Dendrobium oppositifolium (Kraenzl.) N.Hallé

Pignal, Marc, Laudereau, Christian, Gâteblé, Gildas & Laudereau, Pierre-Louis, 2022, Dendrobium petrophilum (Kraenzl.) Garay ex N. Hallé, a well-named species describing its unusual chasmophytic ecology, Adansonia (3) 44 (1), pp. 1-9 : 6-9

Dendrobium oppositifolium (Kraenzl.) N.Hallé

( Figs 2E ; 3 F-J; 4 )

Flore de la Nouvelle-Calédonie & Dépendances 8: 119 ( Hallé 1977). — Eria oppositifolia Kraenzl. , Vierteljahrsschrift der Naturforschenden Gesellschaft in Zürich 74: 90 ( Kränzlin 1929). — Tetrodon oppositifolius (Kraenzl.) M.A.Clem.& D.L.Jones , Orchadian 12: 310 ( Clements & Jones 1998).

— Type: New Caledonia. Auf den Araucarien auf dem Plateau des Koniambo, Koné , [on the Araucaria on the Plateau de Koniambo], fl., 18.I.1925, A.U. Däniker 894 (holo-, Z [ Z-000016413 ], image seen).

Dendrobium multilobatum Guillaumin , Mémoires du Muséum national d’Histoire naturelle, série B, Botanique 8: 36 (1957). —

Type: New Caledonia. Bord de forêt de montagne près de la côte, 500 m de la route de la Mgne [ Montagne ] des Sources , fl., 29.XII.1950, Hürlimann 468 (holo-, Z [ Z-000016357 ], image seen ; iso-, P [ P00121211 !] fragment).

ETYMOLOGY. — The epithet refers to the leaves which are opposite.

PHENOLOGY. — The species flowers mainly during the hottest season between October and March but from herbarium specimens, flowering has also been observed in July. Fruits have been recorded all the year (based on herbaria and field observations).

ECOLOGY. — This species lives as an epiphyte on trees, usually in rainforests, forest edges and sometimes in more open vegetation conditions ( Araucaria spp. ) at higher altitudes. Most of the observations and specimens are from open or low forests ranging from 200 to 1200 m above sea level. Because Dendrobium oppositifolium seems to favour semi-shaded conditions, it has been rarely observed in dense rainforests where it might occur within the difficult to access canopy of the large and highest trees.

CONSERVATION STATUS. — It is a common endemic species distributed from the South to the North of mainland Grande Terre and even on Île des Pins [Isle of Pines]. Even if some plants and populations are threatened by anthropogenic fires and by illegal removal (the species is protected in the Northern province) from plant and orchid hunters, the species is globally not threatened. It has been successfully cultivated in Paris museum greenhouses as well as by local orchid growers, but remains very difficult to maintain. We agree with the RLA Endemia assessment made on 29 January 2016 ( Butin et al. 2020b) classifying the species as Least Concern (LC).

ADDITIONAL MATERIAL EXAMINED. — New Caledonia. Province Nord, Ouégoa , Mandjélia , 780 m, forêt, 4.I.1978, P.R.J. Bamps 6123 ( P [ P00115105 ]!). — Kone, Plateau de Kaniambo , Koné , 18.I.1925, A.U. Däniker 894 ( P [ P02106271 ] photocopy with an additional drawing of the flower by N. Hallé!). — Ouégoa, Crête au Sud du Col d’Amos , 17.III.1966, H.S. MacKee 14573 ( P [ P00115093 ]!). — Hienghène, Massif de Ton-Non : Roches Ouaième , 10.I.1968, H.S. MacKee 18246 ( P [ P00115091 ]!). — Pouembout, Mt. Paéoua , 15.II.1968, H.S. MacKee 18427 ( P [ P00115087 ]!). — Ouégoa, Haute Diahot : Tendé ( Expl. For. Frouin ), 500- 660 m, 12.III.1968, H.S. MacKee 20003 ( NOU [ NOU003683 ]!; P [ P00115086 ]!). — Ouégoa, Pouébo :Crête entre Mandjélia / Salandané , 15.III.1969, H.S. MacKee 21281 ( P [ P00115085 ]!). — Ouégoa, Pouébo: Mandjélia / Salandané , 26.II.1970, H.S. MacKee 21630 ( P [ P00115083 ]!). — Poya, Ponérihouen : Contrefort E Mt. Aoupinié, 26.IV.1972, H.S. MacKee 25330 ( P [ P00115097 ]!). — Poya, Pente S Mt. Boulinda , 30.VII.1973, H.S. MacKee 27014 ( P [ P00115080 ]!). — Pouébo, Pouébo, 24.VII.1974, H.S.MacKee 28970 ( P [ P00115104 ]!). — Hienghène, Panié , 12.I.1976, H.S. MacKee 30664 ( P [ P00115079 ]!). — Poya, Ponérihouen : Crête sommet Mt. Aouipinié , 10.V.1976, H.S. MacKee 31199 ( P [ P00115096 ]!). — Kaala-Gomen, Crête SW Mt. Taom , 13.VII.1979, H.S. MacKee 37144 ( P [ P00115112 ]!). — Pouébo, Pouébo: Oumbarinien , 9.I.1981, H.S. MacKee 38553 ( P [ P00115111 ]!). — Hienghène, Pente E Mt . Panié, 11.II.1981, H.S. MacKee 38737 ( P [ P00115110 ]!). — Houaïlou, Bourail : Mé Jéjéhari , 5.II.1985, H.S. MacKee 42444 ( P [ P00115114 ]!). — Mt Colnett: Versant Est , 800 m, forêt humide, Schistes , 2.II.2003, A. Mouly, G. McPherson & U. Svenson 94 ( P [ P00591695 ]!). — Poindimié, Massif du Tchingou , face Est, 29.III.2001, J. Munzinger 572 ( P [ P00239087 ]!). — Pouembout, Paéoua Mt 800-1100m, 1100 m, forêt à Nothofagus, 26.I.2010, J. Munzinger 6021 ( NOU [ NOU053561 ]!). — Hienghène, Dawenia (zone), 929 m, 14.II.2010, J. Munzinger et al. 6319 ( NOU [ NOU063498 ]!). — Hienghène, La Guen , cascade (Panié), 910 m, forêt basse, 23.II.2010, J. Munzinger (Leg. Butin, J.- P.) 6468 ( NOU [ NOU063648 ]!). — Mt Panié, 500- 900m, 14.II.2006, Y. Pillon 294 ( NOU [ NOU010843 ]!). — Mont Panié, forêt basse, 14.II.2006, Y. Pillon, J. Munzinger, I. Spir & al. 9486 ( P [ P00684671 ]!). — Kaala-Gomen, Taom Mt (zone), 900 m, 24.III.1982, B. Suprin 1731 ( NOU [ NOU003688 ]!). — Tipindjé: Mont Cantaloupaï (versant N), 16.IX.1983, B. Suprin 2295 ( P [ P00115107 ]!). — Kouaoua: décharge Montmartre , 750 m, 14.II.1978, J.-M. Veillon 3524 ( NOU [ NOU003684 ]!; P [ P00115109 ]!). — Houailou, Mt Menazi , crête vers 900 m versant nord, 6.VII.1989, J.-M. Veillon 7075 ( NOU [ NOU003685 ]!). — Wagap, 1861-1867, E. Vieillard 3284 ( P [ P00115101 ]!). — Kaala-Gomen, près du sommet du Mont Kaala , 1000 m, 2.I.1943, R. Virot 1402 ( P [ P00115098 ]!). — Province Sud: Sarraméa , Mé Améri , 700 m, 29.II.1950, A. Guillaumin 8996 ( P [ P00115094 ]!). — Boulouparis, Mt Do (zone), sous-bois de forêt, 16.I.1982, M. Hoff 4423 ( NOU [ NOU003687 ]!). — Bordure de forêt de montagne, près de la côte, 500 m de la route pour la Montagne des Sources , 29.III.1950, H. Hürlimann 468 ( P [ P00121211 ]!). — Boulouparis, Mont Do , 13.IX.2019, C. Laudereau 269 ( NOU [ NOU091401 ]!). — Païta, Dzumac , 13.IX.2019, C. Laudereau 281 ( NOU [ NOU091400 ]!). — Yaté, Plateau de la Montagne des Sources , 31.III.1967, H.S. MacKee 18200 ( P [ P00115092 ]!). — Bourail, Maoya Mé : contrefort S Djiaouma , 11.II.1970, H.S. MacKee 21554 ( P [ P00115084 ]!). — Boulouparis, Plateau sommet Mt. Do , 26.I.1972, H.S. MacKee 24898 ( P [ P00115082 ]!). — Bourail, 4 km à l’W Mé Aoui, 14.II.1976, H.S. MacKee 32265 ( P [ P00115078 ]!). — Boulouparis, Mt. Do , 22.II.1976, H.S. MacKee 32288 ( P [ P00115095 ]!). — Païta, Mt. Mou , 27.V.1979, H.S. MacKee 36940 ( P [ P00115113 ]!). — Sarraméa, Col Amieu : Mt. Pembai , 1.III.1982, H.S. MacKee 40302 ( P [ P00115115 ]!). — Along old lumber road to top of Mt Mé Ori , above Katrikoin , 900 m, 7.IX.1980, G. McPherson 3054 ( P [ P00115106 ]!). — Thio, Mont Nakada , 18.IV.2001, J. Munzinger 801 ( P [ P00217010 ]!). — Thio, Forêt de Sailles , 4.III.2001, J. Munzinger 1194 ( P [ P00239729 ]!). — Yaté, Massif du Kouakoué , bassin de la Haute Ni, 950 m, 30.IV.2004, M. Pignal, J. Munzinger et P. Lowry 2438 ( P [ P00465755 ]!). — Mont Do, c. 900-1000 m, en lisière de forêt, très souvent sur Araucaria laubenfelsii, 1020 m , 1.II.1972, J.-M.Veillon 2511 ( NOU [ NOU003686 , NOU003686 ]!; P [ P00115102 , P00115103 , P00115108 ]!). — Mont-Dore, Haute Boulari camp no. 3, 500 m, V.1938, R. Virot s.n. ( P [ P00115099 ]!).

DESCRIPTION

Epiphytic plant. Pseudobulbs bifoliate, ovate to turbinate, 8-(20-28)-44 × 4-(6-8)- 25 mm, with 4-5 internodes, bright orange on dry material, covered with 3 deciduous, broad, papyraceous and translucent cataphylls applied to the pseudobulb. Leaf: gutter-shaped pseudopetiole canaliculate, 2-4 mm, blade coriaceous ovate to elliptic 16-(27-39)- 72 × 7-(10-13)- 27 mm, apex obtuse. Inflorescence, 80- (140-240)- 420 mm, with 2-(4-7)-18 flowers, sometimes once branched, flower non resupinate, borne in a subterminal position of the pseudobulb, more or less hanging. Flower: Peduncle, 10 × 0.9 mm. Tepals yellow to brownish green. Median sepal, linear lanceolate, 18.7 × 4 mm, 5 visible veins. Lateral sepals lanceolate, curved proximally, 16.5 × 4.6 mm. Petals spatulate, curved proximally, 17 × 4.3 mm. Lip, 3-lobed, 10 × 5 mm. Hypochile thick, warty, greenish-white, thickened in the centre, extended by 3 very divergent flattened extensions, white with dark pink stains, 2.2-2.3 mm long and 0.6 mm wide. Lateral lobes erect, 3.3 × 1.9 mm, longitudinally striated dark pink, white proximally and bright orange distally, ovate, with a very attenuated tooth on the side showing the proximal lobule of D. petrophilum . Median lobe 3-lobulate, curved, 6 × 5 mm, greenish-white in the centre with a triangular central verrucous crest. Lateral lobules, triangular, slightly deflected, 1 × 1.2 mm, dark pink with greenish-white tip, panduriform median lobule with rounded apex, curved at the tip making it appear emarginate, 5.8 × 6 mm, dark pink. Column white, except the edge of the stigma which is dark pink (protruding 1 mm down), 6 × 2.5 mm with a 4 mm long mentum, and 1.9 mm deep at the point of attachment to the ovary. Stamen: anther cap (connective appendage) white, 1.1 mm wide and 1.4 mm high. Pollinia, 2, yellow, obovoid, 0.9 mm long. Stigma rectangular 1.3 mm wide and 1.6 mm high. Ovary, 4.5 × 1.4 mm. Fruit obovoid, (16-)19-23(-26) × (5-)6-8(-10) mm.

The vegetative system of the two species is very similar. However, the flowers as well as fruits have notable differences in size, shape and colour as summarised in Tables 1 and 2 .

Figures

FIG. 2. — Dendrobium petrophilum (A-D) habitat, ecology and threat compared to D. oppositifolium (E) habitat: A, the type locality at Arama pass crest; B, three plants (arrows) at the Arama pass siliceous crest exposed to full sun and prevailing wind;C, typical chasmetophytic microhabitat within the cracks of the siliceous rocks; D, anthropogenic fire threat showing a burnt colony at the base of a dead burnt trunk of the microendemic Tristaniopsis ninndoensis J.W.Dawson; E, epiphytic habit in a high altitude (c. 1200 m) and open canopy montane forest at Mont Panié. A, Arama pass, 27.VIII.2019; B, Arama pass, 30.IX.2018; C, D, Vache Crevée, 14.XI.2020; E, Mont Panié (Pwé Taao), 31.V.2014. Photos from: A, B, E, G. Gâteblé; C, D, D. Fleurot.

FIG. 3. — Comparison of the flowers of Dendrobium petrophilum (Kraenzl.) Garay ex N.Hallé (A-E) and D. oppositifolium (Kraenzl.) N.Hallé (F-J): A, flower (front side); B, column, profile side (p) and front side (f); C, column and lip, profile side; D, lip, ventral side; E, lip spread out, ventral side (f) and backside (d); Dendrobium oppositifolium: F, flower (front side); G, column, profile side (p) and front side (f); H, column and lip, profile side; I, lip, ventral side (f) and backside (d); J, lip, ventral side (f). Photographs of D. petrophilum are from expeditions at Arama (Northern province), photos C. Laudereau.Photographs of D. oppositifolium, Plateau de Dogny, photos C. Laudereau. Olympus EM1MarkII, 30.V.2020, combined as a board. Scale bars: A, 3 mm; B-E, G-J, 5 mm; F, 4 mm.

FIG. 4. — Distribution of Dendrobium oppositifolium (Kraenzl.) N.Hallé (blue) and D. petrophilum (Kraenzl.) Garay ex N.Hallé (red) in New Caledonia (La Grande Terre and Île des Pins):A, focus in the Poum area.Grey shaded areas represent ultramafic outcrops. Circles correspond to herbarium specimens while squares correspond to in situ observations from various authors and compiled by Endemia.nc.Tm, To and Tp represent respectively the type localities of D. multilobatum Guillaumin, D. oppositifolium and D. petrophilum names.

Tables

TABLE 1. — Comparaison des caractères morphologiques entre Dendrobium petrophilum (Kraenzl.) Garay ex N.Hallé et D. oppositifolium (Kraenzl.) N.Hallé. Les caractères indiqués par * sont basés sur plus de 600 mesures et sont présentés selon la convention (min-) quartile 1-quartile 3 (-max).

	Dendrobium petrophilum	Dendrobium oppositifolium
Écologie	lithophyte/chasmophyte	épiphyte
Pseudobulbe (mm)*	(23-)32-40(-74) × (4-)6-8(-13)	(8-)20-28(-44) × (4-)6-8(-25)
Limbe (mm)*	(19-)26-41(-58) × (6-)8-10(-12)	(16-)27-39(-72) × (7-)10-13(-27)
Inflorescences (mm)*	plutôt dressées,	plus ou moins retombantes,
	(70-)260-320(-380)	(80-)140-240(-420)
Fleurs/infl.*	(9-)10-13(-21)	(2-)4-7(-18)
Fleurs	Tépales jaunes et labelle rose pâle bordé de blanc,	Tépales jaunes et labelle rose soutenu, à lobes latéraux
	lobes latéraux roses	du labelle orangés
Tépales	moins de 7 mm	plus de 15 mm
Sépale médian	lancéolé	linéaire linéaire-lancéolé
Sépales latéraux	peu recourbés à la base	très recourbés à la base
Pétales	peu recourbés à la base	très recourbés à la base
Labelle	c. 5 mm de long environ,	c. 10 mm de long environ,
	extensions peu divergentes de 1 mm de long,	extensions très divergentes de plus de 2 mm de long,
	mésochile à gibbosités de 0,7 mm d’épaisseur,	mésochile verruqueux,
	lobe médian trilobulé de moins de 2,5 mm de longueur	lobe médian panduriforme de plus de 5 mm de longueur
Stigmate	rectangulaire à ouverture à peu près aussi haute que	rectangulaire à ouverture manifestement plus haute que
	large, bordé de rose pâle	large, bordé de rose foncé
Fruit* (mm)	obovoïde à sphérique, (13-)13-15(-17) × (7-)8-10,	obovoïde, (16-)19-23(-26) × (5-)6-8(-10), verdâtre
verdâtre avec des bandes violettes

TABLE 2. — Comparison of morphological characters between Dendrobium petrophilum (Kraenzl.) Garay ex N.Hallé and D. oppositifolium (Kraenzl.) N.Hallé. Characters indicated by * are based on more than 600 measurements and are presented as (min-) quartile 1-quartile 3 (-max).

	Dendrobium petrophilum	Dendrobium oppositifolium
Ecology	lithophytic/chasmophytic	epiphytic
Pseudobulb (mm)*	(23-)32-40(-74) × (4-)6-8(-13)	(8-)20-28(-44) × (4-)6-8(-25)
Leaf blade (mm)*	(19-)26-41(-58) × (6-)8-10(-12)	(16-)27-39(-72) × (7-)10-13(-27)
Inflorescences (mm)*	rather erect,	more or less falling down,
	(70-)260-320(-380)	(80-)140-240(-420)
Flowers/infl*	(9-)10-13(-21)	(2-)4-7(-18)
Flowers	tepals yellow and lip pale pink edged with white;	tepals yellow and lip dark pink; lateral lobes orange
	lateral lobes pink
Tepals	less than 7 mm	more than 15 mm
Median sepal	lanceolate	linear lanceolate
Lateral sepals	slightly curved at the base	strongly curved at the base
Petals	slightly curved at the base	strongly curved at the base
Lip	c. 5 mm long, slightly divergent extensions of 1 mm	c. 10 mm long, very divergent extensions of more
	in length, mesochile with gibbosity of 0.7 mm thick,	than 2 mm in length, mesochile warty, median lobe
	median lobe trilobular, less than 2.5 mm long	panduriform more than 5 mm long
Stigma	rectangular with an opening about as high as it is	rectangular with an opening that is clearly higher than
	wide, edged with pale pink	wide, bordered with dark pink
Fruit* (mm)	obovoid to spherical greenish with purple	obovoid, greenish
	strips (13-)13-15(-17) × (7-)8-10	(16-)19-23(-26) × (5-)6-8(-10)