Different ways to obtain similar results: the development of the corolla and epipetaly in Rubieae (Rubioideae, Rubiaceae)

Background and aims – Rubieae is a tribe in the subfamily Rubioideae characterised by herbaceous plants with verticillate leaves and flowers with a rudimentary or absent calyx and a short, cup-shaped corolla. This is in contrast to the flowers of most other Rubiaceae, in which the tubular corolla is longer than the corolla lobes. Also, the description by Payer, a French 19th century pioneer of floral ontogenetic research, of the floral development in Asperula, Galium, and Rubia deviates from recent insights about the development of tubular corollas, which are based on investigations of flowers of tropical Rubiaceae. Tubular corollas are currently considered as resulting from the development of underlying annular intercalary meristems, whereas Payer explained the tubular corollas in the three taxa by postgenital fusion. We therefore tested both hypotheses in six Rubieae genera, including the three taxa studied by Payer.Methods – Floral ontogeny of ten species in six Rubieae genera based on scanning electron (SEM) and light microscopy (LM). Conclusions – Our results suggest that, in all species studied, the mature phenotype of the corolla as well as the epipetaly of the stamens is caused by a combination of three developmental processes (the development of a stamen-corolla tube, the development of a corolla tube sensu stricto, and postgenital fusion), and the relative moment of activation of each of these processes during floral development (plastochron variation or heterochrony)

Two new species of Phialiphora (Spermacoceae, Rubiaceae) exemplify drought adaptations in western Madagascar

Background – Phialiphora (Spermacoceae, Rubiaceae) is a herbaceous genus restricted to unconsolidated white sands in open spaces in dry forests in northwestern Madagascar. The genus is characterized by the semi-succulent nature of its leaves and stems, its basal leaf rosette, its head-like inflorescences subtended by large leaf-like involucrate bracts and its isostylous flowers. Hitherto, only two species were described.Methods – Classical methods of herbarium taxonomy are followed.Key results – Two new Phialiphora species, P. glabrata De Block and P. valida De Block, are described, which brings the number of species in the genus to four. The two new species differ from the two previously described species by their glabrous branches, bracts, ovaries, calyces and fruits. They are easily distinguished from each other by the shape and size of the calyx lobes. A detailed description, illustration, distribution map and preliminary conservation assessment is given for the new species, which are assessed as critically endangered. We also present a key for the genus and discuss in detail the typical branching system, the capsules and the dispersal mechanism of Phialiphora. The description of these two new species exemplifies the uniqueness of the dry vegetations on unconsolidated white sands in western Madagascar, which are characterized by a high level of endemicity

Floral ontogeny links Dialypetalanthus (Condamineeae) with the floral developmental morphology of other Rubiaceae

Background – Vegetative and fruit characters of the Amazonian genus Dialypetalanthus point to a position in Rubiaceae. However, its floral morphology is so deviant that the genus was often placed in a family of its own. Even relationships outside Gentianales were postulated. Current molecular phylogenetic studies firmly show that Dialypetalanthus belongs to Rubiaceae. Aims – This study aims to understand the idiosyncratic floral morphology in Dialypetalanthus and to compare it with the floral development in two other Condamineeae genera as well as in other Rubiaceae for which ontogenetic data are available. Material and methods – SEM and LM based floral ontogeny in Dialypetalanthus fuscescens, Mussaendopsis beccariana, and Pogonopus exsertus. Results and main conclusions – Flowers in Dialypetalanthus develop a stamen-corolla-calyx tube, which can be considered as a floral morphological link between the genus and the other Rubiaceae. The polyandrous androecium originates from an annular intercalary meristem at the adaxial side of the stamen-corolla-calyx tube

MoccaDB - an integrative database for functional, comparative and diversity studies in the Rubiaceae family

<p>Abstract</p> <p>Background</p> <p>In the past few years, functional genomics information has been rapidly accumulating on Rubiaceae species and especially on those belonging to the <it>Coffea </it>genus (coffee trees). An increasing number of expressed sequence tag (EST) data and EST- or genomic-derived microsatellite markers have been generated, together with Conserved Ortholog Set (COS) markers. This considerably facilitates comparative genomics or map-based genetic studies through the common use of orthologous loci across different species. Similar genomic information is available for e.g. tomato or potato, members of the Solanaceae family. Since both Rubiaceae and Solanaceae belong to the Euasterids I (lamiids) integration of information on genetic markers would be possible and lead to more efficient analyses and discovery of key loci involved in important traits such as fruit development, quality, and maturation, or adaptation. Our goal was to develop a comprehensive web data source for integrated information on validated orthologous markers in Rubiaceae.</p> <p>Description</p> <p>MoccaDB is an online MySQL-PHP driven relational database that houses annotated and/or mapped microsatellite markers in Rubiaceae. In its current release, the database stores 638 markers that have been defined on 259 ESTs and 379 genomic sequences. Marker information was retrieved from 11 published works, and completed with original data on 132 microsatellite markers validated in our laboratory. DNA sequences were derived from three <it>Coffea </it>species/hybrids. Microsatellite markers were checked for similarity, <it>in vitro </it>tested for cross-amplification and diversity/polymorphism status in up to 38 Rubiaceae species belonging to the Cinchonoideae and Rubioideae subfamilies. Functional annotation was provided and some markers associated with described metabolic pathways were also integrated. Users can search the database for marker, sequence, map or diversity information through multi-option query forms. The retrieved data can be browsed and downloaded, along with protocols used, using a standard web browser. MoccaDB also integrates bioinformatics tools (CMap viewer and local BLAST) and hyperlinks to related external data sources (NCBI GenBank and PubMed, SOL Genomic Network database).</p> <p>Conclusion</p> <p>We believe that MoccaDB will be extremely useful for all researchers working in the areas of comparative and functional genomics and molecular evolution, in general, and population analysis and association mapping of Rubiaceae and Solanaceae species, in particular.</p

Tarennella, a new Pavetteae (Rubiaceae) genus from eastern Madagascar

Background – This contribution is part of an ongoing study on the taxonomy and the phylogenetic relationships of the Malagasy representatives of the tribe Pavetteae (Rubiaceae).Material and methods – Taxonomic methods follow normal practice of herbarium taxonomy. A molecular study using the plastid markers rps16, trnT-F, petD, and accD-psa1, the nuclear ribosomal marker ITS and the nuclear MADS-box gene marker PI was executed.Key results – Five new species are described from littoral, lowland, or mid-elevation humid forests in eastern Madagascar. They are characterized by compact inflorescences with small, sessile flowers, a densely pubescent style, large placentas with 2–3 immersed ovules, seeds with a small, superficial hilum not surrounded by a thickened annulus, and pollen grains with supratectal elements. The phylogenetic tree, which included three of the five new species, showed an unresolved backbone but high support for distal nodes grouping species. The new species form a distinct monophyletic clade among the other Malagasy Pavetteae genera and are recognised at genus level under the name Tarennella. Provisional IUCN Red List assessments show that Tarennella homolleana is Vulnerable, T. cordatifolia and T. sanguinea are Endangered, T. puberula is Critically Endangered, and T. coronata is Critically Endangered (Possibly Extinct)

Ixora kalehensis, a new Rubiaceae species from the Democratic Republic of the Congo

Background – The rain forest genus Ixora currently comprises 37 species in Continental Africa. Within the framework of a treatment of the genus for the Flore d’Afrique centrale, a new species is described from D.R. Congo, despite its being known from only two specimens.Methods – Standard methods of herbarium taxonomy are followed.Key results – Ixora kalehensis De Block, a new species from the Central Forest District in D.R. Congo, is described and illustrated. Ixora kalehensis remains under-collected and relatively poorly known but can nevertheless easily be distinguished from other Ixora species. The most distinctive character is the colour of the dried leaves: blackish on the upper surface and vivid brown on the lower surface. Other important characters are the small-sized, compact and sessile inflorescences and the large tree habit. The species is only known from two specimens collected in the 1950s and its preliminary IUCN status is Endangered (EN B2ab(iii)). The lack of more recent herbarium material highlights that the collecting effort in D.R. Congo remains substandard. It is hoped that the formal description of Ixora kalehensis will draw attention of international and local collectors and will result in more material and greater knowledge of the species. The description of this species brings the number of Ixora species to thirteen for central Africa (D.R. Congo, Rwanda and Burundi) and to twelve for D.R. Congo. An identification key to the species of D.R. Congo is provided

Monograph of the western Indian Ocean genus Paracephaelis (Rubiaceae – Pavetteae), with description of thirteen new species

The western Indian Ocean genus Paracephaelis is revised. Sixteen species are endemic to Madagascar, 12 of which are new for science: P. aristata sp. nov., P. bardotiae sp. nov., P. capitulifera sp. nov., P. gautieri sp. nov., P. grandifructa sp. nov., P. longipedicellata sp. nov., P. orientalis sp. nov., P. pauciflora sp. nov., P. ranirisonii sp. nov., P. russata sp. nov., P. sambavensis sp. nov., and P. seyrigii sp. nov. Paracephaelis trichantha occurs on the east coast of continental Africa and on the islands of the Aldabra Group. One other species is newly described from the Comoros, P. comorensis sp. nov. Paracephaelis is characterized by sessile inflorescences, pubescent inflorescence and flower parts, ovules arranged at the periphery of the placenta, laterally flattened seeds with entire endosperm and a shallow elongate hilum, and pollen with supratectal elements. Of the Malagasy endemics, five species are assessed as Critically Endangered with P. sambavensis sp. nov. possibly Extinct in the Wild, three are Endangered, four are Vulnerable, one is Near Threatened, and three are Least Concern. Outside Madagascar, P. trichantha and P. comorensis sp. nov. are assessed as Vulnerable

Eight new species of Ixora (Ixoreae - Rubiaceae) from Madagascar

Background and aims – Ixora L. is one of the largest genera of the Rubiaceae, and badly known taxonomically. New species are described as a precursor to the author's revision of Ixora in Madagascar. Methods – Methods follow normal practice of herbarium taxonomy. Key results – Eight new Ixora species from Madagascar are recognized. Detailed descriptions, illustrations and distribution maps are provided for each species

Natural history specimens collected and/or identified and deposited.

Natural history specimen data collected and/or identified by Petra De Block, https://orcid.org/0000-0001-7210-7868. Claims or attributions were made on Bionomia, https://bionomia.net using specimen data from the Global Biodiversity Information Facility, https://gbif.org