Plectrocnemia zolotuhini Melnitsky et Ivanov, 2023

Plectrocnemia zolotuhini Melnitsky et Ivanov, 2023 (previously known from Rovno amber)

New material: SIZK K-8732a.

Updated list of the Polycentropodidae known from Rovno amber is given below. Symbol † indicates fossil taxa (genus or species).

Polycentropodidae Ulmer, 1903

1. † Archaeoneureclipsis martynovi Melnitsky et Ivanov, 2016

2. † Electrocyrnus perpusillus Melnitsky et Ivanov, 2010

3. Holocentropus † affinis (Pictet, 1856)

4. Holocentropus † atratus (Pictet, 1856)

5. Holocentropus † curvatus Ulmer, 1912

6. Holocentropus † flexiflagrum Melnitsky et Ivanov, 2010

7. Holocentropus † incertus (Pictet, 1856)

8. Holocentropus † kobodok Melnitsky et Ivanov, 2013

9. Holocentropus † totuttotam Melnitsky, Ivanov et Perkovsky, 2024

10. Holocentropus † tutkaktut Melnitsky, Ivanov et Perkovsky, 2021

11. Holocentropus † vetustus (Germar, 1813)

12. Holocentropus † vottakvot Melnitsky, Ivanov et Perkovsky, 2024

13. Holocentropus † zhiltsovae Melnitsky et Ivanov, 2013

14. Nyctiophylax † ispokonvekov Melnitsky, Ivanov et Perkovsky, 2025

15. Nyctiophylax † terreusbos Melnitsky et Ivanov, 2013

16. Nyctiophylax † totaktoetak Melnitsky, Ivanov et Perkovsky, 2024

17. Nyctiophylax † varians Ulmer, 1912

18. Plectrocnemia † aristovi Melnitsky et Ivanov, 2023

19. Plectrocnemia † astroblema Melnitsky, Ivanov et Perkovsky, 2025

20. Plectrocnemia † barbata (Pictet, 1856)

21. Plectrocnemia † idsukachevae Melnitsky, Ivanov et Perkovsky, 2025

22. Plectrocnemia † kirmikhia Melnitsky, Ivanov et Perkovsky, 2021

23. Plectrocnemia † lata (Pictet, 1856)

24. Plectrocnemia † nastigermania Melnitsky et Ivanov, 2013

25. Plectrocnemia † pluripotentia Melnitsky, Ivanov et Perkovsky, 2024

26. Plectrocnemia † posleotbora Melnitsky, Ivanov et Perkovsky, 2025

27. Plectrocnemia † stremglav Melnitsky, Ivanov et Perkovsky, 2025

28. Plectrocnemia † ukrainica Melnitsky et Ivanov, 2013

29. Plectrocnemia † zolotuhini Melnitsky et Ivanov, 2023

30. Polycentropus † grigorenkoi Melnitsky et Ivanov, 2016

Discussion

The recent findings prove the genus Plectrocnemia to be the most speciose among the caddis genera in Rovno amber, overriding the genus Holocentropus , other species-rich fossil genus from the Rovno Holocentropus having 2.5 times more species common with Baltic amber.

Findings made in the recent five years in Rovno amber quintupled the number of endemic species of Plectrocnemia . At least partly, this is due to the increase in the number of localities studied: five species of the genus are already known from localities other than Klesov, and four species are known only from them. The change in the number of Plectrocnemia species depending on the number of studied localities is also clearly visible in modern regional faunas: thus, in the thoroughly studied fauna of Michigan, four out of ten species are known from no more than five localities out of 443, and another three species from 14–17 localities (Houghton et al. 2017).

The total number of polycentropodid species known from Rovno amber has doubled over the past five years, including the number of Rovno amber endemic species of Nyctiophylax – tripled, Rovno amber endemic species of Holocentropus – doubled. As a result, the genus Plectrocnemia includes 23.5% of Rovno amber Trichoptera species (all Polycentropodidae – 59%), eight Plectrocnemia species from Klesov – 27.5% of all Klesov trichopterans (18 polycentropodid species – 58%), in Varash District Polycentropodidae constitute 75% of species (three from four), Plectrocnemia – 50% of species (this paper).

The striking level of dominance of polycentropodids (and in particular of the genus Plectrocnemia ) in late Eocene European ambers and latest Eocene of Florissant ( Ivanov et al. 2016), compared to any modern faunas, is evident even in the comparison with North American regional faunas (noticeably richer in Polycentropodidae , and particularly Plectrocnemia , than European ones). For example, in the Michigan fauna (Houghton et al. 2017), the genus Plectrocnemia accounts for only 3.4% of species (all Polycentropodidae combined, 28 species, makes 9.5%; by number of specimens in Michigan Plectrocnemia accounts for ca. 1.4%, and all Polycentropodidae for 5.5%. Comparison with the modern Benelux fauna (232 Trichoptera species) suggests the presence of only 13 polycentropodid species (5.6%), including three Plectrocnemia (1.3%) according to Tempelman et al. (2022). Similar calculations on the Russian fauna (643 species: Ivanov 2011) provides 5.4% of Polycentropodidae species. Apparent sympatry of the Rovno Polycentropodidae proven in the given publication was documented for the first time by the syninclusions of the species Plectrocnemia zolotuhini and P. aristovi , as well as of Plectrocnemia lata and Holocentropus atratus ( Table 1).

Ulmer (1912) placed in Plectrocnemia barbata Pictet, 1856 a large series of specimens with strongly varying genital structures, from different collections (Ivanov & Melnitsky 2013). This variation rises a question of the independence of these variations as separate species, hence the degree of domination of this and similarly variable species P. lata Pictet, 1856 is uncertain. Nonetheless, these variable species provide together more findings than any other amber Polycentropodidae . Apart of the presence of these species in the Rovno fauna, they were widespread across the Russo-Scandia including its south-west (south and southwest of modern Sweden) that was a source of Danish amber ( Lyubarsky et al. 2024; Simutnik et al. 2025 and references therein). The amber piece NHMD 115294 (housed in the Natural History Museum of Denmark) with male of Plectrocnemia lata from Danish amber have been determined to species level by W. Wichard, and his determination did not meet any substantial objection.

In Bitterfeld amber, only endemic species were reported ( Melnitsky et al. 2025 and references therein). The relative dominance of one or two Plectrocnemia species in extant regional faunas is not unusual: for example, in the Michigan fauna, 77% of specimens belong to two out of ten species (Houghton et al. 2017). Nonetheless the trend on maintaining of the high share of Polycentropodidae in fossil resins suggests the principal difference of faunal structure in the recent and Eocene aquatic biocenoses. Some chances for the better understanding palaeoecology at least commonest species gives the study of syninclusions ( Perkovsky et al. 2010, 2012; Perkovsky & Rasnitsyn 2013; Perkovsky 2017; this paper), e. g., most species of Orthocladius live in running waters.

Acknowledgements

The authors are grateful to Oleg Bogelsky and Danylo Koval from Amber Galbin Group (both - Rivne, Ukraine), Mykola Khomych (Rivne, Ukraine) and Alex Kondratyuk (Berezne, Ukraine) for the help with obtaining some specimens and anonymous reviewers for improving the overall quality of the manuscript.

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