Abstract

Despite recent fruitful attempts to elucidate microbial biogeography in more detail, knowledge of distribution still lags behind for dinophytes. Evolutionary phenomena, such as cryptic speciation and modification due to the environment, hamper reliable conclusions about the distribution of this important plankton group. We combined newly collected samples from the Black Sea (ten new strains from three localities) with occurrence data, which have been gathered extensively over the past decade, in order to provide the first global distribution maps of four specific ribotypes assigned to the Scrippsiella lineage (Thoracosphaeraceae, Peridiniales) collected at a total of 39 sites. They showed a wide, partly overlapping distribution and shared the presence primarily at the coastal localities. Differences in abundance of specific ribotypes were observed, but the ribotype corresponding to the globally most frequently encountered species Scrippsiella acuminata has not yet been found in the Black Sea. We discuss the significance of DNA-based records for distribution maps particularly of unicellular organisms such as dinophytes. Based on a collective approach as exemplified in our study, we may start to understand in detail the ecological basis and the dynamics of the individual colonisation/invasion events, species establishment and consequent distribution in the microbiome, all of which have been changing drastically due to the ongoing climate change.

Abstract

Centaurea solstitialis L. (yellow starthistle, Asteraceae) is a Eurasian native plant introduced as an exotic into North and South America, and Australia, where it is regarded as a noxious invasive. Changes in ploidy level have been found to be responsible for numerous plant biological invasions, as they are involved in trait shifts critical to invasive success, like increased growth rate and biomass, longer life-span, or polycarpy. C. solstitialis had been reported to be diploid (2n = 2x = 16 chromosomes), however, actual data are scarce and sometimes contradictory. We determined for the first time the absolute nuclear DNA content by flow cytometry and estimated ploidy level in 52 natural populations of C. solstitialis across its native and non-native ranges, around the world. All the C. solstitialis populations screened were found to be homogeneously diploid (average 2C value of 1.72 pg, SD = +/- 0.06 pg), with no significant variation in DNA content between invasive and non-invasive genotypes. We did not find any meaningful difference among the extensive number of native and non-native C. solstitialis populations sampled around the globe, indicating that the species invasive success is not due to changes in genome size or ploidy level.

Abstract

Background Rochefortia is a small taxon of woody plants in the Ehretiaceae (Boraginales) exhibiting coriaceous leaves with cystoliths, small whitish flowers and drupaceous fruits containing four pyrenes. It shares the dioecious sex distribution with its sister group Lepidocordia and can be delimited from the latter (and all other Ehretiaceae) by the presence of thorns. Neotropical Rochefortia is distributed over most Caribbean islands, Central America and northern South America. Twenty-eight validly published names (corresponding to twenty-one typified taxa at the species level and below) are available in Rochefortia, but the precise number of species to be accepted has been elusive before this revision. New information In the course of the present revision, 353 herbarium collections, comprising approximately 540 Rochefortia specimens, were entried into a BRAHMS data base providing information about protologues and types and retrospective georeferences if possible. Based on the combination of molecular and morphological data we propose to recognise nine species of Rochefortia, namely R. acanthophora, R. bahamensis, R. barloventensis, R. cubensis, R. cuneata, R. lundellii, R. oblongata, R. spinosa and R. stellata (the remaining nineteen validly published names are synonymised under such names). Morphological description of each species and an identification key are provided.

Abstract

Dioecious and thorny Rochefortia Sw. is a poorly known though distinct element of the Ehretiaceae comprising woody plants restricted to the Caribbean and the adjacent American mainland. The approximately ten species display a great morphological variability and overlapping taxonomic boundaries, which makes it difficult to differentiate them (particularly in the Caribbean region). We investigated the phylogenetic relationships of Rochefortia using DNA sequence data from one nuclear locus (Internal Transcribed Spacer) and three chloroplast DNA loci (rps16, trnL-trnF, trnS-trnG). The monophyly of Rochefortia was confirmed, with a sister group relationship between an American mainland clade and a Caribbean clade. The latter segregates into three, morphologically rather variable lineages, distributed either in the Lesser Antilles or in the eastern Greater Antilles or in the western Greater Antilles. Thus, geographic occurrence rather than morphology is indicative of taxonomic delimitation in Rochefortia.

Abstract

Taxonomic diversity of Neotropical Rochefortia is not completely assessed at present. We report the existence of a new species: Rochefortia barloventensis sp. nov., distributed across multiple islands of the Lesser Antilles. We provide a morphological description, a molecular diagnosis and a botanical illustration. Specimens belonging to the new species were previously assigned to Caribbean R. cuneata or to South American R. spinosa because of morphological similarity. Molecular sequence data shows a clear delimitation of the new species from all other species of Rochefortia justifying the recognition of a novel taxon.

Abstract