Figure 1. Flowers and fruits of Dendrokingstonia.
A, B, Dendrokingstonia gardneri: A, flower; B, fruit with two monocarps.
The genus Dendrokingstonia (Annonaceae) is taxonomically revised and palynologically studied. Three species are recognized, one of which, D. gardneri, is described as new to science. One new combination, D. acuminata, is made. The genus occurs from southern Thailand to Peninsular Malaysia and Sumatra. On the basis of macromorphology and pollen characters, it is considered to be related to Monocarpia. Both genera show a combination of macromorphological characters that is rare in the family, i.e. considerably enlarged stigmas, leaves with percurrent tertiary veins, a highly reduced number of carpels per flower and relatively large monocarps with a thick, hard wall. Scanning and transmission electron microscopy show that the pollen grains of Dendrokingstonia and Monocarpia are monosulcate monads with a columellate infratectum and a more or less bulging intine at the sulcus.
Keywords: new combination; new species; palynology; systematics; taxonomy
Dendrokingstonia gardneri Chaowasku, sp. nov. ( Figs 1A, B,)
Type: Thailand, Trang, Khao Banthat Wildlife Sanctuary, Ton Plew Waterfall, x.2006, in fruit, Gardner & Sidisunthorn ST 2575a (holotype L0298137!; isotypes BKF, K).
Dendrokingstoniae nervosae et D. acuminatae aliquantum diversa, floribus solitariis (vs. fasciculatis), toro elevato (vs. plano), sepalis connatis (vs. liberis), staminum multum plurimorum differt. Praeterea in D. gardneri petioli plerumque breviores, folii basis semper cuneata, versus obtusa ad rotundata in alioribus.
Distribution: Southern Thailand and Northern Peninsular Malaysia (Fig. 5).
Habitat, ecology and phenology: Occurring in undulating forests or in shady understorey of (primary) lowland (moist) evergreen forests; at base of limestone cliffs or on limestone tufa next to permanent waterfalls. Elevation: under 50 m to 130 m. Flowering specimens: collected in February and April. Fruiting specimens: collected in October, January and March.
Field notes: Bole straight, monopodial. Bark smooth or rugged, dark brown, greyish-green, pale grey or mid-grey, slash inner bark fibrous, yellow or brown, slash wood white or pale yellowish-white. Leaves glossy dark green above, paler green below, young leaves whitish. Flowers downturned, sepals yellow in open flowers, petals cream or dull brownish-yellow. Fruits pale brownish-yellow outside, pale yellow inside.
Etymology: Named after the chief collector (Simon Gardner) who kindly sent the interesting specimens to L for identification.
Figure 5. Distribution of Dendrokingstonia: D. acuminata (filled triangles); D. gardneri (filled squares); D. nervosa (filled circles).
A taxonomic revision and pollen morphology of the genus Dendrokingstonia (Annonaceae)