Polyalthia evecta

Bunchalee, Pasakorn, Leeratiwong, Charan & Sinbumroong, Aroon, 2025, Polyalthia khaosokense (Annonaceae), a new species from Peninsular Thailand with a key to the Polyalthia evecta species complex, Phytotaxa 683 (2), pp. 184-188 : 187

Key to Polyalthia evecta complex in Thailand

The P. evecta complex is characterized by their inflorescences: leaf-opposed, supra-axillary, internodal (Bunchalee, 2019), terminal or cauliflorous. The leaves base is unequal, ranging from subcordate to cordate. The inflorescences bear complete flowers with thick outer and inner tepals, but the inner larger than the outer tepals, and truncate apices on the anther connective (Bunchalee et al., 2021). The pollen grains are ovoid to subovoid (Bunchalee, 2019).

1. Inner tepals subequal or less than two times longer than outer tepals

- Inner tepals two times or more longer than outer tepals ...................................................................................................................2.

2. Leaf apex retuse, obtuse, acute, or slightly acuminate; inner tepals 6‒8 mm long.............................................................................. ........................................................................................................................... P. intermedia ( Pierre, 1881: t. 31A) Bân (2000: 95)

- Leaf apex acuminate or cuspidate; inner tepals 8‒15(‒18) mm long................................................................................................3.

3. Outer tepals 2.0‒ 2.5 mm long; primary leaf vein flattened on upper surface ...................................................................................... ................................................................................. P. chantaranothaii Bunchalee & Chalermglin in Bunchalee et al. (2021: 276)

- Outer petals 3.0‒6.0 mm long; primary leaf vein grooved on upper surface....................................................................................4.

4. Leaf oblong to narrowly elliptic, apex cuspidate; inflorescences terminal; pedicels 8.0‒10.0 mm long, 1.5‒1.8 mm diam .............. ..................................................................................................................................................................................... P. khaosokense

- Leaf elliptic, oblanceolate or rarely lanceolate, apex acuminate or acute; inflorescences leaf-opposed, supra-axillary, terminal or cauliflorous; pedicels 3.0‒8.0 mm long, 0.3‒1.0 mm diam ..............................................................................................................5.

5. Outer tepals 3.0‒ 3.5 mm long; pedicels 5.0‒8.0 mm long, 0.3‒0.5 mm diam.; leaf elliptic or rarely lanceolate to oblanceolate ...... ........................................................................................................................ P. kanchanaburiana Khumch. & Thongp. (2005: 35)

- Outer tepals 4.0‒6.0 mm long; pedicels 3.0‒5.0 mm long, 0.8‒1.0 mm diam.; leaf oblanceolate ...................................................... ............................................................................................................................ P. khaoyaiensis Bunchalee & Chantar. (2019: 171)