Chrysalidocarpus mijoroanus (Eiserhardt & W.J.Baker) Eiserhardt & W.J.Baker

Eiserhardt, W.L., Dransfield, J., Rakotoarinivo, M. et al. (2018). Four new species of Dypsis (Arecaceae: Arecoideae) from Madagascar. Kew Bulletin 73: 44. https://doi.org/10.1007/s12225-018-9776-z

Type

Madagascar, Antsiranana, Sava, Antalaha, Vinanivao, Tanany Rabe Pierre (Ankorabe), 60 m a.s.l., 15°43'51"S, 50°12'55"E, 17 Nov. 2015, Eiserhardt et al. 135 (holotype K!, isotypes MO!, P!, TAN!).

Morphology General Habit

Moderately robust solitary canopy palm to 15 m, bearing 13 – 16 spirally arranged leaves in crown

Morphology Stem

Stem 15 – 20 cm in diam., unevenly columnar; leaf scars closely spaced and more prominent at stem apex; internodes 2 – 11 cm (to 20 cm in juveniles), grey-brown with abundant lichen growth

Morphology Leaves

Leaf 3.5 – 4 m long including petiole (to 6 m in juveniles); sheath short and open, 60 – 65 cm long, with abundant rusty red-brown lanate indumentum, with thinner grey-white indumentum beneath that extends throughout petiole and rachis, inner surface of sheath bright pink-red, crownshaft not well-defined, c. 130 cm long, c. 40 cm wide; petiole 60 – 70 cm long, concave on adaxial surface; leaflets 80 – 89 each side of rachis, mostly irregularly arranged in different planes and variously fascicled, but also regularly arranged in places (especially towards leaf apex), concolorous, with abundant ramenta distributed patchily along abaxial surface of midrib, especially dense near base, with smaller rusty brown scales on abaxial surface of margins and ribs; basal leaflets 66 – 110 cm long, 1.2 – 1.6 cm wide, linear, single-fold, rein-like towards the apex; middle leaflets 77 – 84 cm long, 2.8 – 3.9 cm wide, linear, single-fold, transverse veinlets inconspicuous; apical leaflets 18 – 30 cm long, 1.5 – 2.2 cm wide, linear-lanceolate, not united, single- to 2-folded, usually with filiform vestigial extension of rachis to 24 cm extending between them

Morphology Reproductive morphology Inflorescences

Inflorescence c. 2.5 m long, interfoliar, widely spreading, upright and arching, branched to 2 – 4 orders, green, with red-brown indumentum as sheath on peduncle and rachis, becoming more sparse with subsequent orders of branching; prophyll 60 – 65 cm long, 8 – 15 cm wide, with red-brown indumentum as sheath; peduncular bract not seen; peduncle 100 – 110 cm long, c. 6 cm wide, ellipsoid in section; primary branches c. 32, to c. 70 cm long; rachillae 28 – 45 cm long, 3.5 – 4.5 mm in diam.; rachilla bracts inconspicuous; triads 1.5 – 2 mm apart, spirally arranged, developing in shallow pits

Morphology Reproductive morphology Flowers

Female flower not seen Male flower 2.4 – 2.8 mm long, 1.9 – 2.4 mm in diam. in early bud, green; sepals 3, 1.5 – 1.9 mm long, 1.3 – 1.6 mm wide, cucullate, glabrous; petals 1.6 – 1.8 mm long, 1.4 – 1.5 mm wide, rounded, glabrous; stamens 6; filaments 0.5 – 0.6 mm long, free, spindle-shaped; anthers 0.9 – 1.1 mm long, 0.4 – 0.5 mm wide, dorsifixed, dehiscence latrorse; pistillode 1.4 – 1.6 mm long, c. 0.4 mm in diam

Morphology Reproductive morphology Fruits

Fruit not seen

Morphology Reproductive morphology Seeds

Seed not seen

Distribution

Known only from the type locality on the eastern side of the Masoala peninsula (Madagascar).

Ecology

Primary lowland humid forest. Deep humus over white sand.

Vernacular

Sira, or sira-mafy (Betsimisaraka).

Conservation

Critically Endangered (CR) [B2a,b (iii)+D]. The known population is located in a forest fragment at the edge of the Masoala National Park, relatively close to human habitation. A decline in the quality of the habitat is predicted and this could impact on the long-term survival of this small population.

Note

This palm is instantly recognisable by its gnarled appearance, with its somewhat irregular stem, poorly defined crownshaft and plumose leaves, as well as the abundant red-brown indumentum that covers the leaf sheath. With its plumose leaves, open sheaths and spreading inflorescences with slender rachillae it is reminiscent of Dypsis tokoravina Beentje. This latter species is a gigantic palm, one of the largest in Madagascar, and certainly did not come to mind when we saw D. mijoroana in the field. Perhaps data from molecular analysis will indicate whether the two taxa are closely related or not. Dypsis mijoroana can be distinguished by its much smaller size, and the very dense red brown indumentum on the sheaths reminiscent of, for example, D. lastelliana. The inflorescence is substantially smaller than in D. tokoravina. The species is named after Dr Mijoro “Joro” Rakotoarinivo, whose work has greatly improved our knowledge of Madagascan palm taxonomy, ecology and conservation. This palm shares its characteristic rusty red-brown indumentum with Dypsis lastelliana (Baill.) Beentje & J. Dransf. and D. leptocheilos (Hodel) Beentje & J. Dransf., but is easily distinguished from those species by its plumose leaves.