Helorus coruscus Haliday, 1857

Vogel, Jonathan, Sauren, Jerome & Peters, Ralph S., 2024, New evidence on the identity of the European Helorus species (Hymenoptera, Proctotrupoidea, Helorida), Biodiversity Data Journal 12, pp. e 122523-e 122523 : e122523-

Helorus coruscus Haliday, 1857 stat. rev.

Materials

Type status: Other material. Occurrence: recordedBy: GBOL III; individualCount: 1; sex: male; disposition: in collection; associatedSequences: GBHYG 1780-23; occurrenceID: 3B01B70A-65B1-5175-9B46-C835398C153A; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Hesse; municipality: Werra-Meißner-Kreis; locality: Witzenhausen, Dohrenbach, " Gut Fahrenbach " (Loc. 9) ; decimalLatitude: 51.3111; decimalLongitude: 9.8513; Event: eventID: 147; samplingProtocol: sweep net; eventDate: 2020-10 - 16; year: 1857; habitat: cow meadow next to beech forest with rich vegetation; Record Level: institutionID: ZFMK; collectionID: ZFMK-TIS- 2628160; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: Wendt, Ingo; individualCount: 1; sex: male; disposition: in collection; associatedSequences: GBHYG 2835-24; occurrenceID: 3AC99442-CD26-57CC-AFBE-43D13622FDAC; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Baden-Württemberg; municipality: Stuttgart; locality: Wilhelma, Futtergarten ; decimalLatitude: 48.804; decimalLongitude: 9.2052; Event: eventID: 165; samplingProtocol: Malaise trap; eventDate: 2014-10 - 8 / 22; year: 1857; Record Level: institutionID: ZFMK; collectionID: ZFMK-TIS- 2629307; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: ZFMK et al.; individualCount: 1; sex: male; disposition: in collection; associatedSequences: GBHYG 2947-24; occurrenceID: 8C9ADB82-0DA0-594A-B587-E345AA7F1AF5; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Rhineland-Palatinate; municipality: Ahrweiler; locality: Niederzissen, Bausenberg ; verbatimElevation: 321 m; decimalLatitude: 50.4647; decimalLongitude: 7.2222; Event: eventID: 48; samplingProtocol: Malaise trap; eventDate: 2017-7 - 14 / 20; year: 1857; habitat: MF 5. dry grassland; Record Level: institutionID: ZFMK; collectionID: ZFMK-TIS- 2629461; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: ZFMK et al.; individualCount: 1; sex: male; disposition: in collection; associatedSequences: GBHYG 2948-24; occurrenceID: 844A6D2D-4576-545F-BE3D-5009CB56E1C5; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Rhineland-Palatinate; municipality: Ahrweiler; locality: Niederzissen, Bausenberg ; verbatimElevation: 321 m; decimalLatitude: 50.4647; decimalLongitude: 7.2222; Event: eventID: 48; samplingProtocol: Malaise trap; eventDate: 2017-7 - 14 / 20; year: 1857; habitat: MF 5. dry grassland; Record Level: institutionID: ZFMK; collectionID: ZFMK-TIS- 2629462; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: ZFMK et al.; individualCount: 1; sex: male; disposition: in collection; associatedSequences: GBHYG 2949-24; occurrenceID: DC91AA40-E5CF-50A0-BF4E-E98D5E123FEA; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Rhineland-Palatinate; municipality: Ahrweiler; locality: Niederzissen, Bausenberg ; verbatimElevation: 321 m; decimalLatitude: 50.4647; decimalLongitude: 7.2222; Event: eventID: 48; samplingProtocol: Malaise trap; eventDate: 2017-7 - 14 / 20; year: 1857; habitat: MF 5. dry grassland; Record Level: institutionID: ZFMK; collectionID: ZFMK-TIS- 2629463; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: ZFMK et al.; individualCount: 1; sex: male; disposition: in collection; associatedSequences: GBHYG 2950-24; occurrenceID: D173B5C7-5F72-5EC5-B7D4-BD359ECE56E8; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Rhineland-Palatinate; municipality: Ahrweiler; locality: Niederzissen, Bausenberg ; verbatimElevation: 321 m; decimalLatitude: 50.4647; decimalLongitude: 7.2222; Event: eventID: 48; samplingProtocol: Malaise trap; eventDate: 2017-7 - 14 / 20; year: 1857; habitat: MF 5. dry grassland; Record Level: institutionID: ZFMK; collectionID: ZFMK-TIS- 2629464; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: ZFMK et al.; individualCount: 1; sex: male; disposition: in collection; associatedSequences: GBHYG 2953-24; occurrenceID: A8776A21-E78A-5C50-8259-EE57617A967B; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Rhineland-Palatinate; municipality: Ahrweiler; locality: Niederzissen, Bausenberg ; verbatimElevation: 321 m; decimalLatitude: 50.4647; decimalLongitude: 7.2222; Event: eventID: 48; samplingProtocol: Malaise trap; eventDate: 2017-7 - 14 / 20; year: 1857; habitat: MF 5. dry grassland; Record Level: institutionID: ZFMK; collectionID: ZFMK-TIS- 2629467; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: ZFMK et al.; individualCount: 1; sex: male; disposition: in collection; associatedSequences: GBHYG 2954-24; occurrenceID: 2BF9AB75-0A59-5491-AE9D-3A10D4CBFA7E; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Rhineland-Palatinate; municipality: Ahrweiler; locality: Niederzissen, Bausenberg ; verbatimElevation: 321 m; decimalLatitude: 50.4647; decimalLongitude: 7.2222; Event: eventID: 48; samplingProtocol: Malaise trap; eventDate: 2017-7 - 14 / 20; year: 1857; habitat: MF 5. dry grassland; Record Level: institutionID: ZFMK; collectionID: ZFMK-TIS- 2629468; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: ZFMK et al.; individualCount: 1; sex: male; disposition: in collection; associatedSequences: GBHYG 2955-24; occurrenceID: 42B1FBD4-4A33-55FE-A83E-B671A3977035; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Rhineland-Palatinate; municipality: Ahrweiler; locality: Niederzissen, Bausenberg ; verbatimElevation: 321 m; decimalLatitude: 50.4647; decimalLongitude: 7.2222; Event: eventID: 48; samplingProtocol: Malaise trap; eventDate: 2017-7 - 14 / 20; year: 1857; habitat: MF 5. dry grassland; Record Level: institutionID: ZFMK; collectionID: ZFMK-TIS- 2629469; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: ZFMK et al.; individualCount: 1; sex: male; disposition: in collection; associatedSequences: GBHYG 2956-24; occurrenceID: 49101134-DE11-5E41-93FD-13FDE3DB7501; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Rhineland-Palatinate; municipality: Ahrweiler; locality: Niederzissen, Bausenberg ; verbatimElevation: 321 m; decimalLatitude: 50.4647; decimalLongitude: 7.2222; Event: eventID: 48; samplingProtocol: Malaise trap; eventDate: 2017-7 - 14 / 20; year: 1857; habitat: MF 5. dry grassland; Record Level: institutionID: ZFMK; collectionID: ZFMK-TIS- 2629470; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: ZFMK et al.; individualCount: 1; sex: female; disposition: in collection; associatedSequences: GBHYG 2957-24; occurrenceID: F145997E-4523-58DC-8B87-C81CE62B8BE5; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Rhineland-Palatinate; municipality: Ahrweiler; locality: Niederzissen, Bausenberg ; verbatimElevation: 321 m; decimalLatitude: 50.4647; decimalLongitude: 7.2222; Event: eventID: 48; samplingProtocol: Malaise trap; eventDate: 2017-7 - 14 / 20; year: 1857; habitat: MF 5. dry grassland; Record Level: institutionID: ZFMK; collectionID: ZFMK-TIS- 2629471; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: ZFMK et al.; individualCount: 1; sex: male; disposition: in collection; associatedSequences: GBHYG 2958-24; occurrenceID: 3C208580-4659-53FA-8960-52C908882D5E; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Rhineland-Palatinate; municipality: Ahrweiler; locality: Niederzissen, Bausenberg ; verbatimElevation: 321 m; decimalLatitude: 50.4647; decimalLongitude: 7.2222; Event: eventID: 48; samplingProtocol: Malaise trap; eventDate: 2017-7 - 14 / 20; year: 1857; habitat: MF 5. dry grassland; Record Level: institutionID: ZFMK; collectionID: ZFMK-TIS- 2629472; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: ZFMK et al.; individualCount: 1; sex: male; disposition: in collection; associatedSequences: GBHYG 2959-24; occurrenceID: 677B3192-F88F-573B-962B-7F6020FC4027; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Rhineland-Palatinate; municipality: Ahrweiler; locality: Niederzissen, Bausenberg ; verbatimElevation: 321 m; decimalLatitude: 50.4647; decimalLongitude: 7.2222; Event: eventID: 48; samplingProtocol: Malaise trap; eventDate: 2017-7 - 14 / 20; year: 1857; habitat: MF 5. dry grassland; Record Level: institutionID: ZFMK; collectionID: ZFMK-TIS- 2629473; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: ZFMK et al.; individualCount: 1; sex: male; disposition: in collection; associatedSequences: GBHYG 2960-24; occurrenceID: A59B26A1-84B7-5C62-9119-6CEFD5ED7BE8; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Rhineland-Palatinate; municipality: Ahrweiler; locality: Niederzissen, Bausenberg ; verbatimElevation: 321 m; decimalLatitude: 50.4647; decimalLongitude: 7.2222; Event: eventID: 48; samplingProtocol: Malaise trap; eventDate: 2017-7 - 14 / 20; year: 1857; habitat: MF 5. dry grassland; Record Level: institutionID: ZFMK; collectionID: ZFMK-TIS- 2629474; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: Gilgenbach, Carolin; individualCount: 1; sex: male; disposition: in collection; associatedSequences: GBHYG 3706-24; occurrenceID: 1E9CD1E8-C093-540C-8A61-8D033E2B6987; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Rhineland-Palatinate; municipality: Alzey-Worms; locality: Wine fields north of Monsheim ; verbatimElevation: 145 m; decimalLatitude: 49.6406; decimalLongitude: 8.213699999999999; Event: eventID: 1101; samplingProtocol: Malaise trap; eventDate: 2021-8 - 5 / 24; year: 1857; habitat: shrub islands between wine fields, mostly poplars; Record Level: institutionID: ZFMK; collectionID: ZFMK-TIS- 2632746; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: Jan Soors; individualCount: 1; sex: female; disposition: in collection; associatedSequences: GBHYG 1848-23; occurrenceID: 349EA166-0AB7-5A08-96B9-68813736DF28; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Belgium; countryCode: BE; stateProvince: Antwerpen; municipality: Mechelen; decimalLatitude: 51.032; decimalLongitude: 4.488; Event: eventID: 1361; samplingProtocol: light trap; eventDate: 2017-7 - 7 / 7; year: 1857; habitat: Private garden; Record Level: institutionID: ZFMK; collectionID: ZFMK-TIS- 2635112; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: Endrestöl, Anders; individualCount: 1; sex: female; disposition: in collection; associatedSequences: no DNA barcode available; occurrenceID: C561CC85-E601-5B8A-B91B-4D9C1B8D447B; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Norway; countryCode: NO; stateProvince: Oslo; municipality: Oslo; locality: N Bleikøya ; verbatimElevation: 10 m; decimalLatitude: 59.88916; decimalLongitude: 10.74232; Event: samplingProtocol: Malaise trap; eventDate: 2008-7 / 8 - 15 / 29; year: 1857; habitat: forest edge / shore; Record Level: institutionID: NHMUIO; collectionID: http://purl.org/nhmuio/id/ea2b6743-af51-409e-bf52-e1b5213c1154; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: Gauss; individualCount: 1; sex: female; disposition: in collection; associatedSequences: no DNA barcode available; occurrenceID: DF1B1294-57D1-55AE-89C1-E8634EA016DD; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; locality: Burg Birkenhof ; Event: eventDate: 1983-10 - 13; year: 1857; Record Level: institutionID: ZFMK; collectionID: ZFMK-HYM- 00039661; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: Rheinwald; individualCount: 1; sex: female; disposition: in collection; associatedSequences: no DNA barcode available; occurrenceID: 853C2487-9071-573B-8FF7-6B9A7E6D4B63; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; locality: Plieningen ; Event: eventDate: 1962-10 - 16; year: 1857; Record Level: institutionID: ZFMK; collectionID: ZFMK-HYM- 00039662; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: Jaume-Schinkel, Santiago; individualCount: 1; sex: male; disposition: in collection; associatedSequences: no DNA barcode available; occurrenceID: 5DDB0FFD-B003-5F41-BB5D-1BB4EDA870BA; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Rhineland-Palatinate; municipality: Ahrweiler; locality: Niederzissen, Bausenberg ; verbatimElevation: 313 m; decimalLatitude: 50.4672; decimalLongitude: 7.2212; Event: eventID: 1396; samplingProtocol: double Malaise trap; eventDate: 2022-7 - 12 / 27; year: 1857; habitat: upper part of volcanic mountain, next to oak tree; Record Level: institutionID: ZFMK; collectionID: ZFMK-HYM- 00039664; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: Jaume-Schinkel, Santiago; individualCount: 1; sex: male; disposition: in collection; associatedSequences: no DNA barcode available; occurrenceID: 94091472-FC77-5565-8754-4D0190600DCC; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Rhineland-Palatinate; municipality: Ahrweiler; locality: Niederzissen, Bausenberg ; verbatimElevation: 313 m; decimalLatitude: 50.4672; decimalLongitude: 7.2212; Event: eventID: 1396; samplingProtocol: double Malaise trap; eventDate: 2022-7 - 12 / 27; year: 1857; habitat: upper part of volcanic mountain, next to oak tree; Record Level: institutionID: ZFMK; collectionID: ZFMK-HYM- 00039665; basisOfRecord: PreservedSpecimen

Type status: Other material. Occurrence: recordedBy: Jaume-Schinkel, Santiago; individualCount: 1; sex: male; disposition: in collection; associatedSequences: no DNA barcode available; occurrenceID: 4456BA83-6E82-5F92-92C7-67743FE16EED; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Location: country: Germany; countryCode: DE; stateProvince: Rhineland-Palatinate; municipality: Ahrweiler; locality: Niederzissen, Bausenberg ; verbatimElevation: 313 m; decimalLatitude: 50.4672; decimalLongitude: 7.2212; Event: eventID: 1396; samplingProtocol: double Malaise trap; eventDate: 2022-7 - 12 / 27; year: 1857; habitat: upper part of volcanic mountain, next to oak tree; Record Level: institutionID: ZFMK; collectionID: ZFMK-HYM- 00039666; basisOfRecord: PreservedSpecimen

Type status: Holotype. Occurrence: individualCount: 1; sex: male; disposition: in collection; associatedSequences: no DNA barcode available; occurrenceID: 9517A59B-323B-55F0-996C-D93D9618375B; Taxon: family: Heloridae ; genus: Helorus ; specificEpithet: coruscus ; scientificNameAuthorship: Haliday, 1857; Event: eventDate: 1882-2 - 20; year: 1857; Record Level: institutionID: NMINH; collectionID: NH: 1881.18. 1; basisOfRecord: PreservedSpecimen

CO 1 barcode

n = 16. Maximum intraspecific distance: 0.5 %. Minimum distance to closest species ( H. ruficornis ): 1.8 %. Consensus sequence (625 bp):

AATTATAGGTTTATCATTAAGAATAATTATTCGAATAGAATTAAGATCACCCAATTCTCTAATTAAAAATGATCAAATTTATAATTCAATTGTTACAATACATGCCTTTATAATAATTTTTTTTTTTATTATACCAATTACTGTTGGAGGATTTGGAAATTGATTAACACCAATAATAATAATATCCCCAGATATATCATTTCCTCGAATAAATAATTTAAGATTTTGATTTTTATTACCAAGAATCTTCTTAATAATATCAGGAAGAATTATTGATCAAGGATCAGGAACAGGATGAACAATTTATCCACCATTATCATTAAATTTAGCTCATAATGGAAAATCAGTTGATTTAACTATTTTATCTCTACATATTGCTGGAATTTCATCTATTTTAGCATCAATTAATTTTATTACAACAATTTTAAATATAAAAATTAAATCATTTAATATAGAAAAAATTAATTTATTTCTTTGATCAATACTTTTAACAACAATTTTACTTCTTCTATCTTTACCAGTTTTAGCTGGAGGAATTACAATAATTTTATCAGACCGAAATTTAAACTCTTCATTTTTTGACCCAAGAGGAGGTGGTGACCCAATTCTTTTTCAACATCTATTT

Remarks

The synonymisation of H. coruscus under H. ruficornis was proposed by Townes (1977) without examining the type of H. coruscus . He based his action on Pschorn-Walcher (1955) who had not personally seen the type of H. coruscus either (spelled H. corruscus (sic) by Pschorn-Walcher (1955)), but for his part, based his taxonomic assessments on “ Dr. Nixon, London ”. This is G. E. J. Nixon (1905-1987), an esteemed specialist on various groups of parasitoid Hymenoptera . Nixon had reported to Pschorn-Walcher that he had compared some of the material from the “ material examined ” in Pschorn-Walcher (1955) (without further indication of which specimens in particular) with the type of H. coruscus in Dublin. Based on this comparison and Nixon’s statement, Pschorn-Walcher (1955) concluded that, even though they are very similar (literally “ eng verwandt ”), H. ruficornis and H. coruscus are two separate species. How and why Townes (1977) took these considerations to formally synonymise H. coruscus under H. ruficornis is unclear. Later, Meyer (2001) in his list of Helorus species from Germany also stated that he observed morphological differences between the two species in question and, ergo, listed them both, yet without formal taxonomic action. The genetic differences and the molecular species delimitation methods we applied result in ambiguity (Fig. 2 ). Only by a combination of the results from the analyses of DNA barcode data with the morphological examination, including the primary types of both H. coruscus and H. ruficornis , are we able to take taxonomic action and formally re-instate H. coruscus from synonymy.

The two species are not easy to diagnose. The specimens examined here match the characters given by Pschorn-Walcher (1955) and Pschorn-Walcher (1971) only in part. Pschorn-Walcher (1955) does not provide a formal diagnosis of H. coruscus , but complements his additions to the description with characters to differentiate H. coruscus from H. ruficornis in his key to the species. Most importantly, he gives differences in the pterostigma index that we can corroborate. The pterostigma of H. coruscus is more robust, index 1.9–2.5 (holotype 2.1) (n = 22) (with only two specimens with a pterostigma index> 2.3) (Fig. 4 D), compared to the more elongated pterostigma of H. ruficornis (index 2.5–2.9 (holotype 2.6) (n = 6) (Fig. 5 and Fig. 7 C). The shape is comparable with the drawings of Pschorn-Walcher (1955); the range is different, though, with Pschorn-Walcher (1955) giving a pterostigma index of 2.0–2.3 for H. coruscus and 2.3–2.6 for H. ruficornis , i. e. some of his H. ruficornis would fall into the range of our H. coruscus . Additionally, Meyer (1969) gave some pterostigma values for both species, based on (a handful of) specimens from Germany, i. e. 2.1 for H. corruscus (sic) and 2.4 for H. ruficornis . Due to the low number of examined specimens, these data are of limited value, but show a more elongated pterostigma for H. ruficornis as well. The data provided by Mühlhäuser (2014), B. Sc. thesis) also show the same general difference; pterostigma index for H. coruscus (treated as a variation of H. ruficornis ) of 2.3, for H. ruficornis 2.8, based on numerous specimens from Sweden. For completeness, Van Achterberg (2006), who did not differentiate between H. coruscus and H. ruficornis , gave pterostigma index values for H. ruficornis as 2.1–2.5 and thereby reports the combined ranges of the two species. Note that the way in which different authors measured the index may differ slightly, which might explain, for example, the (minor) difference between our index ranges and those given by Pschorn-Walcher (1955). The general conclusion that H. coruscus has a more robust and H. ruficornis has a more elongate pterostigma remains valid. In addition to the pterostigma index, the following characters were used by Pschorn-Walcher (1955) to differentiate between H. coruscus and H. ruficornis . First, the length: width ratio of flagellomeres 1 and 2 (called “ Index I ” and “ Index II ” by Pschorn-Walcher (1955)) shows longer / more slender antennal segments in H. ruficornis than in H. coruscus in both sexes. The specimens examined here exhibited overlapping values, with the exception of Index I (length: width of flagellomere 1) in females (4.0– 4.2 in H. coruscus vs. 4.5–4.6 in H. ruficornis (holotype 4.6 )). The sample size, however, of n = 2 per species (Suppl. material 1) is very small. Second, antennal colour is slightly different, with H. ruficornis having a touch of red in both sexes, hence its name and H. coruscus having yellow or brown antennae ( Pschorn-Walcher 1955). Unfortunately, the holotype of H. coruscus lacks its head, including the antennae, but the fresh specimens we assigned to either species do not show any notable differences in antenna colour. Third, according to Pschorn-Walcher (1955), the hypopygium should be distinctly punctate in H. coruscus and less so in H. ruficornis . In our specimens and the respective types, we see no such distinct differences, i. e. all hypopygia are fairly distinctly punctate, with the exception of a specimen of H. ruficornis from the Förster collection ( NHMW) that is also mentioned by Pschorn-Walcher (1955). It carries a label “ type ” and was collected on 11 / 09 / 1860 (see below for a statement on the lectotype designation in H. ruficornis ). This specimen is suspiciously dull and smooth / non-punctate in the area anteriorly to the hypopygium and the hypopygium is obscured; we think this an artefact. Van Achterberg (2006) also uses hypopygium sculpture in his key, stating that, in H. ruficornis (including H. coruscus ), the female hypopygium is smooth. We cannot confirm this statement (see above). Fourth, Pschorn-Walcher (1955) gives petiole index values (shorter in H. coruscus and longer in H. ruficornis , though overlapping, petiole index = length: maximum width (measured dorsally )) which we cannot corroborate, based on our fresh specimens and the types (2.3–3.1 (3.0) (n = 18) in H. coruscus ; 2.7–3.3 (2.7) (n = 6) in H. ruficornis , see also Suppl. material 1). Finally, H. coruscus should be usually black in colour and H. ruficornis dark red-brown ( Pschorn-Walcher 1955). After examination of fresh material and types, we find no species-specific differences in body colour. Meyer (1969) imaged male genitalia of both species; these are obviously not from the (female) holotypes and, in addition, do not seem to differ distinctly. Therefore, we refrained from examining male genitalia ourselves. The morphological diagnostic characters we found to differentiate between H. coruscus and other species of Helorus , including H. ruficornis , are summarised in the identification key below.

Figures

Figure 2. 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.

Figure 4. 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.

Figure 5. Pterostigma index values in H. coruscus stat. rev. and H. ruficornis. The values of the primary types are indicated with dots next to the boxes. Graphs were created by using R, while the data points of the types were added using Inkscape.

Figure 7. Helorus ruficornis Förster, 1856 lectotype female (NHMW). A habitus lateral (image flipped vertically); B labels; C pterostigma. Scale bars: A 1000 µm, C 500 µm.