Angiopteris madagascariensis de Vriese

Senterre, Bruno, Rouhan, Germinal, Fabre, Isabelle, Morel, Charles & Christenhusz, Maarten J. M., 2014, Revision of the fern family Marattiaceae in the Seychelles with two new species and a discussion of the African Ptisana fraxinea complex., Phytotaxa 158 (1), pp. 57-75 : 64-66

Angiopteris madagascariensis de Vriese in Vriese & Harting (1853: 23). Fig. 3

Type: — MADAGASCAR. Without locality, 1834, J. Goudot s.n. (holotype P!-00466551 , isotypes P!-00696299 , P!- 00696300 ).

Synonym:— Angiopteris evecta auct. non (G.Forst.) Hoffm., e.g. sensu Baker (1877: 517).

Perennial ferns, 3–4 m high. Rhizomes 50–90 cm tall × 50 cm in diameter, upright, globular or trunk-like, covered with remaining bases of old leaves. Roots branched, stout, 6 mm in diameter. Stipules 5–7 × 5–9 cm, fleshy, often proliferous, black, covered with brown scales, the scales smaller than those on the petioles, aerating areas 3–4 × 1 mm, mostly towards base, slightly immersed, elliptic, whitish, stipule margins regularly laciniate or digitate, with falcate linear lobes. Fronds 400–500 cm, spirally arranged, densely set, 10–12 cm apart, 5–7 functional fronds per plant, arching. Petioles 120–170 cm long, 5 cm in diameter, terete, rounded adaxially, with a basal pulvinus (ca. 10 cm long, 6–8 cm in diameter at base), not winged, yellow (when dry) or green (when fresh), flesh whitish inside, densely scaly (especially towards base on young leaves), scales 8–10 × 0.1–0.2 mm, golden brown, inconspicuous wart-like bases of old scales present, small, aerating areas 2.0–2.5 × 1.0– 1.5 mm, abundant throughout up to rachises, only slightly discolorous. Laminae 280–330 × 200–220 cm, bipinnate, with undivided pinnules except for the 1–3 basal pinnae that are bipinnate towards base, elliptic, longer than the petioles. Rachises terete, rounded adaxially, not winged, yellow (when dry) or green (when fresh), sparsely pubescent. Pinnae petiolulate. Petiolules 30–50 mm (up to 200–350 mm for basal pinnae, 20 mm in distal pinnae), not articulate, rounded adaxially, pulvini 30 mm long, 20 mm in diameter at base (when fresh). Pinnae alternate, 10–12 on each side of frond, 23–26 cm apart (closer towards apex), not overlapping. Basal pinnae progressively and slightly reduced, perpendicular to rachises, oblong. Middle pinnae 100 × 35 cm, ascendant towards apices (acrotropic), oblong. Distal pinnae progressively reduced. Terminal pinna absent, the rachis terminated in a mucron. Secondary rachises terete, rounded adaxially, not winged, green (when fresh), sparsely pubescent. Pinnules (observed on a middle pinna) petiolulate. Secondary petiolules ca. 5 mm, not articulate, rounded adaxially. Pinnules alternate or subopposite or opposite, 34–36 on either side, 2.2–3.3 cm apart, not overlapping. Basal pinnules similar to other pinnules. Middle pinnules 20–22 × 2.5 cm, slightly ascendant towards apices (acrotropic), elliptic to nearly oblong. Distal and terminal pinnules similar to other pinnules. Pinnule blades entire, bases attenuate or obtuse, slightly asymmetrical, not decurrent on the petiolules, margins scarcely serrate, teeth 12–13 per cm, margins glabrous, slightly revolute, apices progressively acuminate, acumen 2–4(–5) cm, green or olive above, yellowish below, membranous, glabrous. Venation pinnate, midveins reaching the apex, secondary veins distinct, undivided or furcate (at bases and up to more than midway to the margins), 0.7–0.8 mm apart, straight, oblique, terminating in teeth apices, venuloids 2.0– 3.5 mm long, intramarginal, ending after the line of sori, evanescent, nearly up to mid-way between the margin and the costa if observed in transparency, straight. Sori more or less densely placed, 300–350 per pinnule, in one row on each side of the midvein, intramarginal and from the base nearly to the acumen, at 1–2 mm from the margin, shortly immersed, oblong or elliptic, not indusiate. Sporangia 6–12 per sorus, nearly free, basally fused.

Representative specimens examined: — SEYCHELLES. Mahé: L.H. Boivin s.n. (P-01646348, P-01646344, P-01646338, P-01646346), 400 m, 27 February 1882, Th. Delacour 36 (P-01332779, P-01646336), J. Stanley Gardiner s.n. (K), J. Horne 199 (K), L. Humblot s.n. (P-01332835, P-01332836), A. Pervillé 207 (P-01332837, P-01646350, P-01646349), H.J. Schlieben 11726 (K), s.c. s.n. (P-01646337), Mériau s.n. (P-01646342, P-01646341); Casse Dent, 400 m, 30 May 2008, B. Senterre 5353 (SEY), 550 m, 6 July 2011, B. Senterre & N. Labiche-Barreau 6123 (P-02432632, SEY); Casse-Dent à Congo Rouge, 18 April 1972, H. Jacquemin 988 (P-01332834, P-01646339); Congo Rouge, 300-800 m, July 1970, J. Procter 4076 (K, P-01646332, SEY); La Réserve, 400 m, May 1987, F. Friedmann 5485 (P-01646333); Mare aux Cochons, near Mt. Jasmin, M.J. Whitehead 56 (K); Mission Viewing Lodge, D. Lorence 1810 (K); Morne Blanc, près du sommet, November 1982, F. Friedmann 4367 (P-01592104); Trois Frères, April 1981, F. Friedmann 3752 (P-01646334, P-01646335); Silhouette: 500 m, 14 September 1993, C.S. Awmack 407 (SEY); Sans Sentiment, J. Stanley Gardiner s.n. (K). Without locality: Barkly s.n. (BM), L.H. Boivin s.n. (P-01646345), A. Pervillé s.n. (P-01646343, P-01646340).

Distribution: —Endemic to islands in the Western Indian Ocean. It is known from Madagascar, Mayotte, La Réunion, Mauritius and the Seychelles, where it is widely distributed on the islands Mahé and Silhouette. It has been expected and searched for in the ravines of nearby Praslin, but was not found on that island.

Ecology: —Common in submontane and lower montane ravine evergreen rain forests between 300 and 750 m, progressively replaced by Angiopteris chongsengiana and Ptisana laboudalloniana at elevations above 750 m; penetrating the lowland belt in wet ravines down to ca. 150 m as isolated individuals.

Conservation: —This species is locally relatively common and also occurs on other Mascarene Islands and in Madagascar. We estimate its IUCN red list category to be LC (Least Concern), although a formal assessment is yet to be made.

Vernacular name:—‘Baton monsenyer’ (Creole), a name given in reference to the resemblance of the crosier, or developing leaves, with the cross of cardinals.

Morphological affinities: —Originally, specimens from the Seychelles were identified as A. evecta . This was the first species of Angiopteris to be described and because herbarium material is fragmentary and therefore not diagnostic, the majority of Angiopteris were initially identified with that name before the genus became better known. As we understand now, Angiopteris evecta is a species from Australasia and the Pacific (holotype from Tahiti) and has occasionally naturalised elsewhere in the Tropics (see Christenhusz & Toivonen 2008). It is distinguished by the presence and length of its false veins, i.e. almost to the costa vs. intramarginal for A. madagascariensis . The Seychelles specimens are very much like those from Madagascar, although we have not found any Madagascan specimens with the basal 1–2 pinnae having pinnate basal pinnules (observed only in fully developed individuals). Nevertheless, this is a common feature in other Angiopteris species and may be environmentally induced.

Figures

FIGURE 3. A–E: Angiopteris chongsengiana. A. View of the ‘stipules’ and rhizome (photograph by B. Senterre), B. Winged secondary rachis, with sessile pinnules (photograph by I. Fabre), C. Mature sporangia and venuloids (photograph by B. Senterre), D. Wart-like bases of old scales on petiole (photograph by B. Senterre), E. Typical apex of a pinna (photograph by I. Fabre); F–J: Angiopteris madagascariensis. F. Massive rhizome ca. 60–70 cm high (photograph by B. Senterre), G. secondary rachis not winged (photograph by I. Fabre), H. Old sporangia and venuloids (photograph by B. Senterre), I. ‘Stipule’ (photograph by I. Fabre), J. Typical aspect of the basal pinna, bipinnate on mature individuals (photograph by I. Fabre).