Calamus manglaensis 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 : 257

Calamus manglaensis Henderson & Nguyen Quoc Dung sp. nov.

Type:— VIETNAM. Kon Tum: Kon Plong district, Dak Long commune, Ho Chi Minh Highway, just north of intersection of road from Mang Den to Bato, 14°41’N 108°21’E, 1468 m, 16 October 2015, A. Henderson & Nguyen Quoc Dung 4031 (holotype VFM!, isotype NY!). Fig. 4 .

It differs from all other species of Calamus by its pistillate inflorescences branched to 1 order and seeds covered with a non-tanniniferous, slimy sarcotesta.

Stems clustered, climbing, 20.0 m long, 0.8(0.6–1.0) cm diameter. Leaf sheaths tubular, closed opposite the petiole, with a knee below the petiole; leaf sheath spines few, scattered, shortly recurved on a swollen base, not leaving a distal impression in the sheath; ocreas short, membranous, usually non-spiny, with external and internal abscission zone, splitting and falling early; flagella well-developed; petioles 2.8(2.0–3.5) cm long; rachises 22.2(20.0–24.5) cm long, the apices a short stub between the distal pair of pinnae; pinnae 8(7–9) per side of rachis, irregularly arranged in groups, spreading in different planes, elliptic, without spinules on veins, proximalmost pinnae swept back across the sheath; middle pinnae 18.6(18.0–19.4) cm long, 1.6(1.2–1.8) cm wide; distal pair of pinnae joined at their bases for 1.0(0.7–1.4) cm. Inflorescences diverging from sheath near sheath apex; inflorescences erect to arching, slender, elongate, with recurved spines on rachis and rachis bracts abaxially, without a flagellum-like apex; rachis bracts tubular, narrow, persistent, closely sheathing the rachis, not swollen at the apex; rachillae sessile; staminate inflorescences branched to 2 orders, 88.0 cm long; staminate rachillae 6.5 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 1 order, 110.0 cm long; pistillate rachillae 5.2 cm long, with dyads of 1 pistillate and 1 neuter flower; fruits globose, 23.9 mm long, 17.8 mm diameter, color not recorded; fruiting perianths tubular; fruit scales channeled vertically; seeds 1 per fruit, basally attached, large, globose, not reniform in longitudinal section, the dorsal surfaces pitted, covered with a non-tanniniferous, slimy sarcotesta; endosperm with numerous, deep, pit-like ruminations; embryos at or near base of seed.

Distribution and habitat:—Southern Vietnam, known only from Kon Tum province, in montane rainforest at 1203(1000–1468) m elevation.

Taxonomic notes:— In Peters and Henderson (2014) this species would not key. In fact, it is a remarkable species with a unique combination of character states in Calamus . Pistillate inflorescences are branched to 1 order and seeds are covered with a non-tanniniferous, slimy sarcotesta and have deep, pit-like ruminations. Its relationships are unclear.

Additional specimens examined. VIETNAM. Kon Tum: Kon Plong district, Hieu commune, 6 km north on Ho Chi Minh highway from road 24, 1140 m, 14.676N, 108.397E, 24 April 2013, Henderson & Nguyen Quoc Dung 3879 ( NY, VFM) ; Kon Plong district, Mang Canh m., Thach Nham protected forest, 15 km NNE from Mang Den town , 1000 m, 14°43’N 108°19’E, 11 April 2015, Nuraliev, Kuznetsov & Kuznetsova 1336 ( NY) .

Figures

FIGURE 4. Calamus manglaensis. A. Sheath with few, scattered, shortly recurved spines on a swollen base, not leaving a distal impression in the sheath (Henderson 4031). B. Leaf with irregularly arranged pinnae (Henderson 4031). C. Staminate partial inflorescence (image by M. Nuraliev). D. Infructescence with globose fruits (Henderson 4031).