Format: ORAL

Consolata Nanjala1,2,3, Lalita Simpson1, Ai-Qun Hu4, Vidushi Patel5, James Nicholls5, Stephen J. Bent3, Stephan Gale6, Gunter Fischer8, Darren Crayn1, Mark Clements7, Katharina Nargar1,3

1Australian Tropical Herbarium, James Cook University, Smithfield, Queensland 4878, Australia 2College of Science and Engineering, James Cook University, Smithfield, Queensland 4878, Australia 3National Research Collections Australia, Commonwealth Industrial and Scientific Research Organisation (CSIRO), Canberra, Australian Capital Territory 2601, Australia 4Singapore Botanic Gardens, 1 Cluny Road, Singapore 259569 5Australian National Insect Collection, Commonwealth Industrial and Scientific Research Organisation (CSIRO), Canberra, Australian Capital Territory 2601, Australia 6Kadoorie Farm and Botanic Garden, Tai Po, Hong Kong 7Centre for Australian National Biodiversity Research (Joint Venture), Canberra, ACT 2601, Australia 8Missouri Botanical Garden, 4344 Shaw Boulevard, St Louis, United States

The hyperdiverse orchid genus Bulbophyllum constitutes the second largest genus of flowering plants with more than 2,100 species and exhibits exceptional morphological and ecological diversity. The genus, comprising predominantly epiphytic species, exhibits a pantropical distribution with the highest species diversity in tropical Asia (over 1560 species), particularly in the floristic regions of Malesia and Papuasia. The high species richness and complex patterns of morphological diversity within this genus have presented significant challenges to constructing a stable and informative infrageneric classification, and to understanding patterns of evolutionary relationships and trait evolution (including ancestral range evolution). Poor resolution on phylogenetic trees from previous molecular studies based on few DNA loci has greatly hampered our understanding of the diversification of its evolutionary lineages in time and space.Here we present results from a broad-scale plastid phylogenomic study including over 450 samples, representing 398 species and 61 (of 97) sections of Bulbophyllum, with taxonomic focus on the highly diverse Asian clade. Maximum likelihood analyses based on 65 plastid markers yielded well-resolved and well supported phylogenetic reconstructions, clarified infrageneric relationships, and identified several non-monophyletic sections within Bulbophyllum, such as Beccariana, Brachyantha, Cirrhopetalum, Minutissima, Polymeres and Sestochilus. Divergence-time analyses based on secondary calibration points within a broader outgroup sampling in Orchidaceae using BEAST placed the origin of the genus in the early Oligocene and the onset of crown diversification in the late Oligocene. Species distributions were extracted from World Flora Online and biogeographic areas coded based on botanical continents and for a more-fine scaled coding within tropical Asia and Australasia, based on floristic regions following Brummit (2001).Ancestral range analyses were carried out in BIOGEOBEARS testing six biogeographic models. The findings of this study provide important insights into the phylogenomic relationships and spatiotemporal dynamics of the taxonomically complex genus Bulbophyllum.