Dicksonia baudouinii Fournier (1873: 347)

Noben, Sarah & Lehnert, Marcus, 2013, The genus Dicksonia (Dicksoniaceae) in the western Pacific, Phytotaxa 155 (1), pp. 23-34 : 26-28

Dicksonia baudouinii Fournier (1873: 347) . ( Figs. 2A , 3A )

Type:— NEW CALEDONIA. Province unknown: Without locality, without date, A. Baudouin s.n. (holotype P). Dicksonia deplanchei Vieill. ex Baker in Hooker & Baker (1874: 462). Type:— NEW CALEDONIA. Province du Sud :

Mont Mou, [ca. 22°03'47"S, 166°21'07"E,], without date, Deplanche 168 [Herb. Vieillard 2248] (lectotype P-

01513222, here designated, isolectotypes F, MPU, P)

Trunks to 3 m tall, 8 cm diameter, with many persistent petiole bases, frond scars not visible, with a thick layer of adventitious roots soon below the trunk apex. Adventitious buds not observed. Fronds to 150 cm long, holodimorphic, basal parts erect to ascending, distal parts patent, and the crown funnel-shaped. Petioles up to 52 cm long, covered with pale, soft hairs at the very base and long, reddish, erect hairs persisting for most of the petiole length. Petiole hairs to 2.5 cm long at the base, becoming shorter in upper parts, setiform. Laminae to 100 × 110 cm, tripinnate-pinnatifid, basally truncate, apically gradually reduced, coriaceous. Leaf axes [rachises, costae and costules] light brown, inermous, covered with reddish, erect hairs on rachis and lower to middle parts of costae; covered with pale ones towards the tip of the pinnae and on pinnules. Pinnae stalked to 4.5 cm, patent to 8 pairs per frond, lowest pinnae only slightly shorter than largest ones. Sterile pinnae truncate-lanceolate, to 55 × 25 cm; fertile pinnae lanceolate, truncate to rounded at the base, to 45 × 17 cm. Sterile pinnules up to 13 × 3.2 cm, truncate-lanceolate, stalked to 4.5 mm, fertile pinnules up to 10 × 2.2 cm, elongated-lanceolate, subsessile to stalked to 3.5 mm. Sterile segments oblong to lanceolate, stalked to 1 mm, margins serrate to lobed. Fertile segments oblong to lanceolate, stalked to 1.5 mm, margins lobed, each lobe may support one sorus except for the terminal ones. Stalks of both, sterile and fertile, pinnules and segments become shorter towards the tip of the pinnae until they are sessile. Veins of sterile segments adaxially glabrous, abaxially hairy. Veins of fertile segments sparsely hairy adaxially and abaxially, abaxially sometimes glabrous. Vein hairs pale, ciliform. Sori 1.0– 2.1 mm wide, at the end of unbranched lateral veins subcostal to costal, slightly kidney shaped when closed, circular when open; indusia bivalved, outer one greenish, with a thin cartilaginous margin, inner one light brown with entire margins, even at maturity; paraphyses shorter than sporangia, few or absent. Spores tetrahedral-globose, with prolonged lobes, 57.5 µm × 47.5 µm with areoles surrounded by reticulate ridges; perispore granular.

Distribution and habitat: —Evergreen mountain rainforest at (400–) 800–1450 m, on ultra-alkaline soils, mainly in southern New Caledonia.

Etymology: —The name commemorates A. Baudouin, captain of the French marines, who collected the type specimen during his deployment on New Caledonia (1864–1868).

Additional specimens examined:— NEW CALEDONIA. Province du Nord: Crete sommitale de la roche Quiaeme, Massif de Ton-Non, [20°38'53''S, 164°51'58''E,] 900 m, 13 July 1986, M . Mackee 19130 ( P); Massif du Tchingou, 20°53'48''S, 165°00'35''E, 1200 m, 03 April 2001, G . McPherson & J . Munziger 18122 ( MO, P); crête entre le Mont Tio et le Mont Ignambi, 1000 m, 15 August 1996, J.- C . Pintaud & J. P . Tivolier 386 ( P) . Province du Sud: Sommet du Kougui, [22°00'45''S, 166°17'03''E,] 1050 m, 7 November 1868, Balansa 31 ( P); Sommet du Mont Mou, 22°03'53''S, 166°20'56''E, 1200 m, November 1906, G . Bonati 603 ( P); Mont Mou, summit ridge, 1000–1200 m, 27 March 1955, M . Mackee 2280 ( P); Plateau de Dogny, 22°03'53''S, 166°20'59''E, 900–1000 m, 10 September 1958, M . Mackee 6559 ( P); contrefort ouest du Me Maoya au dessus de la mine “Emma”, 1400–1450 m, 2 October 1965, M . Mackee 13502 ( MO, P); Mont Mou, 7 air-km NNW of Paita, 22°03'48''S, 166°21'09''E, 1200 m, 5 July 1979, G . McPherson 1732 ( MO, P); Forêt de Sailles, 21°39'58''S, 166°14'49''E, 1130 m, 6 December 2001, J . Munzinger , B . Suprin & F . Carriconde 1261 ( MO, P); Mont Humboldt, 21°53'01''S, 166°24'50''E, 27 July 2009, J . Munziger , F . Rigault , W . Nigote & C . Grignon 5669 ( NOU, P); Rivière Bleue, borde du sentier “Haute Pourina”, 22°08'S, 166°42'E, 400 m, 1 June 1994, J.- C . Pintaud 57 ( P); Mont Dzumac, 22°02'S, 166°28'E, 900 m, 14 November 1999, H . van der Werff & G . McPherson 16103 ( MO) .

Discussion:— Dicksonia baudounii is most common in the ultramafic outcrop area in the south of New Caledonia. All records from the north refer to trunkless plants that grew in shrubby vegetation on ridges of schist ranges.

Herbarium samples labeled as Dicksonia deplanchei (Mackee 19130, McPherson & Munzinger 18122) originate from such stunted plants and differ further only slightly morphologically from D. boudouini in having very few or now hairs on the veins and larger sori (ca. 2 mm diameter). However, the type of D. deplanchei matches the type of D. baudouini in these and all other observable characters. It is interesting in this regard that Fournier (1873) when describing D. baudouini points out the size of the sori of the species, stating that they are largest observed in the genus, but in the type they do not reach the recorded maximum.

Dicksonia baudouinii is most easily recognized among New Caledonia tree ferns by the stalked pinnae and the spreading persistent hairs that usually reach up to the rachis. The only other tree fern species with spreading petiole hairs on that island is D. thyrsopteroides , but in that species the pinnae are subsessile to sessile and the petiole hairs are glabrescent except for the petiole bases.

Figures

FIGURE 2. Morphological features of New Caledonian Dicksonia species: First row (1) sterile (A, C & D) or intermediate segments (B), abaxially; second row (2) fertile segments, adaxially; third row (3) petioles. A. Dicksonia baudouinii. B. Dicksonia perriei, sp. nov. C. Dicksonia munzingeri, sp. nov. D. Dicksonia thyrsopteroides.

FIGURE 3. Morphological features of New Caledonian Dicksonia species: sterile pinnules, adaxially A. Dicksonia baudouinii. B. Dicksonia perriei, sp. nov. C. Dicksonia munzingeri, sp. nov. D. Dicksonia thyrsopteroides.