Friesodielsia chalermgliniana 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 : 79-80

Friesodielsia chalermgliniana Leerat. , sp. nov. (Figs 2,4,5)

Type: — THAILAND. Yala: Betong District, Hala-Bala Wildlife Sanctuary , ca. 500 m elev., 27 May 2022, Leeratiwong 22-1855 (holotype: BKF; isotype: PSU) .

The new species is most similar to F. affinis , but differs in its sparsely pubescent stem, abaxially shiny leaves (vs abaxially glaucous leaves), longer flower pedicels (10–15 mm vs. 6–10 mm), broadly ovate bracts, 5–8 mm (vs. cordate to reniform, 5–11.2 mm long), shorter sepals (7–11.0 mm vs. 10–12 mm) with 5–7 indistinct veins (vs. distinctly 5-veins), outer petals without a raised midrib on the abaxial surface and a greater number of carpels (ca. 30 vs. 7–15).

This species also resembles Friesodielsia biglandulosa but is distinguished by its abaxially not golden-pubescent (vs. golden-pubescent) leaves, the broadly ovate bract 5.0–8.0 mm long (vs. 1.5–4.0 mm and linear), ovate sepals 5.0–10.0 mm wide (vs. lanceolate sepals 2.0– 4.5 mm), longer outer petals (35.0–57.0 mm vs. 25.0–32.0 mm) widest at base (vs. widest at midpoint), larger inner petals (23.0–31.0 Í 4.5–7.0 mm vs 5.0–11.0 Í 3.5–4.5 mm), which are lanceolate and greater than half the length of outer petals (vs. ovate and less than half the length of outer petals) and a hairy stigma (vs. glabrous).

Woody climbers up to 15 m high. Twigs with sparse, brown, appressed pubescence, becoming glabrate. Leaves shiny below, broadly oblanceolate, oblong-oblanceolate or obovate, blades 12–24 Í 6–10 cm, base rounded, rarely broadly cuneate, apex obtuse or acute to acuminate, acumen 3–15 mm long, glabrous except sparsely pubescent on adaxial midrib, appressed-pubescent abaxially, midrib sunken above, secondary veins 8–16 per side; petioles 6–13 mm long, sunken above, sparsely brown-pubescent to subglabrous. Inflorescences internodal to leaf-opposed, 1- or 2-flowered, pedicel 10–15 mm long, densely short-pubescent, bract broadly ovate, 5–8 mm long, attached at or just below the pedicel midpoint, pubescent. Sepals 3, green, valvate, basally connate, ovate, 7.0–11.0 Í 5–1.0 mm, apex acute-obtuse, 5–7-veined, the veins obscure, densely pubescent abaxially, sparsely hairy and glabrous at base adaxially. Petals in two whorls of 3, yellow, valvate, free; outer petals appressed in bud, slightly spreading at maturity, narrowly lanceolate to linear-lanceolate, 35.0–57.0 Í 5.0–11.0 mm, widest basally, triquetrous apically, narrowly obtuse, concave on inner base, finely pubescent abaxially, glabrous, except sparsely pubescent at edge inside; inner petals erect, and coherent apically for about half of their length, narrowly lanceolate, 23.0–31.0 Í 4.5–7.0 mm, narrowly obtuse to slightly acute, sparsely hairy outside, glabrous inside. Stamens clavate, 1.3–2.0 mm long, anther dehiscence extrorse, apex of anther connective flattened, slightly oblique. Carpels ca. 30, oblong to elliptic-oblong, 1.3–1.8 mm long, densely pubescent, stigmas falcate-capitate, cleft down the side, hairy. Fruit and seed unknown.

Distribution and ecology:— Endemic to Yala and Narathiwat Provinces ( Fig. 5 ), in shaded areas of tropical rain forest, ca. 500 m elev.

Phenology:— Flowering April and May.

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

Etymology:— In honour of Piya Chalermglin for his outstanding contributions to the taxonomy of Annonaceae in Thailand.

Conservation status:— This species is currently known only from two collections in the tropical rain forest in the Hala-Bala Wildlife Sanctuary. It has a small population with few (<50) individuals in the natural habitat (area of occupancy <10 km 2), which makes it critically endangered (CR, B2a + b(ii, iii)+C2ai+D, IUCN 2012). Although this area was formerly well-protected, it is near agricultural areas, mainly rubber plantations. This may affect the area of occupancy of the species because of agricultural expansion.

Additional specimen examined:— THAILAND. Narathiwat, Waeng , 16 Apr 1972, Sangkhanchand et al. 1040 (BKF) .

Notes:— The distinctive characters of F. chalermgliniana are broadly ovate bracts, flowers with triquetrous outer petals and inner petals longer than the half length of outer petals.

Both new species belong to a species group within Friesodielsia marked by apically triquetrous outer petals pressed together until the flowers are near anthesis ( Leeratiwong et al. 2021). The two new species raise Thai Friesodielsia species diversity to 18.

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.