Based on molecular and morphological data a new species of Breynia , B. aberrans , is described from Kaeng Krachan National Park (SW Thailand), along the Thai border with Myanmar. An earlier published phylogenetic reconstruction of two nuclear (ITS, PHYC ) and three chloroplast markers ( matK, accD-psaI, trnS-trnG ) placed the new species in Breynia subgenus Sauropus . Typical are the asperities along the branches on one side, the shape of the leaf blades and the pistillate flowers with a long-ovoid ovary ending in a sturdy style and three upright stigmas. This type of pistillate flower is rather unique within Breynia and almost certainly not pollinated by Epicephala moths.
The leaf anatomy of eight (generally informal) groups of Macaranga and Ptychopyxis ( Euphorbiaceae , Acalyphoideae ) was studied based on 79 species (plus various infraspecific taxa) represented by 123 collections. All species showed abaxial, paracytic stomata (perhaps an exception for M . javanica ), a dorsiventral mesophyll, extra-floral nectaries on the leaf surfaces, collateral bundles and druse-like crystals. All Macaranga species showed disc-shaped glandular hairs, a character shared with its sister genus Mallotus, bundle sheet extensions, a generally local hypodermis and quite often papillae, present in various sizes and often concentrated around the disc-shaped glandular hairs that are sunken in cavities shielding the stomata. Some Macaranga species show fibriform sclereids, which are much more abundant in Ptychopyxis . Ptychopyxis has a much higher number of (unhidden) stomata than Macaranga and the bundle sheet extensions and hypodermis were not observed. Cuticular macerations were difficult to make in all specimens as the cuticles were very thin. Transverse sections sometimes failed, especially in Ptychopyxis , due to abaxially extending nerves and thin in between mesophyll.
Aporosa leaves, when dried, generally have small depressions or pits on the upper surface that probably do not occur when the leaves are still fresh. The presence of these pits form a good identification tool to recognize the genus Aporosa . An anatomical relation is made between the pits and the presence of adaxial epidermal mucilage cells. The mucilage cells are also present in the abaxial epidermal layer, but there they are smaller and do not show as pits. The pits are seemingly depressions caused by epidermal cells partly overlying the slightly sunken top cell of the mucilage cells and leaving a kind of hollow. However, in SEM scans the mucilage cells seem to be elevated, which might be due to the vacuum conditions of the SEM or the preparation of the SEM material. The mucilage cells also occur in Baccaurea , part of the sister group of Aporosa , but there the pits are not visible in dried leaves. The negative correlation between the size of the pits and their number (fewer and larger in Aporosa , more and often smaller in Baccaurea ) probably explains why the pits are visible in dried leaves of many Aporosa species only. There is a slight difference between both genera in the presence of druses; large ones are present in mainly Aporosa species, and larger quantities mainly in Baccaurea species.
Based on the molecular phylogenetic analyses of six plastid DNA regions ( mat K and rbc L exons; trn L intron; atp B- rbc L, psb A- trn H and trn L- trn F intergenic spacers) and including 57 samples of Pseuduvaria , as well as thorough morphological studies, Pseuduvaria sirindhorniana ( Annonaceae , Miliuseae ) is described and illustrated here as a new species from Narathiwat, southern Thailand. The new species belongs to a major clade that also includes P. fragrans , P. gardneri , P. glossopetala , P. kwangtungensis , P. multiovulata and P. phuyensis . Pseuduvaria sirindhorniana is morphologically most similar to P. glossopetala , but differs by having basally connate (vs. free) sepals, larger petals, elliptic-ovate (vs. obovate) outer petals, inner petals that are only connivent at the apex (vs. connivent from the base to ± the midpoint and at the apex), with openings formed from the base (vs. openings formed from ± the midpoint). Pseuduvaria kwangtungensis turns out to be a putative sister of the new species, but the two are morphologically dissimilar in several traits, such as leaf base, inner petal appearance and glands on the inner side of the inner petals.
Dibridsoniaparvifolia, a new species of Vanguerieae is herein described and illustrated. Morphologically, D. parvifolia resembles D. culionensis and D. conferta, however, D. parvifolia is well distinguished by a combination of the following characters that includes having small leaf blades, absence of pit-domatia in the axils of secondary veins, corolla throat with white moniliform hairs which occurrence extends toward the tips of the corolla lobes, fruits obovoid, 11-15 by 8-10 mm, displaying more than five costae visible externally, two locules and two compressed pyrenes.
