Friesodielsia betongensis Leerat., 2023

Leeratiwong, Charan, Karapan, Sunate, Satthaphorn, Jiratthi & Johnson, David M., 2023, Two new species of Friesodielsia (Annonaceae) from Peninsular Thailand, Phytotaxa 589 (1), pp. 73-82 : 73-79

Friesodielsia betongensis Leerat. , sp. nov. (Figs 1,3,5)

Type:— THAILAND. Yala: Betong District, Hala-Bala Wildlife Sanctuary , 1000–1200 m elev., 22 May 2022, Leeratiwong 22-1854 (holotype: BKF; isotype: PSU).

The new species is similar to Friesodielsia alpina but differs in having hairy twigs (vs. glabrous), leaves with hairs covering the abaxial surface (vs with hairs only midrib), glabrous pedicels (vs. hairy), shorter bracts (1.5–3.0 mm vs. ca. 4.0 mm), sepals with an obtuse (vs. acute) apex, longer inner petals (10.0–17.0 mm vs 7.0 mm) that are greater than half the length of the outer petals (vs. less than half the length of the outer petals) and hairy monocarps (vs. glabrous) with longer stipes (5.0–7.0 mm vs. ca. 4.0 mm).

Woody climbers and scandent shrubs up to 10 m high. Twigs with dense, brown erect pubescence, becoming subglabrate. Leaves not glaucous below, narrowly oblanceolate, elliptic-oblanceolate or lanceolate, blades 7–15 Í 2–4 cm, base rounded, apex acute to acuminate, acumen 3–8 mm long, glabrate above, with denser hairs on midrib, moderately to sparsely appressed-pubescent below, secondary veins 9–12 per side; petioles 4–7 mm long, flattened above with dense, brown pubescence. Inflorescences supra-axillary to leaf-opposed or terminal, 1(–2)-flowered, pedicel 25–30 mm long, densely pubescent, with a lanceolate bract 1.5–3.0 mm long, attached at or just below the pedicel midpoint. Sepals 3, green, valvate, basally connate, coriaceous, broadly ovate, 2.5–4.5 Í 2.5–5.0 mm, apex obtuse, venation not evident, densely pubescent outside, glabrous except hairy just inside the edge. Petals in two whorls of 3, yellowish cream with pale green base, valvate, free; outer petals appressed in bud, spreading widely at maturity, lanceolate to ovate-lanceolate, 15.0–23.0 Í 4.0– 10.5 mm, triquetrous near apex, obtuse, slightly concave on inner base, finely pubescent outside, sparsely hairy and glabrous at base inside; inner petals erect and coherent at margins for about half of their length apically, lanceolate, 10.0–17.0 Í 3.5–6.5 mm, obtuse to acute, sparsely hairy outside, glabrous inside. Stamens clavate, 1.2–1.6 mm long, anther dehiscence extrorse, apex of anther connective convex. Carpels 40–60, oblong, 1.2–2.0 mm long, densely pubescent, stigmas falcate-capitate, cleft down the side. Fruits of 1–3 monocarps, pedicels 30–35 mm long, with persistent bracts and deciduous sepals. Monocarps green (mature not seen), ellipsoid to ellipsoid-oblongoid, 12–15 Í 7–9 mm, smooth, pubescent, apex apiculate, 0.5–1.5 mm long, stipe 5.0–7.0 Í 2.0– 2.5 mm. Seeds 1 per monocarp, attached basally, broadly ellipsoid, 10–12 Í 6–8 mm, endosperm rumination lamellate.

Distribution and ecology:— Yala Province, Peninsular Thailand ( Fig. 5 ), on hill edges in evergreen forest, 1000– 1200 m elevation.

Phenology:— Flowering and fruiting in May.

Local name:— Bu nga soeng betong (Thai).

Etymology:— From the Betong District, Yala Province.

Conservation status:— This species is known only from gatherings in 2022, when it was collected from the narrow range of hills in evergreen forest, Hala-Bala Wildlife Sanctuary. The forest is well protected, however, and the larger part of it is still unexplored. To clarify the number of individuals/populations and the full distribution, further field studies are needed. Therefore, we have preliminarily assessed the species as data deficient (DD, IUCN Red List Criteria 2019).

Notes:— Friesodielsia betongensis is characterised by its densely erect-hairy stems, long pedicels (25–30 mm), flowers with pale green petal bases, triquetrous outer petals and inner petals longer than half the length of outer petals. This species is one of only two Thai Friesodielsia species occurring at elevations above 900 metres.

Figures

FIGURE 5. Distribution of Friesodielsia betongensis (●) and F. chalermglinii (▲) in Thailand. The map and marked locations were constructed in Rstudio v.3.6.3 (R Core Team, 2020) using ggplots package (Wickham, 2016) and its dependencies.