Dendrobium letocartiorum Munzinger & M. Pignal 2020, sp. nov
Creators: name: Pignal, Marc
name: Munzinger, Jérôme
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Asparagales
Orchidaceae
Dendrobium
Dendrobium letocartiorum

description: 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.
description: Published as part of Pignal, Marc & Munzinger, Jérôme, 2020, Morphological and anatomical investigation of New Caledonian graminoid Dendrobium (Orchidaceae) with the description of two new species, pp. 1-26 in European Journal of Taxonomy 633 on pages 17-21, DOI: 10.5852/ejt.2020.633, http://zenodo.org/record/3765344