For 185 years, the genus Eumachia (Rubiaceae) was considered to include one species from Tonga. Since 2015, 94 more names have been added to it, expanding Eumachia into a pantropical genus of shrubby plants, most of whose members were originally described in Psychotria. Four Psychotria species from Southeast Asia that were identified as potentially belonging in Margaritopsis (now a synonym of Eumachia) have not yet had combinations made in Eumachia. They are considered here, and new combinations are made for Psychotria extensa Miq., P. montana Blume and P. rostrata Blume. The fourth name, Psychotria expansa Blume, is considered a synonym. The identities of Chassalia sangiana Miq. and Psychotria rhodocarpa Teijsm. & Binn. are also discussed. Lectotypes are designated for several names.

Three new species of braconid wasps from Costa Rica are described here: Allorhogas crinitus reared from leaf galls on Protium panamense (Burseraceae), Allorhogas lacuna reared from galls on Melastomataceae and Allorhogas triopsis reared from fruit galls on Psychotria (Rubiaceae). These new species are diagnosed and compared with other species in the genus. These are the first records of an Allorhogas species associated with the plant families Burseraceae and Rubiaceae. It is the third association of Allorhogas with the family Melastomaceae.

Three new species of Rubiaceae from Central Africa are described and illustrated. Chassalia lutescens O.Lachenaud & D.J.Harris (widespread from Cameroon to Democratic Republic of Congo) is recognised inter alia by the T-shaped ventral furrow of the seeds and the orange-yellow discoloration of inflorescences in herbarium specimens. Psychotria nodiflora O.Lachenaud & D.J.Harris (Central African Republic, Congo-Brazzaville and Democratic Republic of Congo), belonging to Psychotria subgen. Psychotria sect. Involucratae, is unique among African species of the genus in having paired axillary inflorescences. Psychotria pteropus O.Lachenaud & D.J.Harris (Central African Republic and Democratic Republic of Congo) belongs to Psychotria subgen. Tetramerae; it is closely related to P. leptophylla Hiern but differs in its narrow corolla tube and globose to ellipsoid fruits.

The new taxa Cypholophus treubii var. aciculata (Urticaceae), Polyosma rampae (Polyosmaceae) and Psychotria apiculata var. altigena (Rubiaceae) are described from montane environments in the Kaijende Highlands of Papua New Guinea. A supplementary description is provided for Solanum nolense (Solanaceae), previously known only from a fruiting collection. Synonymies are suggested for species in Cypholophus, Psychotria, and Rubus (Rosaceae).

Photosynthesis was limited by low-intensity photosynthetically active radiation (PAR) and leaf wetness in a lower montane cloud forest (LMCF) of Cauca, Colombia. Mean PAR intensity remained below the saturation level for leaf-scale net photosynthesis (Pn) throughout the solar day during the wet season and for most of the solar day during the dry season. PAR represented a smaller fraction of total solar radiation (K↓) in LMCF than in lowland rain forest (LRF). In LMCF trees and shrubs, mean PAR-saturated Pn ranged from 4.3–10.6 μmol C m−2 s−1 at 1450 m, and from 3.5–10.2 μmol C m−2 s−1 at 2150 m. Pn was reduced by abaxial wetness in leaves of some trees and shrubs, and eliminated in others. This study indicates that persistent cloudiness and interception of cloud water by leaves limit LMCF productivity.

The photosynthetic light response of Amazonian semi-deciduous forest trees of the rain forest–savanna transition near Sinop Mato Grosso, Brazil was measured between July 2000 and September 2003 to test the hypothesis that the photosynthetic capacity of trees acclimated to different growth light environments will decline during the dry season. Maximum photosynthesis (Amax) and stomatal conductance (gmax) were significantly higher during the wet season; however, the physiological response to drought was not a clear function of growth light environment. For some species, such as Psychotria sp. growing in the mid-canopy, internal leaf CO2 concentration (Ci) was >30% lower during the dry season suggesting that declines in Amax were caused in part by stomatal limitations to CO2 diffusion. For other species, such as Brosimum lactescens growing at the top of the canopy, Tovomita schomburgkii growing in the mid-canopy, and Dinizia excelsa growing in the understorey, dry season Ci declined by <20% suggesting that factors independent of CO2 diffusion were more important in limiting Amax. Dry-season declines in gmax appeared to be important for maintaining a more consistent leaf water potential for some species (T. schomburgkii and D. excelsa) but not others (Psychotria sp.). These results indicate that while seasonal drought exerts an important limitation on the physiological capacity of semi-deciduous Amazonian forest trees, the mechanism of this limitation may differ between species.

Interest in the colour of fruits eaten by vertebrates has a long history (Ridley 1930, Turcek 1963, van der Pijl 1972). Within a given geographical area, colours of bird-consumed fruits compared with mammal-consumed fruits are fairly consistent (Janson 1983, Wheelwright & Janson 1985, Willson & Whelan 1990), but comparisons among different regions reveal selective pressures of different animal groups (Lord 2002, Willson et al. 1989). One consistent pattern among regions is that fruits with a two-colour display typically are eaten by birds (Wheelwright & Janson 1985, Willson & Thompson 1982, Willson & Whelan 1990). Thus, it is thought that such bicoloured displays are specifically adapted to attract birds and plants with these displays presumably benefit from seed dispersal by birds (Janson 1983, Willson & Whelan 1990).

In the species-rich tropics, rapid assessment surveys have become a widely employed method for acquiring bioestimates of site value. Some of Papua New Guinea's most pristine habitats are currently being explored with such surveys. Five new species collected during these investigations are described here. The novelties are Psychotria kamialii sp. nov. (Rubiaceae), P. muellerdomboisii sp. nov., P. pseudomaschalodesme sp. nov., P. wiakabui sp. nov., and Solanum symonianum sp. nov. (Solanaceae). Taxonomic notes are also provided for Aglaia puberulanthera (Meliaceae), and Palmeria gracilis (Monimiaceae).

Plants potentially compete for seed dispersal. Selection may favour temporally segregated fruiting phenologies to minimize this competition and also to maintain resident populations of dispersal agents. Alternatively, selection may favour temporally aggregated fruiting phenologies when the effectiveness of seed dispersal agents varies seasonally or when large, synchronous fruit displays enhance dispersal. These evolutionary scenarios assume that plants share seed dispersal agents. This assumption and temporal overlap in fruiting phenologies were evaluated for the Miconia and Psychotria of central Panama. These two genera accounted for 18 and 27%, respectively, of 1096 fleshy fruits found in regurgitation or faecal samples taken from 2054 birds of 103 species netted in the forest understorey. Two species of manakins accounted for 62% (123/200) of all Miconia fruit taken. Three species of manakins and three species of migratory thrushes accounted for 97% (282/292) of all Psychotria fruits taken. There is a high potential for intrageneric competition for seed dispersal for both plant genera. Null model analyses showed that the fruiting phenologies of Miconia (14 species) are segregated in time, while fruiting of Psychotria (21 species) is highly aggregated. The Miconia were found in up to 24% of the diet samples for the two manakin species, suggesting that Miconia may be a critical resource for both species. The Psychotria fruited when the diversity of understorey fruits was greatest, suggesting a high potential for both intra- and extrageneric competition. The abundance and nomadism of the six bird species that consumed most Psychotria fruit peaked when the Psychotria fruited, supporting the enhancement hypothesis.