Calamus phuocbinhensis Henderson & N. Q. Dung, 2013

Henderson, Andrew & Dung, Nguyen Quoc, 2013, Four new species of Calamus (Arecaceae) from Vietnam, Phytotaxa 135 (1), pp. 19-26 : 23-24

Calamus phuocbinhensis Henderson & N. Q. Dung sp. nov. ( Fig. 3 )

It differs from related species by its leaf sheaths without tomentum and with few spines, its rachises with recurved spines abaxially, and its short, membranous ocreas consisting of two lateral flanges, not developed above the petiole.

Type:— VIETNAM. Ninh Thuan: Phuoc Binh National Park , near park headquarters, disturbed forest by ecotourism trail, 11.986N, 108.747E, 323 m elevation, 18 April 2013, A. Henderson & Nguyen Quoc Dung 3857 (holotype, VFM! isotype, NY!) .

Stems clustered, 8–15 m long, 1.3–2.1 cm diameter with sheaths, 1.2–1.4 cm diameter without sheaths. Sheaths completely green, with very few, flat, brown spines to 1.5 cm long; ocreas short, membranous, consisting of two lateral flanges, not developed above petiole, soon falling; flagella 165 cm long; knees present; cirri absent; petioles 4–8 cm long on upper leaves, to 24 cm long on lower leaves; rachises 97–125 cm long with 44–45 pinnae per side, these irregularly arranged in clusters and spreading in different planes, linear, minutely spiny along the margins and mid-vein adaxially; middle pinnae 19.3–29.5 cm long, 1.2 cm wide; apical pair of pinnae joined for 0.2–0.5 cm. Staminate inflorescences not seen; pistillate inflorescence rachis bracts tubular, terminating below the partial inflorescences; flowers and fruits not seen.

Distribution and habitat:— Endemic to southern Vietnam in Ninh Thuan Province in seasonal forest at 323 m elevation.

Local names and uses:— may. No uses are reported.

Additional specimen examined:— Vietnam. Ninh Thuan: Phuoc Binh National Park , near park headquarters, disturbed forest by ecotourism trail, 11.986N, 108.747E, 323 m, 18 April 2013, A. Henderson & Nguyen Quoc Dung 3853 ( AAU, NY, VFM) .

Discussion:— Although the two specimens are incomplete and lack both flowers and fruits, and with only an old, decaying inflorescence present, we have no doubt that they represent an undescribed species. In fact, the sheaths and leaves of this species are the most distinctive and easily recognized of all Vietnamese palms. In Evans et al. ’s (2001a) treatment of Calamus in neighboring Laos, this palm would key to C. viminalis Willdenow (1799: 203) , based on its presence of a flagellum and irregularly arranged pinnae lying in different planes. In the same study of Calamus cited above (Henderson, in prep.), C. phuocbinhensis (named for the National Park in which it occurs) is placed in a clade comprising two other species; C. viminalis and C. siamensis Beccari (1902: 203) , characterized by the rachis with straight spines abaxially and the very short staminate rachillae with the flowers arranged in glomerules. Calamus phuocbinhensis differs from both of these in its leaf sheaths without tomentum and with few spines, its rachises with recurved spines abaxially, and in particular its short, membranous ocreas consisting of two lateral flanges, not developed above the petiole. In both C. viminalis and C. siamensis the ocrea is completely tubular and developed above the petiole.

Figures

FIGURE 3. Calamus phuocbinhensis. A. Leaf sheath with lack of tomentum, few spines, and small ocrea. B. Pinnae, irregularly arranged and spreading in different planes. (A–B from Henderson & Nguyen Quoc Dung 3853).