The species identification problem in mirids (Hemiptera: Heteroptera) highlighted by DNA barcoding and species delimitation studies

Abstract

Due to the difficulties associated with detecting and correctly identifying mirids, developing an accurate species identification approach is crucial, especially for potential harmful species. Accurate identification is often hampered by inadequate morphological key characters, invalid and/or outdated systematics, and biases in the molecular data available in public databases. This study aimed to verify whether molecular characterization (i.e. DNA barcoding) is able to identify mirid species of economic relevance and if species delimitation approaches are reliable tools for species discrimination. Cytochrome c oxydase 1 (cox1) data from public genetic databases were compared with new data obtained from mirids sampled in different Italian localities, including an old specimen from private collection, showing contrasting results. Based on the DNA barcoding approach, for the genus Orthops, all sequences were unambiguously assigned to the same species, while in Adelphocoris, Lygus and Trigonotylus there were over-descriptions and/or misidentifications of species. On the other hand, in Polymerus and Deraeocoris there was an underestimation of the taxonomic diversity. The present study highlighted an important methodological problem: DNA barcoding can be a good tool for pest identification and discrimination, but the taxonomic unreliability of public DNA databases can make this method useless or even misleading.

Cryptic Diversity in Cladosporium cladosporioides Resulting from Sequence-Based Species Delimitation Analyses

“…Indeed, this method greatly differs from the others in terms of mean values of the C tax index, which is a measure of reciprocal congruence between methods, revealing poor delimitation performance for the considered species. These findings are in line with a previous work that suggested that the mPTP method is more conservative than GMYC [ 25 ]. Species delimitation analysis unequivocally ascribes groups F and G, as well as the singleton CPC 10142, to different species, with a 100% consensus among methods.…”

“…Apical groups (A to E) are more closely related to reference strains of C. cladosporioides , while basal groups (F and G) are less closely related to C. cladosporioides than to C. tenuissimum, C. colocasiae, C. oxysporum, C. vignae, C. angustisporum, C. subuliforme and C. cucumerinum , suggesting compromised taxonomic annotations. Indeed, group F includes two strains of C. anthropophilum and is consistently reported as a different species by all tested species delimitation methods, as well as group G. The presence in public repositories of mismatches between gene sequences and the species names assigned to the isolates from which they were obtained is frequently reported [ 24 , 25 ] and represents a source of potentially propagating errors [ 26 ]. Moreover, the development of new species delimitation methods and the fast growth of the number of described species require more efforts for maintaining and updating public databases [ 27 ].…”

Combined COI barcode‐based methods to avoid mislabelling of threatened species of deep‐sea skates

“…Currently, one of the main limitations in skate species identification appears to be the invalid and/or outdated information contained in public databases (Cerutti‐Pereyra et al ., 2012). Delimitation methods and specimen assignment approaches have proved to be helpful in solving species identification issues, especially in the presence of taxonomically difficult lineages (Piemontese et al ., 2020). In integrative taxonomic and systematic studies, species delimitation methods are increasingly applied to delineate species‐level entities and ascertain the number of species in a sample (Dellicour and Flot, 2018 and references therein).…”

Molecular Taxonomy of South Africa’s Catsharks: How Far Have We Come?

“…With limited access to taxonomic expertise, molecular taxonomy has gained recognition as an effective tool for resolving discrepancies in species boundaries [51,52]. In previous cases of ambiguous morphological classifications, molecular taxonomy has been used to aid in the description of new species [34,39,40,78,79] as well as the resurrection of synonymised species [36,38,80,81].…”

“…However, reliable specimen identification is ultimately limited to the accuracy of existing knowledge available on open-access databases such as the Barcode of Life Data System (BOLD) [46] or GenBank ® [47]. Recent studies have suggested that the use of a molecular taxonomic approach, implementing both species delimitation and specimen assignment methods, has proven beneficial for the maintenance and validation of DNA reference libraries [48][49][50][51]-especially for taxonomically difficult lineages [52,53]. As such, the aim of the current study was to review and contribute to the availability of COI and NADH2 sequences for South Africa's catsharks, comprising eight genera across two families.…”