Identification guide to larvae of Caucasian Epeorus (Caucasiron) (Ephemeroptera, Heptageniidae) Author Hrivniak, Ľubos Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Branisovska 31, 37005 Ceske Budejovice, Czech Republic & Faculty of Sciences, University of South Bohemia, Branisovska 31, 37005 Ceske Budejovice, Czech Republic lubos.hrivniak@gmail.com Author Sroka, Pavel Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Branisovska 31, 37005 Ceske Budejovice, Czech Republic https://orcid.org/0000-0003-4367-6564 Author Bojkova, Jindriska Department of Botany and Zoology, Masaryk University, Kotlarska 2, 61137 Brno, Czech Republic Author Godunko, Roman J. Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Branisovska 31, 37005 Ceske Budejovice, Czech Republic & Department of Invertebrate Zoology and Hydrobiology, University of Lodz, Banacha 12 / 16, 90237 Lodz, Poland https://orcid.org/0000-0003-2196-3327 godunko@seznam.cz text ZooKeys 2020 986 1 53 http://dx.doi.org/10.3897/zookeys.986.56276 journal article http://dx.doi.org/10.3897/zookeys.986.56276 1313-2970-986-1 CDFA38CA1B6F424D85246B540E63E954 2A3CD185EDDF52BDB0AD1E5DA924299B Epeorus (Caucasiron) insularis (Braasch, 1983) Figs 30 , 31 , 32 Iron znojkoi insularis Braasch, 1983 Epeorus (Caucasiron) insularis (Braasch, 1983); in Hrivniak et al. (2020b) Type locality. Greece, Samos Island, stream east of Pirgos, 37°3'N / 26°49'E ; 300 m a.s.l. Distribution. Known only from few sites in Samos Island (Fig. 30 ). Habitat. Larvae inhabit small forested streams at 128-440 m a.s.l. (Fig. 30 ). Main morphological diagnostics of larvae. (i) abdominal terga V-VII with T-shaped medial macula (Fig. 31I ); (ii) abdominal sterna V-VII with reddish to brownish longitudinal stripe (Fig. 31B, J ); (iii) tergum X without postero-lateral projections (Fig. 32J ); (iv) gill plates VII (in natural position from ventral view) narrow (Figs 31K , 32H, I ); (v) gill plates III with well-developed projection (Fig. 32G ); (vi) setae on abdominal terga hair-like (Fig. 32E ); (vii) denticles along posterior margin of tergum VII relatively short and poorly sclerotized (Fig. 32E ). Remarks. Morphology . Coloration of abdominal terga and sterna as in E. (C.) znojkoi s.l. (Fig. 7N-P ). Taxonomy . This species was described by Braasch (1983) based on imagines as a subspecies of E. (C.) znojkoi . Elevated to species level in Hrivniak et al. (2020b) based on a phylogenetic analysis of all Caucasian Epeorus (Caucasiron) species. The type series is currently deposited in SMNS. Figure 30. Geographical (left) and vertical (right) distribution of Epeorus (Caucasiron) insularis . Figure 31. Epeorus (Caucasiron) insularis , larva: A habitus in dorsal view B habitus in ventral view C habitus in lateral view D head of male in dorsal view E head of female in dorsal view F-H middle leg in dorsal view I abdominal terga J abdominal sterna II-VI K gills VII (in natural position from ventral view). Figure 32. Epeorus (Caucasiron) insularis , larva: A labrum (left half in dorsal view right half in ventral view) B incisors of left mandible C incisors of right mandible D setae on dorsal surface of femora E surface and posterior margin of abdominal tergum VII F gill I G gill III H gill VII (flattened on slide) I gill VII (in natural position from ventral view) J abdominal segments VIII-X in lateral view K sternum IX of female with observed variability.