Adam P. Karremans

Recent origin and rapid speciation of Neotropical orchids in the world's richest plant biodiversity hotspot

Summary The Andean mountains of South America are the most species‐rich biodiversity hotspot worldwide with c. 15% of the worlds plant species, in only 1% of the worlds land surface. Orchids are a key element of the Andean flora, and one of the most prominent components of the Neotropical epiphyte diversity, yet very little is known about their origin and diversification. We address this knowledge gap by inferring the biogeographical history and diversification dynamics of the two largest Neotropical orchid groups (Cymbidieae and Pleurothallidinae), using two unparalleled, densely sampled orchid phylogenies (including more than 400 newly generated DNA sequences), comparative phylogenetic methods, geological and biological datasets. We find that the majority of Andean orchid lineages only originated in the last 20–15 million yr. Andean lineages are derived from lowland Amazonian ancestors, with additional contributions from Central America and the Antilles. Species diversification is correlated with Andean orogeny, and multiple migrations and recolonizations across the Andes indicate that mountains do not constrain orchid dispersal over long timescales. Our study sheds new light on the timing and geography of a major Neotropical diversification, and suggests that mountain uplift promotes species diversification across all elevational zones.

A New Species of Stelis (Orchidaceae: Pleurothallidinae) from Peru

Abstract Stelis peruviana from the cloud forest of Yanatile, Cusco, Peru is described and illustrated. This new species is most similar to Stelis spathuliformis, from which it differs by its yellow flowers, shorter lanceolate sepals, and wider, shorter, obovate lip with irregular margins. Information on its habitat, phenology, and conservation status, as well as a key to the Peruvian species of Stelis previously classified in Pleurothallis subgen. Acuminatia sect. Acuminatae are given.

An eccentric new species of Stelis from Peru (Orchidaceae: Pleurothallidinae)

Stelis hualluapampensis, a new species from the cloud forests of Hualluapampa, in the Tayacaja province, Peru, is described and illustrated. Information on its distribution, habitat, phenology, and conservation status, and comparison with its closest relatives are given.

A New Brachionidium (Orchidaceae: Pleurothallidinae) from the First Botanical Expedition to the Volcán Cacho Negro, Costa Rica

Abstract A new species of Brachionidium from Costa Rica is described and illustrated. Brachionidium cornu-nigricum, from the Volcán Cacho Negro, a remote, previously unexplored location in Costa Rica, is most similar to B. filamentosum. It differs in the white sepals, short-acuminate sepals and petals up to 1 cm long, the triangular, unlobed lip, the oblong glabrous callus provided with two small basal lobes, and the eight pollinia.

Specklinia dunstervillei, a New Species Long Confused with Specklinia endotrachys (Orchidaceae: Pleurothallidinae).

Specklinia dunstervillei is described as a new species in recognition of the distinctness of a Venezuelan species related to and confused with Specklinia endotrachys. It was illustrated for the first time by G. C. K. Dunsterville in 1963 from a plant collected in Trujillo on the Cordillera de Merida. The newly named species can be easily recognized by its small habit, short leaves and small reddish-orange flowers, the non-ascending dorsal sepal and the obtuse petals that are shortly apiculate. Specklinia dunstervillei is formally described and illustrated once again and compared morphologically and genetically with its closest relatives.

Anchored hybrid enrichment generated nuclear, plastid and mitochondrial markers resolve the Lepanthes horrida (Orchidaceae: Pleurothallidinae) species complex

Phylogenetic relationships in species complexes and lineages derived from rapid diversifications are often challenging to resolve using morphology or standard DNA barcoding markers. The hyper-diverse genus Lepanthes from Neotropical cloud forest includes over 1200 species and many recent, explosive diversifications that have resulted in poorly supported nodes and morphological convergence across clades. Here, we assess the performance of 446 nuclear-plastid-mitochondrial markers derived from an anchored hybrid enrichment approach (AHE) coupled with coalescence- and species network-based inferences to resolve phylogenetic relationships and improve species recognition in the Lepanthes horrida species group. In addition to using orchid-specific probes to increase enrichment efficiency, we improved gene tree resolution by extending standard angiosperm targets into adjacent exons. We found high topological discordance among individual gene trees, suggesting that hybridization/polyploidy may have promoted speciation in the lineage via formation of new hybrid taxa. In addition, we identified ten loci with the highest phylogenetic informativeness values from these genomes. Most previous phylogenetic sampling in the Pleurothallidinae relies on two regions (ITS and matK), therefore, the evaluation of other markers such as those shown here may be useful in future phylogenetic studies in the orchid family. Coalescent-based species tree estimation methods resolved the phylogenetic relationships of the L. horrida species group. The resolution of the phylogenetic estimations was improved with the inclusion of extended anchor targets. This approach produced longer loci with higher discriminative power. These analyses also disclosed two undescribed species, L. amicitiae and L. genetoapophantica, formally described here, which are also supported by morphology. Our study demonstrates the utility of combined genomic evidence to disentangle phylogenetic relationships at very shallow levels of the tree of life, and in clades showing convergent trait evolution. With a fully resolved phylogeny, is it possible to disentangle traits evolving in parallel or convergently across these orchid lineages such as flower color and size from diagnostic traits such as the shape and orientation of the lobes of the petals and lip.

Recent origin of Neotropical orchids in the world's richest plant biodiversity hotspot

• The Andean mountains of South America are the most species-rich biodiversity hotspot worldwide with about 15% of the world’s plant species, in only 1% of the world’s land surface. Orchids are a key element of the Andean flora, and one of the most prominent components of the Neotropical epiphyte diversity, yet very little is known about their origin and diversification. • We address this knowledge gap by inferring the biogeographical history and evolutionary dynamics of the two largest Neotropical orchid groups (Cymbidieae and Pleurothallidinae), using two unparalleled, densely-sampled orchid phylogenies (including 400+ newly generated DNA sequences), comparative phylogenetic methods, geological and biological datasets. • We find that the majority of Andean orchid lineages only originated in the last 15 million years. Most Andean lineages are derived from lowland Amazonian ancestors, with additional contributions from Central America and the Antilles. Species diversification is correlated with Andean orogeny, and multiple migrations and re-colonizations across the Andes indicate that mountains do not constrain orchid dispersal over long timescales. • Our study sheds new light on the timing and geography of a major Neotropical radiation, and suggests that mountain uplift promotes species diversification across all elevational zones.

A New Pleurothallis from Colombia, with a Note on Ancipitia and Colombiana (Orchidaceae: Pleurothallidinae)

Abstract A new species of Pleurothallis from Valle del Cauca, Colombia, is described and illustrated. Pleurothallis ottocari is similar to the Ecuadorian P. scoparum, but differs in the widely elliptic leaf, the smaller flowers, the incurved dorsal sepal, the purplish-tinted petals, which are conspicuously curved downwards above the middle, and the basally sub-truncate lip. Brief comments are given as to the reason for not using the generic names Ancipitia and Colombiana, to which the new species would otherwise belong.

Three New Species of Dracontia (Pleurothallidinae, Orchidaceae) from Costa Rica

Abstract Three new species of Dracontia are described and illustrated from Costa Rica and comparisons with close relatives are made. A short discussion for the preference of describing them in Dracontia instead of Stelis is given. The three species are afterwards described: Dracontia montis-mortense, a species with a unique whitish lip with three purple stripes, which is found along the Pan-American Highway on the Cerro de la Muerte, and has been confused with Dracontia dracontea; Dracontia pileata, recognized by its hat-like dorsal sepal, and Dracontia viridi-flava, recognized by its all green-yellow flowers and erase lip. The latter species are both native to the south-Pacific watershed of the Talamanca Cordillera and closely related to Dracontia conochila and Dracontia hydra. A key to the Costa Rican species of Dracontia is given, accompanied by a discussion of the included species.