Polystichum maevaranense Tardieu

Roux, Jacobus P., 2001, A review of the fern genus Polystichum (Pteropsida: Dryopteridaceae) in Madagascar and the Mascarene region, Adansonia (3) 23 (2), pp. 265-287 : 278-279

5. Polystichum maevaranense Tardieu

Notul. Syst. (Paris) 15: 166 (1956); in Humbert, Fl. Madag. , fam. 5: 319 (1958). — Type: Humbert & Capuron 25019, Madagascar, Centre-Nord: montagnes au nord de Mangindrano (haute Maevarano) jusqu’au sommet d’Ambohimirahavavy (partage des eaux Mahavavy-Androranga), 1900 m (holo-, P!; iso-, L!); only known material.

Plants terrestrial. Rhizome short, erect to suberect, to 6 mm in diameter, beset with closely spaced persistent stipe bases, roots, and paleae, the paleae densely impregnated, ebeneous to black, crustaceous with a narrow ferrugineous membranous margin, nitid, broadly attached, linear-lanceolate, the margins with widely spaced short outgrowths, the apex terminating in an acicular cell, to 7 × 1.2 mm. Fronds caespitose, to 6 per plant, suberect to arching, to 610 mm long; stipe proximally castaneous, brown higher up, adaxially sulcate, to 310 mm long, to 3 mm in diameter, proximally densely paleated, the paleae similar to those on the rhizome, to 15 × 2 mm, distally moderately paleated, the paleae dark brown, short-stalked, narrowly triangular, cordate to cordate-imbricate, the margin proximally with simple or branched, straight or curved outgrowths, the apex entire, terminating in an acicular cell; lamina 1-pinnate, lanceolate to narrowly oblong, with 12-15 pinna pairs, the proximal pinnae not reduced, the proximal pinna pair deflexed, to 250 mm long; rachis brown, sulcate adaxially, densely paleated, the paleae castaneous to ferrugineous, short-stalked, narrowly linearattenuate, narrowly triangular, or subulate, cordate to cordate-imbricate, often hastate, the margin proximally beset with simple or branched, straight or curved outgrowths, the apex entire, subulate, terminating in an acicular cell, to 8 mm long, proliferous near the apex, with 1-3-paleated buds per frond borne abaxially in the axils of the distal pinnae, the paleae ferrugi- neous, broadly attached, lanceolate to narrowly ovate, cordate, the margins with short marginal outgrowths, the apex terminates in an acicular cell, to 3 × 0.7 mm; pinnae glossy green adaxially, pale green abaxially, approximate to alternate, proximally widely spaced, distally more closely spaced but not overlapping, proximally shortstalked, distally sessile, firmly herbaceous to coriaceous, to 66 mm long, to 18 mm wide, proximally oblong-attenuate, distally lanceolate to trullate, strongly inaequilateral, auriculate acroscopically, the auricle on the proximal pinnae incised near to the costa, broadly elliptic, the pinnae obliquely lobate, serrate, pungent, adaxially glabrous or with a few subulate paleae along the sulcated costa, abaxially moderately beset with stiff ferrugineous, short-stalked, subulate to narrowly triangular paleae, with a few simple or branched outgrowths at the base, the apex terminates in an acicular cell, to 2 mm long. Venation obscure. Sori essentially uniseriate, often pluriseriate proximally, medial to inframedial, circular, to 1.5 mm in diameter; sporangium with 10(-13-)14-indurated annulus cells; indusium stramineous, persistent, minutely repand, maximum radius 0.58(-0.6-) 0.65 mm; spores brown, perispore smooth to glebose, variously perforated, echinulate, exospore 30(-33.68-)40 × 22(-14.96-)28 µm. Chromosome number unknown. — Fig. 6 A-C.

DIAGNOSTIC FEATURES AND RELATIONSHIPS. — Polystichum maevaranense is characterized by a thin suberect rhizome, rhizome and stipe paleae that are crustaceous, dark brown to black and glossy, the long stipe and the narrowly lanceolate pinna outline. The proliferous buds are borne along the rachis in the distal part of the frond. Also, the palea morphology distinguishes it from any other taxon in the region.

Polystichum maevaranense is poorly known and the material at hand is insufficient for it to be confidently placed in any section hitherto described.

DISTRIBUTION AND ECOLOGY. — A littleknown species endemic to Madagascar, where it is reported to grow at an elevation of 1900 m in wet forests on gneiss laterites in the northern part of the island .

Figures

Fig. 6. — Stipe and lamina paleae in Polystichum species.— Polystichum maevaranense: A, rachis palea; B, proliferous bud palea; C, apex of B showing the cellular structure. Humbert 15019 (P). — Polystichum pauciaculeatum: D, stipe palea. Leandri et al. s.n. (P); E, margin of D showing the cellular structure; F, lamina palea, abaxial surface. Humbert 11121 (P). — Polystichum tsaratananense: G, stipe palea; H, apex of G showing the cellular structure. Humbert & Capuron 25035 (P); I, lamina palea (abaxial surface); J, apex of I showing the cellular structure. Humbert 18144 (P). — Polystichum wilsonii: K, stipe palea; L-M, lamina palea, abaxial surface. K-L, Alluaud 241 (P); M, Esterhuysen 26699 (BOL).