Pristiphora leucopus (Hellen, 1948)

Nematus vitreipennis Eversmann in Kawall, 1864: 295, syn. n. Nomen oblitum. Note. Kawall (1864) published an unaltered manuscript from Eversmann’s legacy. Lectotype ♀ (DEI-GISHym30027; here designated) in ZIN, examined. Type locality: foothills of Ural mountains [In promontor. Uralensibus], Russia.

Nematus (Pristiphora) ruficornis var. leucopus Hellén, 1948: 116. Nomen protectum. No syntypes were found in MZH. Type locality: Joutseno, South-Eastern Finland, Finland and Pionerskoye [ Kuolemajärvi], Leningrad Oblast, Russia. Note. The lectotype of Nematus vitreipennis (which was the only specimen found under this name in Eversmann’s collection in ZIN) agrees well with the summer morph (completely pale metafemur) of P. leucopus (Grearson and Liston 2012). The name Nematus vitreipennis has apparently not been used as valid since 1884 (Brischke 1884), whereas Pristiphora leucopus has 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. leucopus is P. armata . Differences between these two species were extensively discussed by Grearson and Liston (2012). Whereas P. leucopus exhibits 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. leucopus can 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 penis valves (Figs 85-86 and Figs 9-10 in 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 pletely smooth 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. confusa tend to be more distinct (Figs 62-63).

Genetic data.

Based on COI barcode sequences, P. leucopus belongs 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. leucopus from P. armata (Fig. 2). The single heterozygous female would have a sequence identical to the single available P. armata sequence if heterozygous sites (double peaks in chromatograms) were excluded. All the six heterozygous sites in P. leucopus include also the nucleotide found in P. armata, possibly indicating haplotype sharing between these two taxa.

Host plants.

Tilia cordata Mill. (Kangas 1985; Grearson 2006; Grearson and Liston 2012), Tilia x vulgaris Hayne (Grearson 2006).

Distribution and material examined.

Western Palaearctic. Specimens studied are from Austria, Finland, Germany, Great Britain, Russia, and Sweden.