Nematus vitreipennis Nematus (Pristiphora) ruficornis var. leucopus Nematus vitreipennis P. leucopus Nematus vitreipennis Pristiphora leucopus North-Western Palaearctic species of the Pristiphora ruficornis group (Hymenoptera, Tenthredinidae) Prous, Marko Vikberg, Veli Liston, Andrew Kramp, Katja Journal of Hymenoptera Research 2016 2016-08-29 51 1 54 8CE586A4-BB90-5002-AC96-84E15C5AAC7B (Hellen, 1948) Hellen 1948 Hellen 1948 Insecta Tenthredinidae Pristiphora CoL Animalia Pristiphora leucopus Hymenoptera 23 24 Arthropoda species leucopus   Nematus vitreipennisEversmann in Kawall, 1864: 295, syn. n. Nomen oblitum. Note. Kawall (1864)published an unaltered manuscript from Eversmann'slegacy. Lectotype ♀ (DEI-GISHym30027; here designated) in ZIN, examined. Type locality: foothills of Ural mountains [In promontor. Uralensibus], Russia.  Nematus (Pristiphora) ruficornis var. leucopus Hellen, 1948: 116. Nomen protectum. No syntypes were found in MZH. Type locality: Joutseno, South-Eastern Finland, Finland and Pionerskoye [ Kuolemajaervi], Leningrad Oblast, Russia. Note. The lectotype of Nematus vitreipennis(which was the only specimen found under this name in Eversmann'scollection in ZIN) agrees well with the summer morph (completely pale metafemur) of P. leucopus( Grearson and Liston 2012). The name Nematus vitreipennishas apparently not been used as valid since 1884 ( Brischke 1884), whereas Pristiphora leucopushas been used as the valid name for this taxon more than 25 times by more than 10 different authors since 1955 ( Lindqvist 1955). According to Article 23.9.1 ( ICZN 1999), the prevailing usage must be maintained.  Similar species. The most similar species to  P. leucopusis  P. armata. Differences between these two species were extensively discussed by Grearson and Liston (2012). Whereas  P. leucopusexhibits seasonal dimorphism of adults, involving leg colour and shape of the serrulae of the lancet, no such dimorphism has been observed in  P. armata. Briefly, both male and female specimens which have a completely or nearly completely pale metafemur (Fig. 22) can be distinguished from  P. armata(metafemur of which is always completely or in most part black). Other specimens, with a black or mostly black metafemur (Fig. 21), cannot be distinguished externally. Unfortunately, differences in lancets (Figs 54-57) and penis valves (Figs 83-86) are also small and might not always be detectable. According to Grearson and Liston (2012)the general proportions of the lamnium of  P. leucopus(Fig. 54) are more slender than that of  P. armata(Figs 56-57), but this does not always work, because  P. leucopuscan have a distinctly wider lamnium than  P. armata, though serrulae are in this case somewhat weaker (Fig. 55). Males can perhaps be distinguished through small differences in penisvalves (Figs 85-86and Figs 9-10in Grearson and Liston 2012), as described by Grearson and Liston (2012)(see also under  P. armata). Females with a black metafemur might also be confused with some specimens of  P. confusa(if they have a com pletelysmooth mesepisternum). Usually,  P. leucopus(Fig. 29) has a uniformly dark brown pterostigma (usually basally dark brown and apically brown in  P. confusa; Fig. 28), but the specimens with pterostigma apically paler than basally might not be externally distinguishable from  P. confusa. However, small differences in the lancets can help distinguish these species, as ctenidia in  P. confusatend to be more distinct (Figs 62-63).  Genetic data. Based on COI barcode sequences,  P. leucopusbelongs to the same BIN cluster (BOLD:AAQ2302) as  P. armata(Fig. 1). The nearest neighbour (BOLD:AAG3568) is 2.76% different. BOLD:AAG3568 includes  P. aphantoneura,  P. bifida,  P. confusa,  P. luteipes,  P. opaca,  P. pusilla,  P. staudingeri, and  P. subopaca. Neither does our limited nuclear data allow separation of  P. leucopusfrom  P. armata(Fig. 2). The single heterozygous female would have a sequence identical to the single available  P. armatasequence if heterozygous sites (double peaks in chromatograms) were excluded. All the six heterozygous sites in  P. leucopusinclude also the nucleotide found in  P. armata, possibly indicating haplotype sharing between these two taxa.  Host plants.   Tilia cordataMill. ( Kangas 1985; Grearson 2006; Grearson and Liston 2012),  Tilia xvulgarisHayne ( Grearson 2006).  Distribution and material examined. Western Palaearctic. Specimens studied are from Austria, Finland, Germany, Great Britain, Russia, and Sweden.