Asplenium atlanticum Lino & Sylvestre, 2023

Lino, Vanessa, Reis, Atiles, Sylvestre, Lana Da Silva & Mynssen, Claudine Massi, 2023, Asplenium atlanticum (Aspleniaceae), a new endemic fern from the Brazilian Atlantic Forest, Phytotaxa 603 (1), pp. 81-88 : 83-86

Asplenium atlanticum Lino & Sylvestre , sp. nov. ( Figs. 1 , 2 , 3 , 4 ).

Type: — BRAZIL. Santa Catarina: Urubici, Santa Bárbara , no interior da mata no campo de altitude, 27°58’07” S, 49°18’38” W, 1300 m, 06 January 2021, V . Lino , B . Botura , F . Gonzatti , G. P . Coelho & J . Külkamp 283 (holotype RB! barcode RB01454638 , isotypes FURB! R! UPCB! US!).

Description: —Plants terrestrial. Stems erect, 1–1.3 cm in diameter, covered with scales, stem scales clathrate, linear-lanceolate and lanceolate, 2–4.1(–5.1) × 0.1–0.2 mm, (0.2–)0.3–0.5(–0.6) mm at the basal portion, concolorous, reddish, glandular at the apex, margins with glandular cells. Leaves monomorphic, (25.5–)28–31(–36) cm long. Petioles non-alate, 11–14.4(–16) × 0.1–0.2 cm, brown, dull, with linear scales, adaxial side grooved. Laminae deltoid to lanceolate, 2-pinnate, 14–18(–21) × 4–5(–8) cm, green when fresh, olive-green to yellow or bright brown when dried, chartaceous, apex acute to acute-attenuate, base truncate. Rachises non-alate, or slightly alate on the distal portion, grooved on the adaxial side, dull, green when fresh, yellow or bright brown when dried, with yellowish glandular hairs and filiform glandular scales, especially in the pinna axils. Pinna stalks 0.18–0.5(–0.9) cm long, with glandular hairs similar to those of the rachises. Pinnae in (8–)9–10(–11) pairs, ascending to patent, lanceolate, 3–4(–6.9) × 1–1.5 cm, base truncate, slightly excavate on the basiscopic side, margin dentate, with pinnules followed by a triangular and entire distal region, pinnae apex obtuse to acute. Pinnules in 1–3(–4) pairs, ovate, (0.7–)1.0–1.3(–1.6) × 0.6–1 cm, base cuneate, apex obtuse. Distal pinnae entire, oblong to ovate, basiscopic side excavate. Apical pinnae pinnatifid. Veins free, 2–3-furcate, 2–4-furcate in the basal pinnae, not reaching the margin. Sori elliptic to linear, in 1–2(–3) pairs on the acroscopic basal pinnules, 0.1–0.4(–0.5) cm, in 3–4(–7) pairs on the triangular distal region, 0.1–0.5 cm. Indusia yellowish, inserted along one side of the veins, membranaceous, margins entire. Sporangia with uniseriate pedicel. Spores monolete, 45–50 μm, perispore cristate-alate, with undulate wings 5 µm long, narrow, regular, anastomosed ridges fenestrate at the basis, with a smooth margin, and rugged areolas, which can exhibit a central protuberance.

Distribution and habitat: — Asplenium atlanticum occurs in cloud forests, Araucaria moist forests, and near rivers in the upper montane rainforest valleys. This species has been recorded in a few protected and non-protected areas in Brazil, within Paraná, Rio Grande do Sul, and Santa Catarina states. TDWG code: 84 BZS-PR BZS-RS BZSSC. It grows as terrestrial in the understory of forests, at 800 to 1550 m elevation ( Fig. 4 ) (only one specimen was observed growing in soil between rocks).

Etymology: —The specific epithet refers to the Atlantic Forest in southern Brazil. Asplenium atlanticum is endemic to this region.

Conservation status: —Since Asplenium atlanticum has a restricted number of known populations (less than 10), of which at least three are in areas surrounded by grazing cattle, and because of an extent of occurrence of 23,983 km 2 and area of occupancy of 40 km 2, we suggest this species meets the IUCN criteria (IUCN 2022) of an endangered species (EN: B2b ii + iii). We decided to adopt the most conservative classification due to the restricted occurrence of this species in Santa Catarina, with few known populations from Paraná and only one from Rio Grande do Sul.

Taxonomic notes: — Asplenium atlanticum spores have prominent undulate wings that are ca. 5 µm long, narrow, regular, fenestrate at its basis, anastomosed ridges with a smooth margin, and rugged areolas with a single central protuberance that is ca. 2 µm diameter (or rarely absent). This kind of perispore ornamentation is observed in different lineages of Asplenium , as Asplenium serratum complex species (Reis 2022, Reis et al. 2022). Asplenium atlanticum is similar to A. martianum by the 2-pinnate laminae, cristate spores with a central protuberance in the areola, lanceolate stem scales, and by A. martianum specimens that have laminae with dentate margin and linear sori ( Table 1 ). However, A. atlanticum has longer stem scales, deltoid to lanceolate laminae, pinnae with an obtuse to acute apex, ovate pinnules, and a terrestrial habit (vs. shorter stem scales, ovate-lanceolate to triangular laminae, pinnae with an attenuate to attenuate-caudate or acute apex, lanceolate to deltoid or oblong pinnules and can be terricolous or epiphytic in A. martianum ) ( Table 1 ). A. atlanticum also is related to A. muellerianum . However, this species usually has 1-pinnate laminae, lateral pinnae with an attenuate to attenuate-caudate apex, and ovate-orbiculate to oblong pinnules, and is epiphytic or terricolous ( Table 1 ). Furthermore, Asplenium pseudonitidum is another species that can be mistaken with A. atlanticum by its 2-pinnate laminae, lanceolate pinnae, and terrestrial habit, but among other characters, the lustrous petiole (vs. dull petiole in A. atlanticum ) allows its differentiation ( Table 1 ). All four species are endemic to the Atlantic Forest and occur in sympatry.

Additional specimens examined: — BRAZIL. Paraná: Campina Grande do Sul, Parque Estadual Pico Paraná, Morro Caratuva, 1550 m, 25°14’ S, 48°50’ W, 26 February 2008, Pereira 190a (UPCB); Contenda, Rodovia do Xisto, 05 September 1969, Hatschbach 22149 (HB, MBM, MO, UPCB). Rio Grande do Sul: Bom Jesus, 14 January 1942, Sehnem 966 (HUCS, US). Santa Catarina: Anitápolis, Trilha dos Índios, 1270 m, 27°55’58.3” S, 49°18’21.8” W, 29 August 2021, Lino 360 (RB); Joinville, Rodovia Dona Francisca, 800 m, 26°12’52” S, 49°05’46” W, 14 August 2021, Lino 324 (RB); Rio Rufino, Morro das Torres, 1432 m, 27°54’00” S, 49°51’36” W, 07 May 2009, Gasper 1887 (FURB); Urubici, Santa Bárbara, 1300 m, 27°58’08” S, 49°18’38” W, 06 January 2021, Lino 285 (RB).

Key to Asplenium atlanticum and morphologically related species

1. Lustrous petiole ....................................................................................................................................................... A. pseudonitidum

- Dull petiole .........................................................................................................................................................................................2

2. Lamina 2-pinnate to 3-pinnate, ovate-lanceolate to triangular; pinnules lanceolate to deltoid or oblong; stem scales always lanceolate....................................................................................................................................................................... A. martianum

- Lamina 1-pinnate and/or 2-pinnate, deltoid or lanceolate; pinnules ovate, ovate-orbiculate, or oblong; stem scales lanceolate or linear-lanceolate..................................................................................................................................................................................3

3. Lamina 1-pinnate, rarely 2-pinnate, always lanceolate, 25–32(–44) cm long; lateral pinnae with attenuate to attenuate-caudate apex; stem scales linear-lanceolate........................................................................................................................... A. muellerianum

- Lamina always 2-pinnate, deltoid or lanceolate, 14–18(–21) cm long; lateral pinnae with obtuse to acute apex; stem scales lanceolate and linear-lanceolate..................................................................................................................................... A. atlanticum

Figures

FIGURE 1. Asplenium atlanticum. A. Habit. B. Basal pinna. C. Basal pinnula detail showing scales and hairs of the pinna base and margin, veins, and sori. D. Glandular hair from the rachises and pinnae. E. Lanceolate stem scale. F. Linear-lanceolate stem scale. Illustration by Giovanna Hygino.

FIGURE 2. Asplenium atlanticum. A. Cloud Forest in Urubici, Santa Catarina, habitat of A. atlanticum. B. Habit of a terrestrial specimen. C. Adaxial surface of the pinnae. D. Abaxial surface of the pinnae. Photos by: A–B. Vanessa Lino; C–D. Josimar Ķlkamp.

FIGURE 3. Spores of Asplenium atlanticum. A–B. Cristate-alate spores, anastomosed fenestrate ridges with smooth margins, and rugged areolas with central protuberances. A. Equatorial view (Lino 283, RB). B. Distal polar view (Gasper 1887, FURB). SEM images by Vanessa Lino.

FIGURE 4. Distribution map of Asplenium atlanticum.