Euura spiraeae (Zaddach, 1883)

Prous, Marko, Liston, Andrew, Monckton, Spencer K., Kramp, Katja, Vårdal, Hege, Vikberg, Veli, Heibo, Erik & Mutanen, Marko, 2025, West Palaearctic species of Euura Newman, 1837 (Hymenoptera, Tenthredinidae), European Journal of Taxonomy 977, pp. 1-377 : 228-230

302 Euura spiraeae (Zaddach, 1883)

Figs 88 , 315–316 , 540–541

Nematus spiraeae Zaddach, 1883 in Brischke 1883: 189. Syntypes ♀ ♂, should be in ZSM, but have not been located. Type locality: Germany, Munich area.

Pteronidea subflava Lindqvist, 1958: 100–102 . Suspected synonymy by Zhelohovcev & Zinovjev (1988) is here confirmed. Syn. nov.

Nematus dengi Wei, 2003 in Wei & Nie 2003: 54–55, 197. Holotype ♀ (CSFU), not examined. Type locality: China, Hubei, Xianfeng, Maheba. Syn. nov.

Euura spiraeae okutaniana Hara & Shinohara, 2022 in Hara et al. 2022: 10–16. Holotype ♀ (NSMT), not examined. Type locality: Japan, Honshu, Gifu Pref., Takayama, Okuhida Onsengo. Syn. nov.

Euura spiraeae hokkaido Hara & Shinohara, 2022 in Hara et al. 2022: 16. Holotype ♀ (NSMT), not examined. Type locality: Japan, Hokkaido, Utashinai, Nishiyama. Syn. nov.

Diagnosis

Females could be confused with darker specimens of the Euura ribesii group. Details of the lancet can distinguish them: basal-most annulus narrower (less than 0.5 times as long as broad) and setae longer and more hair-like in spiraeae than in the ribesii group (basal-most annulus more than 0.5 times as long as broad and setae shorter and more spine-like). Males (extremely rare in Europe) could perhaps be best recognized by the combination of ventrally pale abdomen and penis valve structure. The pterostigma varies from pale to black in females, possibly also in males.

A female identified as N. dengi in SDEI (DEI-GISHym83965) does not differ in any significant way from E. spiraeae . The lancet of DEI-GISHym83965 does seem to have longer setae than two other saws we examined from Europe ( E. spiraeae does not lack setae as implied in the original description of dengi ), but this does not seem to be sufficient evidence for the existence of an additional species. A male from China (DEI-GISHym1916) is possibly conspecific.

A male from Switzerland (DEI-GISHym14075) has a brown, rather round pterostigma, pale clypeus, supraclypeal area, pronotum and tegula; clypeus with distinct emargination; abdomen ventrally pale; projection of tergite 8 rather large (which seems to be similar in dengi DEI-GISHym1916).

The studied specimens from China (DEI-GISHym83965, DEI-GISHym1916) are darker than European specimens, with black pronotum, clypeus, and supraclypeal area (pale in most if not all European specimens). The specimens from China ( dengi ) fit best with Euura spiraeae hokkaido from Japan. Euura spiraeae okutaniana is even darker than dengi and European spiraeae , with a completely black hind tibia and apically black metafemur (at least basal two-thirds of tibia pale and metafemur nearly completely pale in dengi and European spiraeae ). The penis valve of spiraeae okutaniana, with a slight invagination between valvispina and ventroapical lobe of paravalva, does not seem to be distinguishable from the European male (DEI-GISHym14075; Fig. 540 ), but is slightly different from dengi (DEI-GISHym1916; Fig. 541 ), which lacks the invagination between valvispina and ventroapical lobe of the paravalva. However, this type of difference in penis valves does not seem likely to be reliable, because similar or greater differences are frequently found within other species of Euura . The apparent differences in the length of a cercus relative to valvula 3 (reaching at most to the middle of valvula 3 in European spiraeae according to Hara et al. 2022, but beyond the middle of valvula 3 in Japanese specimens) could be affected by preservation of the specimens (cerci tend to get retracted towards the head, away from the tip of valvula 3, as the abdomen dries). For example, in the Chinese female (DEI-GISHym83965), which otherwise fits spiraeae hokkaido, the proportional relations of cerci and valvula 3 look similar to those in European specimens ( Fig. 88A ) while European specimens can look similar to spiraeae okutaniana ( Fig. 88B ). The clearest observed differences between Japanese and European spiraeae are in the larvae. The Japanese larvae (Hara et al. al 2022) have a row of distinct lateral black spots on the abdomen or thorax and abdomen, which seem to be lacking in the European larvae. However, the parthenogenetic European spiraeae may only represent a subset of variation of a more widespread (perhaps primarily East Asian) species. Wider sampling and sequencing could help to reveal the extent of variation of E. spiraeae and whether more than one species is involved.

Type material examined

Holotype Pteronidea subflava

SWEDEN – Uppland • ♀; Stockholm, Frescati ; 59.36° N, 18.06° E; R. Malaise leg.; NHRS, NHRS-HEVA000003961 .

Host plants

Aruncus dioicus (Walter) Fernald in Europe, but also Spiraea spp. in Japan (together with Aruncus dioicus ). More than one generation per year in suitable conditions ( Pschorn-Walcher &Altenhofer 2000).

Genetics

COI

Based on 10 specimens, maximum within-species distance is 0.61% and the nearest neighbour, diverging by a minimum of 7.29%, is Euura salicis .

Nuclear

Only one sequence available, a female with haplotypes diverging by 0%. The nearest neighbour, diverging by a minimum of 4.14%, is Euura myosotidis .

Distribution and material examined

Palaearctic. Specimens studied are from China, Finland, France, Germany, and Switzerland.

Figures

Fig. 88. Euura spiraeae (Zaddach, 1883) valvula 3 in dorsal view. A. DEI-GISHym83965 (China). B. DEI-GISHym81498 (Germany).

Figs 313–316. Lancets of Euura Newman, 1837.313. poecilonota (Zaddach, 1876) DEI-GISHym21400. 314. pumilio (Konow, 1903) DEI-GISHym19767. 315. spiraeae (Zaddach, 1883) ZMUO.029419 (Finland). 316. spiraeae DEI-GISHym83965 (China).

Figs 534–545. Penis valves of Euura Newman, 1837 (534–543, 545) and Pristiphora Latreille, 1810 (544). 534. hyperborea (Thomson, 1871) DEI-GISHym31674. 535. imperfecta (Zaddach, 1876) ZMUO.030832. 536. itoi (Okutani, 1955) DEI-GISHym13850. 537. poecilonota (Zaddach, 1876) DEI- GISHym12527. 538. pumilio (Konow, 1903) DEI-GISHym31087. 539. salicis (Linnaeus, 1758) DEI- GISHym17954. 540. spiraeae (Zaddach, 1883) DEI-GISHym14075 (Switzerland). 541. spiraeae DEI- GISHym1916 (China). 542. vaga (Fabricius, 1781) DEI-GISHym13874. 543. telos Liston & Prous nom. nov. DEI-GISHym80794. 544. Pristiphora biscalis (Förster, 1854), Nematus meridionalis André, 1880, lectotype DEI-GISHym89376. 545. fagi Zaddach, 1876 DEI-GISHym13853.