Calamus cinereus 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 : 251-252

Calamus cinereus Henderson & Nguyen Quoc Dung sp. nov.

Type:— VIETNAM. Binh Thuan: Tanh Linh District, Nui Ong Nature Reserve, 11.02N, 107.71E, 158 m, 21 October 2009, A. Henderson, Bui Van Than & Nguyen Quoc Dat 3626 (holotype HN!, isotype NY!). Fig. 1 .

It differs from similar species ( C. bimaniferus , C. kontumensis , C. oligostachys , C. parvulus , C. tetradactylus ) in its pinnae that are dull gray indumentose abaxially.

Stems clustered, climbing, 4.0(2.0–6.0) m long, 0.7(0.4–0.9) cm diameter. Leaf sheaths tubular, closed opposite the petiole, with a knee below the petiole; leaf sheath spines slender to stout, triangular, concave at the base proximally, horizontally spreading, scattered, yellowish-brown; ocreas short, membranous, usually non-spinulose, with external and internal abscission zone, splitting and falling early; flagella well-developed; petioles 10.2(2.3–20.0) cm long; rachises 42.6(23.0–50.0) cm long, the apices filiform or sometimes just a short stub between the distal pair of pinnae; petioles and rachises with long, straight, yellowish, black-tipped, usually solitary spines abaxially and laterally; pinnae 8(6–10) per side of rachis, arranged in remote clusters, the pinnae of a cluster spreading in different planes, elliptic, usually without spinules on veins adaxially or abaxially, the lateral veins diverging then converging, both terminating apically or slightly subapically, dull gray indumentose abaxially; middle pinnae 18.4(14.5–23.5) cm long, 2.6(2.0–3.6) cm wide; distalmost few (usually 4) pinnae in a close group, the distalmost pair joined for much of their length and oriented in line with the rachis, the adjacent pair oriented at approximately 45º angle to the rachis; distal pair of pinnae joined at their bases for 5.2(4.5–7.0) 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, or sometimes flagellum-like apex absent; 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, sometimes partially splitting if the partial inflorescence inserted below the bract apex; rachillae sessile; staminate inflorescences branched to 3 orders, 105.0(90.0–120.0) cm long; staminate rachillae 1.8(1.4–2.3) cm long; staminate flowers arranged in alternate, opposite rows; 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, 51.3(32.5–70.0); pistillate rachillae 2.6(2.0–3.0) cm long, with dyads of 1 pistillate and 1 neuter flower; fruits globose, mature size and color not recorded; fruiting perianths tubular; fruit scales channeled vertically; seeds 1 per fruit, basally attached, small, globose, with a ventral depression, reniform in longitudinal section, the dorsal surfaces not recorded; raphe branches 2, bifurcating from the attachment of seed and running along ventral side; endosperm and embryos not recorded.

Distribution and habitat:—Southern Vietnam in lowland rainforest at 588(150–890) m elevation.

Taxonomic notes:— In Peters and Henderson (2014) this species would key to C. tetradactylus , and under that species Peters and Henderson mention plants with indumentose pinnae, although they are not formally described. Calamus cinereus is certainly similar to C. tetradactylus and related species ( C. bimaniferus , C. kontumensis , C. oligostachys , C. parvulus ) but differs in its pinnae that are dull gray indumentose abaxially. It also bears a superficial resemblance to C. griseus Dransfield (2000: 157) , from Thailand, Peninsular Malaysia, and Sumatra, but that species is closely related to C. javensis .

Additional specimens examined. VIETNAM. Binh Thuan: Tanh Linh District, Nui Ong Nature Reserve , 11.02N, 107.71E, 158 m, 21 October 2009, Henderson et al. 3625 ( 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 4148 ( NY, VFM) ; same locality, same date, Henderson & Nguyen Quoc Dung 4154 ( VFM). Lam Dong: Da Huoai District, Deo Bao Loc on road between Bao Loc and Ho Chi Minh City, 11.45N, 107.71E, 676 m, 25 October 2009, Henderson et al. 3639 ( HN, NY) ; Bao Loc District, Dap Loa Commune, Nam Hoai Forestry Company , 11.433N, 107.700E, 544 m, 15 July 2010, Henderson et al. 3721 ( HN, NY) ; Di Linh District, road from Di Linh to Phan Thiet , 11°22’N 108°05’E, 890 m, 14 October 2016, Henderson & Nguyen Quoc Dung 4142 ( VFM) ; same locality, same date, Henderson & Nguyen Quoc Dung 4143 ( NY, VFM) ; same locality, same date, Henderson & Nguyen Quoc Dung 4144 ( NY, VFM) ; road southwest from Bao Loc, Deo Bao Loc, 11°27’N 107°43’E, 16 October 2016, Henderson & Nguyen Quoc Dung 4170 ( VFM). Dong Nai: Cat Tien National Park , road to north of park headquarters, 11°26’N, 107°23’E, 150 m, 25 May 2007, Henderson et al. 3389 ( HN, NY) ; Cochinchina, 4 km au nord de Dinh Quan, prov. de Bien Hoa, no date, Poilane 21718 ( A) .

Figures

FIGURE 1. Calamus cinereus. A. Sheath and abaxial surface of pinnae with dull gray indumentum (Henderson 3389). B. Short, membranous, non-spinulose ocrea, splitting and falling early (Henderson 3625). C. Leaf with 4 distalmost pinnae in a close group, the distalmost pair joined for much of their length and oriented in line with the rachis, the adjacent pair oriented at approximately 45º angle to the rachis (Henderson 3625). D. Infructescence (Henderson 3626).