Urophyllum pulchristipulum 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 : 107-110

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

( Figs 11 ; 12 )

Urophyllum pulchristipulum Yooprasert, Culham & Utteridge , sp. nov. is similar toU. schmidtii C.B.Clarke and U. pseudoschmidtii Yooprasert, Culham, Yahara,Tagane & Utteridge , sp. nov., but differs in its stipules, which are broadly subcordate, with conspicuous netted veins and abaxially glabrous, whereas in U. schmidtii , they arelinearoblong, have only inconspicuous netted veins and abaxially densely hairy. Its inflorescences are sessile umbellate rather than pedunculate umbellate as always found in U. schmidtii .

TYPE. — Cambodia. Ratanikiri [Ratanakiri] Province: Virachay [Virachey] National Park , Western slopes and ridge leading to Mt. Yak Kham , East of Ho Chi Minh trail, 48P. 756282: 1587299 [14°20’45.24”N, 107°22’34.25”E], 800-1100 m elev., 13.XII.2005, Thomas et al. 26 (♀) (holo-, E [ E00220453 ]! ; iso-, L [ L.2972067 ]!) .

ETYMOLOGY. — The specific epithet refers to its stipules which have beautiful subcordate shape and neatly arranged network venation.

DISTRIBUTION. — Cambodia: Ratanakiri Province. Endemic, to date only known from the type specimen from Virachey National Park ( Fig. 3 ).

HABITAT. — Mixed evergreen forest and bamboo thickets, on slope; elev. 800-1100 m.

PHENOLOGY. — Flower season is unknown. A specimen with fruits collected in December.

CONSERVATION STATUS. — Data deficient (DD). Because only one specimen of Urophyllum pulchristipulum Yooprasert, Culham & Utteridge , sp. nov. has been collected from Virachey National Park (IUCN category II) in Cambodia, it does not provide enough data to estimate EOO and AOO for this species. The species has a potential to be found within nearby National Parks including Chu Mom Ray (in Viêtnam, IUCN category II), Dong Ampham and Xe Pian National Protected Areas (In Laos PDR, both in IUCN category VI) where the habitat is similar. Further collections in the areas should be carried out to assess existence of the species.

DESCRIPTION

Shrub. Indumentum almost glabrous, hairy only on petiole ridges, stipule base and margin. Branches quadrate to terete; young shoots flattened, ridged. Stipules caducous, usually left only at shoot, subcordate, 9-11 mm long, 3-5 mm wide, appressed to the stem but not folded, abaxially glabrous, conspicuous netted veins in sicco. Leaves chartaceous, elliptic to oblong, 5.4-8.3 cm long, 1.3-2.2 cm wide, apex acuminate, base cuneate to obtuse; adaxially glabrous, abaxially sparsely hairy on veins, drying dull brown to dark green adaxially, dull light yellowish brown abaxially; secondary veins 7-8 pairs, festooned brochidodromous, angle decreasing basally; tertiary veins mixed percurrent, angle decreasing exmedially and increasing basally, obtuse angle to the midrib; petioles 3.7-5.3 mm long, canaliculate, adaxially densely hairy on ridges, abaxially glabrous. Inflorescence axillary, sessile umbellate, bracts lanceolate leafy-like, c. 1.9 mm long, only fruits bearing pistillate plant known. Fruits baccate, subglobose, 1.6-2.5 mm diam. in sicco; pedicel 1.4-1.9 mm; calyx lobes 5, persistent, 0.7-0.9 mm long.

REMARKS

Despite lacking flowers and staminate plants for Urophyllum pulchristipulum Yooprasert, Culham & Utteridge , sp. nov., it is unique by its subcordate stipules with the abaxial side glabrous, sessile umbellate inflorescence in pistillate plants and is only species recorded from north-eastern Cambodia (Ratanakiri Province) to date. The other Urophyllum species found in Cambodia is U. schmidtii recorded from eastern Thailand (Chanthaburi and Trat provinces) through southwestern Cambodia (Koh Kong and Kampong Speu provinces), which has linear-lanceolate stipules, abaxially densely hairy and a pedunculate umbellate inflorescence. An additional morphologically similar species isU. pseudoschmidtii Yooprasert, Culham, Yahara, Tagane & Utteridge , sp. nov., however the stipules also differ from U. pulchristipulum Yooprasert, Culham & Utteridge , sp. nov. in the same way as U. schmidtii .

Figures

FIG. 11. — Urophyllum pulchristipulum Yooprasert, Culham & Utteridge, sp. nov.: A, fruiting branch; B, stipule; C, petiole, adaxial view (C1), side view (C2); D, infructescence; E, abaxial leaf lamina. Drawn by Mahsarahka Rungkrajang. Drawn from Thomas et al. 26. Scale bars: A, 1 cm; B, C, 0.5 mm; D, E, 3 mm.

FIG. 12. — Holotype of Urophyllum pulchristipulum Yooprasert, Culham & Utteridge, sp. nov. Digitised image from Royal Botanic Garden Edinburgh (E), Specimen E00220453 (http://data.rbge.org.uk/herb/E00220453).

FIG. 3. — Occurrences of Urophyllum annamense (Pierre ex Pit.) Yooprasert, Culham & Utteridge, stat. nov. (), U. brochidodromum Yooprasert, Culham & Utteridge, sp. nov. (), U. pulchristipulum Yooprasert, Culham & Utteridge, sp. nov. () and U. pseudoschmidtii Yooprasert, Culham, Yahara, Tagane & Utteridge, sp. nov. ().