(Fig. 41)
? Diactinia pryeri: Viidalepp 1977: 574 (Sakhalin).
? Ecliptopera pryeri: Viidalepp 1996: 25 (Sakhalin).
Ecliptopera pryeri: Vasilenko & Dubatolov 2021: 258 (Yasnomorskoe).
Material examined. 4 ♂, 2 ♀, S Kholmsk, 5.X.2008, 28.VII.2018, 30.VIII.2019, 08.IX.2019, 13–17.VII.2021, 30.VIII.2021; 1 ♂, Yasnomorskoe, 23.VII.2019.
Distribution. Russia (S RFE: SW Sakhalin, S Kurils—Kunashir and?Iturup), Japan (Hokkaido, Honshu, Shikoku),? South Korea.
Remarks. T The finding of E. pryeri in Sakhalin significantly expands its distribution range to the north. The larval hostplant is unknown. In Sakhalin the moths fly from late July to early October, possibly in one generation.
Viidalepp (1977, 1996) first reported E. pryeri from Sakhalin, the Kurils, and the continental part of the south of RFE, without indicating Ecliptopera silaceata ([Denis & Schiffermüller] on these territories. Subsequent studies did not discover E. pryeri in RFE, but reveal E. silaceata leuca (Djakonov), which is widely distributed here, including Sakhalin (for details see Beljaev 2016: 616-617). This put under question the cited indication of E. pryeri for Russia (Mironov et al. 2008: 339, note 7543). However, the finding of a true E. pryeri in Sakhalin, flying together with E. s. leuca, raises the question, whether Viidalepp’s reports of E. pryeri from Sakhalin and the Kurils are correct; relevant specimens have to be re-examined.
The data on E. pryeri in the GBIF (2022) need to be revised. All specimens from the localities on continental RFE, adopted from IZBE, evidently, should be associated with E. s. leuca (Table 2). Most likely, the specimens from the extreme north of Sakhalin (Okhinskii district: Kurina 2022d) should be E. s. leuca. But the specimen from SW Sakhalin from Pyatirechye (“Pjatiretšje”: Kurina 2022e) might be E. s. leuca or the true E. pryeri. In view of the described situation, the indications of E. pryeri from Iturup Island (Bryk 1942: 73; Kurina 2022f) also require revisions. The specimens in the GBIF from Korea are also doubtful to be E. pryeri, since the distribution of this species in Korea needs to be confirmed (Kim et al. 2016: 376–377). So, currently E. pryeri should be considered endemic to Japan and neighbouring islands.
In comparison with typical West Palaearctic E. silaceata, E. s. leuca is similar to E. pryeri in narrower transverse lines on the forewing and in possessing a more straight portion of the postmedial line ahead of the vein M3, whereas in typical E. silaceata this portion is usually clearly arched outward. This resemblance, apparently, served as a source for the misidentification mentioned above. In addition, both, E. s. leuca and E. pryeri, are similar to the sympatric taxon, Ecliptopera capitata capitulata (Staudinger). To avoid the misidentifications, we give a key to these geometrids by appearance.