Dypsis gronophyllum Rakotoarin. & J.Dransf., Kew Bull. 65(2): 285 (2010)

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Distribution

Map uses TDWG level 3 distributions (http://www.nhm.ac.uk/hosted_sites/tdwg/geogrphy.html)
Madagascarpresent (M. Rakotoarinivo & J. Dransfield, New species of Dypsis and Ravenea (Arecaceae) from Madagascar in Kew Bulletin 65. 2010)A
Southeast of Madagascar, known only from the forest of Vondrozo. (M. Rakotoarinivo & J. Dransfield, New species of Dypsis and Ravenea (Arecaceae) from Madagascar in Kew Bulletin 65. 2010)A

Habitat

  • Lowland humid evergreen forest on white sands, in valley bottoms in very humid forest; 590 m. (M. Rakotoarinivo & J. Dransfield, New species of Dypsis and Ravenea (Arecaceae) from Madagascar in Kew Bulletin 65. 2010)A

Discussion

  • Related to the species defined by Dransfield & Beentje (1995) in group 8 of Dypsis. This species differs from Dypsis thiryana and D. trapezoidea in its much larger habit, its much broader and thicker leaflets and much more robust inflorescences. It differs from D. schatzii Beentje by its larger size and the pinnate leaves with praemorse leaflets instead of possessing an entire bifid leaf. The species epithet is based on the Greek for eroded or grooved leaf, referring to the praemorse leaflet tips, but it also alludes to the striking resemblance in habit between this Dypsis and the completely unrelated Hydriastele pinangoides (Becc.) W. J. Baker & Loo from New Guinea, previously included in the now synonymised genus Gronophyllum. (M. Rakotoarinivo & J. Dransfield, New species of Dypsis and Ravenea (Arecaceae) from Madagascar in Kew Bulletin 65. 2010)A

Diagnosis

  • Foliolis praemorsis D. trapezoideae J. Dransf.et Et D. thiryanae (Becc.) Beentje & J. Dransf. affinis sed habitu multo maiore, inflorescentia robustiori bene distincta. (M. Rakotoarinivo & J. Dransfield, New species of Dypsis and Ravenea (Arecaceae) from Madagascar in Kew Bulletin 65. 2010)A

Conservation

  • Critically Endangered [CR (B2a+b(iii); D)]. Known only from Vondrozo where it is restricted to humid areas, all of these in an area less than 10 km2. About 40 mature individuals have been seen in the field while its habitat is subject to human exploitation for wood or for other natural resources. (M. Rakotoarinivo & J. Dransfield, New species of Dypsis and Ravenea (Arecaceae) from Madagascar in Kew Bulletin 65. 2010)A

Description

  • Clustering palm with 2 - 4 stems. Stems slender, to 4 m tall, 1 - 1.5 cm diam., erect, grey brown, internodes 1 - 4 cm long, covered with red scales below the crown, lenticels present in the lower part of the stems, nodal scars 1 - 2 mm wide. Leaves 7 - 12 in the crown, pinnate, porrect to spreading; sheaths 11 - 13.8 cm long, 1.4 - 2 cm diam., open for 2.2 - 7 cm in the upper part, forming a well defined crownshaft, sparsely to densely covered in red hairs on the abaxial surface, auricles 1.8 - 3.4 × 0.3 - 0.7 cm; petiole 1.7 - 5 cm long, c. 4 mm wide, adaxially flattened, abaxially rounded, scaly; leaf rachis 19.5 - 37 cm long, in midleaf 1 - 1.5 mm wide, triangular in cross section; leaflets irregularly arranged, 7 - 9 on each side of the rachis, at intervals of 1.4 - 8 cm, blade leathery, dark bluish green, proximal leaflets 9 - 18 × 0.8 - 1.4 cm, median leaflets 7 - 15 × 2.2 - 3 cm, distal leaflets 5 - 9 × 2.4 - 3.5 cm, irregularly praemorse, bands of scattered red scales along margins and occasionally on the major and minor veins. Inflorescence interfoliar, branching to 1 or 2 orders, peduncle 28 - 42 cm long, 4 - 5 mm diam., densely hairy in exposed parts; prophyll 9 - 13 × 0.8 - 1 cm, inserted at 2 - 5 cm from the base of the peduncle, distal part open for 2 - 3.5 cm, 2-keeled, sparsely to densely scaly; peduncular bract inserted at about 10 cm from the base of the peduncle, 24 - 27 cm long, c. 7 mm in the cross section, split to 3 - 5 cm, scaly, persistent; rachis 14 - 20 cm long, densely puberulous, with 4 - 6 branched and/or 7 - 11 unbranched first order branches; rachillae 3.6 - 8 cm long, 1 - 1.5 mm diam., glabrous, triads inserted at a distance of 1.5 - 3 mm, axis in first order branches up to 3 cm long. Staminate flowers with sepals c. 0.8 × 1 mm, imbricate, slightly waxy; petals 3, ellipsoid, valvate, striate, c. 1.5 × 1 mm; stamens 6, uniseriate, filaments c. 0.4 mm, anthers 0.8 - 1 × 0.2 - 0.5 mm, elongate, medifixed, versatile; pistillode minute, c. 0.8 mm. Pistillate flowers with sepals , c. 0.8 - 1 × 1 - 1.5 mm, imbricate, keeled, irregularly waxy, dentate at the margins; petals 3, c. 2 × 1 mm, ellipsoid, striate; gynoecium c. 1 mm high, staminodes 6, much smaller and encircling the gynoecium. Fruits not seen. (M. Rakotoarinivo & J. Dransfield, New species of Dypsis and Ravenea (Arecaceae) from Madagascar in Kew Bulletin 65. 2010)A

Materials Examined

  • MADAGASCAR. Fianarantsoa, Vondrozo: Madiorano, Anivontany, 3 Sept. 2007, M.Rakotoarinivo et al. 350 (holotype K!; isotype TAN!). (M. Rakotoarinivo & J. Dransfield, New species of Dypsis and Ravenea (Arecaceae) from Madagascar in Kew Bulletin 65. 2010)A

Bibliography

A. M. Rakotoarinivo & J. Dransfield, New species of Dypsis and Ravenea (Arecaceae) from Madagascar in Kew Bulletin 65. 2010