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Recent fieldwork has revealed multiple populations in several localities that correspond morphologically to the type of Cyrtandra kipahuluensis H. St. John, collected by C.N. Forbes in 1919. Since the type was the only collection of this species until recent discoveries, and because it had an atypical zygomorphic calyx morphology, the specimen was considered to be a putative hybrid by Wagner et al. (1990, 1999). However, within the past decade, this distinctive calyx morphology has been found to be consistent, occurring in numerous populations across East Maui and in a single locality in West Maui. These new data provide substantial evidence that these populations should be recognized as a distinctive species.

Aim The diversity and composition of species pools within oceanic archipelagos is determined by a combination of colonization, abiotic tolerance, in situ diversification, biotic interactions and extinction. The signature of biogeographic events and evolutionary processes, however, may be masked by recent coalescence and hybridization between closely related species. We used the species-rich plant genus Cyrtandra (Gesneriaceae) to investigate the roles of colonization and hybridization in shaping community assemblages on the geologically young Hawai'i Island. Location Hawaiian Islands. Taxon Cyrtandra (Gesneriaceae). Methods We sampled 29 Cyrtandra taxa and putative hybrids across the main Hawaiian Islands and generated single nucleotide polymorphisms (SNPs) from nine single-copy nuclear genes. Maximum likelihood and Bayesian inference were used to reconstruct phylogenetic relationships, divergence times were estimated using secondary calibrations and island ages, and ancestral area estimation was done using likelihood models. Lastly, we used a Bayesian population assignment test and principal components analysis to infer population genetic structure. Results Cyrtandra colonization of the main Hawaiian Islands appears to have followed the progression rule, whereby the oldest high Hawaiian Islands (Kaua'i and O'ahu) were colonized first, followed by colonization of the younger islands as habitat became available. Hawai'i Island was colonized four times, with two dispersal events from O'ahu and two from Maui Nui. The different colonization events gave rise to significantly uneven numbers of species, and hybridization among the incipient lineages was detected in the form of intermediate genotypes. Main conclusions Our investigation into community assembly in a species-rich plant genus on a geologically young oceanic island revealed a history of multiple colonizations and hybridization among colonizing lineages. The rapid diversification (3.5 species/My) of one of four Cyrtandra lineages on Hawai'i Island may be the result of hybridization between genetically diverse lineages that stem from independent colonization events. Multiple colonization events followed by a merging of lineages may be particularly common during early-stage community assembly on islands and, through the generation of genetic variation, may be especially important for species diversification.

Cyrtandra (Gesneriaceae), with over 800 species, is a mega-diverse genus which presents considerable taxonomic challenges due to its size. A well-sampled phylogeny of the genus across Southeast Asia has confirmed that all but one of the sections within Clarke’s 1883 genus-wide infrageneric classification are polyphyletic. It also shows that there are high levels of homoplasy in key morphological characters, although it is possible to use morphological characters to define clades in parts of the phylogenetic tree. There is some geographic structure in the phylogeny, but there is also evidence of dispersal between islands. A practical approach for tackling the taxonomy of Cyrtandra in the region, through phylogenetically informed taxonomic revisions of geographic areas, an approach which combines evidence from molecular, morphological and distribution data, is discussed. Completing our understanding of species diversity and delimitation in this genus will allow us to maximise the use of Cyrtandra as a tool for studying biogeography, speciation, diversification and conservation prioritisation in the rainforests of Southeast Asia.

Tropical rainforest communities are often characterized by a small number of species‐rich genera that contribute disproportionately to the alpha diversity in these habitats. In the Pacific Basin, there are nearly 200 species of Cyrtandra, most of which are white‐flowered woody shrubs that are single‐island endemics. Within these island communities, multiple Cyrtandra species are commonly observed to occur sympatrically in wet forest understories, forming swarms of what appear to be ecologically similar taxa. The aim of this study was to determine whether species of these plants are randomly assembled with respect to phylogenetic relatedness and traits that are ecologically relevant. I examined assembly patterns across three Pacific archipelagoes using a combination of 10 functional traits and a well‐resolved phylogeny comprising 34 species of Cyrtandra. Coexisting species were found to be more closely related and more phenotypically similar than would be expected by chance. This pattern was observed at both regional (island) and local (site) spatial scales. The retention of phylogenetic signal in floral traits and the strong influence of these traits on the observed degree of phylogenetic clustering may indicate that generalist insect pollinators act as a biotic filter on oceanic islands, driving selection for similar floral morphology among closely related species of Pacific Cyrtandra. Phylogenetic signal was also detected in leaf size, which contributed to niche clustering at both spatial scales. Coupled with a propensity for long‐distance dispersal, and the restricted distribution of Cyrtandra to rainforest understories, this finding suggests that environmental filtering along this trait axis may be more important than dispersal limitation in determining species assemblages. This study supports the theory that plant species are not randomly assembled, and instead, that niche‐based processes structure biodiversity at regional and local spatial scales in diverse congeneric species assemblages. In the Pacific Basin, multiple Cyrtandra species are commonly observed to occur sympatrically in wet forest understories, forming swarms of what appear to be ecologically similar taxa. The aim of this study was to determine whether species of these plants are randomly assembled with respect to phylogenetic relatedness and traits that are ecologically relevant. The retention of phylogenetic signal in floral traits and the strong influence of these traits on the observed degree of phylogenetic clustering may indicate that pollinators act as a biotic filter for closely related species of Cyrtandra.

As part of ongoing molecular phylogenetic work on the large Gesneriaceae genus Cyrtandra, new insights into the taxonomy and relationships of the Cyrtandra of Japan, Taiwan and Batan Island in the northern Philippines have emerged. Cyrtandra umbellifera is confirmed as a species with a distribution that includes both Taiwan and Batan Island. Cyrtandra yaeyamae is found to be distinct from the widespread C. cumingii, with a distribution that includes both the Ryukyu Islands in Japan and Batan Island.

Cyrtandra obliquifolia K.R. Wood & W.L. Wagner (Gesneriaceae), a new shrub species known only from Kaua‘i, Hawaiian Islands, is described and illustrated with notes on its distribution, ecology, and conservation status. The new species is morphologically most similar to Cyrtandra wawrae C.B. Clarke but differs by its unique combination of oblique, non-peltate, auriculate leaf bases, more deeply divided calyx lobes, inflorescence with fewer flowers and lacking profusely umbellate cymes. Cyrtandra obliquifolia is known from only two localities which have undergone severe habitat degradation from landslides and invasive plants and animals and is determined to be Critically Endangered (CR) when evaluated under IUCN criteria.

Conservation and research of highly diverse plant taxa can be a considerable challenge due to unmanageable numbers of species with potentially complex relationships often resulting in difficulties in species identification. Cyrtandra , the largest genus of the family Gesneriaceae, exemplifies these challenges. The lack of identification resources for the ca. 170 species of Bornean Cyrtandra has left many specimens unidentified, slowing down the research efforts in the area. This project addresses this by constructing the first taxonomic key to all Bornean Cyrtandra and by describing the workflow of creating identification resources for highly diverse taxa, using the online biodiversity data management platform Xper3 (https://app.xper3.fr/). The key is now published and freely accessible online. Online multi-access taxonomic keys provide a promising tool for biodiversity research by combining an accessible user-friendly platform with dynamic tools for taxonomic research, making them particularly well suited for tackling highly diverse taxonomic groups.

Eleven new species of Cyrtandra (Gesneriaceae) from Sulawesi are described and illustrated: C. albiflora Karton. & H.J.Atkins, C. boliohutensis Karton. & H.J.Atkins, C. gambutensis Karton. & H.J.Atkins, C. hekensis Karton. & H.J.Atkins, C. hendrianii Karton. & H.J.Atkins, C. hispidula Karton. & H.J.Atkins, C. kinhoii Karton. & H.J.Atkins, C. multinervis Karton. & R.Bone, C. nitida Karton. & H.J.Atkins, C. rantemarioensis Karton. & R.Bone and C. rubribracteata Karton. & H.J.Atkins. Illustrations, maps and preliminary conservation assessments are provided for all the species.

Island systems have long been useful models for understanding lineage diversification in a geographic context, especially pertaining to the importance of dispersal in the origin of new clades. Here we use a well-resolved phylogeny of the flowering plant genus Cyrtandra (Gesneriaceae) from the Pacific Islands to compare four methods of inferring ancestral geographic ranges in islands: two developed for character-state reconstruction that allow only single-island ranges and do not explicitly associate speciation with range evolution (Fitch parsimony [FP; parsimony-based] and stochastic mapping [SM; likelihood-based]) and two methods developed specifically for ancestral range reconstruction, in which widespread ranges (spanning islands) are integral to inferences about speciation scenarios (dispersal-vicariance analysis [DIVA; parsimony-based] and dispersal-extinction-cladogenesis [DEC; likelihood-based]). The methods yield conflicting results, which we interpret in light of their respective assumptions. FP exhibits the least power to unequivocally reconstruct ranges, likely due to a combination of having flat (uninformative) transition costs and not using branch length information. SM reconstructions generally agree with a prior hypothesis about dispersal-driven speciation across the Pacific, despite the conceptual mismatch between its character-based model and this mode of range evolution. In contrast with narrow extant ranges for species of Cyrtandra, DIVA reconstructs broad ancestral ranges at many nodes. DIVA results also conflict with geological information on island ages; we attribute these conflicts to the parsimony criterion not considering branch lengths or time, as well as vicariance being the sole means of divergence for widespread ancestors. DEC analyses incorporated geological information on island ages and allowed prior hypotheses about range size and dispersal rates to be evaluated in a likelihood framework and gave more nuanced inferences about range evolution and the geography of speciation than other methods tested. However, ancestral ranges at several nodes could not be conclusively resolved, due possibly to uncertainty in the phylogeny or the relative complexity of the underlying model. Of the methods tested, SM and DEC both converge on plausible hypotheses for area range histories in Cyrtandra, due in part to the consideration of branch lengths and/or timing of events. We suggest that DEC model-based methods for ancestral range inference could be improved by adopting a Bayesian SM approach, in which stochastic sampling of complete geographic histories could be integrated over alternative phylogenetic topologies. Likelihood-based estimates of ancestral ranges for Cyrtandra suggest a major dispersal route into the Pacific through the islands of Fiji and Samoa, motivating future biogeographic investigation of this poorly known region.

1. Understanding the role of environmental change in the decline of endangered species is critical for designing scale-appropriate restoration plans. For locally endemic rare plants on the brink of extinction, frugivory can drastically reduce local recruitment by dispersing seeds away from geographically isolated populations. Dispersal of seeds away from isolated populations can ultimately lead to population decline. For localized endemic plants, fine-scale changes in microhabitat can further limit population persistence. Evaluating the individual and combined impact of frugivores and microhabitat heterogeneity on the short-term (i.e. transient) and long-term (i.e. asymptotic) dynamics of plants will provide insight into the drivers of species rarity. 2. In this study, we used 4 years of demographic data to develop matrix projection models for a long-lived shrub, Cyrtandra dentata (H. St. John & Storey) (Gesneriaceae), which is endemic to the island of O'ahu in Hawai'i. Furthermore, we evaluated the individual and combined influence of a non-native frugivorous bird, Leiothrix lutea, and microhabitat heterogeneity on the short-term and long-term C. dentata population dynamics. 3. Frugivory by L. lutea decreased the short-term and long-term population growth rates. However, under the current level of frugivory at the field site the C. dentata population was projected to persist over time. Conversely, the removal of optimum microhabitat for seedling establishment (i.e. rocky gulch walls and boulders in the gulch bottom) reduced the shortterm and long-term population growth rates from growing to declining. 4. Survival of mature C. dentata plants had the greatest influence on long-term population dynamics, followed by the growth of seedlings and immature plants. The importance of mature plant survival was even greater when we simulated the combined effect of frugivory and the loss of optimal microhabitat, relative to population dynamics based on field conditions. In the short-term (10 years), however, earlier life stages had the greatest influence on population growth rate. 5. Synthesis and applications. This study emphasizes how important it is to decouple rare plant management strategies in the short vs. long-term in order to prioritize restoration actions, particularly when faced with multiple Stressors not all of which can be feasibly managed. From an applied conservation perspective, our findings also illustrate that the life stage that, if improved by management, would have the greatest influence on population dynamics is dependent on the timeframe of interest and initial conditions of the population.