Identification of sawflies and horntails (Hymenoptera, ‘Symphyta’) through DNA barcodes: successes and caveats

Abstract

The 'Symphyta' is a paraphyletic assemblage at the base of the order Hymenoptera, comprising 14 families and about 8750 species. All have phytophagous larvae, except for the Orussidae, which are parasitoids. This study presents and evaluates the results of DNA barcoding of approximately 5360 specimens of 'Symphyta', mainly adults, and 4362 sequences covering 1037 species were deemed of suitable quality for inclusion in the analysis. All extant families are represented, except for the Anaxyelidae. The majority of species and specimens are from Europe, but approximately 38% of the species and 13% of the specimens are of non-European origin. The utility of barcoding for species identification and taxonomy of 'Symphyta' is discussed on the basis of examples from each of the included families. A significant level of cryptic species diversity was apparent in many groups. Other attractive applications include the identification of immature stages without the need to rear them, community analyses based on metabarcoding of bulk samples and association of the sexes of adults.

North-Western Palaearctic species of Pristiphora (Hymenoptera, Tenthredinidae)

“…Still, barcodes can be used at least to identify species groups, which would need more thorough investigation based on morphology or nuclear genes. Problems in using COI barcodes for species identification are known in many other groups of sawflies, but appear to be most frequent within Nematinae (Schmidt et al 2017). Theoretical considerations (Patten et al 2015) also suggest that when interspecific hybridisation takes place in haplodiploid groups, such as Hymenoptera, mitochondrial DNA crosses species boundaries more readily than nuclear DNA.…”

“…Some of the sequences analysed here were originally published by Nyman et al (2006Nyman et al ( , 2010, Prous et al (2014Prous et al ( , 2016, and Schmidt et al (2017).…”

Pachyprotasis kojimai sp. nov.—the “Pachyprotasis nigronotata” of Japanese authors (Hymenoptera: Tenthredinidae)

“…These data were obtained in the course of the project of Schmidt et al (2016) and during the present study. The only additional data available from GenBank concern P. rapae, P. antennata, P. simulans Klug, 1817 andP.…”

“…DNA extraction and sequencing of specimens of other Pachyprotasis species with DEI-GISHym and BC ZSM HYM numbers included in the calculation of the cladogram were performed by the Canadian Centre for DNA Barcoding (CCDB) in Guelph, Canada (see Schmidt et al 2016 for details). The Pachyprotasis sequences used for the tree (Fig 5) are available in GenBank, except for the two specimens from Taiwan which are accessible through the website of Barcode of Life Data Systems (www.barcodinglife.com).…”

Big and beautiful: the Megaxyela species (Hymenoptera, Xyelidae) of East Asia and North America

“…Even more surprising in the course of this study was the discovery of a very large genetic distance (13.5%) between these species, which led to the recognition of M. langstoni as a separate species. Equally large interspecific genetic gaps have been reported for Pleroneura and Xyela by Blank et al (2013) and Schmidt et al (2017).…”