Madhuca kanchanaburiensis Chantar., P. Kunasit & Kladwong 2022, sp. nov.

Madhuca kanchanaburiensis Chantar., P.Kunasit & Kladwong, sp. nov. (Figs. 1–3)

Madhuca kanchanaburiensis is morphologically similar to M. malaccensis (Clarke 1882: 547) Lam (1925: 167) and M. punctata Fletcher (1937: 378) in leaf shape and the size of petioles and sepals, but differs from both species in the conspicuous (vs. vanishing) secondary veins at leaf margin, longer corolla (15–17 mm vs. 8–9 mm) and woolly filament (vs. hirsute in M. malaccensis and glabrous in M. punctata). In addition, M. kanchanaburiensis has longer pedicels (2.2–3.5 cm) and glabrous corolla and anther, whereas M. malaccensis has shorter pedicels (0.7–1 cm) and hairy corolla and anther. Madhuca kanchanaburiensis is also different from M. punctata by its acute or obtuse (vs. retuse) leaf apex, transverse (vs. reticulate) tertiary venation and fewer (18–20 vs. 28) stamens (see Table 1).

Type: — THAILAND, Kanchanaburi, Thong Pha Phum District, Wat Tha Khanun, ca. 120 m alt., 22 Jan. 2022, Chantaranothai, Kunasit & Kladwong 2022/1 (holotype KKU!, isotypes BKF!, QBG!, PSU!).

*Based on description of Chantaranothai (2014)

Tree ca. 20 m tall; stems whitish grey, cracked; branches greyish brown, whitish brown woolly when young. Leaves spirally tufted at the ends of branches; lamina chartaceous, obovate, elliptic or obovate-elliptic, 10–17 × 5–9 cm, apex acute or obtuse, base rounded or sometimes slightly oblique, glabrous adaxially, densely pale whitish brown woolly abaxially; midrib grooved adaxially near the lamina base and becoming raised at the middle part toward the apex, rounded abaxially; secondary veins 12–14(–16) pairs, conspicuous toward the margin; tertiary veins transverse; petioles 2.2–3 cm long, grooved at apex, rounded at base, whitish brown woolly; stipules linear, 5–7 × 1–1.5 mm long, glabrous adaxially, whitish brown woolly abaxially, caducous. Flowers 3–5 in axils of leaves or fallen leaves at the ends of branches; pedicels angular, 2.2–3.5 cm long, whitish brown woolly. Sepals 4, whitish brown woolly outside except for near the margin of the inner sepals, glabrous inside; outer sepals broadly ovate, 8–10 × 5–7 mm; inner sepals ovate, 7–9 × 5–6 mm. Corolla 15–17 mm long, glabrous; tube ca. 5 mm long; lobes 8–10, oblanceolate or oblong oblanceolate, the margin of the upper half involute, 10–12 × 4–5 mm. Stamens 18–20, 6–8 mm long; filament filiform, ca. 2 mm long, brownish woolly; anther sagittate, ca. 3 mm long, glabrous; connective appendages acuminate or oblong, 1.5–3 mm long. Ovary subglobose, 8–9-loculed, whitish hairy, glabrous when young; style 2–2.5 cm long, glabrous. Fruits subglobose or ellipsoid, ca. 2 by 1.5 cm, apex acuminate with style remnant, whitish-brown hairy, 1- seeded. Seeds ellipsoid but laterally flattened, ca. 12 × 9 × 2 mm, scar elliptic.

Thailand: —SOUTH-WESTERN: Kanchanaburi Province (Thong Pha Phum District).

Distribution: —Known only from the type locality.

Ecology: —On limestone mountain top, 120–275 m alt.

Vernacular: —Masang kan (มะซางกาญจน์); the Thai name is given by the authors. “Masang” means a kind of Madhuca and “kan” is a short name for Kanchanaburi Province.

Etymology: —The species is named after Kanchanaburi Province, Thailand where it occurs.

Provisional IUCN Conservation Assessment: —Four mature individuals of this species were collected from two populations in open areas on two different limestone mountain tops (Fig. 3) suggesting that this species is endemic to Kanchanaburi Province in the south-western floristic region of Thailand. Based on GeoCat (Bachman et al. 2011), this species has an Extent of Occurrence (EOO) of 0.014 km 2 and an Area of Occupancy (AOO) of 0.017 km 2 and meets the Critically Endangered criterion. However, five additional mature trees and many seedlings were found along two trails to the mountain tops that are the part of the Wat Tha Khanun temple property. Madhuca kanchanaburiensis grows on a limestone cliff, which is inaccessible from the footpath with a two-sided barrier. Furthermore, this temple is respected by the local community and tourists. As a result of growing in inaccessible areas on the temple property, both populations are highly protected from encroachment and human activities. Apart from the type locality, the authors suspected that this species might be distributed on another limestone mountain top which has not been further explored. Therefore, we propose its conservation status to be Data Deficient (DD) based on the IUCN Red List Categories (IUCN Standards and Petitions Committee, 2019).

Notes: —The young ovary of M. kanchanaburiensis is glabrous, but whitish hairs will develop during maturation at the fruiting stage (Fig. 2, E).

Additional specimens examined: — THAILAND. Kanchanaburi, Thong Pha Phum District, Wat Tha Khanun, ca. 275 m alt., 22 Jan. 2022, Chantaranothai, Kunasit & Kladwong 2022/3 (BKF, KKU, QBG); ibid., 11 Feb. 2022, Kunasit 158 (KKU); ibid., 11 February 2021, Kunasit 159 (KKU).