Dryopteris antarctica (Baker) C.Chr.

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 : 20-25

Dryopteris antarctica (Baker) C.Chr.

( Figs 3 ; 4)

Index filicum, Supplementum 1906 -1912: 29 (20

Dec. 1913). — Nephrodium antarcticum Baker , Journal

of the Linnean Society, Botany 14: 479, 480 (1875). —

Type: Island of “Amsterdam” (Saint Paul), G. Staunton

s.n. (holo-, BM!).

Dryopteris callolepis C.Chr., Notizblatt des Botanischen Gartens und Museums zu Berlin-Dahlem 9: 177 (1924). — Type: Kenya, “ Mt. Aberdare : regio bambusina superior, ± 2800 m, 31 März 1922”, R.E. & T.C.E. Fries 2554 (holo-, BM!).

Aspidium spinulosum sensu Pappe & Rawson , Synopsis filicum Africae australis : 38 (Jan.-Jul. 1858), non Aspidium spinulosum Sw. (1801: 38) .

Aspidium spinulosum Sw.var. dilatatum sensu Kuhn, Filices africanae: 142 (Oct. 1868), non Aspidium dilatatum (Hoffm.) Sm. (1804: 1125) .

Dryopteris spinulosa (O.F.Müll. ex Roth) Kuntze subsp. dilatata sensu Bonap. , Notes ptéridologiques 15: 16 (25 Feb. 1924), non D. dilatata (Hoffm.) A.Gray (1848: 631) .

Nephrodium spinulosum sensu Peter, Feddes Repertorium, Beiheft 40 (1): 56 (1929).

Dryopteris austriaca (Jacq.) Woyn. subsp. dilatatum sensu Chiov., Lavori dell’Instituto Botanico, Università di Modena 6 (I/XI): 140 (1935), non Dryopteris dilatata (Hoffm.) A.Gray (1848: 631) .

Dryopteris dilatata sensu Tardieu, Flore de Madagascar et des Comores (plantes vasculaires), 5e Famille. Polypodiacées (sensu lato) 5 (1) Dennstaedtiacées. (10) Aspidiacées ): 316 (May 1958), non (Hoffm.) A.Gray (1848: 631).

A C F F B D E G

A-E, G

OTHER MATERIAL EXAMINED. — Madagascar. Massif de l’Andringitra (Iratsy):vallées de la Riambava et de l’Antsifotra et montagnes environnantes, reste de forêts, vers 2000 m, 27.XI-8.XII.1924, Humbert 3760 (P00349521).

Mauritius. Des bois du centre de l’Île de France, Bory de St Vincent s.n. (P00349525).

Réunion. Fonds de la Rivière de l’est-Massif de la Fournaise, 1850 m, 02.IV.1971, Cadet 3183 (P00349522). — Réunion (Île Bourbon), 1892, Cordemoy 41 (P00349524, P00349527). — Île Bourbon, Richard 669 (K). — À la plaine des Cafres, Richard 37 (P00349528). — Dans les forêts élevées, Île Bourbon, sine coll. 358 (P00349526). — À la plaine des Cafres, du côté du Volcan, sine coll. 669 (P00349523).

Saint Paul. Stauton s.n. (BM). — Saint Paul, in humid situations all over the island, Jelinek 123 (BM).

DESCRIPTION

Plants terrestrial or epilithic.Rhizome short, erect to suberect, closely branched, up to 5 mm in diameter, set with roots, crowded trophopods and scales, the scales ferrugineous to castaneous, often bicolorous, chartaceous, sessile, lanceolate to narrowly ovate, up to 9 × 3 mm, cordate to cordate-imbricate, the margins entire or with scattered glands, the apex filiform, terminating in a moniliform series of cells. Fronds crowded, caespitose, arching, up to 1.03 m long; stipe base castaneous, stramineous higher up, proximally adaxially flattened, shallowly sulcate distally, up to 460 mm long and 4.5 mm in diameter, moderately set with glands and spreading scales, the scales ferrugineous, often slightly darker centrally, chartaceous, sessile, ovate to broadly ovate, up to 11 × 4.5 mm, truncate to cordate-imbricate, entire or with scattered glands, the apex terminates in a short series of moniliform cells; lamina herbaceous to thinly herbaceous, up to 3-pinnate, ovate, up to 600 mm long, anadromous, catadromous towards apex, with up to 17 petiolated pinna pairs; rachis greenish, adaxially sulcate, becoming narrowly winged towards apex, often set with glands and moderately to sparsely scaled, the scales ferrugineous to stramineous, chartaceous, sessile or short-stalked, lanceolate to subulate, up to 4 × 2 mm, cuneate to cordate-imbricate, entire or with scattered glands, the apex terminates in a short uniseriate series of cells, the cells oblong or moniliform, scales on the adaxial surface of rachis linear to filiform, up to 5 × 0.4 mm; pinnae petiolate, the petiole up to 20 mm long, the basal pinnae inaequilaterally ovate, up to 2-pinnate, those higher up aequilaterally narrowly ovate to oblong-acuminate, up to 170 × 90 mm, basal pinna pair mostly longest, basiscopically developed, opposite to alternate, widely spaced at base, more closely spaced towards the apex and mostly somewhat imbricate, with up to 8 petiolated pinnule pairs; pinna-rachis adaxially shallowly sulcate, the sulcus confluent with that of the rachis, narrowly winged for most of its length, set with glands, also sparsely scaled, the scales stramineous, chartaceous, sessile or short-stalked, narrowly ovate to subulate, up to 3 × 0.6 mm, cuneate to cordate, entire to closely set with glands and globose to subglobose non-glandular cells along the margin and often also on surface, or with short moniliform hairs along the margin, the apex filiform, terminating in a short moniliform series of cells; pinnules petiolate, the petiole up to 2 mm long, symmetric or inaequilaterally narrowly ovate to oblong-obtuse, 1-pinnate, often acroscopically developed, acroscopic pinnule on basal pinnae up to 28 × 12 mm, basiscopic pinnule on basal pinnae up to 65 × 25 mm, not or slightly imbricate, with up to 4 petiolated segment pairs; pinnule-rachis adaxially shallowly sulcate; segments broadly ovate to oblong-obtuse, up to 18 × 9 mm, basiscopically decurrent, spaced, never imbricate, lobed, the lobes strongly dentate, adaxially glabrous, or sparsely set with glands (52-)116(-156) mm long along the veins, often also with hairs and filiform scales near the base, abaxially sparsely to moderately set with glands similar to those on the adaxial surface, often also with hairs and (sparsely) scaled, the hairs moniliform with scattered glands, the scales stramineous, chartaceous, sessile or short-stalked, ovate to subulate, up to 1.8 × 0.7 mm, cuneate to truncate, entire or variously set with clavate glands and globose to subglobose non-glandular hairs along the margins, the scale apex filiform, terminating in a short or long series of moniliform cells. Venation pinnately branched in segments, vein branches forked or simple, often slightly abbreviated when fertile, evident, ending in the teeth near the margin, endings often slightly thickened. Stomata mostly of polocytic type, (40-)50(-64) mm long. Sori circular, at or near the apex of mostly shortened anadromous vein branch, discrete at maturity, up to 1.2 mm in diameter; sporangium stalk simple, capsule with (11-)16(-21) indurated annulus cells; indusium brown, firmly herbaceous, reniform, entire to erose, often glandular along margin, up to 1.2 mm in diameter. Spores ellipsoidal, monolete, perispore with compressed reticulate folds, densely echinulate, (44-)50(-58) × (32-)35(-42) mm (Tryon & Lugardon 1990: 428, fig. 159.44, as “ D. callolepis ”). Chromosome number: 2n = 164 ± 4 (Vida in Widén et al. 1973: 2129).

DIAGNOSTIC FEATURE AND RELATIONSHIPS Dryopteris antarctica is characterised by being restricted to high elevations, and the short, closely branched, erect to suberect rhizome generally enveloped by trophopods. Also characteristic are the firmly chartaceous, often bicolorous rhizome and stipe scales which appear entire, but which often bear glands along the margin. The scale apex and marginal outgrowths generally terminates in a short or long moniliform series of cells. The apical part of the lamina hairs terminates in a similar moniliform series of cells. The strongly dentate segments, and the mostly shortened, fertile vein branches are further diagnostic features of the species.

Widén et al. (1999: 19) found D. antarctica to be very similar to D. dilatata (Hoffm.) A.Gray from Europe and Alaska in both morphology and chemistry. My observations on the scale morphology of the species support this suggestion.

VARIATION

Considering the wide and disjunct distribution of Dryopteris antarctica , the species shows little variation in overall morphology. Micromorphological variation includes the sporadic occurrence of glands along the indusium margin, and the often significant variation in the length of the glands (52-156 µm) occurring on the lamina.Stoma length of collections throughout the distribution range falls within the same size range (40-64 µm), which does not suggest different ploidy levels in the species. Variation has also been observed in the degree to which the lamina scales are set with glands. In collections from Saint Paul, the scale margins and laminae are closely set with clavate glands, whilst collections from the African continent are never as closely glandular. Non-glandular globose to subglobose cells have been observed on the scale laminae of collections from both Saint Paul and Africa. Morphologically, D. callolepis cannot be separated from D. antarctica and is therefore considered synonymous.

DISTRIBUTION AND HABITAT

Dryopteris antarctica is remarkably disjunct in its distribution, occurring on the isolated island of Saint Paul (37°52’S, 77°35’E) in the south Indian Ocean , and in Africa where it is confined to the Western Cape and the south-western corner of the Eastern Cape. The species also occurs at 1850 m on Réunion island, and at 2000 m on Massif d’Andingitra in southern Madagascar, and on Mauritius ( Fig. 5 ) .

REMARKS

Fraser-Jenkins (1986: 208) noted that D. callolepis is synonymous with D. antarctica . It was, however, again tentatively separated from D. callolepis for “geographical convenience and because of their distinct chemistry” (Widén et al. 1999: 19). The type of D. antarctica is in the Banks Herbarium at the British Museum of Natural History.

Figures

FIG. 3. — Specimen of Dryopteris antarctica (Baker) C.Chr., de Cordemoy 41 (P00349527). Photo: MNHN, Paris Herbarium, 2009.

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.