The response of vascular epiphyte communities following natural or human disturbance has been little studied. Over 5 y, we evaluated the post-stripping recolonization of vascular epiphytes in cloud forest. Vascular epiphytes were experimentally removed from branch and trunk plots (1 m in length) on five trees in two secondary cloud forest fragments in southern Mexico. Similarity between colonizer and established communities was compared in each fragment using a further five trees with no stripping. All seedlings were recorded yearly. Non-vascular epiphyte cover was estimated in each plot. The recolonization rate was very high; after 5 y, epiphyte density of the colonizer community (27.4 ± 6.8 individuals per segment) reached similar values to those of the established community (26.7 ± 3.3) in nearby trees. While similarity (composition and abundance) between the colonizer community and established community was high (81%), diversity accumulation curves indicated that the colonizer community presents a lower diversity of epiphytes (5.5 equivalent species) than the established community (11.4). Colonization of xerophytic bromeliads was high, while pteridophytes and orchids presented reduced recovery. The immediately surrounding source of propagules had a strong influence on recolonization. In both the colonizer and established communities, dominance rank was bromeliads > peperomias > pteridophytes. The results show that the recovery capacity of epiphytic vegetation in secondary forest is high, if propagule sources are close by. However, at 5 y after disturbance, it is unclear whether the colonizer community would present the same species composition as the established community or if it would give rise to a different community.

In several eastern Mediterranean countries orchids are collected from the wild for the production of salep, a beverage made of dried orchid tubers. The drivers of this collection and trade have changed over time. We investigated which genera and species are harvested for salep production, whether any cultivation takes place, the chain of commercialization, and the economic value of tuber collection. Fieldwork and interviews in north-western Greece included 25 collectors and street vendors, the owners of two companies, and one herbal shop. The results show that several orchid species are traded for the production of salep, and none are cultivated. Tubers collected in Greece, Albania and Turkey are sold in northern Greece for EUR 55–150 per kg on average. Recent catalysts such as the increasing demand for traditional, organic and alternative foodstuffs, and the 2009 economic downturn, have led to a revival of salep consumption, with an increasing number of salep harvesters from Greece and Albania scouring the mountains for harvestable tubers, using unsustainable harvesting practices.

Bulbophyllum nepalense Raskoti & Ale (Orchidaceae) from Nepal is described and illustrated. Notes on the diagnostic characters used to distinguish it from the similar species Bulbophyllum retusiusculum are provided.

Chemical baits corresponding to natural orchid fragrance chemicals were used to attract and sample male orchid bees in terra firme and flood plain forest sites on the Tambo-pata Reserve in south-eastern Perú. The study was conducted monthly for two years. A total of 38 species of bees was collected at these chemical baits, and although most species were collected from both habitats, 11 species were significantly more common in one habitat than the other. There was considerable variation in the number and types of chemicals to which each of the orchid bee species was attracted.

Two cycles of seasonal abundance occurred annually in the number of orchid bee individuals and species collected at the chemical baits. A major peak occurred a month following onset of the wet season, and a minor peak occurred during the dry season. Species body size was related to seasonal activity, but additional factors such as flowering phenology and nest parasites were also probably involved.

The number of orchid bee species found on the Tambopata Reserve was similar to the number found in forest sites of eastern and central Brazil, Costa Rica, and Panamá. This homogeneity in species richness is in marked contrast to other insect groups such as Odonata, Lepi-doptera, Asilidae (Diptera), Tabanidae (Diptera), and Cicindelidae (Coleoptera), for which the species numbers recorded on the Tambopata Reserve are the highest for any similar sized area in the world.

Kinaka or Chikanda has been eaten by people in parts of Zambia, northern Malawi and south-western Tanzania for hundreds of years. Prepared from the boiled root tubers of terrestrial orchids, and principally from species of the genera Disa, Habenaria and Satyrium, it was formerly a traditional village delicacy and did not pose a threat to orchid populations. However, the past decade has witnessed a dramatic rise in demand in Zambia, particularly in urban areas. This has triggered a burgeoning commercial market and has now prompted traders to seek tubers from Tanzania's Southern Highlands, an important centre of endemism for upland species of orchid. The resulting cross-border trade, its dynamics and the implications for Tanzanian orchids are reported here for the first time. Whilst all orchid species are in CITES Appendix II, collectors are currently harvesting between 2.2 and 4.1 million tubers per year for export to, and consumption in, neighbouring Zambia. As many as 85 species may be at risk from this trade, and there is evidence that large areas in Ufipa, Mbeya and Kipengere have already been stripped of their orchids. A decline in traditional Tanzanian consumption of Kinaka seems to be having little or no impact on harvesting volumes. Orchid collection across the Southern Highlands is now escalating at a rate that may be far from sustainable. The consequences for Tanzanian biodiversity and for one of Africa's most important areas for orchids are profound.

Bactrocera Macquart (Diptera: Tephritidae) is a genus of nearly 500 species, the majority of which are endemic to tropical South-East Asia and Australasia (Drew 1989). Nearly all Bactrocera have frugivorous larvae that feed on the fleshy fruit of tropical trees, shrubs, and vines, and some species are major horticultural pests (White & Elson-Harris 1992). In this paper,where the term ‘fruit fly’ is used, we are referring explicitly to species of Bactrocera.

The arthropod fauna inhabiting 90 individuals of three different species of epiphyte was investigated in the moist lowland forest of the Barro Colorado National Monument in Panama. In total, 3694 arthropods belonging to 89 morphospecies and 19 orders were collected. While arthropod abundance was primarily a function of host plant biomass irrespective of epiphyte species, there were pronounced differences in species richness, species composition and guild structure of the arthropod faunas of the three epiphyte species. Although all study plants were growing in close proximity on the same host tree species, there was remarkably little overlap in the species assemblages across epiphyte taxa. The inhabitant species also differed dramatically in their ecological functions, as feeding guild and hunting guild analyses indicated. The influence of plant size, structure and impounded leaf litter on arthropod diversity is discussed. We conclude that epiphytes are microhabitats for a diverse and numerous fauna, and that different species of epiphytes foster both taxonomically and ecologically very distinct arthropod assemblages.

The terrestrial orchid genus Bhutanthera Renz (subfamily Orchidoideae, tribe Orchideae), comprising five species, three newly described here, is established. A new species, Herminium pygmaeum Renz, and three new varieties, Bulbophyllum cauliflorum Hook.f. var. sikkimense N. Pearce & P. J. Cribb, Cephalanthera erecta (Thunb.) Bl. var. oblanceolata N. Pearce & P. J. Cribb, and Gymnadenia orchidis Lindl. var. pantlingii Renz, are here newly described. Five new combinations and one new name are proposed. Four new sections of Bulbophyllum are also established and their relationships discussed.

SUMMARY 367

I. INTRODUCTION 367

II. NUMBER 368

III. SIZE 379

IV. AIR SPACE IN THE SEEDS 381

V. FLOATATION AND DISPERSAL 383

1. Air 383

(a) Physical considerations 383

(b) Dispersal 387

(c) Birds 415

2. Water 416

(a) Physical considerations 416

(b) Dispersal 416

VI. CONCLUSIONS 417

Acknowledgements 417

References 418

Orchid seeds are very small, extremely light and produced in great numbers. Most range in length from c. 0.05 to 6.0 mm, with the difference between the longest and shortest known seeds in the family being 120-fold. The ‘widest’ seed at 0.9 mm is 90-fold wider than the ‘thinnest’ one, which measures 0.01 mm (because orchid seeds are tubular or balloon-like, ‘wide’ and ‘thin’ actually refer to diameter). Known seed weights extend from 0.31 lg to 24 μg (a 78-fold difference). Recorded numbers of seeds per fruit are as high as 4000000 and as low as 20–50 (80000–200000-fold difference). Testae are usually transparent, with outer cell walls that may be smooth or reticulated. Ultrasonic treatments enhance germination, which suggests that the testae can be restrictive. Embryos are even smaller: their volume is substantially smaller than that of the testa. As a result, orchid seeds have large internal air spaces that render them balloon-like. They can float in the air for long periods, a property that facilitates long-distance dispersal. The difficult-to-wet outer surfaces of the testa and large internal air spaces enable the seeds to float on water for prolonged periods. This facilitates distribution through tree effluates and/or small run-off rivulets that may follow rains. Due to their size and characteristics, orchid seeds may also be transported in and on land animals and birds (in fur, feathers or hair, mud on feet, and perhaps also following ingestion).

Three new species of Bhutanese orchids, Aphyllorchis sanguinea, Cheirostylis sherriffii and Hetaeria pelota, and one new Sikkimese species, Lecanorchis sikkimensis, are newly described. Their generic placement and affinities are discussed. A new combination in Cheirostylis is made for the Taiwanese Zeuxine tabiyahanensis Hayata. Records of five orchid species new to Bhutan are also presented.