Dryopteris schizopaleata Eb.Fisch. & Lobin, 2023

Fischer, Eberhard & Lobin, Wolfram, 2023, Synoptic Revision of the exindusiate species of Dryopteris (Dryopteridaceae) from Central Africa (Democratic Republic of the Congo, Rwanda, Burundi) with description of Dryopteris schizopaleata sp. nov. from Rwanda, Phytotaxa 587 (2), pp. 136-148 : 138-140

publication ID	https://doi.org/ 10.11646/phytotaxa.587.2.3
DOI	https://doi.org/10.5281/zenodo.7734522
persistent identifier	https://treatment.plazi.org/id/BB79E074-FFAB-FFC4-B5C8-8406FE85AF21
treatment provided by	Plazi
scientific name	Dryopteris schizopaleata Eb.Fisch. & Lobin
status	sp. nov.

Treatment

Dryopteris schizopaleata Eb.Fisch. & Lobin View in CoL sp. nov. ( Figs. 1 E–F View FIGURE 1 , 2–3 View FIGURE 2 View FIGURE 3 , 4 A–B View FIGURE 4 ).

Type :— RWANDA. Western Province : Nyungwe National Park, Cyamudongo Forest, forest floor along stream, 1941 m, 18 September 2021, 2°32`26.89`` S, 28°59`20.46``E, E.Fischer s.n. (holotype BR0000015253521 V!; isotype B200220601 !, B200220602 !, B200220603 !) GoogleMaps .

Diagnosis: — Dryopteris schizopaleata is exindusiate, and shares this character in Africa only with D. manniana , D. filipaleata and D. ruwenzoriensis . From D. manniana it is easily separated by the lack of gemmae.A striking character to recognise the new species are the unique scales, which are broadly and irregularly fimbriate at the apex, differing from D. filipaleata and D. ruwenzoriensis ( Fig. 4 View FIGURE 4 ). Dryopteris filipaleata has a scale apex that is irregularly denticulate, terminating in a short uniseriate series of cells. In Dryopteris ruwenzoriensis the scales apex terminates in a short uniseriate series of oblong cells.

Description: —Terrestrial fern. Rhizome erect, scaly, scales broadly–ovate, dark to light brown, up to 4 × 2.3 mm, at apex deeply and irregularly fimbriate, divided into long uniseriate and irregular fissures. Fronds tufted. Stipes (22.8–)27–41.5(–57,1) × 0.3–0.5 cm, at the base thickened to 5–6 cm, densely covered with scales that are bent downward and similar to those from rhizome. Lamina 57–87 × 31–62 cm, broadly–ovate, fresh green, bipinnate-pinnatifid. Rachis middle to dark brown, scaly, winged, secondary rachis and costules sparsely set with trichomes 0.25–0.3 mm, cells 0.3 × 0.05 mm. Pinnae in 14–20 pairs, alternate, arranged in an angle of 45°, (15.2–)21–26(–36.8) × (7–)9.9–12(–14.8) cm, basal pinnae only slightly reduced. Pinnules in 15–17 pairs 3–5.4(–7.6) × (0.8–)1–1.7(–2.2) cm, opposite to subopposite; pinnule lobes in (8–)11–13 pairs, 0.5–1.2 × 0.3–0.5 cm, with rachis winged, veins branched, only in basal pinnules few dichotomosly branched. Sori up to 5–10 per pinnule, almost round, exindusiate, 0.78–0.96 × 0.63–0.82 mm. Spores with perispore folded to form narrow or compressed reticulate ridges, 32.5–34 × 25.7–27 µm, ridges 7–13 × 2–2.5 µm.

Additional specimens seen (Paratype):— RWANDA. Western Province : Nyungwe National Park, Cyamudongo Forest , forest floor along stream, 1955 m, 18 April 2022, 2°32`26.89`` S, 28°59`20.46`` E, E. Fischer s.n. ( KOBL) GoogleMaps .

Distribution:— Rwanda, Nyungwe National Park, Cyamudongo Forest, only known from the type locality.

Habitat:—Montane forest floor along stream, partly extending into buffer zone with pines, 1940–1960 m

Etymology:—The name refers to the main character, the scales from the rhizome and base of stipes, with which the new species is easily recognized.

Notes:— Dryopteris schizopaleata sp. nov. was collected in the Nyungwe National Park, a very species-rich area of montane rainforest, with 1468 species of ferns and seed plants recorded, of which 259 are endemic (224 Albertine Rift Endemics, 35 Local Endemics, Fischer unpubl.).

The Cyamudongo Forest is only 300 ha in size, an isolated part of the Nyungwe National Park by 8 km of unprotected land. Despite this, Cyamudongo is exceptional in its beta-diversity. Here 674 species of vascular plants are recorded, including 88 endemics; 42 of these endemic species are exclusively found in Cyamudongo.

Concerning the ferns and fern allies, 39.8% (57 out of 143 species) recorded from Nyungwe National Park are found in Cyamudongo Forest, and 11 species are considered endemic (species numbers after Fischer unpubl.).

Two other new fern species, Asplenium uschiae Eb.Fisch. & Lobin (2023a) and Diplazium cyamudongense Eb.Fisch. & Lobin (2023b) have also been discovered in Cyamudongo.

Conservation status: —With only a single collecting site, it is not possible to calculate an Extent of Occurrence (EOO) according to the IUCN criteria ( IUCN 2012, 2022). The area of occupancy (AOO = 9 km 2) falls within the limits for the Critically Endangered category. However, as the species occurs within a well-protected area, and therefore to experience no threat or decline, it cannot be assessed in any threat category; therefore, it should be assessed as Least Concern (LC).