Euodynerus (Pareuodynerus) quadrifasciatus (Fabricius, 1793)

(Figs 13A–J; 14N; 15C, K)

Vespa quadrifasciata Fabricius, 1793: 266, ♂ — “Dania” (Copenhagen).

Vespa simplex Fabricius, 1793: 267 — “Kiliae” (holotype male coll. Fabricius).

Vespa quadricincta Fabricius, 1793: 266 — “Kiliae” (holotype female coll. Fabricius).

Odynerus lindenii Lepeletier, 1841: 624, ♀ — “ Environs de Paris et Montpellier” (coll. Lepeletier,? MRSN).

Odynerus tomentosus Thomson, 1870: 86, ♀, ♂ (in subgenus Lionotus) — Sweden (MZLU).

Pseudepipona sachalinensis Yasumatsu, 1938: 15, ♀ — “ Sakhaline ” (KUZC).

Euodynerus quadrifasciatus var. pseudonotata Blüthgen, 1939: 10, ♀ — “Bozen” (ZMB).

Euodynerus quadrifasciatus atripes Giordani Soika, 1976: 292, ♀ — [Korea] “Prov. Ryang-gang, Plateau Chann-Pay, Sam-ziyan, 1500 m ” (HNHM). Syn. nov.

Euodynerus quadrifasciatus rufipes Gusenleitner, 1984: 165, 166, ♀, ♂ (in subgenus Pareuodynerus) — “ Türkei, Horasan, Arastal ” (holotype male OLML [examined]). Syn. nov.

Euodynerus quadrifasciatus eburnus Yamane in Yamane & Tano 1987: 340, ♀, ♂ — “ Toyotaki, Sapporo, Hokkaidô, Japan ” (holotype female EIHU). Syn. nov.

Distribution. Trans-Palaearctic species, ranging from the Iberian Peninsula in the West to Japan in the East (Fateryga et al. 2020). The records from North-West Africa are considered doubtful.

Notes. Giordani Soika (1976) described the subspecies atripes from the Korean Peninsula, providing a very short description not allowing a precise recognition of the taxon; this subspecies was later redescribed by Kim (2012) and recorded from Japan (Yamane & Tano 1987) and Russia (Kim 2012). A male specimen from Shanxi (China) (Fig. 13D), corresponding with subspecies atripes according to the description and pictures provided by Kim (2012), was barcoded, showing a genetic distance of 5.21–6.22% from specimens ranging from Italy to Eastern Russia (Figs 13A–C), which on the other hand have an intraspecific distance of 0.00–1.07%. Interestingly, the genetic distance between E. quadrifasciatus s. str. and E. quadrifasciatus atripes is barely below the average distances between E. quadrifasciatus s. l. and E. notatus (6.15%) and E. posticus (8.52%). This distance is however not supported by any evident morphological difference, and in the phylogenetic analysis E. quadrifasciatus atripes forms with the other specimens of E. quadrifasciatus a clade supported by a bootstrap value of 99 (Fig. 10), leading to its synonymy under the nominotypical subspecies.

No specimens of the Hokkaido endemic subspecies E. quadrifasciatus eburnus were available for study, but Yamane (1990) compared it with E. quadrifasciatus atripes providing only the paler pattern as a diagnostic character, therefore it can be synonymized under the nominotypical subspecies.

Gusenleitner (1984) described the subspecies rufipes from northeast Turkey, close to the Caucasus, differentiating it from the nominotypical subspecies by narrower modified area on female vertex, weaker sculpture of male clypeus, stronger sculpture of the mesosoma and finer macropunctures on T2, in addition to the black and ivory pattern with red legs. The study of several specimens of E. quadrifasciatus ranging from Southern Europe to Asian Far East, including a paratype and pictures of the holotype of E. quadrifasciatus rufipes (Fig. 13I), however showed how these characters are variable: the modified area on female vertex ranges from as wide as ocellar triangle to much wider than it, a similarly strong sculpture of the mesosoma is observed in specimens from Italy and China, the fine macropunctures on T2 are observed in specimens from Estonia and the sculpture of male clypeus is highly variable. The different pattern also fits into a range of variability common to numerous other species of Eumeninae (e.g. Stenodynerus difficilis (Morawitz), Eumenes sareptanus André), in which specimens coming from the Caucasus or neighboring regions have ivory markings and reddish legs. Furthermore, a male specimen of E. quadrifasciatus from Dagestan, identical to the paratype of E. quadrifasciatus rufipes except for the slightly denser punctures of T2, was sequenced, showing no genetic difference from the rest of the Western Palaearctic populations. The subspecies rufipes is therefore synonymized.