Dendrobium letocartiorum Munzinger & M.Pignal, 2020

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 : 17-21

Dendrobium letocartiorum Munzinger & M.Pignal , sp. nov.

urn:lsid:ipni.org:names:77209476-1

Figs 1 C–D, F–G, T, 3 E–G, 4 Ba, 5 G, 10 , 11

Diagnosis

Dendrobium bilobo Lindl. affinis , sed foliorum rostratis vaginis (versus truncatas), sine atropurpureis maculis labello, dorsali sepalo triangulari, 12 × 2 mm (versus ovatum 4–5 × 2–3 mm), lateralibus sepalis 12 × 4 mm (versus 6. 5 × 4. 5 mm), petalis linearis vel paulo lanceolata, 11 × ca 1 mm (vs lanceolata, 3. 5–4 × 1. 5–2 mm), gynostegio cum atropurpureis faciali interni maculis (vs pallide purpureis aut albis), praecipue differt.

Etymology

The species is dedicated to our friends Irène and Daniel Létocart who collected and cultivated this plant in 1978–1980, providing H.S. MacKee with material for the first herbarium specimens, and also to the Létocart family, whose many members are active naturalists, creators of the Endemia website, and with whom we have made many field trips.

Type material

NEW CALEDONIA – Province Nord • Mont Colnett, versant Est; 20°29′13″ S, 164°42′39″ E; alt. 700 m; border zone between the altitude rainforest and the savanna of burns, schists; 3 Nov. 2003; fl. & fr.; Mouly 99; holotype: P [ P00777176 ]!; isotypes: P [ P00777177 ]!, NOU [ NOU090448 !]. – Dendrobium crassifomentum Hallé ined. in herb .

Paratypes

NEW CALEDONIA – Province Nord • Mont Colnett ; alt. 720 m; 29 Oct. 2003; fl.; Butin s.n.; P [ P00352883 ] • Mont Colnett ; 20°29′17″ S, 164°42′43″ E; alt. 720 m; 10 May 2003; fl.; Butin s.n.; P [ P00493892 ] • Mont Mandjelia , Pouébo, 20°23′51″ S, 164°31′57″ E; 10 Dec. 2016; C. Laudereau 98; NOU [ NOU090376 ] • Mont Mandjelia, Pouébo , 20°23′51″ S, 164°31′57″ E; 23 Dec. 2016; C. Laudereau 21 3; NOU [ NOU090375 ] • Colnett Oua Ina, Pouébo , 20°30′35″ S, 164°43′56″ E; 5 Jan. 2017; C. Laudereau 239; NOU [ NOU090374 ] • Pouébo, Mont Mandjélia ; 20°23′51″ S, 164°31′57″ E; 24 Oct. 2018; C. Laudereau 1155; NOU [ NOU090373 ] • Mont Mandjélia ; [20°24′2″ S, 164°31′41″ E]; 29 Sep. 1978; H.S. MacKee 35761 (leg. D. Létocart); P [ P00118401 ] • Tchamba ; [21°1′22″ S, 165°13′36″ E]; 21 Dec. 1978; H.S. MacKee 36261 (leg. D. Létocart); P [ P00118403 ] • Haute Diahot: Tendé ; [20°24′28″ S, 164°31′17″ E]; alt. 700 m; humid forest, micaschists; 12 Dec. 1979; H.S. MacKee 37117; P [ P00118404 ] • Pouébo, Mont Mandjélia ; [20°24′2″ S, 164°31′41″ E]; alt. 750 m; humid forest, schists; 26 Jan. 1980; H.S. MacKee 37760 (leg. Bégaud); P [ P00118405 ] • Pouébo, Mont Mandjélia ; [20°24′2″ S, 164°31′41″ E]; alt. 750 m; 14 Mar. 1980; H.S. MacKee 37908 (leg. D. Létocart); P [ P00118402 ] • ibid.; 20 Dec. 1980; H.S. MacKee 38198 (leg. D. Létocart); P [ P00118406 ] • Roches Ouaième ; alt. 950 m; 14 Jun. 2005, J. Munzinger 2915, Y. Pillon & J.-P. Butin; NOU [ NOU007988 ] • Mandjélia ; 2 Dec. 2006; bt. fr.; J. Munzinger 4016, D. Létocart, I. Létocart, R. Amice & O. Chapelle; NOU [ NOU017301 ] • Mont Panié ; [20°37′27″ S, 164°46′56″ E]; J. Munzinger 4326, H. Blaffart, M. Wanguene, O. Chapelle & J. Tiavouane; NOU [ NOU018878 ] • Dawenia, west buttress of Colnett ; 20°32′15″ S, 164°41′39″ E; 14 Nov. 2010; J. Munzinger 6290, Ph. Birnbaum, M. Callmander, I. Pounds, J.-P. Butin & H. Vandrot; NOU [ NOU063469 ]. – Province Sud • Col d’Amieu: Mt. Pembai ; [21°35′20″ S, 165°50′30″ E]; alt. 800 m; humid forest, schists; 15 Apr. 1976; fr.; H.S. MacKee 31229 (leg. Bégaud); P [ P00118400 ] .

Description

Erect epiphyte. Roots whitish, ca 1–2 mm wide, at the base of the plant (axillary roots lacking). Stems reaching 60 cm long, slightly flattened, completely covered by the sheaths of the old leaves, lamina remaining only in the upper half, yellow-orange on dry material. Internodes ca 25 mm long at the base of the stem. Leaves spirally arranged, dark shiny green above, light green below (fide collectors’ notes), ca 75 × 7 mm. Midrib impressed on adaxial surface, very prominent on abaxial surface. Two lateral nerves very conspicuous, <1–2 mm from the margin (see discussion of anatomy below), numerous prominent smaller nerves visible, all convergent at the apex. Base narrow, forming a flattened pseudopetiole. Extremity emarginate, asymmetrical, the two lobes often diverging. Sheath striated in its upper half and ending in a beak opposite to the lamina and applied on the stem. Inflorescence 1-flowered, emerging through a slit of the foliar sheath. Pedicel 3.5 mm long. Ovary ca 3 mm long, non-resupinate. Bract acuminate, 2–3 mm long. Flower pale green to yellow, ca 12 mm long. Dorsal sepal triangular, 12 × 2 mm. Lateral sepals triangular, 12 × 4 mm at the base, with 7 nerves. Petals linear or slightly lanceolate, 11 × ca 1 mm. Lip entire, red, approximately elliptic, margin thin and undulate, 10 mm long and 3 mm wide, obscurely tricarinated. Mentum, 3 mm long. Column, 2.5 mm high and 2 mm wide with a fimbriate margin. Fruits very few despite an abundant flowering, yellow-greenish to brown when mature, ovoid, 8 mm in diameter, with base slightly narrower. Bracts persistent. Dried seed with transparent testa, ca 267 × 86 μm, fusiform, with extremity slender and base truncate, extremity strongly spiraled. Hydrated seed ovate, sacciform. Cells cubic or with extremities rounded, elongate, ca 43–110 × 7.3–10.2 μm, with thick edges, spiral orientation and smooth cellular walls. Embryo spherical elongate, ca 6–7 μm wide, inserted in the lower ¾ of the testa.

Taxonomic notes

Dendrobium letocartiorum sp. nov. has always slightly flattened stems. The species has affinities with D. bilobum Lindl. , but the flower is bigger and the lip does not have a dark red spot on the adaxial surface. Leaf anatomy shows that D. letocartiorum sp. nov. is very similar to D. camaridiorum , having thin leaves, 24–28 vascular bundles in one line and largest bundle in position 5(–6). They only differ by the margins in transverse section, which are obtuse in D. letocartiorum sp. nov. and truncate in D. camaridiorum ( Fig. 4B ).

Phenology

Flowering and fructification periods need further observations. The fruits were observed in the field and in cultivation (in New Caledonia) during the months of January, May, July, October, November and December and flowering specimens are from May and November.

Distribution and ecology

This endemic species occurs on the main island, in the central chain and on the Panié range in North-East coast. It grows on edges of humid forest, and also on rocks as a lithophyte and is known from 700–800 m a.s.l. The species has been observed also in Plateau de Dogny (Sarraméa) (C. Laudereau, pers. comm.)

IUCN status

This species is currently known from only four locations in New Caledonia, based on herbarium specimens. Dendrobium letocartiorum sp. nov. was evaluated as Near Threatened (NT) by the New Caledonian Red List Authority, considering the species apparent rarity and the low threat to its habitat.

Figures

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

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.

Fig. 10. Dendrobium letocartiorum Munzinger & M.Pignal sp. nov. A. Habit. B. Flower, profile. C. Flower, lateral sepal removed. D. Lateral sepal. E. Dorsal sepal. F. Petal. G. Lip. H. Column. I. Fruit. J. Seed. Scale bar: A = 2 cm, B, I = 1 cm, C–H = 5 mm, J = 40 μm (A. Mouly 99, holotype [P00777176]). Drawing by Dominique Storez.

Fig. 11. Distribution of D. letocartiorum Munzinger & M.Pignal sp. nov., based on herbarium specimens (●) and field observations (), ‘T’ indicates the type collection.