Ravenea beentjei Rakotoarin. & J.Dransf., Kew Bull. 65(2): 298 (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
Known only from Vondrozo forest, in southeast Madagascar. (M. Rakotoarinivo & J. Dransfield, New species of Dypsis and Ravenea (Arecaceae) from Madagascar in Kew Bulletin 65. 2010)A

Habitat

  • Common in lowland humid forest, in valleys and swampy areas; 600-650 m. (M. Rakotoarinivo & J. Dransfield, New species of Dypsis and Ravenea (Arecaceae) from Madagascar in Kew Bulletin 65. 2010)A

Discussion

  • Similar to Ravenea robustior and R. krociana in having solitary inflorescences whether in male or female plants but differing from these in the lack of a ventricose trunk, a more delicate inflorescence, with pendulous rachillae, and having staminate flowers with usually 12 stamens rather than six. The presence of three seeds in the fruit is also rather unusual. The specific epithet honours Henk Beentje, monographer of Ravenea and co-author of Palms of Madagascar (M. Rakotoarinivo & J. Dransfield, New species of Dypsis and Ravenea (Arecaceae) from Madagascar in Kew Bulletin 65. 2010)A

Diagnosis

  • Rakotoarin. & J. Dransf. sp. nov. inflorescentiis staminatis et pistillatis solitariis R. robustiori Jum. & H. Perrier et R. krocianae Beentje similis, sed trunco non ventricoso, inflorescentiae rachillis pendulis, floribus staminatis plerumque stam-inibus 12 vice 6 differt. (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 one population in Vondrozo, where it is restricted to frequently flooded areas. In an Extent of Ocurrence estimated to be less than 7 km2, only about 40 mature individuals have been recorded in the field. The forest of Vondrozo is managed by the local community but logging operations still occur. (M. Rakotoarinivo & J. Dransfield, New species of Dypsis and Ravenea (Arecaceae) from Madagascar in Kew Bulletin 65. 2010)A

Description

  • Medium-sized, solitary, dioecious palm. Trunk 3.5 - 10 m tall, 8- 15 cm diam., internodes 4- 11 cm, bark brown, wood soft, base of the crown bulbous, c. 11 cm across. Leaves 8- 15 in the crown, porrect to pendulous, arching, marcescent, occasionally trapping litter; sheath 50-90 x 10-15 cm, yellowish but covered with brown blackish indumentum, margins disintegrating and fibrous; petiole 30- 150 cm long, 3.5- 3.8 ?x 1.5-2 cm in cross section, slightly channelled, margins sharp, abaxial surface covered in caducous white to greyish tomentum; rachis 2 . 3.50 m long, 1.2- 2 ?x 2.2- 2.6 cm in cross section in mid-leaf, keeled, pale green, with irregular grey to brown tomentum, becoming glabrescent; leaflets stiff, regularly arranged, arranged in one plane, dark green, 46 . 55 on each side of the rachis, the proximal leaflets 52- 123 ?x 0.8- 2 cm, the median leaflets 116-124 ?x 4.8- 6 cm, the distal leaflets 21- 42 ?x 0.8- 2.9 cm, leaflets spaced 4-6 cm apart, abaxial surface with scattered brown scales and ramenta. Inflorescences interfoliar, solitary. Staminate inflorescence pendulous, branched to 2 orders, peduncle 24- 38 cm long, 0.8- 1 cm wide, prophyll not seen, peduncular bracts several but only 2 preserved, c. 77 and 82 cm long, c. 9 cm wide, purplish, covered in red brown tomentum, rachis c. 48 cm long; rachillae 9- 15 cm long, c. 0.5 mm wide; pedicel 0.6- 1.2 mm. Staminate flowers yellow, calyx connate for c. 0.4 mm, lobes 1.6 -2 ?x 0.8- 1 mm; petals free, 6.2- 6.5 ?x 4.5- 4.7 mm, with scattered minute red dots near the apex; stamens (6) 12, 2 opposite each petal, and 2 opposite each sepal, filaments 0.4- 0.8 mm, anthers c. 3.5 x 1.4 mm., pistillode minute. Pistillate inflorescence erect, branched to 1 order, peduncle 19- 25 cm long, c. 1.6 cmacross, yellowish, covered with red brown tomentum; prophyll c. 30 x 8 cm, pinkish, covered with red brown tomentum; peduncular bractsc. 85x 6 cm, ± equal in size, purplish-pink, abaxial surface densely covered in red brown tomentum in the upper part; rachis 30-35 x 1.5- 1.7 cm, yellow but sparsely to densely covered with red brown tomentum, with 6 . 18 rachillae; rachillae 35- 48 cm long, glabrescent, sinuous, pedicels 3.7- 5.2 mm long. Pistillate flowers yellow, sepals connate for c. 1.6 mm, lobes c. 0.8 ?x 0.7 mm; petals unequal, spathulate, coriaceous, 1.3- 6.5 x 4.5 - 5.4 mm; staminodes 12, minute; gynoecium c. 7.4 x 8 mm, gibbous, triloculate, stigmas recurved. Fruits blackish, subglobose, perianth persistent, stigmatic remains apical, 1.4- 1.6 x 1.5 - 1.6 cm, epicarp c. 0.8 mm thick, mesocarp 1.8 mm thick, spongy, endocarp spongy. Seeds 3; 1.3-1.4 x 0.7- 0.8 mm, seedcoat black, 0.1 mm thick; endosperm homogeneous. (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, 22º47'39"S, 47º11'18"E, 6 Oct. 2006, M. Rakotoarinivo 317 (holotype K!; isotype TAN!) & M. Rakotoarinivo 321 (K!, 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