Dendrobium unicarinatum Kores, 1989

Pignal, Marc & Munzinger, Jérôme, 2020, Morphological and anatomical investigation of New Caledonian graminoid Dendrobium (Orchidaceae) with the description of two new species, European Journal of Taxonomy 633, pp. 1-26 : 3-7

Dendrobium unicarinatum Kores

Figs 1B , I–J, P, 2 , 3 H–I, 4 A, 5 H

Allertonia 5: 97 ( Kores 1989). – Dendrobium crassiformatum Hallé ined. in herb. – Type: FIJI • Viti Levu , Mba Province, vicinity of Nandarivatu ; 17 Nov. 1927; Gillespie 3841; holotype: AMES [ AMES00243052 ] .

Etymology

The epithet refers to the carina of the lip.

Material examined

NEW CALEDONIA – Province Nord • Mont Mandjelia, Pouébo ; 20°23′51″ S, 164°31′57″ E; 21 Feb. 2016; fr.; C. Laudereau 97; NOU[ NOU090363 ] • Cultivated in Nouméa; C. Laudereau 172; (original material data: Roches de la Ouaième ; 20°38′22″ S, 164°51′47″ E, 6 Dec. 2016); NOU [ NOU090377 ] • Roches de la Ouaième, Hienghène ; 20°38′22″ S, 164°51′47″ E; 22 Oct. 2018; fr.; C. Laudereau 1075; NOU [ NOU090364 ] • Ouane Batch , Pouébo ; 20°30′35″ S, 164°43′56″ E; 23 Dec. 2018; C. Laudereau 1112; NOU [ NOU090365 ] • Mont Mandjelia Pouébo ; 20°23′51″ S, 164°31′57″ E; 24 Dec. 2018; fr.; C. Laudereau 1156; NOU [ NOU090366 ] • Grande-Terre, Pouébo: Mont Mandjélia ; [20°24′2″ S, 164°31′42″ E]; alt. 750 m; 7 Jun. 1979; H.S. MacKee & Bégaud 36986; P[ P00118407 ] • Pouébo: Mont Mandjélia ; [20°24′2″ S, 164°31′42″ E]; alt. 750 m; humid forest, schists, 26 Jan. 1980; H.S. MacKee 37759 & Bégaud; P[ P00118408 ] • Roches de la Ouaième , on the crest; [20°38′17″ S, 164°52′0″ E]; alt. 765 m; 4 Nov. 2011; fr.; J. Munzinger 6162, V. Hequet, A. Vandrot, Ph. Birnbaum & I. Pounds; NOU[ NOU063339 ] • Cascade La Guen ; 20°37′0″ S, 164°46′53″ E; humid forest; st.; 21 Nov. 2010; J. Munzinger 6401, P. Lowry , M. Callmander , H. Vandrot, T. & M. Teimpouene; NOU[ NOU063581 ] . – Province Sud • Mont Koghi ; [22°10′55″ S, 166°30′19″ E]; alt. 500 m; humid forest; Jan. 1979; H.S. MacKee 43003 & Labrissière; P[ P00118409 ] • Mont Pembai ; [21°34′47″ S, 165°49′59″ E]; alt. 700 m; humid forest, schists; 31 May 1990; H.S. MacKee 44925; P[ P00124752 , P00124753 ] .

Description

Herb, epiphytic, erect. Roots whitish, ca 1–2 mm wide, at the base of the plant (axillary roots lacking). Stem erect, to 50 cm long, terete or slightly flattened, covered by the sheath of the oldest leaves, blades remaining only in the upper third of the adult stem. Internodes 25 mm long at the base of the stem. Leaves green, shiny above. Blade 49 × 3 mm. Midrib slightly prominent. Two lateral veins visible, <1 mm from the margin (see discussion of anatomy below). Secondaries prominent, convergent at the apex. Base slightly narrower. Apex rounded or emarginate and asymmetrical. Sheath striated in the upper half and ending by a beak opposite to the lamina and applied on the stem. Inflorescence very short, 1-flowered. Ovary non-resupinate. Floral buds white, flower white to bright yellow when open, fleshy. Tepals with a red terminal dot. Dorsal sepal triangular, 4.5 mm long, 3 mm wide at the base, with 5 nerves. Lateral sepals triangular-ovate, oblique, ca 4 × 2.4 mm, with 8 nerves. Petals ovate, asymmetrical, ca 4 × 2 mm, with 3 nerves. Lip white, entire, rectangular, ca 4 × 2.8 mm, with 5–7 nerves, 3 on the carina and 2–4 lateral. Apex triangular, rounded to obtuse. Carina ca 1 mm wide. Column 1.8 mm high and 1.5 mm wide. Fruit globose, ca 6 × 9 mm. Dried seed with transparent testa of 217 × 48 μm, fusiform, with extremity and base slender. Right extremity slightly spiral. Hydrated seed ovate, sacciform. Cells cubic to polygonal, with extremities rounded, ca 48–100 × 5 μm, with edges thick, roughly spiral, with smooth cellular walls. Embryo spherical, ca 12 μm in diameter.

Distribution and ecology

Dendrobium unicarinatum grows in Fiji and in New Caledonia dense humid forest (500–750 m), as an epiphyte on trunks (at the base or at several metres high) and can be very abundant, especially on palms. C. Laudereau (pers. comm.) separates two populations by habit and light exposition: the first erect and in sunny situations, the other pendulous, in shade.

Taxonomic notes

In New Caledonia, D. unicarinatum can be easily identified by a cylindrical or slightly flattened stem, 1-flowered inflorescence and white, non-resupinate flowers. Leaf section shows D. unicarinatum to be the only graminoid New Caledonian Dendrobium having large, obvious and numerous (> 20) supernumerary fibre bundles on both sides, and having the largest vascular bundle in position 2.

Phenology

Further observations are needed to determine the flowering and fruiting periods. In the available herbarium material, flowers were observed on cultivated plants (grown in New Caledonia) in January and in the field from February to March, and fruits in May to January.

IUCN status

This species was not recognized in New Caledonia until now, and was evaluated as Data Deficient (DD) by the New Caledonian Red List Authority.

Figures

Fig. 1. (see full caption on page 5)

Fig. 2. Distribution of D. unicarinatum Kores in New Caledonia, based on herbarium specimens (●) and field observations ().

Fig. 3. Seeds, opening on the right. A–B. D. camaridiorum Rchb.f. A. LM. B. SEM (H.S. MacKee 14228). C–D. D. butinii M.Pignal & Munzinger sp. nov. C. LM. D. SEM (M. Pignal 2384). E–G. D. letocartiorum Munzinger & M.Pignal sp. nov. E. SEM. F. LM. G. SEM (H.S. MacKee 37760). H–I. D. unicarinatum Kores. H. SEM (H.S. MacKee 36986). I. LM (H.S. MacKee 44925). Scale bars: A–F, H–I = 10 μm; G = 30 μm.

Fig. 4. Drawing of transverse sections of leaves of three graminoid species of Dendrobium. A. Total section of D. unicarinatum Kores (H.S. MacKee 44925).Vascular bundles arerepresented by empty circles and are numbered starting from the lamina margin, black spots indicate fibre bundles. B. Leaf margins sections, a. D. letocartiorum Munzinger & M.Pignal sp. nov. (H.S. MacKee 37760); b. D. camaridiorum Rchb.f. (H.S. MacKee 24639). Scale bar = 1 mm.

Fig. 5. Stomata (SEM). A–B. Type I: D. camaridiorum Rchb.f. (H.S. MacKee 14228). C. Type I: D. butinii M.Pignal & Munzinger sp. nov. (M. Pignal 2384). D. Type II: D. butinii M.Pignal & Munzinger sp. nov. (M. Pignal 2384). E. Type I: D. crassifolium Schltr. (H.S. MacKee 43781). F. Type II: D. crassifolium Schltr. (H.S. MacKee 43781). G. Type II: D. letocartiorum Munzinger & M.Pignal sp. nov. (H.S. MacKee 37760). H. Type II: D. unicarinatum Kores (H.S. MacKee 36986). Scale bars = 10 μm.