Elachista dispilella was described on the basis of material collected by Zeller in Głogów (originally Glogau) (Zeller 1839), a town situated in south-western part of Poland. It is the oldest taxon name of the E. dispilella complex. The identity of E. dispilella was established by Parenti (1977) by designating a lectotype for this species and for E. festucicolella Zeller, 1853. E. S. Nielsen, during the preparation of a monograph on North European fauna (Traugott-Olsen & Nielsen 1977), took the view that Parenti had unintentionally transposed the abdomens or the slide labels of E. dispilella and E. festucicolella. Nielsen and G. S. Robinson transferred the slides to the supposedly correct position, with a note: “According to E. S. Nielsen, Parenti accidentally switched the abdomens of festucicolella and dispilella. I have accordingly reversed the labels and numbers on the slides; Parenti’s original labels are below. Specimens untouched; signed G. S. R. [Gaden S. Robinson] 14.VIII. 1979. Representatives of Parenti’s concept of species are illustrated in Parenti (1977). Apparently, the suspicion of Parenti’s error stems from the so far understood ‘traditional’ identity of these species, based on works of Hering (1891), Rebel (1901) and Martini (1902).
After the lectotype designation and the events that followed, the identification of these species has not been straightforward, and specimens with genitalia as illustrated by Parenti (1977) for E. dispilella have been considered E. festucicolella, or following Traugott-Olsen (1990) E. steueri Traugott-Olsen, 1990, E. manni Traugott-Olsen, 1990, E. gebzeensis Traugott-Olsen, 1990, or E. jaeckhi Traugott-Olsen, 1990, with no apparent basis for the distinction of these three, apart from one: Traugott-Olsen & Nielsen (1977) depicted the E. festucicolella as unicolorous white (it is, indeed, unicolorous, but not pure white according to Zeller). However, the specimen illustrated in Traugott-Olsen & Nielsen (1977) is from a population occurring in the island of Öland in Sweden, in which the two spots typical of E. dispilella sensu Zeller are either faintly present or entirely absent.
Another fairly widespread species in Western Europe has been identified as E. dispilella. This concept, however, is not in accordance with Zeller’s original account of this taxon, nor to either of the genitalia of the lectotypes of E. dispilella or E. festucicolella. It is externally similar to the so-called E. dispilella. Traugott-Olsen (1990) recognized that such a species exists, and concluded that it is E. distigmatella Frey, 1859, hitherto considered a synonym of E. dispilella (Hering 1891, Rebel 1901, Martini 1902, Nielsen and Traugott-Olsen (1977). Traugott-Olsen (1990) re-instated it as a valid species, yet somewhat illogically continued considering the identity of E. dispilella and E. festucicolella as in Traugott-Olsen & Nielsen (1977).
Parenti (1981) recognized a taxon with external appearance of E. festucicolella sensu Zeller—and actually also genitalia as in the lectotype of E. festucicolella, designated by Parenti himself, and described it as a new species, E. klimeschi. This decision is hard to understand, especially as in connection of the lectotype designation of E. festucicolella Parenti (1977) does not illustrate the genitalia of the lectotype of E. festucicolella but of an Italian specimen—from where E. klimeschi was later described. The only reason conceivable to us for this decision is that Parenti had become convinced that he had indeed made a mistake while dissecting the genitalia of the lectotypes of E. dispilella and E. festucicolella. There is no information supporting the decision in connection of the very brief original description of E. klimeschi. The matter remains therefore unexplained and odd, especially as Parenti was generally conservative regarding description of new species. The biology, external appearance, or the genitalia of E. klimeschi do not differ from the original account of E. festucicolella by Zeller in any way. A series of specimens, including probable paralectotypes present in the collection of J. M. J. af Tengström, now housed in MZH, show external appearance with two spots as E. dispilella s. authors, but genitalia as E. festucicolella s. authors. Likewise, specimens that externally resemble E. festucicolella have genitalia as E. dispilella s. authors. We have never encountered specimen/genitalia combination as in the lectotypes in BMNH as currently labeled. We take all the above mentioned notions as definite evidence that Parenti never made a mistake when dissecting and designating lectotypes for E. dispilella and E. festucicolella. Therefore, the genital slide numbers of the lectotypes of E. dispilella and E. festucicolella must again be reversed to be B.M. genitalia slide 19364 for E. dispilella and B.M. genitalia slide 19363 for E. festucicolella. Elachista festucicolella is a senior synonym of E. klimeschi Parenti (later emended to E. klimeschiella Parenti, 2002 due to homonymy). Elachista dispilella is the species that has usually been called E. festucicolella. Elachista distigmatella is the species that has been understood to be E. dispilella in Western Europe.
The aim of this study is to revise the taxonomy of the Elachista dispilella species complex using integrated approach. We examined the morphology of extensive material of the E. dispilella complex, including type material. Furthermore, we sequenced DNA barcode region (a standard 658 bp fragment of mitochondrial COI gene) of 101 specimens to obtain additional insights into genetic patterns within and between the species Full taxonomic and collection data, including GenBank accession numbers, of these 101 specimens is available through the public dataset DS-ELADIS at BOLD database at http://www.boldsystems.org, accessible from http://dx.doi.org/10.5883/ DS-DISPI.