Systematics of the Trembleya sensu stricto clade of Microlicia (Melastomataceae, Lavoisiereae).

A systematic monograph of the Trembleya s.s. clade is presented, a Brazilian endemic lineage of Melastomataceae comprising 11 species and currently recognised as part of Microlicia s.l. (Melastomataceae). First, we investigate phylogenetic relationships within Lavoisiereae using two nuclear markers and two sampling datasets (102 and 134 terminals). Then, we provide a systematic revision and new circumscription of the Trembleya s.s. clade, including line drawings, photos of living specimens, leaves and floral parts, distribution maps, a key to the 11 accepted species, comments on morphology, reproductive biology, richness, endemism, biogeography and recommended conservation assessments. A nomenclatural update of all taxa previously treated in Trembleya is also provided, including the designation of 45 lectotypes and the proposal of 38 new synonyms.

A nuclear phylogenomic study of the angiosperm order Myrtales, exploring the potential and limitations of the universal Angiosperms353 probe set.

PREMISE: To further advance the understanding of the species-rich, economically and ecologically important angiosperm order Myrtales in the rosid clade, comprising nine families, approximately 400 genera and almost 14,000 species occurring on all continents (except Antarctica), we tested the Angiosperms353 probe kit. METHODS: We combined high-throughput sequencing and target enrichment with the Angiosperms353 probe kit to evaluate a sample of 485 species across 305 genera (76% of all genera in the order). RESULTS: Results provide the most comprehensive phylogenetic hypothesis for the order to date. Relationships at all ranks, such as the relationship of the early-diverging families, often reflect previous studies, but gene conflict is evident, and relationships previously found to be uncertain often remain so. Technical considerations for processing HTS data are also discussed. CONCLUSIONS: High-throughput sequencing and the Angiosperms353 probe kit are powerful tools for phylogenomic analysis, but better understanding of the genetic data available is required to identify genes and gene trees that account for likely incomplete lineage sorting and/or hybridization events.

Low bee visitation rates explain pollinator shifts to vertebrates in tropical mountains.

Evolutionary shifts from bee to vertebrate pollination are common in tropical mountains. Reduction in bee pollination efficiency under adverse montane weather conditions was proposed to drive these shifts. Although pollinator shifts are central to the evolution and diversification of angiosperms, we lack experimental evidence of the ecological processes underlying such shifts. Here, we combine phylogenetic and distributional data for 138 species of the Neotropical plant tribe Merianieae (Melastomataceae) with pollinator observations of 11 and field pollination experiments of six species to test whether the mountain environment may indeed drive such shifts. We demonstrate that shifts from bee to vertebrate pollination coincided with occurrence at high elevations. We show that vertebrates were highly efficient pollinators even under the harsh environmental conditions of tropical mountains, whereas bee pollination efficiency was lowered significantly through reductions in flower visitation rates. Furthermore, we show that pollinator shifts in Merianieae coincided with the final phases of the Andean uplift and were contingent on adaptive floral trait changes to alternative rewards and mechanisms facilitating pollen dispersal. Our results provide evidence that abiotic environmental conditions (i.e. mountain climate) may indeed reduce the efficiency of a plant clade's ancestral pollinator group and correlate with shifts to more efficient new pollinators.

Dilochia deleoniae (Orchidaceae), a new species from Mindanao, Philippines.

A new species, Dilochia deleoniae Tandang & Galindon (Orchidaceae), from Mindanao Island, Philippines is described and illustrated herein. This species is distinct from other known Philippine Dilochia species by its terrestrial habit and is distinguished from all known Dilochia species by its monopodial inflorescence, rarely branching in two, and a pale yellow to dull orange or brownish-yellow labellum devoid of purple spots.

Erratum: Author Correction: Modularity increases rate of floral evolution and adaptive success for functionally specialized pollination systems.

[This corrects the article DOI: 10.1038/s42003-019-0697-7.].

Modularity increases rate of floral evolution and adaptive success for functionally specialized pollination systems.

Angiosperm flowers have diversified in adaptation to pollinators, but are also shaped by developmental and genetic histories. The relative importance of these factors in structuring floral diversity remains unknown. We assess the effects of development, function and evolutionary history by testing competing hypotheses on floral modularity and shape evolution in Merianieae (Melastomataceae). Merianieae are characterized by different pollinator selection regimes and a developmental constraint: tubular anthers adapted to specialized buzz-pollination. Our analyses of tomography-based 3-dimensional flower models show that pollinators selected for functional modules across developmental units and that patterns of floral modularity changed during pollinator shifts. Further, we show that modularity was crucial for Merianieae to overcome the constraint of their tubular anthers through increased rates of evolution in other flower parts. We conclude that modularity may be key to the adaptive success of functionally specialized pollination systems by making flowers flexible (evolvable) for adaptation to changing selection regimes.

Bimodal Pollination Systems in Andean Melastomataceae Involving Birds, Bats, and Rodents.

Floral adaptation to a single most effective functional pollinator group leads to specialized pollination syndromes. However, adaptations allowing for pollination by two functional groups (bimodal pollination systems) remain a rarely investigated conundrum. We tested whether floral scent and nectar traits of species visited by two functional pollinator groups indicate specialization on either of the two pollinator groups or adaptations of both (bimodal systems). We studied pollination biology in four species of Meriania (Melastomataceae) in the Ecuadorian Andes. Pollinator observations and exclusion experiments showed that each species was effectively pollinated by two functional groups (hummingbirds/bats, hummingbirds/rodents, flowerpiercers/rodents), nectar composition followed known bird preferences, and scent profiles gave mixed support for specialization on bats and rodents. Our results suggest that nectar-rewarding Meriania species have evolved stable bimodal pollination strategies with parallel adaptations to two functional pollinator groups. The discovery of rodent pollination is particularly important given its rarity outside of South Africa.

Beyond buzz-pollination - departures from an adaptive plateau lead to new pollination syndromes.

Pollination syndromes describe recurring adaptation to selection imposed by distinct pollinators. We tested for pollination syndromes in Merianieae (Melastomataceae), which contain bee- (buzz-), hummingbird-, flowerpiercer-, passerine-, bat- and rodent-pollinated species. Further, we explored trait changes correlated with the repeated shifts away from buzz-pollination, which represents an 'adaptive plateau' in Melastomataceae. We used random forest analyses to identify key traits associated with the different pollinators of 19 Merianieae species and estimated the pollination syndromes of 42 more species. We employed morphospace analyses to compare the morphological diversity (disparity) among syndromes. We identified three pollination syndromes ('buzz-bee', 'mixed-vertebrate' and 'passerine'), characterized by different pollen expulsion mechanisms and reward types, but not by traditional syndrome characters. Further, we found that 'efficiency' rather than 'attraction' traits were important for syndrome circumscription. Contrary to syndrome theory, our study supports the pooling of different pollinators (hummingbirds, bats, rodents and flowerpiercers) into the 'mixed-vertebrate' syndrome, and we found that disparity was highest in the 'buzz-bee' syndrome. We conclude that the highly adaptive buzz-pollination system may have prevented shifts towards classical pollination syndromes, but provided the starting point for the evolution of a novel set of distinct syndromes, all having retained multifunctional stamens that provide pollen expulsion, reward and attraction.

A specialized bird pollination system with a bellows mechanism for pollen transfer and staminal food body rewards.

Bird pollination has evolved repeatedly among flowering plants but is almost exclusively characterized by passive transfer of pollen onto the bird and by nectar as primary reward [1, 2]. Food body rewards are exceedingly rare among eudicot flowering plants and are only known to occur on sterile floral organs [3]. In this study, we report an alternative bird pollination mechanism involving bulbous stamen appendages in the Neotropical genus Axinaea (Melastomataceae). We studied the pollination process by combining pollination experiments, video monitoring, and detailed analyses of stamen structure and metabolomic composition. We show that the bulbous stamen appendages, which are consumed by various species of passerines (Thraupidae, Fringillidae), are bifunctional during the pollination process. First, the appendages work as bellows organs in a unique pollen expulsion mechanism activated by the passerines. As the birds seize an appendage with their beaks in order to remove it from the flower for consumption, air contained in the appendage's aerenchymatous tissue is pressed into the hollow anther. The resulting air flow causes the expulsion of a pollen jet and the deposition of pollen on the bird's head and beak. Second, the stamen appendages provide a hexose-rich, highly nutritious (15,100 J/g) food body reward for the pollinating passerines. This discovery expands our knowledge of flowering plant pollination systems and provides the first report of highly specialized bellows organs for active pollen transfer in flowering plants. In addition, this is the only known case of a food body reward associated with reproductive structures in the eudicot clade of flowering plants.

A revised circumscription for the Blakeeae (Melastomataceae) with associated nomenclatural adjustments.

Systematic investigations and phylogenetic analyses of the Blakeeae (Melastomataceae) have indicated that Topobea should be synonymized under Blakea, and Huilaea under Chalybea. Presented here is a detailed description of the Blakeeae, a key to its two accepted genera, and a listing of 62 new combinations, including 3 new names, necessitated by the transfer of Topobea as follows: Blakea acuminata (Wurdack) Penneys & Judd, comb. nov., Blakea adscendens (E.Cotton & Matezki) Penneys & Judd, comb. nov., Blakea albertiae (Wurdack) Penneys & Almeda, comb. nov., Blakea amplifolia (Almeda) Penneys & Almeda, comb. nov., Blakea arboricola (Almeda) Penneys & Almeda, comb. nov., Blakea asplundii (Wurdack) Penneys & Judd, comb. nov., Blakea barbata (Gleason) Penneys & Judd, comb. nov., Blakea brenesii (Standl.) Penneys & Almeda, comb. nov., Blakea brevibractea (Gleason) Penneys & Judd, comb. nov., Blakea bullata (E.Cotton & Matezki) Penneys & Judd, comb. nov., Blakea calcarata (L.Uribe) Penneys & Judd, comb. nov., Blakea calophylla (Almeda) Penneys & Almeda, comb. nov., Blakea calycularis (Naudin) Penneys & Almeda, comb. nov., Blakea castanedae (Wurdack) Penneys & Judd, comb. nov., Blakea clavata (Triana) Penneys & Judd, nom. nov., Blakea cordata (Gleason) Penneys & Almeda, comb. nov., Blakea cuprina Penneys & Judd, nom. nov., Blakea cutucuensis (Wurdack) Penneys & Judd, comb. nov., Blakea dimorphophylla (Almeda) Penneys & Almeda, comb. nov., Blakea discolor (Hochr.) Penneys & Judd, comb. nov., Blakea dodsonorum (Wurdack) Penneys & Almeda, comb. nov., Blakea eplingii (Wurdack) Penneys & Judd, comb. nov., Blakea ferruginea (Gleason) Penneys & Judd, comb. nov., Blakea fragrantissima (Almeda) Penneys & Almeda, comb. nov., Blakea gerardoana (Almeda) Penneys & Almeda, comb. nov., Blakea glaberrima (Triana) Penneys & Judd, comb. nov., Blakea henripittieri (Cogn.) Penneys & Almeda, comb. et nom. nov., Blakea hexandra (Almeda) Penneys & Almeda, comb. nov., Blakea horologica Penneys & Judd, nom. nov., Blakea induta (Markgr.) Penneys & Judd, comb. nov., Blakea inflata (Triana) Penneys & Judd, comb. nov., Blakea insignis (Triana) Penneys & Judd, comb. nov., Blakea intricata (Almeda) Penneys & Almeda, comb. nov., Blakea killipii (Wurdack) Penneys & Judd, comb. nov., Blakea lentii (Almeda) Penneys & Almeda, comb. nov., Blakea longiloba (Wurdack) Penneys & Judd, comb. nov., Blakea longisepala (Gleason) Penneys & Judd, comb. nov., Blakea macbrydei (Wurdack) Penneys & Judd, comb. nov., Blakea maguirei (Wurdack) Penneys & Judd, comb. nov., Blakea maurofernandeziana (Cogn.) Penneys & Almeda, comb. nov., Blakea mcphersonii (Almeda) Penneys & Almeda, comb. nov., Blakea modica (Wurdack) Penneys & Judd, comb. nov., Blakea mortoniana (Wurdack) Penneys & Judd, comb. nov., Blakea muricata (Lozano) Penneys & Judd, comb. nov., Blakea pascoensis (Wurdack) Penneys & Judd, comb. nov., Blakea pluvialis (Standl.) Penneys & Almeda, comb. nov., Blakea sessilifolia (Triana) Penneys & Judd, comb. nov., Blakea setosa (Triana) Penneys & Judd, comb. nov., Blakea standleyi (L.O.Williams) Penneys & Almeda, comb. nov., Blakea stephanochaeta (Naudin) Penneys & Judd, comb. nov., Blakea steyermarkii (Wurdack) Penneys & Judd, comb. nov., Blakea suaveolens (Almeda) Penneys & Almeda, comb. nov., Blakea subbarbata (Wurdack) Penneys & Judd, comb. nov., Blakea subscabrula (Triana) Penneys & Judd, comb. nov., Blakea subsessiliflora (Wurdack) Penneys & Judd, comb. nov., Blakea superba (Naudin) Penneys & Judd, comb. nov., Blakea tetramera (Almeda) Penneys & Almeda, comb. nov., Blakea tetroici (Wurdack) Penneys & Judd, comb. nov., Blakea toachiensis (Wurdack) Penneys & Judd, comb. nov., Blakea trianae (Cogn.) Penneys & Judd, comb. nov., Blakea verrucosa (Wurdack) Penneys & Judd, comb. nov., Blakea watsonii (Cogn.) Penneys & Almeda, comb. nov.

Comparative anatomy and morphology of nectar-producing Melastomataceae.

BACKGROUND AND AIMS: Most neotropical Melastomataceae have bee-pollinated flowers with poricidal anthers. However, nectar rewards are known to be produced in about 80 species in eight genera from four different tribes. These nectar-producing species are pollinated by both vertebrates and invertebrates. METHODS: The floral morphology and anatomy of 14 species was studied in six genera of nectar-producing Melastomataceae (Blakea, Brachyotum, Charianthus, Huilaea, Meriania and Miconia). Anatomical methods included scanning electron microscopy, and serial sections of paraffin-embedded flowers. KEY RESULTS: All vertebrate-pollinated melastome flowers have petals that do not open completely at anthesis, thus forming a pseudo-tubular corolla, while closely related species that are bee pollinated have rotate or reflexed corollas. In most species, nectar secretion is related to stomatal or epidermal nectaries and not filament slits as previously reported. Moreover, the nectar is probably supplied by large vascular bundles near the release area. Blakea and Huilaea have nectary stomata located upon the dorsal anther connective appendages. Brachyotum also has nectary stomata on the anther connectives, but these are distributed lengthwise along most of the connective. Meriania may release nectar through the anther connective, but has additional nectary stomata on the inner walls of the hypanthium. Miconia has nectary stomata on the ovary apex. Charianthus nectaries were not found, but there is circumstantial evidence that nectar release occurs through the epidermis at the apex of the ovary and the lower portions of the inner wall of the hypanthium. CONCLUSIONS: Nectar release in Melastomataceae is apparently related to nectary stomata and not filament slits. The presence of nectary stomata on stamens and on ovary apices in different lineages suggests that the acquisition of nectaries is a derived condition. Nectary location also supports a derived condition, because location is strongly consistent within each genus, but differs between genera.