Lanonia poilanei 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 : 161-162

Lanonia poilanei Henderson & Nguyen Quoc Dung sp. nov. ( Fig. 3 ).

Type:— VIETNAM. Khanh Hoa: new road from Nha Trang to Da Lat, 12.232N 108.775E, ca. 550 m, 9 July 2014, A. Henderson & Nguyen Quoc Dung 3936 (holotype VFM!, isotype NY!).

It differs from Lanonia centralis in its elongate costas and scarcely tomentose rachis bracts.

Stems solitary or clustered, 0.8–4.0 m tall, 3.5–5.0 cm diameter. Leaf number not recorded; sheaths 20.0 cm long; ligules 5.0–14.0 cm long; petioles 0.5–1.8 m long, thorny on lower ca. half; blades 55.0–76.0 cm across, split into 10–20, approximately equally wide segments, these with minute brown scales abaxially; costa 9.7–21.5 cm long; central segment sometimes petiolulate, split into two lobes, these 42.5–61.0 cm long, 6.5–24.5 cm wide at the apex; lateral segment 35.5–45.5 cm long, 2.0– 2.3 cm wide at the apex; segments briefly indented at the apex. Inflorescences erect or curving, 70.0–110.0 cm long; staminate inflorescences branched to 4 orders; prophylls not recorded; peduncles without peduncular bracts; rachis bracts flattened, scarcely tomentose; partial inflorescences to 4; rachillae 5.0–10.0 cm long, minutely hairy; staminate flowers not seen; pistillate inflorescences branched to 3 orders; prophylls 37.5 cm long; peduncles with 0–1 peduncular bracts; rachis bracts flattened, scarcely tomentose; partial inflorescences 1–2; rachillae 7.5–18.5 cm long, minutely hairy, erect, with a spine-like apex; pistillate flowers solitary, not seen at anthesis; fruits 8.0 mm long, 6.6 mm diameter, globose, borne on a cupular, 1 mm long, swollen calyx; epicarp smooth, ripening white then red.

Distribution and habitat:—Southern Vietnam in Khanh Hoa and Ninh Thuan provinces in forest on steep, rocky slopes at 334–1250 m elevation.

Taxonomic notes:— Lanonia poilanei appears most similar to L. centralis , from further north in central Vietnam. It differs from that species in its elongate costas (9.7–21.5 cm long versus 2.5–5.0 cm long) and scarcely tomentose rachis bracts. It is also larger, with larger leaves (central segment lobe 42.5–61.0 cm long, 6.5–24.5 cm wide versus 40.0–45.0 cm long, 4.5–8.0 cm wide). However, it is unusually variable and still not well understood. The type and the two other specimens examined come from the eastern slopes of the Da Lat Plateau between Nha Trang and Da Lat. They have a petiolulate central segment, a character state previously known only in Licuala . Two sterile specimens from Hon Ba have unusually broad central segment lobes. A specimen from Hon Heo has a highly branched staminate inflorescence. Specimens from Nui Chua resemble those from the eastern slopes of the Da Lat Plateau but lack the petiolulate central segment. It is not clear if some of this variation is based on sexual dimorphism because there are not enough specimens to test. In L. hexasepala , with an approximately similar distribution, staminate plants appear to have narrower segments and pistillate broader. In Licuala , specimens from Hon Ba, Hon Heo, and Nui Chua are more obviously different and are here described as distinct species (see below).

Additional specimens examined. VIETNAM. Khanh Hoa: road from Nha Trang to Da Lat , 12°13’N 108°45’E, ca. 800 m, 13 October 2016, Henderson & Nguyen Quoc Dung 4130 ( NY, VFM) ; Khanh Vinh District, road from Nha Trang to Da Lat , 12.233N, 108.766E, 605 m, 7 July 2010, Henderson & Bui Van Thanh 3676 ( HN, NY) ; Ninh Hoa District, Tien Du commune, Hon Heo mountain , 12.450N, 109.233E, 334 m, 6 July 2010, Henderson & Bui Van Thanh 3672 ( HN, NY) ; Nui Hon Heo près de Nhatrang, 5 October 1922, Poilane 4913 ( P) ; Mère et l’Enfant près de Nhatrang, 4 November 1922, Poilane 5016 ( P) ; kilo 35 route de Nhatrang a Ninh Hoa, 700 m, 17 October 1923, Poilane 8255 ( P) ; Dien Khanh District, Hon Ba Nature Reserve , 12.100N, 108.966E, 910 m, 10 July 2010, Henderson & Bui Van Thanh 3695 ( NY, HN) ; same locality, same date, Henderson & Bui Van Thanh 3696 ( HN, NY). Ninh Thuan: Ninh Hai District, Nui Chua National Park , 11°48’N, 109°10’E, ca. 800 m elevation. 27 Jul 2007, Henderson, Ninh Khac Ban, & A Ruc Cui 3470 ( HN, NY) ; Ninh Hai District, Nui Chua National Park , 11.80N, 109.16E, ca. 800 m elevation. 26 Oct 2009, Henderson, Bui Van Than, Nguyen Quoc Dat, & A Ruc Cui 3643 ( HN, NY) ; Ninh Hai District, Vinh Hai Municipality, NEE slopes of Nui Chua mountain to SW of point 11°43’N, 109°08’E, 600–700 m, 27 March 2004, Regalado et al. HLF 4201 ( HN) ; same locality, 28 March 2004, Regalado et al. HLF 4313 ( HN) .

Figures

FIGURE 3. Lanonia poilanei. Left, habit (from Henderson & Bui Van Thanh 3695). Right, immature fruits (from Henderson & Bui Van Thanh 3676).