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

Castanopsis grandicicatricata N. H. Xia & D. H. Vuong, sp. nov. (Figs. 1, 2)

Diagnosis:— The new species is similar to Castanopsis javanica, but differs mainly in its cupules 6–7 cm in diameter (vs. 2.5–5 cm), scar covering 2/3 of nut (vs. scar covering 1/4–1/3 of nut) and thickly papery leaf texture (vs. thickly leathery).

Type: — VIETNAM. Nghe An: Thanh Chuong District, Thanh Chuong Protection Forest, 18º41′01″ N, 105º09′12″ E, ca. 300 m, 27 August 2011, D. H . Vuong 2011082701 (holotype VNF!; isotypes IBSC!, VNF!, VNM!).

Trees, 20–35 m tall, to 50 cm in diameter; bark greyish brown, slightly shallowly fissured; young shoots sericeous with thick reddish brown thin-walled peltate trichomes; terminal buds, stipules and rachis of inflorescences grayish brown puberulent; branchlets sparsely tufted hairs, second-year branches glabrescent, with scattered small whitish lenticels. Stipules lanceolate, recurved, 3–6 × 1–3 mm, caducous. Petiole 4–8 mm, sparsely pubescent or glabrescent. Leaf blade elliptic or obovate elliptic, 8–15 × 4–6 cm, thickly papery, adaxially glabrous, abaxially with tight layers of yellowish brown thin-walled peltate trichomes, often grayish with age, without non-glandular trichomes, base cuneate to broadly cuneate, margin entire, apex cuspidate or acute; midvein adaxially raised or slightly flat; secondary veins 8–12 on each side of midvein. Male spikelets 8–12 cm long; male flowers solitary or in fascicles of 2–4, perianth 5(–6)-lobed, stamens 10(–12). Infructescences 5–10 cm long; rachis 3–5 mm thick, glabrous, sparsely lenticellate. Cupule globose, 6–7 cm in diameter, base stipitate, 5–7 mm long, inside brown appressed tomentose, wall ca. 1 mm thick, outside wall completely covered by spines; spines straight, 1–2 cm long, glabrescent, base connate in to tree-like branched bundles, 0.5–1 cm long, sparsely puberulent or glabrescent. Nut 1 per cupule, rounded and depressed on both sides, 1.4–1.7 × 2–2.7 cm, basal 2/3 part of the nut adnate to the cupule, the free part sparsely yellowish brown appressed tomentose.

Distribution and habitat: — C. grandicicatricata is known from two localities: one in Central Vietnam (Nghe An province, Thanh Chuong Protection Forest), near the border with Laos and another in North Vietnam (Phu Tho province, Xuan Son National Park). In Thanh Chuong Protection Forest, C. grandicicatricata grows in evergreen broad-leaved forest on the slope or valley of mountains and occurs commonly as a codominant together with some Lithocarpus (Fagaceae) and Dipterocarpaceae species, between 50– 400 m. In Xuan Son National Park, this species sparsely appears in evergreen broad-leaved forest on the valley of limestone mountains at the elevation of 400–500 m, and usually associates with some species such as C. choboensis Hickel & A. Camus (1928: 122), Caryodaphnopsis tonkinensis (Lecomte 1913: 107) Airy-Shaw (1940: 75), Saraca dives Pierre (1899: pl. 386B).

Conservation: —Populations of C. grandicicatricata have been conserved very well at Thanh Chuong Protection Forest and Xuan Son National Park. According to IUCN Red list Categories and Criteria (IUCN 2012), C. grandicicatricata should be considered as Data Deficient (DD) because of not having adequate information of biological and ecological characteristics and extent of the habitat of this species. Supplement research is needed.

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

Etymology: —The specific epithet refers to the nut having a big scar.

Paratypes: — VIETNAM. Nghe An: Thanh Chuong District, Thanh Chuong Protection Forest, 18º41.462′ N, 105º10.835′ E, 78 m, 28 August 2011, D. H . Vuong 2011082804 (IBSC!, VNF!); Phu Tho: Tan Son District, Xuan Son National Park, 21º07.947′ N, 104º57.178′ E, 459 m, 23 October 2012, D. H . Vuong 2012102302 (VNF!).

Similar species: —The species is similar to Castanopsis javanica (Blume 1824: 295) A. de Candolle in Hance (1863: 182), in leaf shape, leaf size, cupule base stipitate, spines densely covering the whole cupule surface, rounded and depressed nut. C. grandicicatricata differs mainly in its cupules 6–7 cm in diameter (vs. 2.5–5 cm), scar covering 2/3 of nut (vs. scar covering 1/4–1/3 of nut) and thickly papery leaf texture (vs. thickly leathery).

C. grandicicatricata also resembles C. mekongensis A. Camus (1938: 653). Both have big cupules (with ca. 6 cm in diameter), cupule outside wall completely covered by spines, base of spines connate into bundles and nut oblate. C. grandicicatricata is distinguished from the latter by its leaf blade 8–15 cm long (vs. 15–25 cm), secondary veins 8–12 pairs (vs. 12–16 pairs), abaxially glabrescent (vs. densely pubescent), cupule base stipitate (vs. sessile), cupule wall ca. 1 mm thick (vs. 2 mm thick), spines glabrescent (vs. pubescent) and scar covering 2/3 of nut (vs. scar covering 1/3 of nut).