Article 43.1 of the ICZN (1999) [Statement of the Principle of Coordination applied to genus-group names] states: “A name established for a taxon at either rank in the genus group is deemed to have been simultaneously established by the same author for a nominal taxon at the other rank in the group; both nominal taxa have the same type species, whether it was fixed originally or subsequently.” Thus, Semenov (1891: 444), when describing the nominal genus Pseudochrysis, is deemed to have described the nominal subgenus Pseudochrysis at the same time. Since all three species listed by Semenov (1891: 444) and included in the genus Pseudochrysis are unambiguously assigned to the subgenus Spintharis, the nominal subgenus Pseudochrysis was initially established with no species included.
Semenov (1891, 1892) treated Euchroeus Latreille, 1809, Spintharis Klug, 1845, Spinolia Dahlbom, 1854, Brugmoia Radoszkowski, 1877 as subgenera of his newly described genus Pseudochrysis, thus disregarding precedence of these genera upon Pseudochrysis. The way to treat the higher taxonomic ranks, such as “Tribus Chrysididae” and “Subtribus Pseudochrysidae” (Semenov 1892), appears unusual as well, considering current standards. It is to be stressed, however, that at the time Semenov published his studies, precisely codified nomenclatorial rules did not exist, and conventions and unwritten rules about it varied across disciplines, countries, and languages. At the 1st (Paris 1889) and 2nd (Moscow 1892) International Zoological Congresses, the need to establish common, widely accepted international rules for all branches of zoology was emphasized. The discussion resulted in the “International Rules on Zoological Nomenclature”, first proposed at the 3rd International Congress for Zoology (Leiden 1895) and published in three languages (French, English, and German) in 1905.
In cases in which the description of a new genus or of a new subgenus does not include any species, Article 67.2.2 of the ICZN (1999) states: “If a nominal genus or subgenus was established before 1931 without included nominal species [Art. 12], the nominal species that were first subsequently and expressly included in it are deemed to be the only originally included nominal species”. According to this statement, a nominal genus or subgenus before 1931 can have been validly established without any originally included nominal species. The nominal subgenus Pseudochrysis is therefore validly established, despite having no nominal species included in it, and the author and the date of publication of the nominal subgenus are Semenov, 1891.
Semenov (1892: 486), in the section “Enumeratio specierum generis Pseudochrysis m.”, was the first author who explicitly stated what species were to be included in Pseudochrysis (Pseudochrysis). According to Article 67.2.2 of the ICZN (1999), the species originally included in the subgenus Pseudochrysis are those, and only those, listed by Semenov (1892). He included eleven species: P. humboldti (Dahlbom, 1845), P. incrassata (Spinola, 1838), P. gratiosa (Mocsáry, 1889), P. coeruleiventris (Abeille de Perrin, 1878), P. transversa (Dahlbom, 1854), P. kohli (Mocsáry, 1889), P. marqueti (du Buysson, 1887), P. aureicollis (Abeille de Perrin, 1878), P. uniformis (Dahlbom, 1854), P. durnovi (Radoszkowski, 1866) [incorrect subsequent spelling of dournovii], and P. neglecta (Shuckard, 1837).
Semenov (1892: 485) in his paragraph “Tabula differentialis subgenerum generis Pseudochrysis m.” provided a key to the subgenera of the genus Pseudochrysis, in which he also designated a type species of each subgenus: Spintharina Semenov, 1892 (type species: Chrysis vagans Radoszkowski, 1877); Spintharis Dahlbom, 1854 (type species: Pseudochrysis (Spintharis) virgo Semenov, 1891); Brugmoja Radoszkowski, 1877 [incorrect subsequent spelling of Brugmoia] (type species: Brugmoia pellucida Radoszkowski, 1877); Euchroeus Latreille, 1809 (type species: Chrysis purpurata Fabricius, 1787); Spinolia Dahlbom, 1854 (type species: Chrysis lamprosoma Förster, 1853); Pseudochrysis Semenov, 1891 (type species: Chrysura humboldti Dahlbom, 1845); Achrysis Semenov, 1892 (type species: Chrysis unicolor Dahlbom, 1831).
Richards (1935: 158), dealing with the genus group names Spintharis Klug and Pseudochrysis Semenov, wrote: “Pseudochrysis Semenow [...] was erected for two species Spintharis (P.) virgo Semenow, 1891 and Euchroeus limbatus Dahlbom, 1854. S. virgo Sem. is here fixed as type”. This statement is in conflict with Semenov’s original description (1891) in at least two points: (1) Semenov (1891) described “Pseudochrysis (Spintharis) virgo, sp. n.” in the genus Pseudochrysis with Spintharis as subgenus, not in the genus Spintharis with Pseudochrysis as subgenus; (2) the number of species included by Semenov (1891) in the subgenus Spintharis are actually three: Pseudochrysis (Spintharis) virgo, Pseudochrysis (Spintharis) limbata (= Euchroeus limbatus), and Spintharis singularis.
It must be emphasized that Semenov (1891) unambiguously included the three species P. virgo, P. limbatus, and P. singularis in the subgenus Spintharis, not in the nominal subgenus Pseudochrysis, the latter being described with no species included. Richards’ (1935) designation is thus incompatible with Semenov’s intended classification. Semenov (1891), in the original description of the genus Pseudochrysis, did not include P. virgo in Pseudochrysis (Pseudochrysis), but in Pseudochrysis (Spintharis), and subsequently (1892) designated P. (S.) virgo as type species of the subgenus Spintharis. Given that Semenov (1892) had already designated Chrysura humboldti Dahlbom, 1845 as type species of Pseudochrysis (Pseudochrysis), Richards’ (1935) designation of P. virgo as type species of Pseudochrysis was both invalid and unnecessary.
Linsenmaier (1951: 26) adopted Richards’ (1935) interpretation of the type species of the genus Pseudochrysis, which made Pseudochrysis a junior subjective synonym of the genus Euchroeus. He realized that there was no valid name available to refer to those species by Semenov (1891, 1892) included in his subgenus Pseudochrysis. Linsenmaier (1951: 31) consequently described Pseudospinolia as a new subgenus of Euchroeus, with Chrysis uniformis Dahlbom, 1854 as type species. Pseudospinolia was raised by Bohart and Kimsey (1980) to genus rank and synonymized by Kimsey (1983) with Spinolia Dahlbom, 1854. In the most recent generic revision of the family, Kimsey and Bohart (1991) granted Pseudospinolia the rank of the genus. However, both the names Pseudospinolia and Pseudochrysis as well as the taxonomic rank have been used heterogeneously by different authors.
We investigated the use of Pseudospinolia and Pseudochrysis in more than 1,300 publications, spanning more than a century. Prior to Linsenmaier’s (1951) description of Pseudospinolia, Pseudochrysis Semenov was treated as a valid genus by the most important authors of that time. For example, Semenov’s (1892) classification was followed by Bischoff (1910, 1913, 1935), Hellén (1920, 1935), Maidl (1922), Noskiewicz (1922), Banzhaf (1930), Invrea (1930, 1933, 1935), Drogoszewski (1934), Špaček (1934, 1935), Bernard (1935), Molitor (1935), Crèvecoeur and Maréchal (1936, 1939), Grandi (1936), Berland and Bernard (1938), Atanassov (1940), Ceballos (1941); Giner Marí (ICZN 1942), Balthasar (1946, 1948), Edney (1947), Cavro (1950), Enslin (1950), and Hammer (1950). Only du Buysson (1896) considered Pseudochrysis as a synonym of Chrysis. However, Trautmann and Trautmann (1919), and Trautmann (1922, 1926, 1927) deeply modified the original interpretation given by Semenov, including in Pseudochrysis several species belonging to different species groups of the genus Chrysis Linnaeus, 1761 (C. amasina Mocsáry, 1889; C. bihamata Spinola, 1838; C. verna Dahlbom, 1854; C. pallidicornis Spinola, 1838; C. abeillei Gribodo, 1879; C. rufitarsis Brullé, 1833), based on the combination of the following characters: “mouth parts elongate over the mandible tip, forewing radial cell more or less open, apical margin of the third tergite full-rim to quadrangular. These species often resemble many species of the genus Chrysis in habitus” (Trautmann 1927: 91).
Even after Linsenmaier’s (1951) description of Pseudospinolia, the name Pseudochrysis remained in use by a significant number of authors till today: Balthasar (1952, 1953, 1954a, 1954b), Invrea (1952, 1955), Tsuneki (1953), Semenov and Nikol’skaja (1954), Fahlander (1954), Zimmermann (1954), de Beaumont (1955), Haupt (1956), Kusdas (1956, 1958), Grandi (1957, 1962), Negru (1960), Móczár (1964, 1967), Hozak and Zeman (1966), Ressl (1966), Balthasar et al. (1967), Semenov (1967), Suárez (1969), Tumšs and Maršakovs (1970), Atanassov (1972), Banaszak (1975, 1980), Kofler (1975), Berland (1976), Nikol’skaya (1978), Skibinska (1982), Zvantsov (1988), Blagoveschenskaya (1990, 1994), Doronin (1996), Kuznetzova (1990), Buganin et al. (2000), Tarbinsky (2000, 2004), Krivonogova and Rudoiskatel (2004), Vinokurov (2004, 2005, 2006), Kalniņš et al. (2007), Rudoiskatel (2007, 2008, 2011), Kochetkov et al. (2008), Brustilo and Martinov (2008), and Kochetkov (2012). In total, we found that 49 authors used the name Pseudochrysis in 51 scientific articles, either as a valid genus or as a subgenus of Spinolia. On the other hand, we found that 99 authors used the name Pseudospinolia as either a valid genus or as a subgenus of Euchroeus in 114 scientific publications. Thus, the name Pseudochrysis has been used till today, although to a lesser extent than Pseudospinolia.
The relevant type specimens of Chrysura humboldti (see Rosa and Vårdal 2015), Chrysis singularis (see Rosa and Xu 2015) and Pseudochrysis virgo (Rosa, Belokobylskij and Fedorova, in litt.) have been studied. Only the type specimen of Chrysis uniformis remained unavailable. Dahlbom’s (1854) description of Chrysis uniformis is based on a (single?) specimen from Loew’s collection, collected in Asia Minor. The first author (P. R.) unsuccessfully searched for the type in the museum collections of Copenhagen, London, Lund, Stockholm, and Vienna, where Loew’s specimens are supposedly deposited. The type of Chrysis uniformis is therefore currently thought to be lost. However, its unique morphology and coloration make Pseudochrysis uniformis an easily recognizable species. It is widespread, locally common (ranging from the Mediterranean region to Central Asia; Linsenmaier 1959; Semenov and Nikol’skaja 1954) and not known to be involved in any major taxonomic problem. We therefore currently consider a neotype designation as unnecessary.
We asked for the opinion of some current or former Commissioners on ICZN. Alberto Ballerio and the former presidents Alessandro Minelli and Denis Brothers fully support our nomenclatorial point of view; Douglas Yanega and Miguel A. Alonso Zarazaga conversely disagree on our interpretation, stating that P. humboldti was not listed in the first article (Semenov 1891) and consequently cannot be selected as type species of Pseudochrysis. It was also suggested that the chrysidologist community should find an agreement about the way to solve the case. We asked for the opinion of hymenopterists currently dealing with Chrysididae or other Hymenoptera. Michael Madl (Austria), Toshko Ljubomirov (Bulgaria), Zaifu Xu (China), David Baldock (England), Juho Paukkunen (Finland), Werner Arens and Christian Schmid-Egger (Germany), Afrouz Farhad (Iran), Gian Luca Agnoli, Guido Pagliano, Fabrizio Rigato and Marcello Romano (Italy), Eduardas Budrys and Svetlana Orlovskytė (Lithuania), Nico Schneider (Luxembourg), Frode Ødegaard (Norway), Bogdan Wiśniowski (Poland), Andrej Gogala (Slovenia), Leopoldo Castro (Spain), Alexander Berg and Mattias Forshage (Sweden), Marco Bernasconi (Switzerland), Erol Yıldırım (Turkey), and Kateryna Martynova (Ukraine) fully support our viewpoint, while Lynn S. Kimsey (U.S.A.) follows Yanega’s opinion.