Cyathea leoniae M. Acuña-Tarazona & E. Huamán-Melo, 2018

Acuña-Tarazona, Margoth, Huamán-Melo, Elluz, Toledo-Aceves, Tarin & Mehltreter, Klaus, 2018, Cyathea leoniae (Cyatheaceae), a new pinnate-pinnatifid tree fern species from Northern Peru, Phytotaxa 344 (2), pp. 191-197 : 192-193

Cyathea leoniae M. Acuña-Tarazona & E. Huamán-Melo , sp. nov. ( Figs. 1 , 2 , 3 ).

Type: — PERÚ. San Martín, Rioja, Distrito Pardo Miguel Naranjos, Bosque de Protección Alto Mayo , Sector Venceremos ; Páramo con formaciones rocosas y parches arbustivos, 3312 m, 5°43´54.1”S, 77°45´23.9”W, 10 Agosto 2016, M. Acuña et al. 1448 (holotype: USM!) .

Diagnosis: —A small indusiate species of Cyathea with pinnate-pinnatifid fronds, sphaeropteroid indusia, and concolorous, castaneous petiole scales. It most closely resembles Cyathea bipinnatifida ( Baker 1874: 456) Domin (1929: 262) in frond shape, but the latter species differs in terms of its exindusiate sori and bicolorous petiole scales with light brown centers and paler margins.

Description: —Small terrestrial tree fern. Trunk 40–50 cm tall with a diameter of 4.1–6.7 cm, ascending, with persisting, patent old petiole bases, stem apex hidden between petioles and new croziers. Fronds 60–95 cm long, strongly ascending or slightly spreading. Petioles up to 38 cm long, red brown, shiny, inermous, with pulverulent scurf consisting of concolorous, castaneous to brown, irregularly shaped to ovate-lanceolate squamules 0.3–0.8 mm long; only adaxially pubescent with translucent to tan, appressed hairs 0.6 mm long. Petiole scales 11–21 × 1–4 mm, abundant at petiole bases, lanceolate, nearly concolorous, orange-brown with slightly paler margins. Laminae 39–68 × 9.5–16 (20) cm, linear-lanceolate, pinnate-pinnatifid to pinnate-pinnatisect, frequently basal pinnae with free pinnules, coriaceous, green adaxially (brown when dried), slightly paler abaxially, with 16–26 pinna pairs, these usually alternate, basal pinnae pairs sometimes subopposite and reflexed, always shorter than the longest central pinnae. Rachises inermous, dark brown to blackish brown adaxially, also partially green abaxially; few minute, brown squamules of 0.2 mm length and twisted, linear, brown squamules 4.5 × 1.5 mm abaxially; translucent to tan, tortuous, appressed, multicellular, 0.5 mm long hairs quite dense adaxially, but sparse abaxially. Pinnae 5–10.7 × 1.2–2.9 cm, linear-lanceolate, short stalked to 1 mm, margins incised 8/10–9/10 to the costae. Costae yellow-green, inermous, adaxially with dense, slightly curved, translucent to tan, long hairs to 0.8 mm, abaxially with many orange-brown, clathrate, bullate squamules 1.8 × 0.7 mm, and few orange-brown, lanceolate flat squamules 2.5 × 0.3 mm. Segments 14 × 5 mm, oblong, with obtuse to rounded tips and crenate margins; costules and ultimate veins adaxially with many acicular, translucent to tan hairs, 0.6 mm long, glabrous between the veins, veins abaxially almost glabrous with few translucent or tan, erect hairs up to 0.5 mm long and with many orange-brown clathrate, bullate squamules, 1 × 0.4 mm, with twisted elongated tips; ultimate veins simple or forked once. Sori costular, ca. 1.0– 1.2 mm diam., each with ca. 40 sporangia, castaneous, indusia sphaeropteroid with apical umbo, receptacles globose, 0.4 mm diam., paraphyses few, straight, thin, tan to brown, shorter than sporangia, to 0.3 mm long. Spores 34–37.5 μm in equatorial diameter, trilete, bright yellow, verrucate.

Etymology: —This species is named in honor of the Peruvian researcher Dr. Blanca León for her contributions to our knowledge of the Peruvian fern flora.

Distribution, habitat and ecology: — Cyathea leoniae is only known from the type locality, where it grows both in elfin forest and paramo vegetation at 2750–3450 m asl, within the Bosque de Protección Alto Mayo in the Peruvian Andes. We observed approximately 130 individuals, clumped in several patches of the elfin forest, and only a few, scattered individuals in the paramo vegetation.

Comments:— Cyathea leoniae can be distinguished from the most similar species such as C. bipinnatifida , C. concordia B. León & R.C. Moran (1996: 511) , C. chontilla Lehnert (2011: 22) , and C. xerica A. Tejedor & G. Calat. (2017: 182) by the characters provided in Table 1. Other morphologically similar species such as Cyathea oreopteroides Lehnert & A. Tejedor (2016: 182) , C. palaciosii R.C. Moran (1995: 57) , C. phegopteroides (Hook. 1865:32) Domin (1929: 263) and C. thelypteroides A. R. Smith (2006: 427) differ from C. leoniae by their exindusiate sori.

Additional material examined:— PERU. Dept. San Martín. Prov. Rioja. Distrito Pardo Miguel Naranjos, Bosque de Protección Alto Mayo. Caserío Jorge Chavez. Sector Venceremos: Dwarf forest with small trees of 5–6 m in height, 2877 m asl, 5°43’24.18”S, 77°45’12.30”W, 02 June 2016, M. Acuña et al. 1411 ( USM) ; Shrubland with high dominance of shrubs from 1–3 m in height, 3056 m asl, 5°43’38.2’’S, 77°45’13.8’’W, 20 October 2016, M. Acuña et al. 1491 ( USM, MO) ; Shrubland with high dominance of shrubs from 1–3 m in height, 2989 m asl, 5°43’36.4’’S, 77°45’11.3’’W, 20 October 2016, M. Acuña et al. 1496 ( USM) .

Figures

FIGURE 1. Illustration of Cyathea leoniae. A. Pinna, adaxial view. B. Fertile segments, abaxial view. C. Frond. D. Petiole scale. E. Margin of petiole scale. F. Flat squamule of pinnae. G. Subullate squamule of pinnae (from holotype, Acuña 1448). Drawing by Margoth Acuña-Tarazona & Elluz Huamán-Melo.

FIGURE 2. Cyathea leoniae. A. Plant in its natural habitat. B. Concolorous, orange-brown petiole scales. C. Adaxial side of frond. D. Sphaeropteroid indusia on abaxial side (from holotype, Acuña 1448). Photographs by Elluz Huamán-Melo.

FIGURE 3. Cyathea leoniae. A. SEM pictures of globose sorus with sphaeropteroid indusium. B.Adaxial view of open sorus with several remaining sporangia. C. Lateral view of two sporangia with their annulus. D. Distal (above) and equatorial (below) view of verrucate spore (from holotype, Acuña 1448). Scale bars—100 μm.