Jacopo Franzoni

Biological research relies on the use of taxa, with species expressed in the form of a Latin binomial. Although taxa are commonly regarded as established entities, they actually represent hypotheses on the distribution of natural biological variation and may change their status as new systematic knowledge becomes available. A long-standing problem affecting systematics and taxonomy, with important consequences for other biological disciplines, is that a binomial itself conveys no information about the strength of the taxonomic hypothesis it represents. Here, we introduce the concept of a standardized heuristic index, named Turrill’s Omega Index (TOI), to estimate the degree of support for a taxonomic hypothesis. Turrill’s Omega Index is a single numerical value calculated by integrating four macro-categories of comparative data: Phenotype, Genealogy, Isolation, and Geography-Ecology. Turrill’s Omega Index provides a practical and reliable framework for quantifying the support for a taxonomic hypothesis, without requiring resolution of the long-standing debate surrounding species delimitation and species concepts. Accordingly, it has the potential to represent a valuable and transformative advance in systematics and taxonomy. In addition, TOI can support conservation decision-making by helping prioritize funding allocation among equally threatened taxa according to their degree of support.

This study presents new chromosome numbers for two native Italian species: Crepis suffreniana (DC.) Steud. (Asteraceae), whose only Italian population is known for the Migliarino-San Rossore-Massaciuccoli Regional Park in Tuscany, and Dianthus furcatus Balb. subsp. furcatus (Caryophyllaceae), a taxon distributed in Italy in the western Alps. Concerning C. suffreniana , our count confirms previously published reports from France. For D. furcatus subsp. furcatus, we report a hexaploid level, contrasting with previous studies on D. furcatus s.l. from the Italian Alps, which documented only the diploid level.

The study of a country’s flora is an open-ended work influenced by environmental changes, advances in taxonomical research, and the development of new data collection methods. In Italy, floristic research has evolved from early botanical records to digital databases allowing real-time updates. This study, conducted within the Italian Botanical Society, aimed at verifying, updating and expanding knowledge on species with uncertain, extinct, or excluded status. Starting in 2021, researchers from all regions of Italy collaborated to review literature, herbarium specimens, and field data. Their efforts culminated in 839 regional-level assessments of 628 taxa, leading to 276 changes in regional status and 25 at the national level. These updates are of great significance for nature conservation efforts by confirming species presence in some regions while verifying extinctions, particularly in fragile aquatic habitats. This research also underscores the importance of botanical collections and historical records to reconstruct the history, dynamics, and current distribution of plant species, and addresses challenges such as limited access to the collections. This study is not only a milestone in Italian floristics but also provides a replicable methodology for updating national floras globally.

This study presents the first chromosome numbers for Italian populations of two species with a Euro-Mediterranean distribution: Atocion rupestre (L.) Oxelman (Caryophyllaceae) and Mantisalca duriaei (Spach) Briq. & Cavill. (Asteraceae). Both counts confirm the chromosome numbers reported for populations of the same species in other European countries.

Background: The plant nuclear genome is organized into discrete chromosomes, whose count is amongst the primary information for the description of an organism and our understanding of its differentiation and adaptation. Although species diversity is not evenly distributed across flowering plant genera, it is unknown whether the extraordinary taxonomic diversity exhibited by 86 big genera, collectively accounting for a quarter of all currently accepted angiosperm species, is supported by adequate information on chromosome numbers. Scope: Leveraging data from the Chromosome Count Database (CCDB), we assess current knowledge of chromosome counts in big plant genera. We do not have any assumption concerning the overall amount of chromosome data collectively available for these genera, but we expect that current knowledge is not complete and that it has been shaped by the main historical events influencing cytogenetics and comparative genomics during the last century. We also hypothesize that chromosome counts are limited for those genera exhibiting higher taxonomic uncertainty and geographical or biological features that hamper plant sampling and reproduction. Conclusions: Overall, the proportion of species with at least one chromosome count is low (14 %), with the temporal trend revealing an unequivocal decline in acquisition of counts after the 1990s, coinciding with advances in DNA amplification and sequencing and in molecular phylogenetics. In addition, logistic regressions confirmed our expectations that the proportion of species with chromosome count per genus is lower for genera with a tropical distribution, primarily being trees or exhibiting specialized pollination to complete sexual reproduction. Contrary to our expectations, taxonomic uncertainty exhibits a strong positive association with the availability of chromosome counts per genus. We argue that higher taxonomic uncertainty has promoted more sampling to aid the circumscription of plant species, highlighting the crucial role of chromosome variation in identifying genomic traits that have supported the diversification of big plant genera.

We present the first vascular flora of the municipality of Pisa. The floristic inventory was built on previous literature and field observations deposited in the online database Wikiplantbase #Toscana, integrated by observations from iNaturalist. The established flora of Pisa includes a total of 1404 specific and subspecific taxa (594 genera, 123 families), out of which 112 are alien species. Silene subconica is excluded from the regional flora of Tuscany, while Solanum nitidibaccatum is reported as a new regional casual alien, and the regional alien status of Salpichroa origanifolia shifts from naturalized to invasive. Native taxa exceed species-area predictions by 33.3%, attesting for a high floristic richness, and there are taxa of high biogeographical and conservation interest. However, also alien taxa exceed predictions by 34.9%, and there are many invasive species, pointing out a high anthropogenic impact in the territory of Pisa, mostly due to urbanization. The biological and chorological spectra reflect the coexistence of typical Mediterranean and central European habitats in this territory, especially within the Migliarino–San Rossore–Massaciuccoli Regional Park. The vascular flora of the municipality is quite rich, although threatened by anthropic pressures, fostering the arrival and establishment of invasive alien species.

Within a practical course of cytotaxonomy organized in Pisa (Italy) on February 2024 by the Group for Floristics, Systematics and Evolution of the Italian Botanical Society, we tested whether relevant differences in karyotype asymmetry and structure occur in four tetraploid European taxa from Paeonia sect. Paeonia (P. mascula subsp. russoi, P. officinalis subsp. huthii, P. officinalis subsp. italica, and P. peregrina). Our results point towards a homogeneous karyotype asymmetry and structure among studied tetraploid species, with no statistically significant difference among taxa and high overlap in variation highlighted by PCA.

Within a practical course of cytotaxonomy organized in Pisa (Italy) on February 2024 by the Group for Floristics, Systematics and Evolution of the Italian Botanical Society, we tested whether using image analysis softwares possible biases are still introduced by different observers. We conclude that observer bias selectively applies in possibly overestimating the length of short arms in a karyotype. As a consequence, the parameters most sensitive to these possible errors are CV_CI and CV_CL, and to a less degree M_CA and THL. To achieve more stable results among observers, a still lacking standardized measurement protocol could be helpful.

Defining species boundaries within plant groups distributed along wide elevational and geographic gradients may lead to unstable taxonomic delimitations using morphological data only. Within the taxonomically challenging genus Dianthus, through an integrative approach we tested the taxonomic value of D. brachycalyx, a putative species endemic to mountain peaks of the central‐southern Apennines, with respect to the widespread central‐Mediterranean D. virgineus. We measured 30 morphological characters in 452 individuals from 25 populations and obtained 3202 single nucleotide polymorphisms using ddRAD‐seq techniques in 394 individuals from 36 populations. For climatic niche comparison, we built a dataset of 348 occurrence points. By comparing morphometric, genetic, and climatic niche data, we showed that D. brachycalyx cannot be considered a distinct species. Morphometric separation between the two species is detectable, but high‐elevation populations of D. virgineus are similar to D. brachycalyx. Genetic analyses revealed that the genetic structure of populations of D. brachycalyx and D. virgineus is mainly shaped by isolation‐by‐distance, irrespective of their taxonomic attribution. The climatic niches of the two species are overlapping, and the niche differences are just due to different availability of climatic conditions in their ranges. Accordingly, multiple lines of evidence do not support a separation of D. brachycalyx from D. virgineus, and the former should be considered a heterotypic synonym of the latter.