Dryopteris wallichiana (Spreng.) Hyl. subsp. madagascariensis (C.Chr.) J.P.Roux

Roux, Jacobus P., 2011, The fern genera Dryopteris and Nothoperanema (Dryopteridaceae) in Madagascar and neighbouring Indian Ocean islands, including Saint Paul, Adansonia (3) 33 (1), pp. 7-67 : 18-20

Dryopteris wallichiana (Spreng.) Hyl. subsp. madagascariensis (C.Chr.) J.P.Roux

( Figs 1 ; 2 )

Synopsis of the Lycopodiophyta and Pteridophyta of Africa, Madagascar and Neighbouring Islands: 124 (Mar. 2009). — Dryopteris paleacea (Lag. ex Sw.) C.Chr. var. madagascariensis C.Chr. , Catalogue des plantes de Madagascar, Pteridophyta: 27 (Feb. 1932), nom. illeg. (McNeill et al. 2006: Art. 32.1[d]). — Dryopteris paleacea (Lag. ex Sw.) C.Chr. var. madagascariensis C.Chr., Dansk Botanisk Arkiv 7: 35, t. 11, figs 5-9 (Oct. 1932). — Dryopteris reichsteinii Fraser-Jenk. , Bulletin of the British Museum, Natural History (Botany): 14 (3): 191 (1986).

— Type: Madagascar, Mt. Tsaratanana , 2400 m, IV.1924, H. Perrier de la Bâthie 16454 (holo-, BM000801013 !; iso-, P00349500 !, P00483234 !, P00483235 !).

OTHER MATERIAL EXAMINED. — Madagascar. Mont Tsaratanana , 2400 m, IV.1924, Perrier de la Bâthie 16454 ( BM 000801013 ; P 00349500 ; P 00483234 ; P 00483235 ) .

Réunion. Habitat in insula Borboniae, Desvaux s.n. ( P 00349605 ). — Cilaos , str. du Cap Bouteille , 1740 m, 18.III.2009 (Herb. E. Grangaud).

DIAGNOSTIC FEATURES AND RELATIONSHIPS

Dryopteris wallichiana subsp. madagascariensis appears to be generally smaller than the other subspecies as the fronds grow up to 1.1 m long and up to 270 mm wide. The proximal basiscopic lobes are basiscopically auricled and frequently also shallowly lobed. The lamina scales terminate in a subulate cell ( Fig. 2D, F ), rather than an elliptic thin-walled cell. The larger stoma length, (40-)53(-64) mm, suggests it being a different cytotype than either subsp. wallichiana and subsp. reichsteinii .

DISTRIBUTION AND HABITAT

Dryopteris wallichiana subsp. madagascariensis appears to be rare in the Madagascan region. In Madagascar, it is known from the Tsaratanana Mountains only, where it occurs at 2400 m. At this altitude, the vegetation consists of evergreen forests with an understory consisting of small trees. More recently, the species was rediscovered in La Réunion, occurring at 1740 m in seasonally wet open montane forests ( Fig. 5 ).

REMARKS

Christensen (1932a: 27) first mentioned the name Dryopteris filix-mas subsp. madagascariensis under D. paleaceae , but the former was not validly published (McNeill et al. 2006: Art. 32.1[d]). It was, however, validly published later ( Christensen 1932b: 35). Fraser-Jenkins (1986: 191) raised this variety to species level as D. reichsteinii . He later determined material from the eastern highlands of Zimbabwe to be a triploid apomict and described this as D. wallichiana subsp. reichsteinii Fraser-Jenkins, 1996 (in Widen et al. 1996: 71). I found material from Madagascar to differ from both subsp. wallichiana and subsp. reichsteinii . For this reason, the name Dryopteris wallichiana subsp. madagascariensis was proposed, based on D. paleacea var. madagascariensis C.Chr.

A 1774 Commerson collection said to have come from “Île de France ”, now Mauritius, is housed in the Lamarck Herbarium, Paris (P00307037 & P00307038). Poiret (1804) based Polypodium umbilicatum on this collection. It was later transferred to Aspidium Sw. ( Desvaux 1811: 320, 321), and still later to Nephrodium Rich. as a variety of N. marginale Mich. ( Desvaux 1827: 260) . The name then appears to have been forgotten as it was not cited for nearly a century until Morton (1973: 265) commented on the type, tentatively ascribing it to D. filix-mas (L.) Schott, but suggested that it may be D. paleacea var. madagascariensis . The origin of the collection is clearly erroneous as the Commerson material is that of D. filix-mas , a species not occurring on Mauritius.

Figures

FIG. 1. — Holotype of Dryopteris wallichiana (Spreng.) Hyl. subsp. madagascariensis (C.Chr.) J.P.Roux at the Natural History Museum, London (BM000801013).

FIG. 2. — Scales of Dryopteris wallichiana (Spreng.) Hyl. subsp. madagascariensis (C.Chr.) J.P.Roux: A, B, stipe scales; C, C’, D, rachis scales; E, scale from abaxial lamina surface; F, G, scales from lamina margin. De la Bâthie 16454 (BM). Scale bars: A-G, 1 mm; C’, 0.1 mm.

FIG. 5. — Distribution of Dryopteris wallichiana (Spreng.) Hyl.subsp. madagascariensis (C.Chr.) J.P.Roux (Δ), and Dryopteris antarctica (Baker) C.Chr. (z). The solid square (·) indicates where both species occur.