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

Abstract

Aquatic macroinvertebrates are a primary component of freshwater ecosystems and one of the most threatened by anthropogenic pressures. Among them, dragonflies are a charismatic group of growing scientific and social interest. However, little is known about the natural history of several species. One paradigmatic example is the declining Orthetrum nitidinerve, a Western Mediterranean endemic anisopteran. We reviewed published and new data on this species, addressing distribution, autecology, and conservation (with a focus on Italy), and provide its first genetic characterization and phylogenetic placement within the genus. In Italy, the species is known from 50 sites so far (only 17 breeding populations) located in Sardinia and Sicily (1841–2019, only 22 from 1990 onward). Records from continental Italy are due to misidentification. The flight period in Italy spans between May and September. Habitat consists of permanent freshwater (mostly helocrene sources, seepages, and small brooks), slow-flowing, shallow, with muddy bottom deposits at elevation from the sea level up to 1000 m asl. All the breeding populations are found in open and sunny landscapes, almost invariably in extensive pasturelands. The species has strongly declined in Sicily, whereas several large populations still occur in Sardinia. The major threats identified so far are agriculture and grazing intensification or abandonment and drought/source desiccation determined by water overexploitation and climate change. The first ever provided mitochondrial COI barcode and ITS nuclear sequences allowed a first tentative phylogenetic placement of the species as a sister group of the O. brunneum/O. lineostigma lineage.

Keywords:

• freshwater invertebrates
• global change
• phylogeny
• Odonata
• Sardinia
• Sicily

Acknowledgements

The authors are grateful to G. Boano (Museo Civico di Storia Naturale di Carmagnola), G. Carchini, C. D’Antonio, G. de Knijf, M. Pavesi (Museo Civico di Storia Naturale, Milano), F. Landi, N. Scatassi, and S. Surdo for sharing unpublished data, publications, and for useful comments. F. Ramazzotti and D. Magnani contributed to the genetic analyses at ZooPlantLab. Several records used for this study were derived from www.observation.org: we would like to thank the platform team. R. Improta and P. Cappelletti (Centro Musei delle Scienze Naturali, Università degli Studi di Napoli “Federico II”) kindly facilitated the control of specimens conserved in the collection “A. Costa”. GA would finally like to thank the friends of Odonata.it for constant support.

Supplemental data

Supplemental data for this article can be accessed here https://doi.org/10.1080/13887890.2020.1828194.

Supporting information

SM1. Alignment of the 206 COI sequences mined from GenBank and used to build DS1

SM2. List of the species included in DS2, with information on the specimen vouchers and GenBank accession numbers for the COI, 16S rRNA and ITS regions

SM3. Substitution models found for DS1 and DS2 according to the different information criteria. AIC = Akaike Information Criterion; AICc = corrected AIC; BIC = Bayesian Information Criterion.

SM4. Pairwise comparisons of Kimura 2-parameter genetic distance within and between Orthetrum species based on the COI region. Interspecific pairwise comparisons are reported below the diagonal whereas the corresponding standard deviations are reported above the diagonal. Intraspecific distances (± standard deviations) distances are indicated along the diagonal. Pairwise genetic distances between O. nitidinerve and other species are highlighted in yellow. n.c. = not calculable.

Availability of data and material

The dataset of the Italian occurrence and breeding sites of Orthetrum nitidinerve created for this study is available from the Figshare repository at https://doi.org/10.6084/m9.figshare.12136041.v1

Author contributions

GA conceived the idea and collected/reviewed the faunistic data. BK provided most of the unpublished data. GA and GB collected samples used for DNA analysis and revised specimens in Napoli. AG stored the biological tissues and performed the lab analyses. DM mined data from BOLD and GenBank and ran the genetic statistical analyses, with the help of AG. All authors contributed to check the final results. GA led the writing of the manuscript, supported by all authors, who critically contributed to the final version.