Italian Odonates in the Pandora’s Box: A Comprehensive DNA Barcoding Inventory Shows Taxonomic Warnings at the Holarctic Scale

Abstract

37Freshwater macroinvertebrates, and specifically Odonata, are considered among the most 38 endangered faunal groups. Their biomonitoring has been progressively supported by DNA-39 based tools whose performance and accuracy rely on validated reference datasets that, in some 40 cases, are lacking or do not cover important biogeographical centres of diversification. 41This study reports the results of a DNA barcoding campaign on Odonata, involving the 42 collection of 812 specimens (448 of which barcoded) from Italy and its main islands (328 43 localities), belonging to the 88 species (31 Zygoptera and 57 Anisoptera) inhabiting the country. 44 Additional BOLD and GenBank data from Holarctic samples of the same taxa expanded the 45 dataset to 1294 DNA barcodes. An integrative species delimitation analysis involving two 46 distance (OT and ABGD) and four tree-based (PTP, MPTP, GMYC, bGMYC) approaches 47 identified warnings of possible taxonomic relevance. Of the 88 investigated species, 85% could 48 be successfully identified by their DNA barcodes, with damselflies showing a percentage of 49 warnings (29%) higher than dragonflies (7%), contrasting with the other available DNA 50 barcoding studies on Odonata (showing up to 95% of identification success). The species 51causing warnings were grouped in three categories depending on if they showed low, high or 52 mixed genetic divergence patterns. Moreover, for the second class of warnings, the analysis of 53 haplotypes revealed unexpected structure at the Italian, Palearctic and Holarctic scale. Overall, 54 the DNA barcoding inventory assembled in this study will provide valuable insights into the 55 systematics and conservation of many odonate species with implications for future DNA and 56 eDNA monitoring-based studies. 57 58

Distribution, autecology, genetic characterization, and conservation of the Western Mediterranean endemic dragonfly Orthetrum nitidinerve (Selys, 1841): insights from Italy

“…trinacria (Selys, 1841)), and these values are high and far above the optimal threshold (calculated on the 57 Italian Anisoptera species, of which six were Orthetrum spp.) of 1.96% found by Galimberti et al (2020).…”

“…Until recently, Orthetrum nitidinerve genetic diversity was unknown and the first sequences were produced in the framework of a COI-based comprehensive DNA barcoding survey of Italian odonates (Galimberti et al, 2020). In the present study, additional ITS sequences were generated, allowing a further characterization of the genetic diversity of the species.…”

“…The intra-specific genetic diversity of other Orthetrum species was also very low, except for a few species, in some cases already suspected to harbour cryptic taxa (e.g. Galimberti et al, 2020;Yong et al, 2014).…”

“…The first dataset (DS1) consisted of all available Orthetrum COI sequences mined from GenBank and the BOLD Systems. This dataset also includes DNA barcode sequences generated for a recent survey of Italian Odonata (Galimberti et al, 2020) and deposited as reference DNA barcode data in the BOLD Systems platform, among which two were referred to O. nitidinerve (identification numbers: ZPLOD661-20 and ZPLOD663-20, collected in Sardinia on July 2019; see specimen webpages available at https://www.boldsystems.org/index.php/MAS_Management_DataConsole?codes = ZPLOD for additional details). Sequences with insertions/deletions or shorter than 500 bp were discarded, and a total of 206 sequences belonging to 30 nominal species were assembled, including Sympetrum vulgatum (Linnaeus, 1758) as an outgroup (SM1).…”

Phylogeography of Lanius senator reveals conflicts between alpha taxonomy, subspecies ranges and genetics

“…Understanding taxonomic boundaries by assessing genetic structure and biogeographic distributions of natural populations is essential to promoting biodiversity conservation (e.g., Lohman et al 2010;Huntley et al 2019;Galimberti et al 2021), and to include phylogenetic inference and speciation dynamics in modern zoology (Degnan and Rosenberg 2009;Shi and Rabosky 2015). In birds, a growing body of literature suggests that many recognized subspecies, which were named via often subtle variations in plumage or morphology, are either poorly circumscribed in terms of geographic distribution, or are invalid when assessed via molecular methods (e.g., White et al 2013;Wojczulanis-Jakubas et al 2014;Semenov et al 2017).…”