Biodiversity Data Journal :
Taxonomy & Inventories
|
Corresponding author: Jonathan Vogel (j.vogel@leibniz-lib.de), Ralph S. Peters (r.peters@leibniz-lib.de)
Academic editor: Jessica Awad
Received: 07 Mar 2024 | Accepted: 24 Apr 2024 | Published: 17 Jun 2024
© 2024 Jonathan Vogel, Jerome Sauren, Ralph Peters
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:
Vogel J, Sauren J, Peters RS (2024) New evidence on the identity of the European Helorus species (Hymenoptera, Proctotrupoidea, Heloridae). Biodiversity Data Journal 12: e122523. https://doi.org/10.3897/BDJ.12.e122523
|
Species of Helorus Latreille 1802 are rarely collected endoparasitoids of Chrysopidae larvae (Neuroptera). Previous work on the limits between the European species of this species-poor genus, based on morphology only, has left some uncertainties. Here, we approach these cases and revisit previous taxonomic decisions using freshly collected and museum material.
We generated the first large-scale Heloridae DNA barcode dataset, combined these with morphological data in an integrative taxonomic approach, and added information from studying all relevant type material. We found five species, Helorus anomalipes (Panzer, 1798), H. coruscus Haliday, 1857 stat. rev., H. nigripes Förster, 1856, H. ruficornis Förster, 1856, and H. striolatus Cameron, 1906, for which we provide an updated identification key. DNA barcode data are added to publicly available DNA barcode reference databases, for all species, except H. nigripes.
CO1 barcoding, integrative taxonomy, Helorus, species delimitation
The family Heloridae Förster, 1856 (Hymenoptera, Proctotrupoidea), includes one extant genus, Helorus Latreille, 1802, with currently 19 valid species worldwide (
In this study, we aim to contribute to our understanding of species limits in the central European species of Helorus. To achieve this, we gathered molecular sequence data from the DNA barcode region (a portion of the 5' end of the mitochondrial cytochrome oxidase 1 gene), as well as morphological data and combined them in an integrative taxonomic approach, also considering all relevant type specimens. For DNA barcoding, we collected fresh material from different regions of Germany, complemented by material from Belgium, and processed it following the established workflow of GBOL/GBOL III Dark Taxa (e.g.
So far, four species were considered valid from central Europe: Helorus anomalipes (Panzer, 1798), H. ruficornis Förster, 1856, H. striolatus Cameron, 1906, and the rare H. nigripes Förster, 1856. While H. anomalipes and H. nigripes are both easily recognised and clearly separated from all other species (
The combination of the first available DNA barcode data from a considerable number of freshly-collected specimens with morphological data of voucher and type specimens allows for some new insights into the identity of the included species. New results and the DNA barcode data deposited in publicly available reference databases (bolgermany.de/ergebnisse/results; boldsystems.org) will make these few, but fascinating species accessible for future ecological and evolutionary studies, conservation, and wider recognition in science and public.
NHMUIO - Naturhistorisk Museum, Oslo, Norway
NHMUK - Natural History Museum, London, United Kingdom
NHMW - Naturhistorisches Museum Wien, Vienna, Austria
NMINH - National Museum of Ireland – Natural History, Dublin, Ireland
RMNH - Nationaal Natuurhistorisch Museum, Leiden, Netherlands
SMNS - Staatliches Museum für Naturkunde Stuttgart, Germany
ZFMK - Museum Koenig Bonn, Germany
ZSM - Zoologisches Staatsmuseum München, Germany
We studied 49 ethanol-preserved specimens which were collected using Malaise traps, sweep netting and light traps at eight different sites in Belgium and Germany between June 2013 and August 2021. The specimens were databased with their metadata, identified to genus level, and preserved in 96% ethanol at 4°C or lower. Additional material came from museum collections, as specified in the respective material examined section.
We point-mounted (after DNA extraction, see below) the specimens and tentatively identified and sexed them according to
Maximum likelihood tree inferred with IQTree and the results of the molecular species delimitations. The first two ranks of ASAP have an identical score. The box colours show the results of the species delimitations that are either congruent (black) or incongruent (red) with our morphological examinations. The dotted lines connecting the outgroup are not to scale. Ultrafast-bootstrap support is shown on the branches.
In all morphological descriptions, we indicate values of the primary types in parentheses in the respective species treatments.
We extracted DNA from ethanol-preserved specimens at the Center for Molecular Biodiversity Research (ZMB) at the ZFMK in Bonn by following the procedures and protocols as described in
Primers used for the amplification of an abbreviated barcode region for Helorus spp. (625bp).
Primer | Direction | Sequence length | Primer sequence | Reference |
---|---|---|---|---|
Heloridae-CV-F | forward | 19 | 5’ TATTTGGAATATGAGCAGG 3’ |
|
HCO2198-JJ | reverse | 25 | 5’ AWACTTCVGGRTGVCCAAARAATCA 3’ |
|
Using IQ-TREE v.2.2.2.6 (
For the molecular characterisation of species, we analysed the distance matrix (Suppl. material
n = 3. Maximum intraspecific distance: 0.2%. Minimum distance to closest species (H. striolatus): 12.3%. Consensus sequence (625 bp):
AATTTTAGGTTTATCAATAAGAATTATTATTCGTATAGAATTAAGTTCACCAAATTCTTTAATTAATAATGATCAAATTTATAATTCTATTGTTACATTACATGCATTTATAATAATTTTTTTTTTTATTATACCAATTACTGTTGGAGGATTTGGAAATTGATTAACTCCTATAATATTAATATCACCTGATATATCATTTCCACGATTAAATAATTTTAGATTCTGACTTTTAATTCCAAGAATTTGTTTATTAACATTTAGAAGAATTAGAGATCAAGGCCCTGGAACAGGATGAACAATTTACCCACCTTTATCTCTTAACTTAAGTCATAGAGGTAAATCTGTAGATTTAACAATTTTATCCCTACATATTGCAGGAATTTCATCAATTTTAGCATCAATTAATTTTATTACAACAATTAATAATATAAAAATTAAATCATTTTTTATAGAAAAAATTAATTTATTTATTTGATCAATATTATTAACTACTATTCTATTATTAATTTCTTTACCTGTTTTAGCTGGAGGAATTACAATAATTTTATCAGATCGAAATTTAAATTCTTCATTTTTTGACCCAAGAGGAGGAGGAGACCCAATTCTCTATCAACATTTATTT
The species treatments of H. anomalipes in
n = 16. Maximum intraspecific distance: 0.5%. Minimum distance to closest species (H. ruficornis): 1.8%. Consensus sequence (625 bp):
AATTATAGGTTTATCATTAAGAATAATTATTCGAATAGAATTAAGATCACCCAATTCTCTAATTAAAAATGATCAAATTTATAATTCAATTGTTACAATACATGCCTTTATAATAATTTTTTTTTTTATTATACCAATTACTGTTGGAGGATTTGGAAATTGATTAACACCAATAATAATAATATCCCCAGATATATCATTTCCTCGAATAAATAATTTAAGATTTTGATTTTTATTACCAAGAATCTTCTTAATAATATCAGGAAGAATTATTGATCAAGGATCAGGAACAGGATGAACAATTTATCCACCATTATCATTAAATTTAGCTCATAATGGAAAATCAGTTGATTTAACTATTTTATCTCTACATATTGCTGGAATTTCATCTATTTTAGCATCAATTAATTTTATTACAACAATTTTAAATATAAAAATTAAATCATTTAATATAGAAAAAATTAATTTATTTCTTTGATCAATACTTTTAACAACAATTTTACTTCTTCTATCTTTACCAGTTTTAGCTGGAGGAATTACAATAATTTTATCAGACCGAAATTTAAACTCTTCATTTTTTGACCCAAGAGGAGGTGGTGACCCAATTCTTTTTCAACATCTATTT
The synonymisation of H. coruscus under H. ruficornis was proposed by
The two species are not easy to diagnose. The specimens examined here match the characters given by
Helorus coruscus Haliday, 1857. A-E holotype male, A habitus in lateral view; B petiole lateral (arrow indicating petiole not being distinctly swollen sub-basally in lateral view; image flipped vertically); C head frontal; D pterostigma; E labels; F female ZFMK-TIS-2629471, habitus lateral. Scale bar: A & F 1000 µm, B-D 500 µm.
Helorus nigripes Förster, 1856: 143
Helorus rugosus Thomson, 1858: 380. Lectotype designated by Pschorn-Walcher (1955)
We could only study historical material of this reportedly rare species, loaned from the RMNH. The specimen shows the distinct coarse reticulation on head and mesosoma (Fig.
Helorus ruficornis Förster, 1856: 143
Helorus flavipes Kieffer, 1907: 267
n = 4. Maximum intraspecific distance: 0.5%. Minimum distance to closest species (H. coruscus): 1.8%. Consensus sequence (625 bp):
AATTATAGGTTTATCATTAAGAATAATTATTCGAATAGAATTAAGATCACCCAATTCACTAATTAAAAATGATCAAATTTATAATTCAATTGTTACAATACATGCATTTATAATAATTTTTTTTTTTATTATACCAATTACTGTTGGAGGATTTGGAAATTGATTAACACCAATAATAATAATATCCCCAGATATATCATTTCCTCGAATAAATAATTTAAGATTTTGATTTTTAGTACCAAGAATCTTTTTAATAATATCAGGAAGAATTATTGACCAAGGATCAGGAACAGGATGAACAATTTATCCCCCATTATCATTAAATTTAGCTCATAATGGAAAATCAGTTGATTTAACTATTTTATCTCTTCATATTGCTGGAATTTCATCTATTTTAGCATCAATTAATTTTATTACAACAATTATTAATATAAAAATTAAATCATTTAATATAGAAAAAATTAATTTATTTCTTTGATCAATACTTTTAACAACAATTTTACTTCTTCTATCTTTACCAGTTTTAGCAGGAGGAATTACAATAATTTTATCAGACCGAAATTTAAACTCTTCATTTTTTGACCCAAGAGGAGGKGGKGATCCAATCCTTTTTCAACATCTATTT
A full list of synonyms was recently given by
The four specimens of H. ruficornis examined herein are very similar to the lectotype of H. ruficornis from NHMW. Note that the lectotype designation was done by
Helorus striolatus Cameron, 1906: 98
Helorus meridionalis Pschorn-Walcher, 1955: 247
n = 26. Maximum intraspecific distance: 0.3%. Minimum distance to closest species (H. anomalipes): 12.3%. Consensus sequence (625 bp):
AATTATTGGTCTTTCAATAAGATTAATTATTCGAATAGAATTAAGTTCTCCTGGATCATTAATTAAAAATGATCAAATTTATAATTCTTTTGTTACTTTACATGCTTTCTTAATAATTTTTTTTTTTATTATACCAATTACTGTTGGAGGTTTTGGAAATTGATTAACACCAATAATATTAATAACCCCAGATATATCATTTCCACGAATAAATAATTTAAGATTTTGATTATTAATCCCTAGAATTTCTTTAATATTATTTAGAAGAATTAGAGATCAAGGTCCAGGAACAGGATGAACAATTTACCCACCTTTATCATTAAATTTAAGTCATAGAGGTAAAGCAGTTGATTTAACAATTTTATCACTTCATATTGCAGGAATTTCTTCAATTTTAGCCTCAATTAATTTCATTACTACAATTTTAAATATAAAAATTAAATCTTTCTCTATTGAAAAAATTAATTTATTTTTATGATCAATACTTTTAACTACAATTTTATTATTAATCTCTTTACCAGTATTAGCTGGAGGAATCACTATAATTTTATTTGATCGAAATATAAATTCTTCATTTTTTGATCCAAGAGGAGGAGGAGATCCAATCCTTTATCAACATCTATTT
H. striolatus can be separated from all other species by the combination of a slender petiole, a long pterostigma, and darker legs (see
The colouration of the legs is lighter in the H. striolatus type than in the H. meridionalis type, but these are only subtle colouration differences that are hardly useful for species delimitation.
Helorus striolatus Cameron, 1906 and its synonym H. meridionalis Pschorn-Walcher, 1955. A-D Helorus striolatus Cameron, 1906: A holotype male habitus dorsal; B holotype labels; C holotype habitus lateral; D male ZFMK-TIS-2632620 habitus lateral. E-F Helorus meridionalis Pschorn-Walcher, 1955: E holotype female habitus lateral (image flipped vertically); F holotype labels; G label of additional specimen on same pin as H. meridionalis holotype (also visible in E). Scale bars 1000 µm.
Key to central European species of Helorus (male and female) |
||
1 | Petiole robust [petiole length:width in dorsal view (= petiole index) ≤ 2.3] and swollen sub-basally in lateral view (Fig. |
2 |
– | Petiole more slender (petiole index ≥ 2.3) and not distinctly swollen sub-basally in lateral view (Fig. |
3 |
2 | With distinct coarse reticulation on head and mesosoma (Fig. |
H. nigripes |
– | Without distinct coarse reticulation on head and mesosoma (Fig. |
H. anomalipes |
3 | Fore- and mid-legs entirely yellow (except black coxae) (Fig. |
4 |
– | Fore- and mid-legs darkened at coxae, trochanters and at least the base of femura (rest yellow) (Fig. |
H. striolatus |
4 | Pterostigma shorter (pterostigma index ≤ 2.5, usually ≤ 2.3, Fig. |
H. coruscus |
– | Pterostigma longer (pterostigma index ≥ 2.5, Fig. |
H. ruficornis |
All European species of the genus Helorus are represented in the studied material. No fresh material of H. nigripes was available to us for sequencing and the species is, hence, not included in the DNA barcode data and analyses. In total, 49 DNA barcode sequences were obtained and 67 specimens were examined morphologically.
The analyses of DNA barcode data imply the presence of three to four species in our material. The ASAP analysis resulted in two partitions with an identical score (1.5). Both partitions are implemented in Fig.
We ultimately based our species delimitations for the species treatments on an integration of both automated molecular species delimitation and morphological examination. We recognise four species within the DNA barcoded material (Fig.
The four clusters/species differ from each other in their DNA barcode sequence. Helorus coruscus and H. ruficornis differ distinctly from the other two clusters/species, by a minimum of 12.5%. Helorus anomalipes and H. striolatus are clearly separated from each other by a minimum 12.3% difference. All 26 specimens of the H. striolatus cluster are genetically identical, although from two different locations. The difference between H. coruscus and H. ruficornis is smaller than the other interspecific differences in the dataset, with a minimum of 1.8% and a maximum of 2.4%.
For more details on the species delimitation, also including the fifth species H. nigripes, see the respective treatments and the identification key.
Helorus is a species-poor genus, but even these can harbour persistent taxonomic problems. Matters are further complicated by the comparative rarity of all included species which leads to small series available for taxonomic studies, both in fresh collections as well as in museum collections, even for the central European region. The addition of the first large-scale DNA barcode sequence data and the examination of the type specimens was key to our contribution and we are confident that we were able to add some clarity and enable future studies on this group of wasps. In fact, helorids have been studied neither in an evolutionary, nor an ecological or conservation context. So far, they have shared the fate of many “Dark Taxa” (sensu
The Federal Ministry of Education and Research of Germany (Bundesministerium für Bildung und Forschung, BMBF) funds the project “GBOL III: Dark Taxa” as Research for Sustainable Development (Forschung für Nachhaltige Entwicklung, FONA; www.fona.de) under the funding reference 16LI1901A-E.
We thank our reviewers Zachary Lahey and Norman Johnson for their productive comments on the manuscript as they helped us to significantly improve the manuscript.
We are grateful to Theo Peeters and the curational staff at the RMNH for organising the gracious loan of the Helorus specimens that were included in the work of Van Achterberg (2006).
We are indebted to Tanja Schweizer, Dominique Zimmermann, Joseph Monks, Stefan Schmidt, Lars Ove Hansen, and Aidan O’Hanlon for making the types and other specimens accessible to us via loan or imaging. Especially Aidan O’Hanlon who provided invaluable help to locate the type specimen of H. coruscus.
We thank Cristina Vasilita for providing us with the then unpublished new primer, suitable to amplify the Helorus DNA barcode region.
We are thankful to Carolin Gilgenbach (with the valuable help of Gerd Reder), Fons Verheyde, Wouter Dekoninck, and Santiago Jaume Schinkel for providing the majority of fresh specimens used in this study.
We want to thank Sophie Smith and Roy Canty for providing invaluable linguistic comments on our manuscript that helped us to improve its quality considerably.
Last, but not least, we want to express our deepest gratitude to the staff members of the molecular lab at the ZFMK and the GBOL team, most notably Vera Rduch, Jana Thormann, Björn Müller, and Björn Rulik, for their diligent work to pave the way for our findings.
Measurements of petiole index, pterostigma index and flagellomere 1 and 2 indices.
Listing all specimens used in the molecular analysis with identity, specimen ID, BOLD ID, barcode sequence length and their use as either out- or ingroup.
Distance matrix of the CO1 barcode sequences.