Polyalthia miliusifolia Wiya, Chanthamrong & Chaowasku, 2025

Wiya, Chattida, Damthongdee, Anissara, Chanthamrong, Kithisak, Ue-Aree, Phasit & Chaowasku, Tanawat, 2025, Uncovering five new species of Polyalthia (Annonaceae, Miliuseae) from Thailand: molecular and morphological congruence, European Journal of Taxonomy 1022, pp. 243-276 : 251-254

Polyalthia miliusifolia Wiya, Chanthamrong & Chaowasku sp. nov.

urn:lsid:ipni.org:names:77365545-1

Figs 1 , 4–5 , 12 ; Table 2

Diagnosis

Morphologically most similar to P. minima , but differs mainly from it in several features (indumentum on young twigs and lower leaf midrib, flowering pedicel length, outer petal shape and apex, number of carpels per flower and stigma shape) as shown in Table 2 .

Etymology

The leaves of the new species look somewhat similar to those of certain species of Miliusa Lesch. ex A.DC. (de Candolle 1832), e.g., M. astiana Chaowasku & Kessler ( Chaowasku & Kessler 2014), M. fragrans Chaowasku & Kessler ( Chaowasku & Kessler 2013), M. fusca Pierre ( Pierre 1881) and M. parvifolia (Kurz) Damth. & Chaowasku ( Damthongdee & Chaowasku 2022; basionym: Kurz 1875); hence, its specific epithet.

Type material

Holotype THAILAND • Cult. in Nakhon Si Thammarat Province (originally from Chalae Subdistrict, Thong Pha Phum District, Kanchanaburi Province); Jul. 2022; fl.; Chanthamrong 74; holotype: CMUB [ CMUB004000901 ] ; isotypes: PBM, QBG .

Paratypes THAILAND • same data as for holotype; Nov. 2020; fl.; Chaowasku 228; QBG • same data as for preceding; Nov. 2022; fl.; Chaowasku 233; QBG • same data as for preceding; Jul. 2023; fl.; Chanthamrong 75; QBG .

Description

Treelets ca 0.6 m tall; young twigs villous with appressed and erect hairs. Petiole 1.0–2.0 mm long, indumentum similar to that of young twigs, slightly grooved above; leaf blade chartaceous, elliptic, rarely elliptic-obovate, 3.7–7.5 × 1.4–2.6 cm, almost glabrous above, villous with appressed and erect hairs below, base obtuse-subcordate to rounded-subcordate, rarely obtuse, apex ±acute, rarely obtuse, rounded or caudately short-acuminate; midrib slightly sunken above, villous with erect hairs, raised below, villous with appressed and erect hairs; secondary veins 7–10 per side, rather indistinct below, angle with midrib 60°–70° (at middle part of leaf blade). Inflorescences 2- or 3-flowered, terminal; peduncle and rachis (when present) inconspicuous; pedicel 1.8–2.0 mm long, velvety with appressed and erect hairs, bearing 1 ovate-triangular bract. Sepals free, broadly ovate to ±transversely ovate, 1.0–1.2 × 1.1–1.8 mm, outside and margin velvety with appressed and erect hairs, inside glabrous. Outer petals broadly ovate to subcircular, 2.3–3.0 × 1.9–2.5 mm, outside tomentose with appressed hairs, margin tomentose with appressed and erect hairs, inside almost glabrous, apex obtuse to rounded; inner petals ±cream in vivo at maturity, ovate-elliptic to elliptic-oblong, 6.8–7.5 × 3.0– 3.5 mm, outside tomentose with appressed hairs, margin tomentose with mostly appressed hairs, inside almost glabrous, apex obtuse to rounded. Stamens ca 28 per flower, 1.0– 1.1 mm long, connective apex truncate, covering thecae. Carpels 3 per flower, ca 1.5 mm long; stigmas globose; ovaries tomentose with appressed hairs; ovule 1 per ovary, basal. Torus depressed subglobose. Fruit unknown.

Habitat (at original locality) and phenology

The new species occurs in dry evergreen forests, near a stream. The elevation (at original locality) is ca 450 m. Flowering material was collected in July and November.

Distribution

Kanchanaburi Province, southwestern Thailand.

Preliminary conservation assessment

Data Deficient (DD).

Figures

Fig. 1. Phylogram derived from Bayesian inference, with support values indicated: SR (maximum parsimony symmetric resampling values) / BS (maximum likelihood bootstrap values) / PP (posterior probabilities). ** = <50%. New species in bold. Scale bar unit: substitutions per site.

Fig. 4. Polyalthia miliusifolia Wiya, Chanthamrong & Chaowasku sp. nov.A. Flower, side view.B. Flower enlarged, side view, showing stamens surrounding carpels. C. Adaxial side of outer (left) and inner (right) petals. D. Stamen: adaxial (left) and abaxial (right) sides. E. Flower with petals and stamens removed, side view, showing carpels on torus. F. Flower with petals, stamens and carpels removed, bottom (left) and top (right) views. A–B, D–E from Chanthamrong 75 (QBG); C, F from Chaowasku 228 (QBG).

Fig. 5. Holotype of Polyalthia miliusifolia Wiya, Chanthamrong & Chaowasku sp. nov. (Chanthamrong 74; CMUB004000901).

Fig. 12. Distribution of Polyalthia chiangmaica Wiya, Damth. & Chaowasku sp. nov. (■), P. miliusifolia Wiya, Chanthamrong & Chaowasku sp. nov. (★), P. esanensis Wiya, Damth. & Chaowasku sp. nov. (●), P. acuminatissima Wiya, Damth. & Chaowasku sp. nov. (▲) and P. maxwelliana Wiya, Chanthamrong & Chaowasku sp. nov. (★). Note that (★) indicates a shared locality of both species.