Calamus yentuensis A.J.Hend. & N.Q.Dung, 2010

Henderson, Andrew & Dung, Nguyen Quoc, 2010, Notes on rattans (Arecaceae) from Vietnam, Phytotaxa 8, pp. 25-33 : 31-33

Calamus yentuensis A.J.Hend. & N.Q.Dung , sp. nov. ( Plate 4 )

A speciebus aliis Calami habitu non scandenti, ocreis prominentibus, pinnis aggregatis, et inflorescentiae flagelliformis differt.

Type:— VIETNAM. Quang Ninh Province: Dong Trieu District, Yen Tu Mountain , pagoda area, 21.11°N, 106.72°E, ca. 100 m, 7 June 2009, A. Henderson & N.Q. Dung 3601 (holotype: FIPI!, isotype: NY!) .

Stems clustered, non-climbing, free-standing, green, to 1.5 m long, 1.2 cm in diameter without sheaths; internodes 2.5 cm long. Leaves 10–12; sheaths open, with rings of black spines to 4.5 cm long, interspersed among many smaller spines; ocreas to 15 cm long, covered with rings of spines as the sheaths, with a tuft of brownish hairs at the apices, becoming split into two ‘ears’; knees absent; flagella absent; petioles to 50 cm long, spiny on all sides as the sheaths; rachis 50–70 cm long, with scattered, solitary spines abaxially; cirri absent; pinnae ca. 43 per side of rachis, 11–25 cm long, 0.5–1 cm wide at the middle, linear, regularly arranged but with gaps, spreading in the same plane, pendulous at the apices, bristly on main veins and lateral veins adaxially and abaxially and along the margins. Staminate inflorescences to 3 m long, arching, flagellate, branched to 3 orders, with 3 partial inflorescences; prophylls not seen; partial inflorescence bracts tubular, briefly splitting at the apices, without spines; rachillae 1 cm long; rachillae bracts 2 mm high, cupular; floral bracteoles cupular; staminate flowers 3.7–4 mm long; calyx tubular, 2–2.2 mm long, briefly 3-lobed; corolla 3–3.3 mm long, split almost to the base into 3 valvate petals; stamens 6; filaments inflexed at the apices; pistillodes well–developed, 2.5 mm long; pistillate inflorescences to 3 m long, arching, flagellate, branched to 2 orders, with 3 partial inflorescences; prophylls not seen; partial inflorescence bracts tubular, splitting laterally, with some recurved spines on outer surfaces; rachillae 8–9 cm long; rachillae bracts 2.5 cm long; floral bracteoles cupular; pistillate flowers 4.5 mm long; calyx 4 mm long, briefly 3-lobed at the apex; corolla 3 mm long, briefly 3-lobed at the apex; staminodes well–developed; fruits globose, brown, ca. 1 cm in diameter; endosperm homogeneous.

Distribution and habitat: — Endemic to northern Vietnam in Quang Ninh Province on Yen Tu Mountain, in disturbed forest at the base of the mountain.

Local names and uses:— may den. The stems are used in furniture making.

Additional specimen examined (paratype):— VIETNAM. Quang Ninh Province: Dong Trieu District, Yen Tu Mountain , pagoda area, 21.11°N, 106.72°E, ca. 100 m, 7 June 2009, A. Henderson & N.Q. Dung 3602 ( FIPI, NY) .

Discussion: —This unusual species differs from all other non–climbing Calamus in Vietnam and adjacent China, by its elaborate ocreas, interruptedly pinnate leaves, and elongate, flagellate inflorescences. It is named for Yen Tu Mountain, its only known locality.

Figures

PLATE 4. Calamus yentuensis. Left. Habit. Right. Leaf sheaths showing ocreas.