Calamus velutinus Henderson & Nguyen Quoc Dung, 2018

Henderson, Andrew & Dung, Nguyen Quoc, 2018, New species and subspecies of Calamus (Arecaceae) from Vietnam, Phytotaxa 347 (4), pp. 251-262 : 259-261

Calamus velutinus Henderson & Nguyen Quoc Dung sp. nov.

Type:— VIETNAM. Dak Lak: Chu Yang Sin National Park, trail to Chu Yang Sin mountain, 800 m, 3 December 2012, Nguyen Quoc Dung, Nguyen Van Tap, Le Van Cham, Le Manh Tuan & Le Dung Thanh VFM-CYS 188 (holotype VFM!, isotype NY!). Fig. 6 .

It differs from Calamus walkeri in its elongate ocreas and splitting and tattering rachis bracts.

Stems clustered or solitary, climbing, 4.3(3.0–5.0) m long, 2.0(1.9–2.2) cm diameter. Leaf sheaths tubular, closed opposite the petiole, with a knee below the petiole; leaf sheath spines stout, triangular, concave at the base proximally, horizontally spreading, scattered to dense, yellowish-brown; ocreas elongate, densely spiny with short brown or black, erect spines; flagella well-developed; petioles 50.0(40.0–60.0) cm long; rachises 175.0(160.0–200.0) cm long, the apices filiform or sometimes just a short stub between the distal pair of pinnae; pinnae 41(36–45) per side of rachis, regularly arranged and spreading in the same plane, linear, with spinules on veins adaxially and abaxially, the lateral veins approximately parallel, one terminating subapically, leaving a distinct or obscure, adaxial ‘broken’ vein; middle pinnae 50.5(43.5–60.0) cm long, 1.7(1.4–2.0) cm wide; distal pair of pinnae joined at their bases for 1.4(0.3–3.0) cm. Inflorescences diverging from sheath near sheath apex, with two diverging ridges distal to point of divergence; inflorescences arching, slender, elongate, with solitary or grouped, recurved spines on rachis and rachis bracts abaxially, terminating in a flagellum-like apex; partial inflorescences not stalked, with a pulvinus in axil of rachis and partial inflorescence; rachis bracts tubular, narrow, persistent, closely sheathing the rachis, not swollen at the apex, splitting and tattering by exsertion of partial inflorescence; rachillae sessile; staminate inflorescences branched to 3 orders, length not recorded; staminate rachillae 0.2 cm long; staminate flowers arranged in densely crowded rows on very short rachillae; staminate sepals shorter than the petals, cupular, 3-lobed at the apex; stamens 6; filaments uniseriate, | inflexed at the apex; pistillate inflorescences branched to 2 orders, 400.0 cm long; pistillate rachillae 4.1(3.5–5.0) cm long, with dyads of 1 pistillate and 1 neuter flower; fruits ellipsoid, 10.7(10.3–11.0) mm long, 6.4(6.0–6.7) mm diameter, yellow; fruiting perianths explanate; fruit scales channeled vertically; seeds 1 per fruit, basally attached, small, ellipsoid, with a ventral depression, reniform in longitudinal section, the dorsal surfaces grooved, covered with a tanniniferous, non-fibrous sarcotesta; raphe branches 2, bifurcating from the attachment of seed and running along ventral side; endosperm homogeneous; embryos at or near base of seed.

Distribution and habitat:—Southern Vietnam in lowland rainforest at 537(158–800) m elevation.

Taxonomic notes:— Calamus velutinus is similar to C. walkeri , differing in its longer ocrea and splitting rachis bracts. Unlike C. walkeri , it has long, bicolored spinules on the abaxial pinnae surfaces.

Additional specimen examined. VIETNAM. Dak Lak: Chu Yang Sin National Park, trail to Chu Yang Sin mountain, 800 m, 3 December 2012, Nguyen Quoc Dung et al. 129 ( VFM, NY). Khanh Hoa: Ninh Hoa District, Ninh Tay Commune , road to hydroelectric dam, 12°35’N 108°58’E, 433 m, 7 October 2016, Henderson & Nguyen Quoc Dung 4066 ( NY, VFM) ; same locality and date, Henderson & Nguyen Quoc Dung 4074 ( NY, VFM) ; Khanh Vinh District, Khanh Trung Commune, 12°22’N 108°49’E, 450 m, 11 October 2016, Henderson & Nguyen Quoc Dung 4102 ( NY, VFM). Binh Thuan: Tanh Linh District , Nui Ong Nature Reserve , 10.96N, 107.63E, 224 m, 18 October 2009, Henderson et al. 3615 ( HN, NY) ; Tanh Linh District, Nui Ong Nature Reserve , 11.02N, 107.71E, 158 m, 21 October 2009, Henderson et al. 3627 ( HN, NY) ; route 55 from Bao Loc to Da Mi Hydroelectric Dam , 11°20’N 107°52’E, 766 m, 15 October 2016, Henderson & Nguyen Quoc Dung 4149 ( NY, VFM) ; route 55 from Bao Loc to Da Mi Hydroelectric Dam , 11°14’N 107°50’E, 766 m, 15 October 2016, Henderson & Nguyen Quoc Dung 4152 ( NY, VFM) .

Figures

FIGURE 6. A. C. velutinus, leaf sheath with elongate, densely spiny ocrea with short brown or black, erect spines (Nguyen Quoc Dung 188). B. Partial pistillate infructescence with tubular, narrow, persistent rachis bracts splitting and tattering by exsertion of partial inflorescence, and ellipsoid fruits (Nguyen Quoc Dung 188).