Winitia thailandana Chaowasku & Aongyong 2020, sp. nov.

Winitia thailandana Chaowasku & Aongyong sp. nov.

urn:lsid:ipni.org:names:77209778-1

Figs 4–6

Diagnosis

Morphologically similar to Winitia expansa, differs by having a non-glaucous appearance on the petal adaxial surface (glaucous in W. expansa) and shallow pits on the adaxial surface of the inner petals (no pitted structures in W. expansa). Moreover, its inflorescences are mostly clustered on large roots and at the unswollen base of trunks, whereas the inflorescences of W. expansa are mostly clustered at the swollen base of trunks.

Etymology

Named after Thailand, a country where this species is endemic.

Type material

Holotype

THAILAND • Surat Thani Prov., Phanom Distr.; 8 May 2017; fl; Aongyong 9; holotype: CMUB; isotypes: G, P.

Paratypes

THAILAND • Surat Thani Province, Phanom District; fl; Chaowasku 51; CMUB • Khlong Phanom National Park; fl; Gardner & Sidisunthorn ST0817; L.

Description

Medium-sized trees 12–14 m tall, dbh ca 27 cm. Young twigs glabrous. Petiole 6–8 mm long, grooved on upper surface, glabrous on both surfaces; leaf blade elliptic to slightly ovate, 13–17.8 × 3.7–5.8 cm, glabrous on both surfaces, in young leaves numerous black dots present on lower surface, base broadly cuneate to obtuse, apex acute-acuminate to acuminate; midrib raised and glabrous on both surfaces, in young leaves numerous black dots present on lower surface; secondary veins 8–10 per side, rather prominent on lower surface and forming loops, angle with midrib 50°–60° (at middle part of leaf blade). Flowers fasciculate, mostly clustered on large roots and at unswollen base of trunks, up to 3 flowers per fascicle, possibly unisexual [only male flowers found]; peduncle when present inconspicuous; pedicel 7–15 mm long, appressed-puberulous, bracts 2(–3), triangular, placed at base, sometimes a bit higher for upper one. Sepals basally connate, triangular-ovate to broadly triangular-ovate, 4.5–5.1 × 3–5 mm, outside appressed-puberulous, inside and margin glabrous. Outer petals ovate to broadly ovate, 10–11 × 9–10 mm, indumentum similar to sepals, outside with scattered warts, inside non-glaucous, apex between acute and obtuse; inner petals elliptic, 9–10 × 6 mm, glabrous on both sides and margin, inside non-glaucous and with shallow pits, apex obtuse to rounded. Torus elongated hemispherical in male flowers, glabrous. Stamens 32–39 per male flower, 1.8–2 mm long, tightly packed, each not bending inward, connective apex ± truncate, not covering thecae; female flowers not found. Monocarps unknown.

Distribution, habitat, and phenology

Surat Thani Province, Phanom District (Fig. 6); occurs in evergreen forests among rugged limestone outcrops; at an elevation of ca 400 m; flowering material collected in May and June.

Field notes

Flowers orange-pink.

Notes

The new species is so far known only from Phanom District. We observed only three individuals, which occur among limestone outcrops beside a trail surrounded by a rubber tree plantation. In Khlong Phanom National Park where this species has also been reported (Gardner et al. 2015) less than ten individuals were found (pers. comm., S. Gardner). Based on our observations and estimations, we believe at least the category “endangered: EN D” (IUCN 2012) is applicable.

Key to genera in the sageraeoid clade

1. Plants bisexual or monoecious. Leaf midrib sunken on adaxial side, leaf venation (especially secondary veins) generally indistinct .............................................. Sageraea Dalzell (Dalzell 1851)

– Plants monoecious. Leaf midrib raised on adaxial side, leaf venation (especially secondary veins) distinct ............................................................................................................................................... 2

2. Flowers dimorphic (in the same individual male flowers smaller with shorter pedicels, female flowers larger with longer pedicels); male and female flowers allocated spatially differently (male flowers ramiflorous, female flowers cauliflorous); petals greenish yellow to cream at maturity, each stigma bilobed (± heart-shaped), torus conical-cylindrical to cylindrical in male flowers; monocarps light brown at maturity ................ Stelechocarpus Hook. f. & Thomson (Hooker & Thomson 1855)

– Flowers monomorphic; male and female flowers intermixed and clustered along trunks, at swollen or unswollen base of trunks, and/or on large roots; petals ± rose-colored at maturity, each stigma with multiple (Ż 5) columnar lobes, torus ± hemispherical in male flowers; monocarps ± blackish brown at maturity ........................................................ Winitia Chaowasku (Chaowasku et al. 2013)