Pristiphora opaca 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 91E3B47A-93C7-5F5B-A083-D68833320546 Lindqvist, 1955 Lindqvist 1955 Insecta Tenthredinidae Pristiphora CoL Animalia Pristiphora opaca Hymenoptera 28 29 Arthropoda species opaca   Pristiphora opacaLindqvist, 1955: 42-43. Holotype ♀ (http://id.luomus.fi/GL.5204) in MZH, examined. Type locality: Pihtipudas, Central Finland.  Similar species. Based on the external morphology, the most similar species are  P. albitibia,  P. confusa,  P. pusilla,  P. sootryeni, and  P. subopaca. The species is best distinguished through the structure of male penis valve (Figs 95-96). Unfortunately, it is rather difficult to distinguish females from  P. subopacaas the differences in the lancets are small (Figs 64- 69). The best character might be the structure of the tangium: on its basal part,  P. opacaappears to have a fold (Figs 64-65) that is absent in other species of the  Pristiphora ruficornisgroup, although this observation is based only on two specimens that had saws intact enough to see this (basal part of both lancets was damaged in the third female available for study, the holotype). There are also slight differences in external morphology between  P. opacaand  P. subopaca. In  P. opaca(Fig. 28), the pterostigma is apically brown and basally dark brown (uniformly yellow in  P. subopaca; Fig. 27), antennae are slightly paler ventrally (uniformly black in  P. subopaca), and claws seem to have a somewhat smaller subapical tooth (Fig. 31) than in  P. subopaca(Fig. 32).  Genetic data. Based on COI barcode sequences,  P. opacabelongs to the same BIN cluster (BOLD:AAG3568) as  P. aphantoneura,  P. bifida,  P. confusa,  P. pusilla,  P. staudingeri, and  P. subopaca(Fig. 1). The nearest neighbour (BOLD:AAQ2302,   P. armataand  P. leucopus) is 2.76% different. Only one TPI sequence is available, which can be distinguished from other species (Fig. 2).  Host plants. Unknown.  Distribution and material examined. Western Palaearctic. Specimens studied are from Finlandand Sweden.