended, exposing the gynoecium K seed with numerous appendices along the periclinal walls. Illustration by Klei Souza based on the holotype (P. M. Gonella et al. 3402).

Figure 2. Paepalanthus magnus A habitat at Pico do Pinhão, with the Pico da Bela Adormecida (Pico do Padre Ângelo) in the background B habit among grasses and quartzitic rocks C rosette in detail D leaves, showing ciliate margin and striate abaxial surface E the base of the leaves, showing the adaxial surface and a scape enclosed by a spathe emerging from a leaf axil F spathe opening G capitulum in posterior view evidencing the involucral bracts H capitulum, lateral view I capitulum, frontal view. A by Lucian Medeiros B – I by PMG.

Figure 3. Paepalanthus magnus. SEM micrograph of the seed coat (from the holotype, P. M. Gonella et al. 3402).

Figure 4. Distribution maps A distribution map of the new species and compared taxa cited in the text B distribution map of P. magnus at Serra do Padre Ângelo region, with other landmarks of the region indicated.

Figure 5. Conservation threats to Paepalanthus magnus A 35 - year fire record (1985–2020) in the region of Serra do Pinhão, part of Serra do Padre Ângelo B fire record in the year 2020 C land use of the region. Data on fire and land use from MapBiomas (2024). A, B Map data © 2024 Google.