Asplenium coronatum A.Reis & Sylvestre, 2022

Reis, Atiles, Lino, Vanessa, Mynssen, Claudine Massi & Sylvestre, Lana Da Silva, 2022, Asplenium coronatum (Aspleniaceae), a new fern species from the Brazilian Atlantic Forest, Phytotaxa 574 (2), pp. 185-190 : 186

Asplenium coronatum A.Reis & Sylvestre , sp. nov. ( Figs. 1 , 2 , 3 ).

Type:— Brazil. Rio de Janeiro : Rio de Janeiro, Monumento Natural dos Morros do Pão de Açúcar e Urca, trail to Urca Hill ridge, 22°57’02”S, 43° 09’ 37”W, 100-220 m, 13 May 2022, Reis et al. 90 (holotype RB! barcode RB01462455 [3 sheets]; Isotypes BHCB!, MBM!, R!, RFA!) .

Description:— Plant rupicolous. Stem erect, 1–1.5 cm in diameter, densely covered with clathrate scales, scales 9.7–21.5(–28.5) × 0.9–2.3(–3.2) mm, (17–)20–37(–54) cells wide, linear-lanceolate to lanceolate, concolorous, light brown, cell walls regularly thick throughout, apex unicostate, glandular, margin with retrorse hairs with glandular tips. Leaves 33–98 cm long, monomorphic. Petiole 5–12 × 0.3–0.6(–1) cm, grooved adaxially, brownish to black, with scales similar to those on the stem at the base. Laminae 23–87 × 5.4–14.3 cm, green when living, green to brownish when dry, elliptic-oblong to lanceolate, chartaceous, apex acute to acuminate-caudate, commonly bearing a proliferous tip, base decurrent, long-attenuate, margin entire, rarely slightly crenulate apically, midrib with few scattered scales with glandular tips. Veins free, spreading at (68–)70°–75° from the midrib, simple to 1–forked at base. Sori linear, 12– 37(–50) mm long, elongate, approximate, ending near margin, indusia firmly membranaceous, margins entire. Spores reniform, monolete, with a cristate-winged perispore, folds and areolas between folds with echinulate ornamentation.

Distribution and habitat:— Asplenium coronatum occurs in submontane dense rainforests and has been recorded in a few protected areas in Rio de Janeiro State. It grows on rocks, in moist and shady sites, usually near streams, at 100 to 400 m of elevation (fig. 4).

Etymology:— The specific epithet refers to the proliferous frond apex, which is common in mature specimens and resembles a crown because of its rosulate shape.

Conservation status:— According to IUCN categories and criteria (IUCN Standarts and Petitions Committee 2022), we suggest the conservation status of this species is Vulnerable (B1abiii+2abiii) due to an extent of occurrence of approximately 3,860 km 2, area of occupancy of 910 km 2, restricted number of known populations (less than 10), and a decline of areas and habitat quality due to human use.

Taxonomic notes:— Asplenium coronatum is similar to Asplenium serratum L. (1753: 1079) because of its entire laminae with free veins that are simple to once forked near the base and end near the margin, linear sori and cristate spores, but differs by its larger stem scales, which are often more than 20 mm long and have regularly thickened cell walls, and by laminae with an irregular, entire to slightly crenulate margin and acute to acuminate-caudate apex that is commonly bifid with a proliferous tip (vs. stem scales ca. 10 mm long, with thickened external cell walls, and laminae with a regularly serrate or crenate margin and acuminate, non-proliferous apex in A. serratum ).

Asplenium coronatum occasionally has abruptly reduced lamina bases, especially in young sporophytes. This character (associated with a proliferous apex) resembles that of Asplenium stuebelianum Hieron (1908: 222) , which can also occur in Atlantic Forest. However, the latter can be easily distinguished by its long petioles, regular dentate lamina margin, and dark brownish stem scales with very thick cell walls. Additionally, our preliminary molecular phylogenetic analysis shows that these two species and Asplenium serratum are not closely related phylogenetically and belong to different lineages within A. serratum complex (Lino et al., unpublished data). The main morphological characters to differentiate these three species are in Table 1 .

Additional specimens examined:— BRAZIL. Rio de Janeiro: Cachoeiras de Macacu, Parque Estadual dos Três Picos, 105 m, 22 April 2013, Damasceno 571 (RB!) ; Guapimirim, Parque Nacional da Serra dos Órgãos, 22°29’37”S, 43°00’03”W, 392 m, 25 November 2020, Reis 46 (R!) ; Niterói, Parque Estadual da Serra da Tiririca , 22°57’09”S, 43°01’09”W, 22 May 2021, Lino 315 (RB!) ; Nova Iguaçu, Reserva Biológica do Tinguá , 27 May 1993, Sylvestre 856 (RBR!) ; Silva Jardim, Reserva Biológica de Poço das Antas , Trilha do Pelonha , 22°30’S, 42°15’W, 3 February 1995, Braga 1896 (RB!) ; Teresópolis, Parque Nacional da Serra dos Órgãos , 22°29’37”S, 43°00’05”W, 350 m, 14 November 2008, Labiak 4523 (MBM!, UPCB!) ; Rio de Janeiro, Monumento Natural dos Morros do Pão de Açúcar e Urca , 12 March 2016, Lino s.n. (RFA 43121!) ; Rio de Janeiro, Monumento Natural dos Morros do Pão de Açúcar e Urca , 22°57’15”S, 43° 09’ 57”W, 150 m, 26 April 2021, Reis 54 (R!) .

Figures

FIGURE 1. Asplenium coronatum.—A. General appearance of the sporophyte. B. Laminae details showing the sori, veins and margin ornamentation. C. Stem scale. (Drawn from Reis et al. 90, holotype RB, by Paula Viana Leonardo)

FIGURE 2. Asplenium coronatum.—Habit and habitat in Monumento Natural dos Morros do Pão de Açúcar e Urca, Rio de Janeiro, Brazil.A. Habit B. Proliferous apex (photos by Atiles Reis).

FIGURE 3. Asplenium coronatum spores with a cristate-alate perispore and echinulate folds and areolas (Lino s.n., RFA).—A–B. Equatorial view—C. Details of folds and areolas (photos by Atiles Reis). Bars = 10 μm.