Research Article |
Corresponding author: Sónia Ferreira ( hiporame@gmail.com ) Academic editor: Shaun Winterton
© 2021 Daniel Oliveira, Cátia Chaves, Joana Pinto, Joana Paupério, Nuno Fonseca, Pedro Beja, Sónia Ferreira.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Oliveira D, Chaves C, Pinto J, Paupério J, Fonseca N, Beja P, Ferreira S (2021) DNA Barcoding of Portuguese Lacewings (Neuroptera) and Snakeflies (Raphidioptera) (Insecta, Neuropterida). ZooKeys 1054: 67-84. https://doi.org/10.3897/zookeys.1054.64608
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The orders Neuroptera and Raphidioptera include the species of insects known as lacewings and snakeflies, respectively. In Portugal, these groups account for over 100 species, some of which are very difficult to identify by morphological analysis. This work is the first to sample and DNA sequence lacewings and snakeflies of Portugal. A reference collection was built with captured specimens that were identified morphologically. DNA barcode sequences of 658 bp were obtained from 243 specimens of 54 species. The results showed that most species can be successfully identified through DNA barcoding, with the exception of seven species of Chrysopidae (Neuroptera). Additionally, the first published distribution data are presented for Portugal for the neuropterans Gymnocnemia variegata (Schneider, 1845) and Myrmecaelurus (Myrmecaelurus) trigrammus (Pallas, 1771).
Cytochrome c oxidase subunit I (COI), DNA barcode, mitochondrial DNA, Portugal, taxonomy
Neuropterida is a superorder of insects which encompasses the orders Neuroptera, Raphidioptera and Megaloptera. The present work focuses on DNA barcoding of the first two orders in Portugal, while DNA barcoding of Megaloptera in the country was addressed in
The order Neuroptera includes the holometabolous insects commonly known as lacewings. With at least 6000 species worldwide, more than 300 of which occur in Europe, Neuroptera accounts for most of the diversity of the Neuropterida (
The small order Raphidioptera Latreille, 1810, groups about 260 species of insects worldwide (
The monophyly of the three orders of Neuropterida (Megaloptera as a sister group of Neuroptera + Raphidioptera) has been solidly established. Nonetheless, taxonomy of the groups is incompletely resolved and internal relationships are not yet established, despite recent studies, especially in the case of Neuroptera (
DNA barcoding was proposed in 2003 as a method to rapidly and accurately identify species (
In this work, we present a contribution to the DNA barcode library for the Portuguese species of Neuroptera and Raphidioptera representing about 50% of known species in the country, alongside new and interesting distributional data. While most species were found to be identifiable through the use of the obtained DNA barcodes, this was not true for some cases in Chrysopidae. This work was conducted within the frame of the InBIO Barcoding Initiative, which aims at producing a comprehensive DNA barcode database for the Portuguese terrestrial invertebrate biodiversity.
Specimens were collected during field expeditions throughout continental Portugal, from 2006 to 2019, and stored in 96% ethanol at the InBIO Barcoding Initiative reference collection (Vairão, Portugal). Specimens were captured during direct searches of the environment or lured by light trapping, the latter with UV LEDs or mercury vapour lamps. Morphological identification was done based on the most recent literature on Iberian Neuroptera and Raphidioptera (
For each species, we selected six specimens for DNA sequencing based on their location of capture, attempting to maximize the geographical coverage of the study. For species with less than six specimens, all were selected for sequencing.
DNA was extracted from most tissue samples using the EasySpin Genomic DNA Microplate Tissue Kit. For specimens belonging to species of smaller sizes (such as those from the Hemerobiidae and Coniopterygidae families), the QIAmp DNA Micro Kit was used, as it is designed to extract higher concentrations of genetic material from samples with small amounts of DNA.
Amplification of the DNA was performed using three different primer pairs, that amplify three overlapping fragments of the same 658 bp region of the COI mitochondrial gene. Initially, we used two primer pairs, LCO1490 (
PCRs were performed in 10 µl reactions, containing 5 µl of Multiplex PCR Master Mix (Qiagen, Hilde, Germany, 0.3 (BF2-BR2) – 0.4 mM of each primer, and 1–2 µl of DNA, with the remaining volume in water. For DNA amplification, an initial denaturation at 95 °C for 15 min was performed followed by 5 cycles at 95 °C for 30 sec, 47 °C for 45 sec, 72 °C for 45 sec (only for LC and BH); then 40 cycles at 95 °C for 30 sec, 51 °C for 45 sec (48 °C for 60 sec for BF2 + BR2), 72 °C for 45 sec; and a final elongation step at 60 °C for 10 min. DNA amplification was performed in T100 Thermal Cycler (Bio-Rad, California, USA).
All PCR products were analysed by agarose gel electrophoresis and samples selected for sequencing were then organised for assignment of sequencing ‘indexes’. One of two types of index were used for each run. For Illumina indexes, samples were pooled into one plate, as described in
Sequencing was performed at the CIBIO facilities on an Illumina MiSeq benchtop system, using a V2 MiSeq sequencing kit (2× 250 bp).
Sequences were filtered and processed with OBITools (
All DNA barcode sequences were aligned in Geneious 9.1.8. with the CLUSTALW (
An analysis of the data with the Automatic Barcode Gap Discovery (ABGD) method (
DNA barcode sequences of 658 bp were obtained for 243 specimens of Neuropterida, representing 54 of the 104 species known to occur in continental Portugal (Fig.
Neuroptera specimens were collected from 67 sampling locations, in 12 districts (Fig.
For the DNA barcode sequences of Neuroptera, average nucleotide composition is 39.4% thymine (T), 16.2% cytosine (C), 28.6% adenine (A) and 15.8% guanine (G). Base frequencies analysis revealed GC-contents of 32% for the DNA barcode fragment. Average genetic p-distances between captured species ranged from 0.46% between Pseudomallada picteti (McLachlan, 1880) and Pseudomallada flavifrons (Brauer, 1851) to 25.91% between Dilar meridionalis Hagen, 1866 and Aleuropteryx iberica Monserrat, 1977 (Suppl. material
Regarding the neighbour-joining analysis (Fig.
The ABGD method yielded partitions generally congruent with morphological identification. Nonetheless, some exceptions were noted. Regarding the Chrysopidae, the ABGD analysis yielded 15 partitions (P = 0.0055) (Fig.
Neighbour-joining tree of Hemerobiidae DNA barcode sequences. Neighbour-joining tree constructed in PAUP* 4.0a167 and contrasted with the results from the ABGD analysis and BIN attribution. Bootstrap values under 90% omitted. Subtrees were collapsed for the monophyletic morphologically identified species. Triangle size for each species is proportional to the intraspecific distance.
Similar to the other two methods used, BIN allocation using BOLD Systems yielded congruent results for most species, with some particular cases of incongruence. In Ascalaphidae, the sequences belonging to the two species of Libelloides were grouped under the same BIN. For Chrysopidae, the BIN framework clustered sequences similarly to ABGD, except for two sequences of Pseudomallada prasinus (INV10273 and INV07344), which were assigned BINs different from each other and the other sequences for the species, as well as one sequence from both Pseudomallada genei and Pseudomallada venosus which were not grouped in the same BIN as the other sequences of the same species (Fig.
DNA barcode sequences were obtained for eight specimens of Raphidioptera, accounting for three of the six species known to occur in Portugal.
Average nucleotide composition of all DNA barcode sequences of Raphidioptera was calculated as 37.2% thymine (T), 18.1% cytosine (C), 29.6% adenine (A) and 15.1% guanine (G). Base frequencies analysis revealed GC-contents of 33% for the DNA barcode fragment. Genetic distances between species ranged from 12.3% between A. maculicollis and H. castellana to 15.9% between H. laufferi and H. castellana. Intraspecific distances ranged from 0.2% in H. castellana to 1.2% in A. maculicollis (Suppl. material
The eight specimens of Raphidioptera were captured in six sampling locations in Bragança and Leiria (Fig.
In this work, DNA barcode sequences and their respective analyses, as well as novel distributional data are provided based on 235 specimens of 51 species of Neuroptera and 8 specimens of 3 species of Raphidioptera. This is the first study focusing on DNA barcoding for these orders in Portugal.
The main goal of this work was to compile a DNA barcode reference collection for the Portuguese species of Neuroptera and Raphidioptera. About 50% of the faunal diversity of the groups is represented in the collection, and DNA barcode sequences were added to the BOLD database for species hitherto unrepresented. The analyses conducted suggest that most of the encompassed species can be identified with the COI gene-based DNA barcodes. This is the case for the Ascalaphidae, Berothidae, Mantispidae, Myrmeleontidae and Nemopteridae families. For the other families, Chrysopidae and Hemerobiidae, further scrutiny is necessary.
Interestingly, despite the congruence of taxonomy and the obtained DNA barcodes for the families Ascalaphidae and Myrmeleontidae, the genetic distances and phylogenetic tree (Fig.
Regarding the Chrysopidae, the results show four groups of species with conflicting results between morphological identification, NJ and ABGD analysis, and BIN attribution. The first consists of the DNA barcode sequences belonging to P. flavifrons and P. picteti, whose sequences were recovered as a single clade (NJ) and placed by ABGD analysis into a single group. Despite possessing distinctive morphological characteristics these are closely-related species with high degree of morphological variation (
The morphospecies P. venosus and P. genei were recovered as monophyletic and ABGD considered each of the species as single units, although two different BINs were attributed to each species.
The Pseudomalla “prasinus” species complex, where P. prasinus and P. abdominalis are included, is the third group with conflicting results between NJ, ABGD and morphological analysis, and has been a subject of interest and contention in Neuropterology for over a century (
A more complex situation is that of Chrysoperla carnea, C. lucasina, C. pallida, C. agilis and C. mediterranea, in which all obtained sequences are grouped by NJ, ABGD and BIN analysis in a single unit. The five species belong to the so-called C. carnea species complex (
The analysis of the sequences obtained from Dilaridae specimens yielded the highest intra and interspecific genetic distances of all studied species. The intraspecific genetic diversity in Dilar meridionalis was 3.67% (N = 4), while the genetic distance between the D. meridionalis and D. saldubensis was 17.7%. Since previous works on DNA barcoding of Neuroptera have poorly (
The two species of Wesmaelius were separated in the NJ analysis as by morphology, though ABGD failed to recover two distinct groups. Furthermore, both the ID engine and BIN analysis in BOLD systems clearly separated the species and grouped the sequences in BINs with other sequences available in the BOLD database of the same two species. Considering these results, we suggest that COI DNA barcode sequences may be used in the identification of these two species.
Another species that presents more than one BIN is Sympherobius pygmaeus. The genetic diversity observed is congruent with previous work (
In our dataset, all species of Raphidioptera showed relatively low intraspecific divergence when compared with the respective interspecific distances. Despite the low number of DNA barcode sequences available and the absence of three of the six species in the dataset, the obtained results suggest that a DNA barcoding approach using a COI gene fragment may be used to discern between species of Portuguese Raphidioptera. This assumption is reinforced by the fact that all six species in the country belong to six different genera and are, as such, predicted to show relatively high interspecific distances between them.
For the large majority of encompassed species, DNA barcoding appears to be a reliable method of identification. While DNA barcoding cannot replace morphological taxonomy experts entirely, especially in taxa where the taxonomy still needs revision, it can aid in species identification in cases where morphology cannot be used. For example, in diet analyses, where only small body parts (or none at all) can be retrieved, using DNA barcoding may be the only method suitable for species identification, allowing the understanding of species interactions and their roles in the ecosystems.
Currently 73 species of Neuropterida present in Portugal have DNA barcoding data available, comprising the 54 species encompassed in this work and the 19 already available in the BOLD database from other countries. Nonetheless, 29 species known to occur in Portugal remain without DNA barcode available and further efforts are needed to fill this gap.
This work provides novel data on the DNA barcoding and geographical distribution of Neuroptera and Raphidioptera species in Portugal. Our results suggest that DNA barcoding using COI Folmer region may be used to identify the great majority of species of Neuroptera and Raphidioptera species recorded in the country. It is not, however, suitable for identification of several species of the Chrysopidae family. In total, there were 22 cases where the first publicly available DNA barcode sequence for a species was obtained but further sampling and sequencing efforts are still needed for many. The completion of DNA barcode databases is an ongoing effort and, in the cases of Neuroptera and Raphidioptera, still require much work, including in Europe, where several species are not yet sequenced. The future, however, looks bright as international initiatives are promoting and aiding in the development of DNA barcode sequences databases for particular regions worldwide (
InBIO Barcoding Initiative is funded by the European Union’s Horizon 2020 Research and Innovation programme under grant agreement No 668981 and by the project PORBIOTA – Portuguese E-Infrastructure for Information and Research on Biodiversity (POCI-01-0145-FEDER-022127), supported by Operational Thematic Program for Competitiveness and Internationalization (POCI), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (FEDER). SF was supported by individual research contract (2020.03526.CEECIND) funded by FCT. The fieldwork benefited from EDP Biodiversity Chair, the project “Promoção dos serviços de ecossistemas no Parque Natural Regional do Vale do Tua: Controlo de Pragas Agrícolas e Florestais por Morcegos” funded by the Agência de Desenvolvimento Regional do Vale do Tua, and includes research conducted at the Long Term Research Site of Baixo Sabor (LTER_EU_PT_002).
Summary table of all used sequences and specimens, with country of origin
Data type: Occurences and access codes to DNA barcodes
Explanation note: For captured specimens, sex, latitude and longitude coordinates (WGS 84), date of capture and IBI reference collection code (IBI) are presented. BOLD accession numbers and BINs (when available) presented for all DNA sequences used..
Genetic distances
Data type: Genetic distances between analysed specimens
Explanation note: Estimates of average genetic divergence (uncorrected p-distances) for species of Neuropterida. Values under the diagonal refer to interspecific divergence while values in the diagonal and in bold represent intraspecific divergence.