**Genetic variability**

Aligned sequences (obtained in our study and downloaded from GenBank) were trimmed to 565, 474 and 713 bp for COI (14 sequences, selected from GenBank—one sequence per species; (see Supplementary Materials—SM6)), 18S rRNA (two sequences selected from GenBank—one sequence per species; see below) and 28S rRNA (13 sequences selected from GenBank—one sequence per species) molecular markers, respectively.

The ranges of uncorrected genetic p-distances between obtained COI sequence of *Meb. skorackii* (GenBank accession number: MW656257) and species of the genus *Mesobiotus*, for which sequences are available from GenBank, are as follows: 20–26%, with the most similar being *Meb*. cf. *barabanovi* (GenBank accession number: MN313170 [23]) and *Meb. occultatus* Kaczmarek, Zawierucha, Buda, Stec, Gawlak, Michalczyk and Roszkowska, [15] (GenBank accession number: MH195152 [15]) and the least similar being *Meb. dilimanensis* Itang, Stec, Mapalo, Mirano-Bascos and Michalczyk [79] (GenBank accession number: MN257047 [79]). In case 18S rRNA only two sequences were compared (because other 24 sequences deposited in GenBank were amplified using different sets of primers) and genetic p-distances between *Meb. harmsworthi* (at present undefined *Mesobiotus* species; GenBank accession number: MH079462 [66]) and *Meb. philippinicus* Mapalo, Stec, Mirano-Bascos and Michalczyk [80] (GenBank accession number: KX129793 [80]) was 0.01%. In turn, the ranges of p-distances between obtained 28S rRNA sequence (GenBank accession number: MW680636) and sequences downloaded from GenBank was: 5–13%, with the most similar being *Meb*. cf. *barabanovi* (GenBank accession number: MN310388 [23]) as well as *Meb. harmsworthi* (at present undefined *Mesobiotus* species; GenBank accession number: MH197264 [66]) and the least similar being *Meb. dilimanensis* (GenBank accession number: MN257049 [79]) (see Supplementary Materials—SM7).
