Urophyllum chinense Merr. & Chun subsp. latistipulum Yooprasert, Culham, Yahara & 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 : 104-107

Urophyllum chinense Merr. & Chun subsp. latistipulum Yooprasert, Culham, Yahara & Utteridge , subsp. nov.

( Figs 9 ; 10 )

Urophyllum chinense subsp. latistipulum Yooprasert, Culham, Yahara & Utteridge , subsp. nov. is similar to U. chinense subsp. chinense Merr. & Chun , but differs in its stipules, which are broadly ovate to elliptic, 4.4-7.6 mm wide and with hairs present only along the midline; whereas in U. chinense subsp. chinense , the stipules are linear-oblong to ligulate, 1.7-2.9 mm wide with hairs present all over. The subspecies also differs in its leaves which are abaxially glabrous to the naked eye and sparsely hairy under magnification, instead of conspicuously densely hairy, visible to the naked eye in U. chinense subsp. chinense .

TYPE. — Viêtnam. Lam Dong Province: Lac Duong District, Da Nhim Commune, Bidoup-Nui Ba NP, Trail next to Ranger station Dung Iar Gieng , 12°09’35.9”N, 108°32’10.1”E, 1621 m elev., 3.VI.2019, Yooprasert et al. VN 112-2 (♀) (holo-, HN! ; iso-, BKF!).

ADDITIONAL SPECIMENS EXAMINED. — Viêtnam. Lam Dong Province, 15 kilomètres au nord de Dankia [north of Dankia], Langbiang, 1500-1800 m elev., 27.X.1930, Poilane 18661 (♀) ( P [ P 04950968]!); Da Lat City, Rong Phon Forest, Suoivang, 1500 m elev., 1.I.1998, Wongprasert 981-15 (♀) ( BKF!); Da Tong, Bidoup Nui Ba NP, beside the road no. DT722, across a stream, 12°5’50.4”N, 108°22’36”E, 1711 m elev., 4.VI.2019, Yooprasert et al. VN 116-5 (♀) ( BKF!; K!); Dam Rong District, Da Long, Bidoup Nui Ba NP, beside the road to Ranger station Da Long, 12°9’21.5”N, 108°21’57.6”E, 1495 m elev., 2.VI.2019, Yooprasert et al. VN 105-1 (sterile) ( BKF!); Lac Duong District, Da Chay [Da Chais Commune], 29 km to NE from Dalat City, on main peak of Bi Dup mt. system, 12°5’N, 108°40’E, 2260 m elev., 21.III.1997, Averyanov et al. VH 2981 (♀) ( AAU!); 31 km NE of Dalat City, vinicities Klong Lanh village, NW macroslope of Bi Dup mt system, 12°8’N, 108°39’E, 1850-1950 m elev., 15.III.1997, Averyanov et al. VH 2651 (♀) ( AAU!); 20.III.1997, Averyanov et al. VH 2941 (♀) ( AAU!); 35 km to NE from Dalat City, W macroslope of Gia Rinh mt. ridge, 12°9’N, 108°41’E, 1800 m elev., 18.IV.1997, Averyanov et al. VH 4075 (♀) ( AAU!); Bidoup Nui Ba NP, 12°2’48.13”N, 108°26’6.67”E, 1918 m elev., 24.VI.2018, Tagane et al. V 8982 (sterile) ( DLU n.v.; FU!); Mt. Langbian, 12°2’46.3”N, 108°26’1.5”E, 1905 m elev., 25.III.2018, Yahara et al.V 7930 (sterile) ( FU!); Trail by Ranger Station Giang Ly, 12°8’44.6”N, 108°40’17.2”E, 1510 m elev., 1.VI.2019, Yooprasert et al. VN 102-7 (♀) ( BKF!); 12°8’48.3”N, 108°40’16.6”E, 1487 m elev., 1.VI.2019, Yooprasert et al. VN 100-1 (♀) ( BKF!; HN!); Trail opposite Ranger Station Giang Ly, crossing a stream, 12°10’47.5”N, 108°41’6.9”E, 1490 m elev., 1.VI.2019, Yooprasert et al. VN 96-1 (sterile) ( BKF!, HN!); Yooprasert et al. VN 96-2 (sterile) ( BKF!); Da Nhim Commune, Bidoup Nui Ba NP, Trail next to Ranger station Dung Iar Gieng [12°7’59.9”N, 108°39’1.9”E], 1439 m elev., 3.VI.2019, Yooprasert et al. VN 107-2 (sterile) ( BKF!); trail to Thac Thien Thai Waterfall, 12°8’41.4”N, 108°31’47.5”E, 1510 m elev., 31.V.2019, Yooprasert et al. VN 82-1 (sterile) ( BKF!) .

ETYMOLOGY. — The subspecific epithet derived from the stipule’s broader shape.

DISTRIBUTION. — Viêtnam. Endemic, to date only known from Lam Dong Province ( Fig. 6 ).

HABITAT. — Primary broadleaved evergreen montane forest and mixed evergreen deciduous forest and bamboo thickets, on slope; elev. 1400-2300 m.

PHENOLOGY. — Collected in flower in June and fruit all year around.

CONSERVATION STATUS. — Vulnerable (VU) B1ab(iii)+2ab(iii). The taxon is endemic and known from 18 collections within six locations in Lam Dong Province (c. 15 km radius). The estimated EOO (441 km 2) and AOO (44 km 2) are within the threshold for the Endangered (EN) category, however five locations are in Bidoup-Nui Ba National Park (IUCN category Ia) where the risk of extinction is low. Only one population in Rung Thong Da Lat Cultural and Historical Site has shown the slowly expanding urban and cultivation areas in the past 12 years on the Google Earth imagery, however the area is listed in IUCN category V where the land use can be balanced between human and nature. For these reasons, this endemic subspecies is rated as Vulnerable.

DESCRIPTION

Shrub or treelet to 7 m, almost glabrous. Branches terete; young shoots flattened, ridged. Stipules caducous usually left only at apex, ovate to elliptic 1.2-2.1 cm long, 0.44-0.76 cm wide, appressed to the stem but not folded, abaxially densely hairy along midline, conspicuous netted veins. Leaves chartaceous, rarely coriaceous, usually elliptic to oblong, rarely ovate to obovate, 10.0- 16.2 cm long, 3.3-6.4 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, dull (rarely shiny) yellowish green abaxially with yellow to brown veins; secondary veins 7-11 pairs, weakly to festooned brochidodromous; tertiary veins mixed percurrent, angle increasing basally, middle of the leaves subperpendicular to obtuse, veins diverging at angle of c. 89°-113° from the midrib; petioles [0.5-]0.7-1.4[-2.1] cm long, canaliculate. Inflorescence axillary, pedunculate to subsessile umbellate, peduncle [0.5-]2.2-7.6[-16.9] mm long, bracts triangular, densely hairy at base, c. 1 mm long, bearing 4-5 flowers in pistillate plant, nectary disk annular, only pistillate plant known. Pistillate flowers calyx fused, 1.0- 2.2 mm long, teeth to shallow lobes 5, 0.3-0.8 mm deep; corolla fused forming a tube at base approaching 1/3 their length, lobes 5, valvate, immature lobes c. 1.5 mm long, densely hairs at throat inside; staminodes 5, anthers without pollen; ovary cupuliform, locules 5; style c. 0.8 mm long in flower bud, sparsely scaly; stigma lobes 5, c. 0.8 mm long, covered with scales. Fruits baccate, subglobose, 5.1-5.8 mm diam. in sicco; calyx and disk persistent. Seed numerous, subelliptic, surface alveolate, orange brown in sicco.

REMARKS

Urophyllum chinense subsp. latistipulum Yooprasert, Culham, Yahara & Utteridge , subsp.nov. is sympatric with U. bidoupense Yooprasert, Culham & Utteridge , sp. nov. in Bidoup-Nui Ba National Park. They are morphologically similar being superficially glabrous in appearance, only sparsely hairy on the abaxial leaf surface under magnification. However, the taxon differs to U. bidoupense Yooprasert, Culham & Utteridge , sp. nov. by its stipules being hairy along the midline abaxially and usually chartaceous leaves drying dull abaxially instead of subglabrous stipules with hairs found only at apex and coriaceous leaves drying shiny abaxially found in U. bidoupense Yooprasert, Culham & Utteridge , sp. nov. Other taxa found in the area are as discussed in the Remarks to U. bidoupense Yooprasert, Culham & Utteridge , sp. nov., which are U. pseudoschmidtii Yooprasert, Culham, Yahara, Tagane & Utteridge , sp. nov. and U. lecomtei . The taxon differs from these taxa by its stipule hairy in the midline, while in the others stipule is hairy all around.

Figures

FIG. 9. — Urophyllum chinense Merr. & Chun subsp. latistipulum Yooprasert, Culham, Yahara & Utteridge, subsp. nov., illustration from pistillate plant: A, flowering branch; B, stem and stipule scar; C, stipule; D, abaxial leaf lamina; E, petiole, abaxial side (E1) and adaxial side (E2); F, inflorescence; G, flower bud; H, staminode; I, adaxial corolla showing staminodes and throat hairs arrangement; J, immature stigma positioning in a flower; K, fruit; L, seed. Drawn by Mahsarahka Rungkrajang. Drawn from Yooprasert et al. VN 112-2. Scale bars: A, 1 cm; B, C, E-G, K, 3 mm; D, 5 mm; H, L, 0.5 mm; I, J, 1 mm.

FIG. 10. — Isotype of Urophyllum chinense Merr. & Chun subsp. latistipulum Yooprasert, Culham, Yahara & Utteridge, subsp. 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. ().