Quercus honbaensis Binh, Tagane & Yahara, 2018

Binh, Hoang Thi, Ngoc, Nguyen Van, Tagane, Shuichiro, Toyama, Hironori, Mase, Keiko, Mitsuyuki, Chika, Strijk, Joeri Sergej, Suyama, Yoshihisa & Yahara, Tetsukazu, 2018, A taxonomic study of Quercus langbianensis complex based on morphology and DNA barcodes of classic and next generation sequences, PhytoKeys 95, pp. 37-70 : 58-61

Quercus honbaensis Binh, Tagane & Yahara sp. nov. Fig. 12

Diagnosis.

Quercus honbaensis is distinguished from Q. langbianensis s. str. in having shorter petiole of 0.8-1 cm long (vs. 1-1.8 cm long), more secondary veins ((10-)14-16 pairs vs. 10-12 pairs) and obconical cupules (vs. cup-shaped).

Type.

VIETNAM. Khanh Hoa Province: Hon Ba Nature Reserve , evergreen forest along river, 12°07'22.79"N, 109°00'13.29"E, alt. 225 m, 24 Feb. 2014, Toyama H., Dang V Son., Tagane S., Fuse K., Yahara T., Nagamasu H., Hop Tran V1378 (holotype: KYO!; isotypes: FU!, VNM!) .

Description.

Tree, 12 m tall. Buds ovoid, ca. 3-4 mm high, ca. 2-3 mm in diam., scales in 4-6 rows, imbricate, ovate-triangular, ca. 1 × 1.5 mm, apex obtuse, margin yel lowish-brown ciliate, appressed hairy on both surfaces. Young twigs greyish-brown, 1-1.2 mm in diam., curly hairy, sometimes sulcate, old twigs greyish-brown, glabrous, lenticellate. Leaf blades lanceolate to oblanceolate, (3.6-)11-16.5 × (1.4-)2-5.2 cm, acute at apex, cuneate at base, margin regularly distinctly serrate in the upper 5/6-3/4(-2/3), glabrous on both surfaces; midrib slightly prominent adaxially, prominent abaxially, lateral veins (9-)10-14(-16) pairs, straight and running into the teeth of margin, slightly prominent adaxially, prominent abaxially, at an angle of 40-45 degrees from midrib, tertiary veins scalariform-reticulate, faintly visible on both surfaces; petioles 0.8-1 cm long, tomentose when young, soon glabrous. Male and female inflorescences not seen. Infructescences axillary, erect, rachis 0.5-1.4 cm long, 1-2 mm in diam., glabrous. Mature fruits 2-3.5 cm high (including cupule), usually 1 (or 2) per infructescence, sessile; cupules obconical, 1.4-1.6 cm high, 1.5-1.8 cm in diam., enclosing 1/3-1/2 of the nut, wall covered with densely whitish- to yellowish-brown hairs, bracts arranged in 6-8 rings, margin of the ring undulate; nut obovoid to ellipsoid, 2.3-2.8 cm high, 1.3-1.7 cm in diam., apex obtuse, sparsely hairy except densely appressed hairy around stylopodia and basal scar, stylopodia up to 3 mm long, basal scar 0.7-0.8 cm in diam., convex.

Phenology.

Fruiting specimens were collected in February.

Distribution and habitat.

VIETNAM. Khanh Hoa Province: Hon Ba Nature Reserve. This species is known only from the type locality. A few individuals were found in evergreen forest from 225-617 m elevation.

Additional specimens examined.

VIETNAM. Khanh Hoa Province: Hon Ba Nature Reserve, 12°06'33.41"N, 108°59'24.89"E, alt. 367 m, 22 July 2013, Tagane S., Yahara T., Nagamasu H., Fuse K., Toyama H., Tran H., Dang V.S., V744 (FU, VNM, the herbarium of Hon Ba NR); 12°06'39.77"N, 108°58'59.23"E, alt. 617 m, 22 Feb. 2014, Toyama H., Dang V.S., Tagane S., Fuse K., Yahara T., Nagamasu H., Tran H., Nguyen V.N., Nguyen Q. C., Do N.T., Ho N.P.H., V1200 (FU, VNM, the herbarium of Hon Ba NR); 12°06'31.2"N, 108°59'14.1"E, alt. 400 m, 13 July 2014, Tagane S., Kanemitsu H., Dang V.S., Tran H., Hanh N., Loi X.N., Thach N.D., Dinh N., Hieu P.N.H., V1548 (FU, VNM, the herbarium of Hon Ba NR); 12°07'22.79"N, 109°00'13.29"E, alt. 225 m, 15 July 2014, Tagane S., Kanemitsu H., Dang V.S., Tran H., Loi X.N., Thach N.D., Dinh N., Hieu P.N.H., V1662 (FU, VNM, the herbarium of Hon Ba NR).

Etymology.

The specific epithet " Quercus honbaensis " is derived from its type locality, Mt. Hon Ba.

Figures

Figure 12. Quercus honbaensis Binh, Tagane & Yahara. A Leafy twig B Infructescence and mature fruits, C, D Side view and base view of the cupule, respectively, E. Inside of cupule, F. Nut. Materials: A-F from Toyama et al. V 1378.