Urophyllum bidoupense Yooprasert, Culham & Utteridge, 2022

Yooprasert, Sawita, Culham, Alastair, Tagane, Shuichiro, Yahara, Tetsukazu, Nguyen, Van Du, Nguyen, Khang Sinh & Utteridge, Timothy M. A., 2022, New species and new status of Urophyllum Wall. (Rubiaceae) from Cambodia and Viêtnam, Adansonia (3) 44 (11), pp. 91-114 : 98-101

Urophyllum bidoupense Yooprasert, Culham & Utteridge , sp. nov.

( Figs 4 ; 5 )

Urophyllum bidoupense Yooprasert, Culham & Utteridge , sp. nov. is similar to U. chinense subsp. chinense Merr. & Chun , but differs in: the stipules which are subglabrous abaxially, the hairs (if present) are only around the apex, and the leaves are glabrous to the naked eye and sparsely hairy with magnification. While U. chinense subsp. chinense has uniformly densely hairy stipules, and hairy leaves to the naked eye. It differs from U. chinense subsp. latistipulum Yooprasert, Culham, Yahara & Utteridge , subsp. nov., as the stipules have hairs along the midline from base to apex.

TYPE. — Viêtnam. Lam Dong Province, Lac Duong District, Bidoup-Nui Ba National Park , Trail by Ranger station Hon Giao, border to Son Thai, Khanh Vinh District, 12°11’14.3”N, 108°42’51.7”E, 1633 m elev., 1.VI.2019, Yooprasert et al. VN 91-1 (♀) (holo-, HN! ; iso-, BKF!) .

ADDITIONAL SPECIMENS EXAMINED. — Viêtnam. Khanh Hoa Province, Khanh Son District, 41 km to NE from Dalat city, E macroslope of Hon Giao mt. ridge, 12°11’N, 108°43’E, 1500-1600 m elev., 22.IV.1997, Averyanov et al.VH 4154 (♂) ( AAU!; HN!) ; Khanh Vinh District, Son Thai, 12°11’47.7”N, 108°43’33.2”E, 1518 m elev., 28.VI.2018, Tagane et al. V 9201 (♂) ( DLU n.v.; FU!; KAG!). — Lam Dong Province, Lac Duong District, Bidoup-Nui Ba NP, trail by Ranger Station Hon Giao, 12°11’11.8”N, 108°42’53.3”E, 1575 m elev., 1.VI.2019, Yooprasert et al. VN 85-3 (♂) ( BKF!; K!) ; 1651 m elev., 1.VI.2019, Yooprasert et al. VN 87-1 (♂) ( BKF!) ; Yooprasert et al. VN 87-3 (♂) ( BKF!) ; Yooprasert et al. VN 87-4 (♂) ( BKF!) ; municipality Da Chay [Da Chais Commune], 35 km to NE from Dalat City, W macroslope of Gia Rinh mt. ridge, 12°9’N, 108°41’E, 1700-1800 m elev., 18.IV.1997, Averyanov et al. VH 4059 (♀) ( AAU!, HN!) .

ETYMOLOGY. — The specific epithet refers to its type locality, Bidoup-Nui Ba National Park.

DISTRIBUTION. — Viêtnam: Lam Dong (Bidoup-Nui Ba National Park) and Khanh Hoa (Son Thai) Provinces ( Fig. 6 ).

HABITAT. — Primary broadleaved evergreen montane forest mixed with conifers in the Hon Giao mountain range; elev. 1500-1800 m.

PHENOLOGY. — Collected in flower and fruit from April to June.

CONSERVATION STATUS. — Least Concern (LC). Urophyllum bidoupense Yooprasert, Culham & Utteridge , sp. nov. is known from only two previous collected specimens within the area of Bidoup-Nui Ba National Park (IUCN category Ia) in 1997. The species was still found in the same locality in 2018 and 2019, close to the Hon Giao Ranger Station, where the habitat was observed to be undisturbed, and the species is common: the plot survey in Hon Giao by third and fourth authors recorded 108 individuals within 0.1 ha. Despite a small AOO (8 km 2), the species is not at risk, therefore it can be rated as Least Concern (LC).

DESCRIPTION

Shrub or treelet to 10 m high, 10 cm in DBH, almost glabrous. Branches terete; young shoots flattened, ridged. Stipules caducous, 1-2 nodes at shoot, oblong-lanceolate to elliptic, 1-2 cm long, 0.3-0.6 cm wide, appressed to the stem but not folded, abaxially glabrous to subglabrous, hairs present at around apex; conspicuous to inconspicuous netted veins. Leaves coriaceous, elliptic to obovate, 7-15 cm long, 3-5 cm wide, apex acuminate, base cuneate, adaxially glabrous, abaxially glabrous to the naked eye, sparsely hairy with short hairs <0.5 mm long under magnification, drying dull yellowish green to brown adaxially, usually shiny yellowish green abaxially with reddish-brown midrib; secondary veins [10]12-16 pairs, weaklybrochidodromous; tertiary veins mixed percurrent, angle increasing basally, middle of the leaves subperpendicular to obtuse, veins diverging at angle of c. 95°-110° to the midrib; petioles [0.8-] 1.1-1.7 cm long, canaliculate.Inflorescence axillary, pedunculated umbellate, peduncle 0.8-4.0 mm long, bract triangular with dense hairs at base and margin, 1-2 mm long, bearing 3-6 flowers in staminate plant, 3-4 flowers in pistillate plant; nectary disk annular, present in both sexes. Staminate flowers calyx fused, teeth 5, 1.1-1.6 mm long; corolla fused forming a tube at base approaching 1/3 their length, lobes 5, valvate, 2-4 mm long, densely hairs at throat inside; stamens 5, filament fused to the corolla tube, anthers 2-celled, dorsifixed, introrse; pistillode present, ovary vestigial. Pistillate flowers calyx fused, teeth to shallow lobes 5, 1- 2 mm long; corolla as staminate flowers; staminodes 5, anthers lacking pollen; ovary cupuliform, locules 5; style c. 2 mm long, sparsely scaly; stigma lobes 5 c. 0.5 mm long, covered with scales. Fruits baccate, subglobose, c. 3 mm diam. in sicco; calyx and disk persistent. Seed numerous, subelliptic, surface alveolate, orange brown in sicco.

REMARKS

Urophyllum bidoupense Yooprasert, Culham& Utteridge , sp.nov. is recognised by its abaxially glabrous to subglabrous stipules. Additional characters useful for identifying the species are coriaceous leaves, abaxially usually a shiny olive colour, glabrous to the naked eye but sparsely hairy under magnification, fruits glabrous, calyx persistent with small teeth to shallow lobes. Urophyllum bidoupense Yooprasert, Culham & Utteridge , sp. nov. is similar to U. chinense subsp. latistipulum Yooprasert, Culham, Yahara & Utteridge , subsp. nov. and their distribution overlaps within Bidoup-Nui Ba National Park.While U. chinense subsp. latistipulum Yooprasert,Culham,Yahara &Utteridge , subsp.nov. is widely distributed in the national park, U. bidoupense Yooprasert, Culham & Utteridge , sp. nov. is restricted to Hon Giao and its adjacent area. The main morphological character that differs between these two taxa are the stipule and leaf morphologies. In U. bidoupense Yooprasert, Culham & Utteridge , sp. nov., the stipules are subglabrous abaxially, hairs present only at apex with coriaceous leaves drying shiny abaxially, whereas the stipules of U. chinense subsp. latistipulum Yooprasert, Culham, Yahara & Utteridge , subsp.nov. are abaxially hairy along midline with leaves usually chartaceous drying dull abaxially. Other species found in the National Park and nearby area (Giang Ly and Iar Giang) are U. pseudoschmidtii Yooprasert, Culham, Yahara, Tagane & Utteridge , sp. nov. and U. lecomtei Pit. The distinguishing character of U. bidoupense Yooprasert, Culham & Utteridge , sp.nov. from these two species is stipules which are subglabrous abaxially, whereas the latter two have conspicuously hairy stipules.

Figures

FIG. 4. — Urophyllum bidoupense Yooprasert, Culham & Utteridge, sp. nov.: A, flowering branch; B, stipules; C, abaxial leaf lamina; D-J, pistillate plant: D, inflorescence; E, flower bud; F, staminode; G, immature stigma positioning in a flower; H, stigma; I, fruit; J, seed, top view (J1) and side view (J2); K-O, staminate plant:K, flower bud; L, stamen; M, corolla, adaxial side (M1) and abaxial side (M2); N, corolla opened out to show stamens and throat hairs arrangement; O, calyx and pistillode. Drawn by Mahsarahka Rungkrajang. Drawn from: A, H, I, Averyanov et al. VH 4154; B-G, O, Yooprasert et al. VN 91-1; J-N, Yooprasert et al. VN 87-1. Scale bars: A, 2 cm; B, 4 mm; C, 5 mm; D, 3 mm; E, G, I, K, M-O, 1 mm; F, H, J, L, 0.5 mm.

FIG. 5. — Isotype of Urophyllum bidoupense Yooprasert, Culham & Utteridge, sp. nov.

FIG. 6. — Occurrences of Urophyllum bidoupense Yooprasert, Culham & Utteridge, sp. nov. () and U. chinense Merr.& Chun subsp.latistipulum Yooprasert, Culham, Yahara & Utteridge, subsp. nov. ().