Lanonia gialaiensis Henderson & Nguyen Quoc Dung, 2017

Henderson, Andrew & Dung, Nguyen Quoc, 2017, New species of Lanonia, Licuala, and Pinanga (Arecaceae) from Vietnam, Phytotaxa 323 (2), pp. 159-172 : 160-161

Lanonia gialaiensis Henderson & Nguyen Quoc Dung sp. nov. ( Fig. 2 ).

Type:— VIETNAM. Gia Lai Province, Ho Chi Minh Highway, East Branch, 14˚33’ N, 108˚26’ E, 1250 m, 22 April 2017, A. Henderson & Nguyen Quoc Dung 4221 (holotype VFM!, isotype NY!).

It differs from species having few leaf segments with the central segment wider than the others and with elongate costas ( L. calciphila , L. dasyantha , L. magalonii , L. verrucosa ) in its smaller size, short costa, non-mottled segments, branched pistillate inflorescences, and densely hairy rachillae.

Stems clustered, to 1.0 m tall, diameter not recorded. Leaf number not recorded; ligules 4.0–5.0 cm long; petioles 18.0– 34.5 cm long, thorny on lower ca. one third, the thorns sometimes bifid; blades 25.0–30.0 cm across, split into 4–12 segments, the central ones wider than the lateral ones, with minute brown scales abaxially; costa 1.5–2.0 cm long; central segment split into two lobes, these 15.5–21.5 cm long, 3.5–4.0 cm wide at the apex; lateral segment 10.5–17.0 cm long, 1.2–1.7 cm wide at the apex; segments briefly indented at the apex. Inflorescences curving, 20.0 cm long; staminate inflorescences not seen; pistillate inflorescences branched to 2 orders; prophylls 8.5 cm long; peduncles without peduncular bracts; rachis bracts flattened, brown tomentose; partial inflorescences 1–2; rachillae 7.5–11.0 cm long, densely hairy; pistillate flowers 3.5 mm long (post-anthesis) solitary, regularly and spirally arranged; calyx glabrous, tubular at the base, 3-lobed above, each lobe splitting again as the fruits develop to give a 6-lobed calyx; corolla glabrous, split into 3, valvate petals, these reflexed as fruits develop; fruits not recorded.

Distribution and habitat:—Southern Vietnam in Gia Lai province in montane forest at 1116–1380 m elevation.

Taxonomic notes:— Lanonia gialaiensis is similar to a group of species ( L. calciphila , L. dasyantha , L. magalonii , L. verrucosa ) having few leaf segments (3–13) with the central one wider than the lateral ones, and elongate costas. It differs from these four in having relatively short costas; from L. dasyantha in having non-mottled leaves; from L. calciphila in having branched pistillate partial inflorescences; and from L. magalonii and L. verrucosa in its densely hairy rachillae.

Additional specimens examined. VIETNAM. Gia Lai: Ho Chi Minh Highway, East Branch , 14˚30’ N, 108˚29’ E, 1116 m, 22 April 2017, A. Henderson & Nguyen Quoc Dung 4222 ( NY, VFM) ; Mang Yang distr., A Yun municip., Kon Ka Kinh National Park , 31 km WNW of K’Bang town, 14˚13’ N, 108˚18’ E, 1380 m, Kuznetsov et al. 1469 ( NY) .

Figures

FIGURE 2. Lanonia gialaiensis. Left, habit. Right, part of inflorescence with immature fruits.