Euura atra (Jurine, 1807), 1839

Liston, Andrew D., Heibo, Erik, Prous, Marko, Vårdal, Hege, Nyman, Tommi & Vikberg, Veli, 2017, North European gall-inducing Euura sawflies (Hymenoptera, Tenthredinidae, Nematinae), Zootaxa 4302 (1), pp. 1-115 : 57-58

Euura atra (Jurine, 1807)

Pteronus ater Jurine, 1807 : Plate 6, Fig. 9 . Described: ♀. Type locality: not mentioned, but supposedly Central Europe (Zinovjev & Vikberg 2006). Type material [not examined] thought to be lost or destroyed (Zinovjev & Vikberg 2006).

Cryptocampus ater: Brischke (1883b) .

Euura atra: Westwood (1839) .

Euura (Euura) atra (Jurine, 1807) : Viitasaari & Vikberg (1985).

Nematus (Euura) ater: Zhelochovtsev (1988) .

Nematus angustus Hartig, 1837: 222 –223. Described: ♀, ♂, recorded host: Salix viminalis . Lectotype, ♀, designated by Kopelke (1996), ZSM [examined]. Type locality: Germany, Berlin area. Syn. nov.

Euura angusta: Cameron (1885) .

Cryptocampus angustus: Konow (1890) .

Euura (Euura) angusta: Kopelke (1996) .

Euura salicicola E. A. Smith, 1879: 41 –42. Described: ♀, ♂, larva, pupa, recorded host: Salix alba . Lectotype, ♀, designated by Zinovjev & Vikberg (2006), USNM [examined]. Type locality: Peoria , Illinois [ USA]. Synonymy with E. atra by Zinovjev & Vikberg (2006).

Cryptocampus helveticus Zaddach, 1883 [in Brischke 1883b]: 205–206. Described: ♀, ♂. Syntypes in ETH Zurich [examined] . Lectotype, ♀, designated by Kopelke (2001: 192). Type locality: Gotthard [ Switzerland]: see clarification below. Synonymy with E. atra by Kopelke (2001).

Euura nigra Provancher, 1888: 346 –347. Described: ♀. Lectotype, ♀, designated by Gahan & Rohwer (1917), Laval University , Quebec [not examined]. Type locality: Cap Rouge [ Canada, Quebec]. Primary homonym of Euura orbitalis var. nigra Norton, 1867 .

Notes on types and taxonomy. The colour characters mentioned by Kopelke (1996) as distinguishing angusta from atra , are probably the result of originally black body parts fading to brown in the only adult specimens of angusta that he was able to examine (the type series). Other differences mentioned by Kopelke (1996, 2006), such as the shape of valvula 3 in lateral view, its setation, and the denser pubescence on the inner orbits, were not observed in the material examined (lectotype and eight paralectotypes of N. angustus ). Kopelke (1996) found galls on S. viminalis at only a single locality, and did not rear adults from them. The scarcity of records by other authors of the E. atra group from this willow species, and the congruence in morphology between atra and angusta , lead us to think that S. viminalis is merely a rarely used, secondary host of E. atra . We accordingly treat E. angusta as a synonym of E. atra . In designating the lectotype and a single male paralectotype of C. helveticus, Kopelke (2001) did not mention if any label data was available, such as locality. However, Zaddach [in Brischke 1883b] stated "Ich erhielt 7 Exemplare aus dem Züricher Museum durch Heer, 3♂ waren gezogen von Bremi aus Gallen vom Kattensee [Katzensee, near Zürich, Switzerland], l♂ gefangen, 2♀ und l♂ aus Gallen vom Gotthard [Switzerland]". It follows that the lectotype is from Gotthard.

Variability. Female: Body length: 3.5–5.3mm. Antennal flagellum apically extensivly pale to completely black. Tegula pale (whitish) to black. Male: 2.9–4.9mm. Female and male: all specimens examined from central and northern Europe have completely black coxae, trochanters and trochantelli. In specimens from Cyprus and Crete, these are extensively pale. The antennal hollows of the latter specimens are also markedly less sculptured, and therefore more shiny. Number of specimens examined: 35.

Genetic data. Apparently distinguishable by COI barcoding from all other species of the subgroup for which data is available. Roininen et al. (1993b) presented allozyme data which substantiate that E. atra has a rather distinctive genotype within the subgroup, and that populations on S. alba and S. × fragilis are conspecific.

Similar species. Because E. atra is found principally in climatically milder, lowland regions, often in river valleys, the species of the atra subgroup with which it is most likely to co-occur is E. salicispurpureae . Females of atra can usually be separated from salicispurpureae by the relative proportions of cerci and ovipositor sheath: see key. Other species in the subgroup have either a markedly boreo-montane distribution, or are largely restricted ( E. weiffenbachiella ) to heath or marshland habitats. Males of the atra subgroup are not morphologically separable.

Bionomics. Host plants: Salix alba , S. × fragilis ( Kopelke 1996) , S. × rubens (= alba × fragilis ) (Kopelke et al. 2003); rarely on Salix viminalis ( Hartig 1837, Kopelke 1996), with only a single record of use of this host in Fennoscandia: Norway, Nord-Trøndelag ( Fjelddalen 1992; as E. atra ). Records from " S. babylonica " (e.g. Wong et al. 1976) possibly relate to hybrids of that species with S. alba and S. × fragilis . Biology: Kopelke et al. (2003), MacCall et al. (1972), Price et al. (1997), Roininen et al. (1993b: as E. atra on S. alba and S. fragilis ), Urban (1992a).

This species usually does not form galls: larvae simply tunnel along the shoots, for a short distance ( Wong et al. 1976, Kopelke 1996, Zinovjev & Vikberg 2006).

Distribution. South, Central and North Europe, including British Isles, north to Sweden and Finland (Taeger et al. 2006). May reach Kyrgyzstan and Kazakhstan in the East ( Zhelochovtsev & Zinovjev 1995), but many earlier records require confirmation. Introduced to North America ( Wong et al. 1976). Occurrence in Sweden: published records; previous published records of E. atra from Sweden may refer to several species. Without checking voucher specimens, or if information on the host plant species is lacking, the identity of the sawfly species involved is not clear. Material examined: Öland.

Figures

FIGURES 2 – 9. Euura, females; 2 erythropyga (11264) face 3 viduata (31672) face 4 plicadaphnoides (31673) head dorsal 5 viduata (31672) head dorsal 6 leucapsis (21458) pterostigma 7 viduata (31672) pterostigma 8 a venusta (21216) ovipositor sheath 8 b glabrifrons (21437) 9 bergmanni (21407) habitus.