Lasianthus ranongensis (Rubiaceae), a new species from Andaman tropical rainforest Thailand.

We describe Lasianthus ranongensis Sinbumr. & Napiroon as a new species in the genus Lasianthus. The new taxon is intensively discussed through taxonomic affinities and information on its habitat, distribution and conservation status is provided. Moreover, line drawings and stereo microscope images of important fertile organs are demonstrated. The new species is morphologically similar to L. stipularis but differs in its having flattened branches (vs. terete), leaf blade elliptic-oblong shape of 15.0-20.0 × 4.0-6.0 cm (vs. oblanceolate-oblong 12.0-16.0 × 3.0-5.5 cm), 9-12 pairs of veins (vs. 9-10 pairs), stipule 5-7 mm long, half covering cymes (vs. 10-12.5 mm long, entirely covering cymes), four or five bracts narrowly lanceolate, 2.5-3.0 mm long (vs. bracts numerous, broadly triangular, 10-15 mm), flowers with cupular calyx (vs. with campanulate calyx), corolla villous on internal surface, and six or seven lobed (vs. pubescent on internal surface and four lobed) and drupes with five pyrenes (vs. with four pyrenes). It is also similar to L. pseudo-stipularis, but from which it is obviously distinguished by its stipule half covers cymes, secondary veins have 9-12 pairs of secondary veins, cupular calyx shape, six or seven lobed corolla, and drupe with five pyrenes, whereas L. pseudo-stipularis has stipule entirely covering cymes, 7-8 pairs of secondary veins, obconic calyx, four lobed corolla, and drupe with four pyrenes.

Updated description of Diospyrosdussaudii Lecomte (Ebenaceae), with lectotypification and notes on its distribution.

Diospyrosdussaudii is a poorly known species and previous descriptions lacked details about its female flowers and fruits. The species had not been recorded since type collections were made in 1913. As a result of our Diospyros research in Thailand, new specimens and data are now available for this species. In this study, we provide an updated morphological description, illustrations, lectotypification and a distribution map. The species was previously reported to be endemic to Laos; as such, the occurrences in Thailand greatly expand the distribution of the species. In addition, we analysed the phylogenetic relationships between D.dussaudii and other Diospyros species from Southeast Asia and other regions, using DNA sequence data from eight plastid regions. Our phylogenetic analyses indicate that D.dussaudii is closely related to D.castanea, D.dasyphylla and D.insidiosa. Their taxonomic affinities are discussed.