Polygala tamdaoensis H.V.Lai & T.V.Do, 2025

Lai, Hung Viet, Do, Truong Van, Ito, Yu, Dang, Tu Minh, Nguyen, Hieu Van, Pham, Huyen Thanh, Nguyen, Nga Quynh & Phan, Truong Van, 2025, Polygala tamdaoensis (Polygalaceae), a new species from northern Vietnam, Phytotaxa 698 (1), pp. 28-34 : 29-32

publication ID	https://doi.org/10.11646/phytotaxa.698.1.3
persistent identifier	https://treatment.plazi.org/id/03EE87BE-7C2E-8C43-FF16-720EFD979640
treatment provided by	Felipe
scientific name	Polygala tamdaoensis H.V.Lai & T.V.Do
status	sp. nov.

Treatment

Polygala tamdaoensis H.V.Lai & T.V.Do View in CoL , sp. nov. ( Figs. 1 View FIGURE 1 & 2 View FIGURE 2 )

The new species is most similar to P. tricholopha , by sharing lanceolate to ovate leaf blade, yellow petals, and reniform-shaped capsules with broad wings, but it clearly differs from the latter by morphological characters of habit (erect shrub vs. small woody climber), inside of petals (glabrous vs. bunched villose at base), outer sepals (boat-shaped vs. helmet-shaped), appendage (not stalk vs. stalk ca. 2 mm), stamens (united to lower 3/4 vs. lower 3/5), and strophiole (2 small and 2 larger wings vs. helmet-shaped).

Type: — VIETNAM. Vinh Phuc province, Tam Dao National Park , elev. 834 m a.s.l., 16 March 2024, Lai Viet Hung HV 25 (holotype NIMM; isotypes HN, NIMM) .

Shrubs, up to 1.2 m tall. Stems glabrous, grey to green or purple. Petioles up to 15 mm long, glabrous, groove on the adaxially. Leaf blade lanceolate to ovate, 6–8 × 2.5–3 cm, base attenuate to cuneate, apex acute or attenuate, both surfaces glabrescent, margin entire; midvein raised abaxially, slightly indented on adaxially, lateral veins 5–7 pairs, anastomosing near the leaf margin. Inflorescences racemose, terminal or axillary, and puberulent. Pedicel ca. 3 mm long, pubescent. Flowers up to 19 mm long. Sepals 5, irregular; outer sepals 3, purple, ciliate at the margin; upper outer sepal boat-shaped, shallow, 5–7 mm long, and hairy at the tip; while lateral outer sepals reniform, ca. 3 × 5 mm; inner sepals 2, purple, petaloid, elliptic, ca. 15 × 8 mm, much veined, apex acute. Petals 3, connate in lower 2/3, yellowish white; lateral petals obliquely oblong, ca. 17 mm long, hairless on the inside, and with an obtuse apex. Keel cucullate, apex with an appendage, not stalked, two pieces cristate with 3–4 lobed. Stamens 8; filaments ca. 17 mm long, lower 3/4 united, forming an open staminal sheath. Anthers ovoid. Disk annular. Ovary ovoid, ca. 2 mm in diam., narrowly winged and glabrous; style ca. 8 mm long, upward gradually thickened. Capsules reniform, ca. 8 mm in diam., broadly winged. Seeds ovate, black, covered by scattered puberulent; strophiole with each two small and large wings.

Etymology: —The specific epithet refers to the name of the type locality, Tam Dao National Park, northern Vietnam.

Phenology: —Flowering and fruiting were observed in 2024 from February to May and from April to August at the type locality.

Distribution and ecology: — Polygala tamdaoensis grows on humid areas under evergreen forests at elevation of ca. 834 m a.s.l., together with some dominant species such as: Asarum petelotii O.C. Schmidt , Gardenia augusta (L.) Merr., Lasianthus japonicus Miq. , Lasianthus henryi Levl. , Litsea cubeba (Lour.) Pers ..

Conservation status:—No populations except the type locality in Tam Dao National Park, Vinh Phuc Province, northern Vietnam, are known for Polygala tamdaoensis . Here we propose the conservation status assessment of P. tamdaoensis according to IUCN (2024) as Data Deficient (DD). In fact, newly described species can be attributed to very different IUCN categories, such as CR ( Wagensommer et al. 2014, El Zein & Bottcher 2024), EN ( Brullo et al. 2015, Ben Mahmoud et al. 2024), VU ( Swanepoel et al. 2021), NT ( Perrino et al. 2018), LC ( Siti-Munirah & Dome 2023), DD ( Chinchilla 2020). Therefore, further field survey in the similar habitats in northern Vietnam is necessary for the correct attribution of IUCN category, because it may reveal additional populations of P. tamdaoensis . Note that the type locality of P. tamdaoensis is currently threatened by the loss of its natural habitat, so that urgent conservation plans must be taken to conserve its natural environment.

Notes:— Polygala tamdaoensis is morphologically closely related to P. tricholopha by sharing a winged reniform capsule, hairy seeds, and pericarp with annular ribs, but is distinguished by the erect habit, the longer and glabrous inner petals, the boat-shaped outer sepals, the not stalked appendages, the stamens united in lower 3/4, and the winged strophiole ( Table 1). The new species also resembles P.tonkinensis and P. saxicola by sharing a shrub habit and racemose inflorescences but differs from the former in the branches (densely pubescent in P. tamdaoensis and glabrescent when young in P. tonkinensis ), the number of venation (5–7 pairs in P. tamdaoensis , 10–15 in P. tonkinensis ), the length of petiole (up to 15 mm long and glabrous in P. tamdaoensis and up to 30 mm long and hairless in P. tonkinensis ), the shape of the outer sepals (boat-shaped in P. tamdaoensis and helmet-shaped in P. tonkinensis ), the shape of inner petals (glabrous in P. tamdaoensis and bunched villose at base in P. tonkinensis ), appendages (not stalked in P. tamdaoensis and stalked in P. tonkinensis ), and the shape of strophiole (winged in P. tamdaoensis and with 3 apically projecting lobes in P. tonkinensis ) and from the latter in the habit (erect shrub in P. tamdaoensis and shrub in P. tamdaoensis ), the length of petiole (up to 15 mm long and glabrous in P. tamdaoensis and up to 3 mm long and glabrous to hairy in P. saxicola ), the inner petals (up to 1.7 mm in P. tamdaoensis and up to 6.5 mm long in P. saxicola ). The new species is morphological similar to P. karensium Kurz. (1872: 392) but clearly different from the latter by characters of root (woody in P. tamdaoensis and storage in P. karensium ), indumentum of branches (densely pubescent in P. tamdaoensis and glabrescent in P. karensium ), and strophiole (winged with two smalland two large wings in P. tamdaoensis and irregularly lobed in P. karensium ) ( Table 1).