Key to the hitherto known final instar larvae of Adicella species of Europe

(modified from Waringer et al. 2017)

1 Head concolorous, orange to brownish; case cylindrical, curved and smooth, constructed of mineral particles (Figs. 5A, 5C)...................................................................................................... 2

- Median parts of head orange to brown dorsally, lateral portions of parietalia with distinct, dark brown muscle attachment spots dorsally and ventrally; case with spiral pattern, constructed of plant material (Figs. 3A, 3G, 4B)........................ 3

2 Abdominal dorsum IX (including both posterolateral setae) with 12 setae; species endemic to Iberic-Macaronesian Region (European Ecoregion I)................................................................ Adicella meridionalis

- Abdominal dorsum IX (including both posterolateral setae) with 14–15 setae (Fig. 5D); widespread species outside of European Ecoregion I........................................................................ Adicella filicornis

3 Metanotal setal area sa3 with 13–18 setae per side (Fig. 4B)....................................... Adicella reducta

- Metanotal setal area sa3 with 1 seta per side (Fig. 3D)......................................................... 4

4 Each pronotal half with 56–65 setae of varying length; each mesonotal sclerite with 11–13 setae; outermost seta of abdominal dorsum IX setal group (Waringer et al. 2017: Fig. 12, arrow) approximately as long as width of this segment...................................................................................................... Adicella syriaca

- Each pronotal half with 35–37 setae of varying length; each mesonotal sclerite with 7–8 setae; outermost seta on abdominal dorsum IX approximately half as long as width of this segment.................................... Adicella cremisa