Verstraete B (2026) IX International Rubiaceae and Gentianales Conference – Program and abstracts. Meise Botanic Garden. https://doi.org/10.5281/zenodo.21885708
ORAL PRESENTATION
Reconstructing the historical spread of Coffea arabica varieties using herbarium genomics
Yves Bawin1,2,3,4,5, Jarkko Salojärvi6,7,8, Stephane Rombauts2,9, Michaël Kelchtermans1,3, Piet Stoffelen2, Erik Smets1,10,11, Olivier Honnay1, Isabel Roldán-Ruiz2,3, Steven B. Janssens1,4, Tom Ruttink2,3
1 Department of Biology, KU Leuven, Leuven, Belgium. 2 Department of Plant Biotechnology and Bioinformatics, Ghent University, Zwijnaarde, Belgium. 3 Plant Sciences Unit, Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), Melle, Belgium. 4 Meise Botanic Garden, Meise, Belgium. 5 Hasselt University, Hasselt, Belgium. 6 School of Biological Sciences, Nanyang Technological University, Singapore, Singapore. 7 Organismal and Evolutionary Biology Research Programme, University of Helsinki, Helsinki, Finland. 8 Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore. 9 Center for Plant Systems Biology, VIB, Ghent, Belgium. 10 Naturalis Biodiversity Centre, Leiden, The Netherlands. 11 Plant Sciences, Institute of Biology Leiden, Leiden University, Leiden, The Netherlands.
Corresponding author: Yves Bawin (yves.bawin@meisebotanicgarden.be)
Arabica coffee (Coffea arabica) is one of the most widely consumed beverages worldwide. It is produced in more than 50 tropical countries from trees that predominantly belong to two major lineages of coffee varieties: Typica and Bourbon. The species C. arabica is endemic to the Afromontane rainforest of southwest Ethiopia. From this region, humans dispersed coffee plants across countries through a series of successive introductions that began in the 15th century. Although historical records document several of these introduction events, they are often ambiguous and difficult to verify. To elucidate relationships among coffee plants from different coffee growing regions, we genetically profiled 351 wild and cultivated C. arabica individuals from living collections and herbarium specimens using genotyping by sequencing, whole genome sequencing, and HiPlex amplicon sequencing. A phylogenetic tree based on 691 polymorphic loci confirmed multiple introduction events described in historical literature. We identified distinct origins for Typica and Bourbon coffee plants, which could be traced back to east Ethiopian and Yemeni accessions, respectively. Our findings provide a robust molecular toolkit for cultivar authentication and establish a phylogenetic framework to support coffee breeding programs and conservation strategies. This study illustrates how herbarium genomics can resolve historical crop dispersal patterns and contribute to the conservation of crop genetic resources.
ORAL PRESENTATION
Homoploid hybrid speciation within a radiation of Coprosma (Anthospermeae, Rubiaceae) on a remote oceanic island
Theodore S. Brook1,2,3, Marco Balducci1, Ian J. Hutton4, Saskia Pearce1,2, Sarah Coates5, Kyle Macleod1, Lizo Masters2, Ilia Leitch2, Sue Bower6, Martin Bidartondo1,2, Trevor C. Wilson7, Alexander S.T. Papadopulos5, Vincent Savolainen1,2
1 Georgina Mace Centre for the Living Planet, Department of Life Sciences, Silwood Park Campus, Imperial College London, Ascot, UK. 2 Royal Botanic Gardens, Kew, London, UK. 3 Science and Solutions for a Changing Planet Doctoral Training Partnership, Grantham Institute, Imperial College London, London, UK. 4 Lord Howe Island Museum, Lord Howe Island, Australia. 5 Molecular Ecology and Evolution Group, School of Environmental and Natural Sciences, Bangor University, Bangor, UK. 6 Bower Bush Ecology, Urunga, Australia. 7 National Herbarium of New South Wales, Botanic Gardens of Sydney, Mount Annan, Australia.
Corresponding author: Theodore S. Brook (t.brook@kew.org)
Hybridisation is sometimes considered an evolutionary dead end, yet its role in generating evolutionary novelty and new species is increasingly recognised. We test the latter in a diverse radiation of Coprosma (Anthospermeae, Rubiaceae) on Lord Howe Island (LHI), a minute remote oceanic island where speciation with gene flow is common. By combining RNA-sequencing with ecological and morphological data, we first identified two new species, bringing the total to seven endemic species of Coprosma on LHI. Importantly, two of these species appear to have originated through homoploid hybrid speciation within this endemic radiation. We suggest that the hybridisation process allowed the colonisation of new niches (primarily determined by elevation) unavailable to either parent, likely through the segregation of transgressive genetic variation and ecological speciation. More broadly, we find widespread ecological differentiation across the radiation that is negatively correlated with pairwise genetic differentiation. These findings support predictions of the syngameon hypothesis – that within an adaptive radiation with ongoing gene flow, hybridisation fuels speciation by generating novel genotypes while reinforcing reproductive barriers as niche space fills. This study highlights the importance of admixture in generating ecological novelty and thus new species, alongside the usefulness of isolated systems such as LHI in studying these processes.
ORAL PRESENTATION
New insights into Psychotria sect. Cephaelis: chemical and palynological evidence reinforces its placement in Palicourea
Carla Poleselli Bruniera1, Isabella Capitanio Rossatto2, Samantha Favero Marcon2, Victor Menezes Sipoloni1, Júlia Nascimento Caldas1, Cynthia Fernandes Pinto da Luz2, Thiago André Moura Veiga1
1 Universidade Federal de São Paulo, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Diadema, São Paulo, Brazil. 2 Instituto de Pesquisas Ambientais, São Paulo, São Paulo, Brazil.
Corresponding author: Carla Poleselli Bruniera (cpbruniera@gmail.com)
Palicourea is a relatively large genus of Neotropical shrubs and small trees of Rubiaceae which includes at least 600 species. After morphological and molecular studies involving Palicourea and other genera of Palicoureeae and Psychotrieae, it became clear that several species of Psychotria subg. Heteropsychotria belong to Palicourea. The section Cephaelis is one of the largest within Psychotria subg. Heteropsychotria and some studies have already demonstrated its placement within Palicourea. The species in this section have inflorescences forming compact capitula, broad and concave bracts at the base that vary in size and colour, a regular calyx, and a corolla with a straight tube lacking internal rings of trichomes. The aim of this study was to identify chemical and palynological traits that reinforce the placement of the species from section Cephaelis within the genus Palicourea. For the palynological analysis, pollen grains from eight species were examined (Pal. colorata, Pal. jungiana, Pal. prunifolia, Pal. ruelliifolia, Pal. subtriflora, Pal. tricholoba, Psy. appendiculata, and Psy. hastisepala). Pollen grains were collected from pre-anthesis buds on herbarium specimens and subjected to standard acetolysis for light microscopy analysis. All pollen measurements were taken using a micrometer eyepiece attached to the microscope. Regarding chemical data, eight species were also analyzed (Pal. hoffmannseggiana, Pal. gracilenta, Pal. ruelliifolia, Pal. sessilis, Pal. stachyoides, Pal. tenerior, Pal. tricholoba, and Psy. hastisepala). Ethanolic extraction was performed on the leaves, and the resulting raw and alkaloid-rich extracts were analyzed using liquid chromatography coupled with high-resolution tandem mass spectrometry. The analyzed species possess large, inaperturate, and microreticulate pollen grains. Regarding chemical traits, we identified the presence of indole alkaloids and strictosidine-like compounds. These data support the placement of these species within Palicourea. Additional species from the section will be analyzed to gather further evidence regarding the group and its relationship with other Palicourea groups.
ORAL PRESENTATION
The genus Tarenna (Rubiaceae) in Peninsular Malaysia
Junhao Chen1,2, Yih Horng Cheah3
1 Singapore Botanic Gardens, National Parks Board, Singapore. 2 Department of Biological Sciences, National University of Singapore, Singapore. 3 Forest Research Institute Malaysia, Kepong, Selangor, Malaysia.
Corresponding author: Junhao Chen (junhao_chen@nparks.gov.sg)
Recent phylogenetic studies have segregated many African and Malagasy species from Tarenna sensu lato, resulting in a narrower delimitation comprising ca 130 species distributed in Asia, Australasia, and the Pacific region. Currently assigned to the tribe Pavetteae of the subfamily Dialypetalanthoideae, Tarenna are trees or shrubs with opposite leaves lacking bacterial nodules, interpetiolar stipules that are basally fused, strictly terminal inflorescences with trichotomous branching, pentamerous bisexual flowers, corolla lobes contorted to the left in bud, exserted stamens and styles/stigmas, the exserted part of style/stigma as long as or slightly longer than corolla lobes, 2-locular ovary with axile placentation, and berry-like fruits. Regional revisions and checklists account for a mere fraction of the species diversity of Tarenna. A provisional treatment of the genus in Peninsular Malaysia by Wong in 1988 enumerated 39 species, with 16 species given only numerals as identifiers. Here, we present the preliminary results of our ongoing revision of the genus in Peninsular Malaysia, contributing to a sound documentation for the Flora of Peninsular Malaysia now at its peak of investigation, with about a fifth of the flora revised since 2005. We report that Tarenna odorata was previously misapplied to a Malayan taxon; the correct name for this species is Tarenna grandifolia, which should be resurrected from synonymy. The name Tarenna wallichii was also formerly misapplied to a species that we recently described as Tarenna khoonmengiana. Our study revealed 11 putatively new species, most of which corresponding to numbered species in Wong’s earlier work.
ORAL PRESENTATION
Tackling the species-rich genus Timonius (Rubiaceae)
Junhao Chen1,2, Pui Kiat Hoo3, Wei Wei Seah1,4, Anna Trias-Blasi5, Timothy Utteridge1,2, Sin Yeng Wong3
1 Singapore Botanic Gardens, National Parks Board, Singapore. 2 Department of Biological Sciences, National University of Singapore, Singapore. 3 Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, Kota Samarahan, Malaysia. 4 Naturalis Biodiversity Center, Leiden, Netherlands. 5 Herbarium, Royal Botanic Gardens, Kew, Richmond, UK.
Corresponding author: Junhao Chen (junhao_chen@nparks.gov.sg)
With nearly 300 species, Timonius is one of the largest genera in the Rubiaceae, characterised by axillary inflorescences, 4–many ovary locules, solitary pendulous ovules, and separate pyrenes. Timonius is most diverse in the Malesian region, particularly New Guinea and Borneo, the world’s second and third largest islands, respectively. Here, we present the results of recent taxonomic and systematic studies that have resulted in new species, new genera and new findings in Timonius and related genera. Timonius was recently revised for Borneo based on a study of over 1200 collections from various herbaria. A new subgenus, Timonius subg. Helospora, was described, and a total of 94 species are recognised for Borneo, including 68 newly discovered in the study, surpassing the 89 species currently known for New Guinea. Most species (ca 95%) in Borneo are considered endemic, paralleling the level known for New Guinea (ca 90%). A new genus Chewlunia, native to the Philippines and northern Borneo, was also described and segregated from Timonius owing to a suite of unique characters. The taxonomy of Timonius remains highly problematic, with many species unassigned to any of the four subgenera presently recognised (viz. subg. Abbottia, Helospora, Pseudobobea, Timonius). Almost all Bornean taxa belong to Timonius subg. Helospora, with only two assigned to Timonius subg. Abbottia. All four subgenera are represented in New Guinea, and all except Timonius subg. Helospora are most diverse in New Guinea. Our preliminary molecular phylogenomic results, using the Angiosperms353 probe set, suggest that Timonius is not monophyletic and the subgenera may warrant recognition as distinct genera.
ORAL PRESENTATION
Some considerations on the ecology of Hamelia patens in Martinique: non-invasive establishment
Jean-Philippe Claude1
1 University of the Antilles, Martinique, France.
Corresponding author: Jean-Philippe Claude (claudejeanphilippe1@gmail.com)
Hamelia patens (Rubiaceae) exhibits a unique biogeographical trajectory on the island of Martinique, located in the Lesser Antilles archipelago (Caribbean). Introduced for ornamental purposes, the species may have escaped from the botanical collections of the city of Saint-Pierre following the eruption of Mount Pelée in 1902, an event that profoundly reshaped the landscapes of the northern part of the island. Despite more than a century of presence, its expansion dynamics remain poorly documented. This study aims to characterize the current distribution of the species and to assess its ecological potential at the island scale. Field observations were combined with a targeted literature review and a spatial analysis performed using the GIS software QGIS (version 3.42.3) to compare the observed occurrences with the environmental conditions favorable to the species (temperature, rainfall, and soil characteristics). Surveys indicate that H. patens remains largely confined to the ruins and built structures of Saint-Pierre, as well as the roadsides of northwestern Martinique. Its current distribution appears significantly more restricted than that suggested by its ecological potential. These results indicate an early but spatially limited establishment, characterized by stable dynamics and reduced secondary dispersal. Despite seemingly favorable environmental conditions, certain ecological or dispersal factors appear to constrain the species’ expansion. This study provides an initial spatial framework for analyzing the establishment dynamics of H. patens in an island context and constitutes a baseline for future ecological monitoring.
ORAL PRESENTATION
Tarenna and Nesotarenna (Dialypetalanthoideae – Pavetteae) in Africa and Madagascar
Petra De Block1, Alex Vrijdaghs1, Brecht Verstraete1, Sylvain G. Razafimandimbison2, Franck Rakotonasolo3,4, Steven B. Janssens1,5
1 Meise Botanic Garden, Meise, Belgium. 2 Swedish Museum of Natural History, Stockholm, Sweden. 3 Kew Madagascar Conservation Centre, Antananarivo, Madagascar. 4 Parc Botanique et Zoologique de Tsimbazaza, Antananarivo, Madagascar. 5 KU Leuven Plant Institute, KU Leuven, Leuven, Belgium.
Corresponding author: Petra De Block (petra.deblock@meisebotanicgarden.be)
The genus Tarenna Gaertn. (subfamily Dialypetalanthoideae, tribe Pavetteae) was recently dismantled in Africa and Madagascar. The 44 continental African species were transferred to the hitherto small genus Cladoceras Bremek. (growing from 2 to 40 species) and the small new genera Alatostigma De Block (4 species) and Sonbridia De Block (2 species), the latter named for the British Rubiaceae specialist Diane Bridson. The six Malagasy species of Tarenna were transferred to the new genus Nesotarenna De Block, a Western Indian Ocean endemic. This reclassification was made possible by combining genetic data with detailed morphological analysis. The newly recognized genera can be distinguished by subtle but consistent traits—such as the shape of the seed coat cells (puzzle-shaped or with straight walls) and the structure of the stigma (with longitudinal wings or smooth). A subsequent revision of Nesotarenna resulted in the description of ten new taxa, nine at species level and one at variety level. Furthermore, the Seychellois endemic Tarenna sechellensis (Baker) Summerh. was placed in synonymy with Nesotarenna madagascariensis (Ten.) De Block. This brings the number of species of Nesotarenna to 15, 13 endemic to Madagascar, two further ones, N. madagascariensis and N. spiranthera (Drake) De Block, also occurring in the Comoros and/or the Seychelles. Within Nesotarenna, two informal groups can be recognized based on flower type. Flowers have the stamens either inserted at the level of the pubescent throat, with the anthers completely or for most of their length exserted and the style/stigma long exserted from the corolla tube at anthesis (spiranthera-type flowers), or, the stamens inserted below the level of the glabrous throat, with the anthers and the style/stigma included for most of their length in the corolla tube at anthesis (thouarsiana-type flowers). Other characters, e.g. stipule shape and size, presence/absence and size of bracts and bracteoles, are at least in part correlated to the flower type.
ORAL PRESENTATION
Genetic diversity of wild Coffea canephora populations in the Yangambi region: current status and conservation threats
Jonas Depecker1
1 Meise Botanic Garden, Meise, Belgium.
Corresponding author: Jonas Depecker (jonas.depecker@meisebotanicgarden.be)
Coffee is the most widely consumed hot beverage and one of the world’s most traded commodities. Approximately 44% of global coffee production comes from Robusta coffee (Coffea canephora), a share expected to increase due to its high disease resistance and broad climatic adaptability. Wild C. canephora originates from the tropical rainforests of Central and West Africa. However, these forests are increasingly threatened by anthropogenic disturbance, which may alter gene flow, reduce genetic diversity, and change population structure. Wild populations are also vulnerable to hybridisation with cultivated coffee, potentially affecting their genetic integrity. Because wild C. canephora represents a vital genetic resource for the long-term sustainability of coffee production, we investigated the effects of forest disturbance and crop-to-wild gene flow on genetic diversity, population structure, and pedigree relationships. We sampled over 400 individuals from 24 plots across three forest categories in Yangambi (DR Congo), together with cultivated plants from home gardens and the INERA Coffee Collection. Samples were genotyped using GBS and analysed with SNPs. Wild populations retained high genetic diversity despite ongoing anthropogenic pressures. Disturbed old-growth forests showed no evidence of genetic erosion compared with undisturbed forests, while the observed excess of heterozygosity across populations reflected the species’ self-incompatible mating system. Population structure was primarily driven by isolation-by-distance, with generally low to moderate relatedness among neighbouring individuals. In contrast, regrowth forests displayed lower allelic richness, reduced relatedness, and no isolation-by-distance, suggesting founder effects following recolonisation from multiple source populations. We also detected cultivated genotypes and cultivated–wild hybrids in areas with human activity, indicating that home gardens can facilitate crop-to-wild gene flow. However, the low frequency of hybrids and the high genetic similarity between cultivated and wild gene pools suggest that widespread introgression remains limited. Continued monitoring is nevertheless essential to safeguard the genetic integrity of wild C. canephora populations.
ORAL PRESENTATION
Diversity of floral features and their phylogenetic affinity in Acranthera, with a focus on Bornean taxa
Pui Kiat Hoo1, Junhao Chen2, Wei Wei Seah2,3, Anna Trias-Blasi4, Sin Yeng Wong1
1 Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, Kota Samarahan, Malaysia. 2 Singapore Botanic Gardens, National Parks Board, Singapore. 3 Naturalis Biodiversity Center, Leiden, Netherlands. 4 Herbarium, Royal Botanic Gardens, Kew, Richmond, UK.
Corresponding author: Pui Kiat Hoo (puikiatben@gmail.com)
Acranthera is a tropical Asiatic genus of understory herbs traditionally characterized by stamens united at their apical connective appendages and attached to the stigma tip. In Borneo, the genus is currently represented by fewer than 30 species, yet it exhibits remarkable morphological diversity, spanning six subgenera as defined in Bremekamp’s 1947 monograph. In preparation for a taxonomic revision of Bornean Acranthera, specimens across major regional herbaria were examined, revealing more than 60 putatively new taxa. While most of these novel taxa align with existing subgenera, several distinct species-groups possess unique floral characters—such as corolla shapes and colourations, and anther-stigma complex morphologies—that challenge the current framework. Most notably, we report the first record of free stamens within Acranthera. While assigning subgeneric ranks to these morphologically unique groups would align with Bremekamp’s system, a molecular evaluation is essential to confirm their monophyly. Here, we present a preliminary phylogenomic analysis encompassing the 10 recognized subgenera and the newly diagnosed species-groups, and offer recommendations for an updated, phylogenetically robust classification of the genus.
ORAL PRESENTATION
The genera Chassalia, Eumachia, Geophila, and Hymenocoleus (Rubiaceae) in tropical Africa
Olivier Lachenaud1, 2, 3
1 Meise Botanic Garden, Meise, Belgium. 2 Service Général de l’Enseignement supérieur et de la Recherche scientifique - Fédération Wallonie-Bruxelles, Brussels, Belgium. 3 Herbarium et Bibliothèque de Botanique africaine, Université Libre de Bruxelles, Brussels, Belgium.
Corresponding author: Olivier Lachenaud (olivier.lachenaud@meisebotanicgarden.be)
Chassalia, Eumachia, Geophila, and Hymenocoleus are four closely related genera of Rubiaceae, which have been included either in tribe Psychotrieae sensu lato (a position followed here) or in a segregate tribe Palicoureeae. The first two genera include mostly shrubs, while the last two are herbs or undershrubs. All occur chiefly in the undergrowth of tropical rainforests, where they are often abundant. Chassalia is a paleotropical genus, while Eumachia and Geophila are pantropical and Hymenocoleus is exclusively African. The author has been working for several years on a revision of these genera in tropical Africa, none being so far available, and an overview of the taxonomy, morphology, and biogeography of the group is presented here. The four genera include 118 African species in total, with respectively 55 species in Chassalia (14 new), 37 in Eumachia (16 new), 7 in Geophila, and 19 in Hymenocoleus (6 new). They are particularly diverse in Atlantic Central Africa, with Chassalia having a secondary diversity center in the Eastern Arc Mountains of Tanzania.
ORAL PRESENTATION
Shade tree species and 15N-labelled urea timing affect nitrogen uptake and distribution in Ethiopian coffee agroforestry systems
Bezawit Mekonnen1,2, Gezahegn Berecha1, Samuel Bodѐ3, Pascal Boeckx3, Haben Blondeel2, Kris Verheyen2, Pieter De Frenne2
1 Department of Horticulture & Plant Sciences, College of Agriculture & Veterinary Medicine, Jimma University, Jimma, Ethiopia. 2 Forest & Nature Lab, Department of Environment, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium. 3 Department of Green Chemistry & Technology, Faculty of Bioscience Engineering, Ghent University, Gent, Belgium.
Corresponding author: Bezawit Mekonnen (bezawit.mekonnen@ju.edu.et)
Nitrogen limitations and low fertilizer recovery constrain coffee productivity in Ethiopia’s smallholder agroforestry systems. This study evaluated the impacts of 15N-labelled urea application under two contrasting shade tree species to identify conditions that maximize nitrogen uptake, fertilizer recovery, and coffee yield. Coffee was grown under two shade-tree species, Albizia (leguminous) and Croton (non-leguminous), and subjected to four 15N-labelled urea treatments: control (T1), single application of 15N-labelled urea (T2), split and early application of 15N-labelled urea (T3), and split and late application of 15N-labelled urea (T4). The strongest treatment effects occurred under the early split application (T3), which consistently produced the highest bean nitrogen yield, fertilizer recovery, and coffee productivity across both shade systems. Bean N yield was 12.4 g N shrub-1 under Albizia and 11.8 g N shrub-1 under Croton, representing the maximum N accumulation observed. Nitrogen derived from fertilizer (NdfF) values was highest in leaves, reaching 11.2% under Albizia and 9.8% under Croton, while fertilizer allocation to beans reached its maximum in T3 (13.1% under Albizia; 19.3% under Croton). Croton exhibited the strongest shift in fertilizer partitioning, with late application (T4) driving 85.3% of recovered N into leaves, sharply reducing reproductive allocation. The greatest improvements in nitrogen use efficiency (NUE), agronomic efficiency (AE), and fertilizer nutrient use efficiency (FNUE) were also recorded under T3 and T4. NUE reached 13 to 15% in Albizia and 9 to 11% in Croton, while AE was 15 g yield g-1 N under Croton. FNUE reached its highest values under split application, with 45% in Albizia and 30% in Croton. Coffee yield responded most strongly to T3, reaching ~500 g shrub-1 under both shade tree species. Overall, early split nitrogen application produced the highest fertilizer recovery and yield, while Albizia enhanced physiological nitrogen efficiency and Croton showed the strongest yield responsiveness.
ORAL PRESENTATION
A review of recent work and future directions in the Canthium alliance (Vanguerieae) in Asia
Louise Neo1, Ridha Mahyuni2, Axel H. Arriola3
1 Singapore Botanic Gardens, National Parks Board, Singapore. 2 Herbarium Bogoriense, Research Center for Biosystematic and Evolution (BRIN), Bogor, Indonesia. 3 Department of Natural Sciences, College of Arts and Sciences, University of the East, Manila, Philippines.
Corresponding author: Louise Neo (louise_neo@nparks.gov.sg)
The Vanguerieae in the Rubiaceae is a monophyletic tribe (subfamily Dialypetalanthoideae) recognisable by a combination of morphological characters such as axillary inflorescences, valvate corolla-lobe aestivation, a swollen stylar knob that functions in secondary pollen presentation, uniovulate locules, pendulous ovules, drupaceous fruits, large embryos with superior radicles, and the absence of raphides. It is distributed worldwide with a high degree of endemicity within tropical Africa and Asia. Within the Vanguerieae, the genus Canthium has long been considered a heterogeneous assemblage. Molecular phylogenetics clarified understanding of generic limits within the tribe and demonstrated the polyphyly of Canthium sensu lato. This has stimulated follow-up work to recircumscribe this genus based on morphological evidence. In Asia, several “spineless” species formerly placed in Canthium have been transferred to either Psydrax or Pyrostria, while the Asian-endemic genera Kanapia, Canthiumera, and Dibridsonia have been newly established. Canthium sensu stricto in Asia is now recognised as the only genus of the tribe with axillary supernumerary buds and spines. Here, we present some of our recent findings on the Southeast Asian members of the Canthium alliance. Over 30 new or newly combined taxa have been recognised in the last 10 years. This indicates that continuing morphological and molecular investigations, particularly in the larger genera such as Psydrax or Pyrostria, should continue to yield more novelties and elucidate a better understanding of this group in Asia, while contributing to overall knowledge of the Vanguerieae.
ORAL PRESENTATION
How do opposite leaves constrain plant architecture? Insights from the Asian Rubiaceae
Louise Neo1, Joan T. Pereira2, Yih Horng Cheah4, Junhao Chen1, Sarawood Sungkaew3, Atchara Teerawatananon5, Voradol Chamchumroon6, Pui Kiat Hoo7, Wei Wei Seah1, Ridha Mahyuni8, Khoon Meng Wong1,3
1 Singapore Botanic Gardens, National Parks Board, Singapore. 2 Forest Research Centre, Sabah Forestry Department, Sabah, Malaysia. 3 Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok, Thailand. 4 Forest Research Institute Malaysia, Kepong, Malaysia. 5 Natural History Museum, National Science Museum, Technopolis, Thailand. 6 Forest Herbarium, Department of National Parks, Wildlife and Plant Conservation, Bangkok, Thailand. 7 Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, Sarawak, Malaysia. 8 Herbarium Bogoriense, Research Center for Biosystematic and Evolution (BRIN), Bogor, Indonesia.
Corresponding author: Louise Neo (louise_neo@nparks.gov.sg)
With over 600 genera and more than 13,000 species, the Rubiaceae can be considered an immensely diverse family. Yet, the predominance of an opposite-decussate leaf arrangement along the primary axis or stem is a very typical feature among the trees, and this would appear to impose limitations on the development of pairs of axillary buds and branches that contribute to the building of overall plant structure. Are the variations only bound by the 25 or so tree architectural models so far diagnosed for the tropics, or is there more than meets the eye? And can such insights potentially aid classification within the family (although earlier declarations deem architecture does not reflect phylogeny)? This presentation aims to discuss these points.
ORAL PRESENTATION
Mexican Rubiaceae continue to amaze us, and also to puzzle us
Helga Ochoterena1
1 Instituto de Biología, Universidad Nacional Autónoma de México, México.
Corresponding author: Helga Ochoterena (helga@ib.unam.mx)
Mexico is a megadiverse country, and it is not the exception for Rubiaceae. Life forms go from trees up to 70 m tall (Blepharidium guatemalense Standl.), to small herbs only a few cm tall (e.g. Mitchella repens L.), with a distribution covering from the wet tropical forests, with more than 5,000 mm of average precipitation per year, to arid lands with less than 150 mm average per year. According to the most recent account, in 2022 Torres-Montúfar and Torres-Díaz estimated that Mexican Rubiaceae include 111 genera (17 endemic) and 711 native species (363 endemic). If these numbers are correct, the proportion of generic diversity in Mexico as compared to the entire world would be extremely high (close to 20%), while the species diversity would be fairly low (about 5%, as compared to the average 10% for the rest of the angiosperm families). Mexican Rubiaceae continue to amaze and to puzzle us with unique character combinations, biogeographic oddities, and controversial molecular phylogenies. During this talk, I will expose some of the recent findings that challenge our understanding of Mexican Rubiaceae evolution and biogeography. As examples, I will present the case of incongruent chloroplast vs nucleus genomic phylogenies, bizarre biogeographic distributions, and amazing morphological evolution within the Mexican territory. This complexity results in controversial estimations of diversity and endemism, especially at generic rank. I will summarize what I consider the most important challenges to be overcome in order to come to a better understanding of the diversity, evolution, and classification of Rubiaceae Mexican taxa.
ORAL PRESENTATION
Bioprospecting antivirals in a hotspot for rubiaceous biodiversity
Diego Felipe Orejuela-Reyes1, Alejandra Arango-Gallego1, María Aurora Londoño-Avendaño1
1 Department of Microbiology, College of Health, Universidad del Valle, Cali, Colombia.
Corresponding author: María Aurora-Londoño-Avendaño (maria.avendano@correounivalle.edu.co)
Recent emerging viral diseases, such as the COVID-19 pandemic, the explosion of dengue cases in the Americas in early 2024, and the Oropouche virus fever outbreak that spread through the Amazon region during 2024 raised the alarms about the need for new strategies for prevention and management of viral diseases. Rubiaceae plants, particularly rich in inhibitors for different stages of virus replication, are represented by more than a thousand species and their morphotypes in Colombia. In this work, a list of the most active biological compounds in studied species is being used in docking and molecular dynamic simulations to understand their interactions with protein targets from viruses relevant for the country; a review of the genera in which phytochemical profiles have been characterized has allowed the identification of species endemic to the Pacific Region of the country likely to contain these sort of compounds. Further in vitro assays with extracts from these plants, combined with the data obtained in silico, are expected to identify endemic species worthy of promotion in agroforestry programs to protect this enclave of rubiaceous diversity.
ORAL PRESENTATION
A century of botanical illustration of Rubiaceae at Meise Botanic Garden
Hilde Orye1, Petra De Block1
1 Meise Botanic Garden, Meise, Belgium.
Corresponding author: Hilde Orye (hildeorye2@gmail.com)
In 1922, Camille Vermoesen became the first botanist at Meise Botanic Garden to publish a study devoted entirely to the Rubiaceae. Over the following century, the family continued to receive considerable attention from Meise taxonomists, including Walter Robyns, Emile De Wildeman, Ernest Petit, and Elmar Robbrecht. To illustrate descriptions of new species, taxonomic revisions and floristic treatments, these botanists collaborated with a number of highly skilled artists who produced countless botanical illustrations. The primary purpose of a botanical illustration is scientific accuracy. Unlike a photograph, an illustration can synthesize multiple observations into a single, ideal representation of a species, highlighting diagnostic characters with exceptional clarity and precision. Although aesthetic appeal is secondary to scientific accuracy, the style and technique of a gifted illustrator can elevate a botanical illustration into a work of art. Botanical illustrations are both universal and timeless, communicating essential information at a glance in a way that even pages of botanical description cannot. Hélène Durand, daughter of Théophile Durand, director of Meise Botanic Garden from 1901 to 1912, was the Garden’s first botanical illustrator. She was succeeded by Albert Cleuter, originally trained as an architect, who worked at Meise for three decades. Other in-house artists with long careers in botanical illustration include Marianne Allard, Antonio Fernandez, and Omer Van de Kerckhove. Several botanists, among them Elmar Robbrecht and Olivier Lachenaud, also produced outstanding botanical illustrations themselves. The long-standing tradition of employing one or two full-time botanical illustrators at Meise Botanic Garden has recently come to an end. Since then, the Garden has relied on a combination of short-term appointments and freelance illustrators, including Marijke Meersman and Hilde Orye. Today, two staff members, Liliane Tytens and Sven Belanger, share the equivalent of 1.5 full-time positions, combining botanical illustration with graphic design. This presentation introduces the botanical illustrators who have created remarkable Rubiaceae illustrations at Meise Botanic Garden throughout the 20th and 21st centuries. Can the individual style of a botanical illustrator be recognised despite the scientific constraints of the discipline? How did the personalities, artistic backgrounds, and working methods of successive illustrators shape a century of Rubiaceae illustration at Meise Botanic Garden?
ORAL PRESENTATION
Phylogeny of the Paleotropical tribe Mussaendeae (Rubiaceae - Dialypetalanthoideae), with particular emphasis on the Madagascar-centered genus Bremeria
Sylvain G. Razafimandimbison1, Niklas Johansson1, Sylvie Andriambololonera2, Catarina Rydin3
1 Department of Botany, Swedish Museum of Natural History, Stockholm, Sweden. 2 Missouri Botanical Garden Program, Madagascar. 3 Department of Ecology, Environment, and Plant Sciences, Stockholm University, Stockholm, Sweden.
Corresponding author: Sylvain G. Razafimandimbison (sylvain.razafimandimbison@nrm.se)
A new generic classification of the tribe Mussaendeae (Rubiaceae) was proposed by Alejandro et al. as a result of the biphyly of the Paleotropical genus Mussaenda L. The genus Bremeria Razafim. & Alejandro was described to accommodate all the arborescent Malagasy and Mascarene Mussaenda species with large flowers and indehiscent fruits. A narrow delimitation of Mussaenda that includes the African and Asian species was proposed. Mussaendeae as presently circumscribed is one of the five Paleotropical Rubiaceae tribes of the subfamily Dialypetalanthoideae, with at least 216 species currently classified in seven genera, the Paleotropical Mussaenda (185 species), Malagasy-Mascarene Bremeria (at least 18 species), tropical African Heinsia (5 species), Malagasy Landiopsis (1 species), Borneean Neomussaenda (2 species), tropical African Pseudomussaenda (4 species), and continental Asian Schizomussaenda (1 species). The monophyly of Bremeria is doubtful, as the type species from the Mascarenes, B. landia (Poir.) Razafim. & Alejandro, reported to have capsular fruits, was not investigated by Alejandro et al. We carried out Bayesian phylogenetic analyses of Mussandeae based on the sequence data from 122 taxa and using three Sabiceeae taxa as outgroups to: 1) re-evaluate the phylogenetic relationships within Mussaendeae; and 2) rigorously assess the the monophyly of Bremeria and the species relationships within the genus. The results of this study will be presented and discussed.
ORAL PRESENTATION
Generic delimitations in the African Pentanisia clade (Rubiaceae, Rubioideae, Knoxieae)
Elmar Robbrecht1, Steven B. Janssens1, Arne Mertens1, Brecht Verstraete1
1 Meise Botanic Garden, Meise, Belgium.
Corresponding author: Elmar Robbrecht (elmar.robbrecht@meisebotanicgarden.be)
During preparation of the treatment of the tribe Knoxieae for Flore d’Afrique centrale, we reassessed the broad circumscription of the genus Pentanisia proposed in the early 21st century. This delimitation appeared inconsistent with the aims of floristics, particularly the use of well diagnosable taxa. We therefore conducted a new molecular analysis of the Pentanisia clade and compared the subclades identified with morphological and biogeographical evidence. Verdcourt’s monograph of the 1950s, which divided Pentanisia into subgenera and sections and segregated Neopentanisia and Paraknoxia, proved largely congruent with our results. We propose to reinstate the genera Chlorochorion, Calanda, Neopentanisia, and Paraknoxia, restricting Pentanisia to Verdcourt’s subgenus Pentanisia and raising his subgenera Holocarpa and Ouranogyne to generic rank. Under this revised circumscription, all seven genera are monophyletic, with morphological support primarily derived from carpological characters.
ORAL PRESENTATION
Delineating areas of endemism for Rubiaceae in the Philippines
Jennifer Helyn R. Saladaga1, Jayson G. Chavez2,3
1 The Graduate School, University of Santo Tomas, Manila, The Philippines. 2 Department of Biological Sciences, College of Science, University of Santo Tomas, Manila, The Philippines. 3 Research Center for the Natural and Applied Sciences, University of Santo Tomas, Manila, The Philippines.
Corresponding author: Jennifer Helyn R. Saladaga (jenniferhelyn.saladaga.gs@ust.edu.ph)
The Philippines is currently recognized as one of the centres of diversity for Rubiaceae. This megabiodiverse archipelago is subdivided into 16 terrestrial ecoregions that are used to guide conservation planning at the national level. The utilization of Areas of Endemisms (AoE) facilitates the identification of spatial patterns of biodiversity, as well as to reveal regions where endemic species are highly concentrated. In this study, the species-rich Rubiaceae was used as a model to explore patterns of plant endemism in the archipelago. We utilized 3,546 georeference occurrence data for 466 endemic species of Rubiaceae (excluding incertae sedis) employing grid-based endemicity modeling at three different spatial resolutions, namely, 0.25°, 0.5°, and 1°. Our NDM/VNDM analysis resulted in several candidate AoEs across the Philippines, and were grouped into five generalized AoEs based on biogeographical context and spatial ecoregions. The recovered AoEs were supported by the presence of multiple endemic species, together with underlying environmental, geological, and climactic histories that shaped the terrestrial biodiversity of the Philippines. However, spatial comparison with the existing terrestrial ecoregions revealed variable congruence, with some of the identified AoEs were aligned to a single ecoregion, while others span multiple ecological boundaries. Although some regions were consistently determined across the three grid sizes, others were merged or fragmented depending on grid resolution, highlighting that analytical scale can influence regionalization. Nevertheless, the results emphasized the impact of biogeographical history, and environmental heterogeneity on spatial patterns of Rubiaceae in the Philippines.
ORAL PRESENTATION
The early commercial coffee cultivation in Africa: a story at the intersection of commerce and science, complemented with some reflections
Piet Stoffelen1
1 Meise Botanic Garden, Meise , Belgium.
Corresponding author: Piet Stoffelen (piet.stoffelen@meisebotanicgarden.be)
Coffea arabica L. was the first and is the most traded coffee species. Its history of distribution is amply discussed, however, with a lot of attention to the America’s but less detailed about its African origin and its successive distribution into SE Asia and back to Africa. For Coffea canephora Pierre ex A.Froehner, the second most important coffee producing species, the story telling is even less complete. Bioscience literature is only referring to its early cultivation in Uganda, or to the discovery and distribution of C. canephora, “robusta” and “Kwilu”, in the late 19th and early 20th century, and, as such, it is neglecting a long latency period of “commercial” cultivation on the African continent, preceding its distribution “out of and back to” Africa in the first decades of the 20th century. The information presented here is assembled from sources such as exploration reports, historic literature, collections, and archives. In this presentation, we summarise the information and complement the current narrative with additional information on the discovery and the cultivation of coffee in West and Central Africa in the late 18th until the early 20th century. We conclude that the “robusta story” is an illustration that botany is rather operating in the back lines than in the front lines, and it is often rather instrumental to economic interests than guiding them. This ambiguity was resulting, in the case of robusta coffee, in “taxonomic” confusion in science and coffee industry, which is continuing up to date. Finally, we warn researchers that, given that the distribution and cultivation of coffee genetic resources within its natural distribution area predates with decades the botanical exploration and documentation, we have to be very careful with the interpretation of distribution and genetic data of coffee species, such as C. liberica and C. canephora.
ORAL PRESENTATION
The Democratic Republic of Congo as a centre of wild coffee diversity: distribution, risks, and conservation needs
An-Sofie Tas1,2, Piet Stoffelen2, Jean-Léon Kambale3, Yves Hatangi2,4,5, Filip Vandelook1,2, Olivier Honnay1
1 KU Leuven, Leuven, Belgium. 2 Meise Botanic Garden, Meise, Belgium. 3 Centre de Surveillance de la Biodiversité, University of Kisangani, Kisangani, DR Congo. 4 University of Kisangani, Kisangani, DR Congo. 5 Gembloux Agro-Bio Tech, University of Liège, Liège, Belgium.
Corresponding author: An-Sofie Tas (an-sofie.tas@kuleuven.be)
The Democratic Republic of Congo (DRC) is a historically important coffee-producing country and one of the world’s major centres of wild Coffea diversity, hosting 12 indigenous species, including two endemics, C. kivuensis and C. dactylifera. As the centre of origin of cultivated Robusta coffee, the DRC holds genetic resources of global significance for coffee breeding, particularly as climate change increasingly threatens the sustainability of coffee production worldwide. Crop wild relatives (CWRs) represent valuable reservoirs of adaptive traits lost during domestication, and wild coffee species have already contributed resistance traits against major diseases. Despite this potential, information on the distribution, ecology, conservation status, and utilization potential of most wild coffee species in the DRC remains fragmented, while accelerating deforestation and habitat degradation place increasing pressure on their natural populations. This study provides a taxonomic-focused review of the wild coffee species of the DRC, aiming to: (1) document their distribution and climatic requirements; (2) conduct a preliminary country-level extinction risk assessment; (3) evaluate current conservation status through analyses of protected area coverage and exposure to deforestation; and (4) determine key priority conservation areas. By consolidating currently fragmented knowledge, this work aims to support evidence-based conservation planning and highlight priority areas for the protection of coffee genetic resources in the DRC. Given the national sovereignty framework governing plant genetic resources, country-level assessments such as this are essential for guiding conservation policy and safeguarding the adaptive genetic diversity of coffee CWRs for future breeding efforts.
ORAL PRESENTATION
A new, new view of the Rubiaceae genus Palicourea (Palicoureeae)
Charlotte M. Taylor1
1 Missouri Botanical Garden, Saint Louis, MO, USA
Corresponding author: Charlotte M. Taylor (charlotte.taylor@mobot.org)
Review of the species of Palicourea Aubl. and a new, broadly sampled molecular phylogeny show the systematics and evolutionary radiations in this diverse Neotropical genus. Palicourea is found through the Neotropics and the largest Rubiaceae lineage here, with ca 760 known species. It is notably variable morphologically, especially in the flower and inflorescence forms presumed to be adaptations for pollination. Palicourea species were previously treated in several genera based on pollination-related features we now know are homoplasious, and the genus is diagnosed by vegetative and fruit characters. Finding these main reproductive characters are homoplasious was a fundamental shift in our view of Palicourea’s evolutionary radiation. Our new phylogeny details repeated parallel radiation in apparent pollination mode (diurnal insects, nocturnal insects, hummingbirds) in nearly all the lineages, and also finds that many lineages show an overall regional distribution at a more basal level. This is the second fundamental shift in Palicourea: that its diversification into the remarkable and repeated range of species and morphological forms has, unexpectedly, often been through parallel morphological radiation within regional lineages, rather than via dispersal of a morphological innovation into other regions. And, we find several cases where plants of different regions that match a species that is morphologically clearly diagnosed have actually arisen in parallel within different lineages. Similar cases of unusual, distinctive morphological forms, apparently pollination-related, that have arisen or been somehow conserved within diversifying lineages are known in other Neotropical groups (Posoqueria, Centropogon), and understanding this evolutionary process will shed significant light on morphological and species diversification in many Neotropical plant groups.
ORAL PRESENTATION
Taxonomic advances and knowledge gaps in Malesian Rubiaceae: insights from Ophiorrhiza (Rubiaceae) and New Guinea diversity studies
Anna Trias-Blasi1, Axel H. Arriola2, Aaron P. Davis1
1 Herbarium, Royal Botanic Gardens, Kew, Richmond, UK. 2 University of the East, Manila, The Philippines.
Corresponding author: Anna Trias-Blasi (a.triasblasi@kew.org)
Ophiorrhiza is a genus of about 385 species, and its native range is tropical and subtropical Asia to the Pacific. Species of Ophiorrhiza are mostly suffrutescent herbs about 50 cm high and are characterized by obcordate, laterally compressed capsules. Species delimitation is usually challenging due to high morphological variability. An annotated checklist of the Ophiorrhiza in New Guinea was recently published recognising 32 accepted names, designating 20 lectotypes, and with 13 names considered incertae sedis due to missing type material or general lack of information. A similar study is underway for Philippine Ophiorrhiza, where preliminary results suggest 34 names being accepted, 28 lectotypes, and two neotypes designated, and one name incertae sedis. These two studies form the basis for future taxonomic and phylogenomic studies of the genus in the entirety of Malesia, to understand the diversity and evolution of this genus in the area and to produce an account for Flora Malesiana and for World Flora Online. Also underway is the assessment of diversity, endemism, and taxonomic effort of the family Rubiaceae in New Guinea. Preliminary results suggest that there are 74 genera, 783 species, and 95 infraspecific taxa. Of these, 7 (9%) are endemic genera, 627 (80%) are endemic species, and 63 (66%) are endemic infraspecific taxa. Taxonomic effort gap analysis has revealed that approximately 20% of genera have no comprehensive revision and 43% were published before the 1950s. Additionally, a key to all genera of Rubiaceae in New Guinea will be provided. Overall, this work constitutes the initial steps in creating a collaborative research program in the Malesian region for selected Rubiaceae taxa.
ORAL PRESENTATION
Update on the generic names in Rubiaceae and the context and patterns in their naming
Brecht Verstraete1, Petra De Block1, Elmar Robbrecht1
1 Meise Botanic Garden, Meise, Belgium.
Corresponding author: Brecht Verstraete (brecht.verstraete@meisebotanicgarden.be)
Rubiaceae is one of the largest and most diverse angiosperm families, yet a comprehensive overview of its generic nomenclature only became available in 2025. That study compiled and analysed all generic names published in the family, examining their classification, authorship, publication date, status, size, and etymology. Here, we present an update to that survey. A total of 1,395 generic names were identified, of which 622 are accepted and comprise about 14,300 species. Generic names range from 3 to 20 letters, with names beginning with P occurring most frequently. Nearly half of all generic names were published during the 19th century, and the average rate of description is 5 new names per year. Naming practices show a strong preference for Greek-derived names and references to plant morphology, especially reproductive characters. Eponyms have remained common throughout the family’s nomenclatural history and have become the dominant naming strategy in recent decades. Authorship patterns reveal a strong historical and ongoing predominance of male and European contributors, while women have been involved in the publication of only 62 generic names.
ORAL PRESENTATION
Understanding the morphological diversity of flowers in Rubiaceae. A floral ontogenetic approach focusing on floral cups
Alexander Vrijdaghs1, Petra De Block1
1 Meise Botanic Garden, Meise, Belgium.
Corresponding author: Alexander Vrijdaghs (alexandervrijdaghs@gmail.com)
Flowers in Rubiaceae usually have a tubular calyx, often topped with small lobes, a tubular corolla with on top corolla lobes, and epipetalous stamens. These floral cups are considered to result from meristematic fusion of the respective primordia or from postgenital fusion. In case of epipetaly, a stamen-corolla tube is formed. The length of the tubular corolla as well as the height of the insertion of the stamens are main factors for floral variation in Rubiaceae. Moreover, in several species, the tubular corolla is fenestrated. In our floral ontogenetic studies in the context of character research, we tried to understand the underlying mechanisms of the development of the floral cups, the corolla splits, and epipetaly. We found that the relative activity of three processes is important: the development of (1) a stamen-corolla tube, (2) a corolla tube sensu stricto, and (3) postgential fusion of petals (lobes). These processes, together with the relative moment of activation of each of them (plastochron variation), determine the morphology of a mature flower. Moreover, with the aid of this model, we were able to understand the apparently atypical flowers of Dialypetalanthus and to relate them with flowers in the other Rubiaceae.
POSTER
Assessing the influence of Rubiaceae on ecosystem functioning in the understory of a tropical forest
Karina Ferreira-Santos1,2, Mário Luís Garbin3,4, Filipe Torres-Leite3, Larissa Kathleen de Souza Carvalho4, Tatiana Tavares Carrijo3, André Tavares Correa Dias1
1 Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil. 2 Arcadia, Belo Horizonte, Brazil. 3 Universidade Federal do Espírito Santo, Alegre, Brazil. 4 Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Brazil.
Corresponding author: Mário Luís Garbin (mario.garbin@ufes.br)
Species richness is a key determinant of ecosystem functioning and can be assessed through litter decomposition experiments. Due to its high diversity and aggregated distribution in the understory, Rubiaceae provides an excellent model for investigating how closely related species influence ecosystem processes. We investigated how a local understory Rubiaceae community affects litter decomposition patterns along a topographic gradient. Species relative abundances were determined in 546 local aggregates of Rubiaceae individuals using circular plots with a 3 m radius, established within an 18.75 ha rectangular plot. Nine Rubiaceae species, representing 68% of the total abundance, were selected based on their abundance and distribution along the topographic gradient: three restricted to valleys, three found in valleys and slopes, one found in slopes and ridges, and two species occurring in all three topographic habitats. Three attributes were quantified: specific leaf area (SLA), leaf dry matter content (LDMC), and leaf nitrogen content (LNC). We randomly selected 86 aggregates for decomposition measurements along the gradient and then compared the decomposition of litter collected in the Rubiaceae aggregates with that collected away from the Rubiaceae aggregates. In a litter bed experiment, we compared litter decomposition among the nine species to quantify variation in decomposition rates and identify traits that determine this variation. Data were analyzed using generalized linear mixed models, boxplots, ANOVA, and linear models. Mass loss was significantly higher within Rubiaceae aggregates than outside them. It was also greater for species occurring across all topographic habitats and only in valleys, and lower for slope and ridge species. Mass loss was positively associated with SLA and negatively related to LDMC. We showed that understory Rubiaceae species influence litter decomposition in this tropical forest, and that closely related Rubiaceae species can have different effects on ecosystem functioning.
POSTER
Does genome size explain functional community patterns? A case study with Rubiaceae in the understory of a tropical forest
Geisiele S. Martins1, Luciana A. Botacim2, Karina Ferreira-Santos3, Filipe Torres-Leite1, Milene M. Praça-Fontes1, Mário Luís Garbin1, Tatiana T. Carrijo1,4
1 Universidade Federal do Espírito Santo, Alegre, Espírito Santo, Brazil. 2 Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Rio de Janeiro, Brazil. 3 Arcadis, Belo Horizonte, Minas Gerais, Brazil.
Corresponding author: Tatiana T. Carrijo (tcarrijo@gmail.com)
Genome size variation (C-value) among plant species has been identified as a determinant of individual performance. However, the effects of such individual performance at the community level in tropical forests remain to be understood. The present study aimed to investigate how genome size relates to species abundances and to functional traits reflecting conservative and acquisitive strategies in an understory Rubiaceae community. For this purpose, genome size was quantified using flow cytometry in the 11 most abundant species of the family occurring in the understory of a forest remnant. Species relative abundances were determined in 546 local aggregates of Rubiaceae individuals using 3 m circular plots within an 18.75 ha rectangular plot. C-values ranged from 0.76 pg to 7.44 pg among the analyzed species. Two matrices were constructed: one with species relative abundances and another with traits related to leaf economics and hydraulic performance, and C-values per species. We calculated community-weighted means (CWM) by multiplying the matrix of species relative abundances by the standardized matrix of species traits. On the one hand, higher C-values were associated with a conservative strategy characterized by higher leaf area and leaf dry matter content. On the other hand, smaller C-values were associated with an acquisitive strategy, characterized by higher stomata and venation densities. These findings support the hypothesis that smaller genomes are associated with a more demanding resource-use strategy, which may be driven by lower replication costs during cell division. On the other hand, larger genomes were associated with a conservative strategy due to the higher costs of cell replication. We found that both conservative and acquisitive strategies were important in explaining community-level abundance patterns. It is concluded that genome size is a relevant functional trait that helps explain community-level patterns of Rubiaceae in the Atlantic Forest.
POSTER
Micropropagation of the endangered tropical species Psychotria subspathacea (Rubiaceae)
Geisiele S. Martins1, Warley C. Silva1, Loren C. Vasconcelos1, Filipe Torres-Leite1, Milene M. Praça-Fontes1, Mário Luís Garbin1, Tatiana T. Carrijo1
1 Federal University of Espírito Santo, Alegre, Espírito Santo, Brazil.
Corresponding author: Geisiele S. Martins (geisiele.martins@edu.ufes.br)
Plant tissue culture represents an effective strategy for germplasm preservation. Micropropagative technology can be applied, for example, for plant species ex situ conservation. In this study, an in vitro cultivation protocol was established for Psychotria subspathacea Müll.Arg., an endangered species of Rubiaceae endemic to the Brazilian Atlantic Forest. Seeds were subjected to scarification and hydrogen peroxide treatment, then disinfected with 70% ethanol and sodium hypochlorite, and inoculated into ½-strength Murashige & Skoog medium (MS medium supplemented with sucrose, ascorbic acid, and agar). Organogenesis was induced from leaves and nodal segments of in vitro-germinated seedlings, using ½-strength MS medium enriched with combinations of naphthaleneacetic acid (NAA) and exogenous cytokinins 6-benzylaminopurine (BAP). After 45 days, the seeds showed 61.9% germination and 9.6% contamination, with viable seedlings at 120 days. Leaf explants exhibited progressive callogenesis without regeneration. In contrast, nodal segments cultured in medium containing 2.5 mg/L BAP showed a high multiplication rate, producing an average of 12 shoots per explant. Although the genus Psychotria is characterized by high levels of endogenous auxins, which favour callus formation, the induction of shoots in nodal segments demonstrates that the application of BAP was effective in breaking apical dominance and promoting axillary proliferation. The distinct response between explants suggests that leaf explants of P. subspathacea may exhibit sensitivity or hormonal concentrations that require a more refined balance for adventitious regeneration. These results confirm the technique’s potential for large-scale production of P. subspathacea and highlight the efficiency of nodal segments for in vitro cultivation of the species.
POSTER
Scientometric analysis of phylogenetic and phylogenomic methods in Spermacoceae (Rubiaceae)
Iane Perdigão1, Daniela C. Zappi2
1 University of Brasília, Brasília, Brazil. 2 Universidade Federal do Recôncavo da Bahia, Cruz das Almas, Brazil.
Corresponding author: Iane Perdigão (iane.unb@gmail.com)
Since the last millennium, the phylogeny of Rubiaceae has been progressively refined, particularly through the incorporation of molecular data, which have strengthened evolutionary hypotheses across different taxonomic levels. More recently, however, the transition to phylogenomic approaches has promoted a significant shift in the way evolutionary relationships are inferred. This study presents a scientometric analysis of the scientific literature on Spermacoceae (Rubiaceae), aiming to quantify and compare the representation of phylogenetic and phylogenomic approaches within the tribe. The analysis was conducted through systematic searches in the Web of Science and CAPES Periodicals databases using the descriptors “Spermacoceae + phylogenetics” and “Spermacoceae + phylogenomics”. The methodological strategy included only indexed articles containing these terms in either the title or abstract, ensuring greater specificity in the sampling process. A total of 62 records associated with phylogenetics were retrieved, spanning the period from 1995 to 2025. However, 15 of these records did not simultaneously contain both descriptor terms in the analyzed fields and were therefore excluded from the final dataset. For phylogenomics, only a single study, published in 2023, was identified, highlighting the incipient application of this approach within the group. The results show that most studies in Spermacoceae have used phylogenetic methods based on a small number of molecular markers, a tradition that originated in the 20th century and remains predominant. In contrast, phylogenomics remains largely underexplored in Spermacoceae, despite the increasing number of publications adopting this approach in other plant families in recent years. This discrepancy suggests that research on the tribe Spermacoceae is still progressing toward the methodological transformation that has redefined large-scale studies such as the Tree of Life. Expanding phylogenomic investigations within the group is therefore essential to overcome the limitations inherent to traditional approaches and to promote more robust advances in understanding its natural history.
POSTER
Phylogenomics and taxonomy of the paleotropical genus Chassalia
Lovisa Thilén1, Ian M. Turner2,3, Martin Cheek2, Sylvain G. Razafimandimbison4, Catarina Rydin1
1 Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden. 2 Herbarium, Royal Botanic Gardens, Kew, Richmond, UK. 3 Singapore Botanic Gardens, Singapore, Singapore. 4 Department of Botany, Swedish Museum of Natural History, Stockholm, Sweden.
Corresponding author: Lovisa Thilén (lovisa.thilen@su.se)
Chassalia Comm. ex Poir. (Palicoureeae, Rubioideae) consists of about 140 species with a distribution across tropical Africa, the Indian subcontinent, and Southeast Asia. The main centre of species diversity is Madagascar, harbouring about 60 species. Most species are small shrubs and treelets, but some are climbers and a few are epiphytic. Members of the genus can be distinguished from other Palicoureeae and the sister tribe Psychotrieae by its persistent, hardened stipules. Further, most of them possess fleshy, distinctly coloured inflorescence axes, sessile flowers with long, often curved, corollas, and pyrenes with a ventral excavation. Previous work has found the genus to be paraphyletic with respect to the herbaceous, pantropical Geophila D.Don.; a specimen from Borneo and a group of East African species were resolved as successive sisters to a clade comprising Geophila and Chassalia in the narrow sense. However, no taxonomic changes were made due to limited sampling of the Southeast Asian Chassalia. Here, we have expanded the sample of East African species and included most species found on the Malay Peninsula and Borneo, many of which were described in a recent revision of Chassalia in Borneo. We obtained genomic data using target capture, and inferred a species tree using coalescent methods. Our results robustly confirm the paraphyletic nature of Chassalia as currently circumscribed. All Borneo endemics and most species from the Malay Peninsula form a clade that is sister to remaining Chassalia and Geophila, followed by a clade of East African species. In order to render Chassalia monophyletic, these two groups should be segregated as separate genera. There is morphological support for the Southeast Asian group and we currently investigate morphology in the East African clade for this purpose. An alternative could be to sink Geophila in Chassalia but such a genus would probably be harder to characterise morphologically.
POSTER
A tale of two thorns: phylogenetic hypothesis to resolve the Benkara and Oxyceros conundrum (Gardenieae-Rubiaceae)
Nathaniel V. Villacorte1, Jennifer Helyn R. Saladaga2, Andrei B. Mercene1, Robbin Y. Garcia1, Jayson G. Chavez1,3
1 Department of Biological Sciences, College of Science, University of Santo Tomas, Manila, The Philippines. 2 The Graduate School, University of Santo Tomas, Manila, The Philippines. 3 Research Center for the Natural and Applied Sciences, University of Santo Tomas, Manila, The Philippines.
Corresponding author: Nathaniel V. Villacorte (nathanvillacorte04@gmail.com)
The tribe Gardenieae comprises a diverse assemblage of woody species that are distributed throughout tropical and subtropical regions. The generic boundaries within the tribe remain poorly understood due to overlapping morphological characters and limited phylogenetic studies; among these are the thorny genera Benkara and Oxyceros. In spite of their long taxonomic history, the two genera are shrouded by nomenclatural issues aside from the utilization of a limited set of characters that differentiates them. The delineation of the two genera predominantly relied on shoot architecture and thorn orientation. Furthermore, recent phylogenetic studies of Gardenieae revealed that the two genera are paraphyletic, necessitating revisiting the suite of characters that are utilized to distinguish them. This study aims to resolve the taxonomic conundrum between Benkara and Oxyceros by reconstructing the phylogeny of Gardenieae with an increased sampling of species circumscribed to the two genera based on five plastid loci (atpB-rbcL, ndhF, rbcL, rps16, and trnT-F) using probabilistic and frequentist methods. The resulting phylogenetic hypothesis supports the earlier findings of the non-monophyly of the two genera, and that thorn development and orientation appeared to have independently evolved multiple times within the group. Hence, we evaluate morphological, palynological, and karyological synapomorphies to propose the necessary nomenclatural changes to accommodate a monophyletic taxonomic entity for a linear generic classification.