Castanopsis multiporcata N. H. Xia & D. H. Vuong 2014, sp. nov.

Castanopsis multiporcata N. H. Xia & D. H. Vuong, sp. nov. (Figs. 3, 4)

Diagnosis:— The species is similar to Castanopsis buruana, but it can be easily distinguished from the latter by having leaf blade 5–8 cm long (vs. 10–15 cm), papery firmness (vs. thinly leathery), abaxially glabrescent (vs. dense stellate hairs), petioles 0.3–0.7 cm long (vs. 1–1.5 cm), cupules 2–2.5 cm diameter (vs. 1–2 cm diameter) and concave scar (vs. flat or convex).

Type: — VIETNAM. Phu Tho: Tan Son District, Xuan Son National Park, Ten mountain, 21º07.246′ N, 104º56.295′ E, 832 m, 24 October 2012, D. H. Vuong 2012102407 (holotype VNF!; isotypes IBSC!, VNF!, VNM!, XSNP!).

Trees, 20–30 m tall, to 80 cm in diameter; bark gray and smooth, branches glabrous, with slightly raised lenticels. Terminal buds ovoid or ovoid-elliptic, 2–5 × 2–3 mm, glabrescent, fimbriate. Stipules narrowly lanceolate, glabrous, 6–7 × 1–1.5 mm, caducous. Petiole 0.3–0.7 cm, glabrous. Leaf blade elliptic, sometimes obovate-elliptic or oblong elliptic, 5–8 × 2–3 cm, papery firmness, adaxially glabrous, abaxially with tight, thin, brown thin-walled peltate trichomes, without non-glandular trichomes, base cuneate, margins entire, apex acute or acuminate; midvein adaxially slightly raised from base to middle but flat to slightly impressed from middle to apex; secondary veins 6–10 on each side of midvein, slender. Male inflorescence rachis pubescent. Female inflorescences 8–15 cm, rachis sparsely and shortly hairy, flower solitary per cupule, styles 3. Infructescence rachis 2–2.5 mm thick, glabrous, sparsely lenticellate. Cupule conical or subglobose, 2–2.5 cm in diameter outside and spines pubescent and with yellowish brown scales, inside dense brown villus, wall 0.5–1 mm thick and exterior visible through spines; spines 5–7 mm long, basally connate and transversely united across 4–5 rings. Nut 1 each cupule, conical, 1–1.5 cm in diameter, densely brown pubescent, 10–11 obviously ridges in cross section; scar concave, 0.8–1.2 cm in diameter.

Distribution and habitat: — C. multiporcata is endemic to Xuan Son National Park, Phu Tho Province in the North Vietnam. It grows sparsely in evergreen broad-leaved forest on the slope of limestone mountains at the elevation of 650– 850 m. Associated species at the type locality include C. tonkinensis Seemen (1897: 55) (Fagaceae), Pometia pinnata J. R. Forster & G. Forster (1775: 110) (Sapindaceae), etc.

Conservation: —Only a few small populations of this taxon are found in Ten mountain and well conserved in the Xuan Son National Park. According to IUCN Red list Categories and Criteria (IUCN 2012), C. multiporcata should be categorized as Data Deficient (DD). More information about the ecology of this species and the extent of the habitat in Indo-China and southwest China regions are needed.

Phenology: —Its flowering period extends from August to September and fruiting from October to November of the following year.

Etymology: —The species epithet “ multiporcata ” refers to the nut with 10–11 ridges in cross section.

Paratypes:— VIETNAM. Phu Tho: Tan Son district, Xuan Son National Park, Ten mountain, 21º07.162′ N 104º56.610′ E, 654 m, 26 May 2011, D. H . Vuong 2011052601 (VNF!); loc. cit., 21º07.246′ N 104º56.295′ E, 832 m, 9 February 2012, D. H. Vuong 2012020901 (IBSC!, VNF!); loc. cit., 7 May 2012, D. H. Vuong 2012050701 (VNF!); loc. cit., 15 August 2012, D. H. Vuong 2012081501 (IBSC!, VNF!).

Similar species: —The new species is similar to C. buruana Miquel (1863: 120) in leaf shape, cupule spines and hairy conical nuts with some ridges in cross section, but can be distinguished from the latter by having leaf blade 5–8 cm long (vs. 10–15 cm), papery firmness (vs. thinly leathery), abaxially glabrescent (vs. dense stellate hairs), petioles 0.3–0.7 cm long (vs. 1–1.5 cm), cupules 2–2.5 cm diameter (vs. 1–2 cm diameter) and concave scar (vs. flat or convex).