1	Medial hypodermal femur spots present (e.g., Fig. 13F, G)	group A
–	Coloration pattern on abdominal sterna present (Figs 4B; 13B; 46B)	subgroup A1, p. 9
–	Coloration pattern on abdominal sterna absent (Figs 28B; 37B; 43B)	subgroup A2, p. 9
2	Medial hypodermal femur spots absent (e.g., Fig. 16F)	group B
–	Coloration pattern on abdominal sterna present (Figs 4B; 7B; 16B; 31B; 34B; 40B; 19J–K)	subgroup B1, p. 10
–	Coloration pattern on abdominal sterna absent (e.g., Figs 10B; 25B)	subgroup B2, p. 11
subgroup A1
1	Abdominal sterna II–VI with a pair of oblique stripes (Figs 4J; 22I, J; 46I)	2
–	Abdominal sterna II–V (VI) with a pair of triangular spots (Fig. 13J) and abdominal terga with lateral stripes extended dorso-posteriorly (Fig. 13H, I, arrows)	E. (C.) nigripilosus (W and Central Greater Caucasus, Turkey, Iraq, N Iran), p. 19
2	Stripes on abdominal sterna II–VI widened anteriorly (Fig. 46I, arrows) and abdominal terga with lateral stripes extended dorso-posteriorly (Fig. 46H, arrows)	E. (C.) zagrosicus (S and SW Iran), p. 45
–	Stripes on abdominal sterna II–VI not widened anteriorly (Figs 4J; 22I, J)	3
3	Abdominal terga V–VII with crown-like medial macula (Fig. 4I)	E. (C.) caucasicus (widespread in the Caucasus), p. 11
–	Abdominal terga V–VII with stripe-like medial macula and a pair of distinct antero-lateral stripes (Fig. 22G, arrows)	E. (C.) iranicus (N Iran), p. 29
subgroup A2
1	Medial hypodermal femur spots distinctly elongated (Fig. 28F–H); setae on abdominal terga wide at base and denticles along posterior margin of tergum VII narrow (Fig. 29E); gill plates III without distinct projection (Fig. 29G); gill plates VII narrow (Figs 28L, M; 29H–L)	E. (C.) longimaculatus (central Greater Caucasus), p. 32
–	Medial hypodermal femur spots rounded, not distinctly elongated, gill plates III with well-developed projection; setae on abdominal terga hair-like (e.g., Fig. 38E)	2
2	Abdominal terga V–VII with stripe-like medial macula and lateral stripes extended dorso-posteriorly (Fig. 37G, arrows); gill plates VII narrow (Figs 37I; 38H–K)	E. (C.) turcicus (NE Turkey, Georgia), p. 40
–	Abdominal terga V–VII with more or less triangular or T-shaped medial macula, lateral stripes not extended dorso-posteriorly (Fig. 43I–K); gill plates VII wide (Figs 43M; 44H, I)	E. (C.) shargi (N Iran), p. 45
subgroup B1
1	Setae on abdominal terga wide at base	2
–	Setae on abdominal terga hair-like	3
2	Abdominal terga II–IX with a pair of postero-medial protuberances (Fig. 34H, arrows; protuberances are most developed on terga VI–VIII and best visible from dorso-lateral view); abdominal terga V–VII with stripe-like medial macula, which is often anteriorly and posteriorly widened (Fig. 34G, H); abdominal sterna II–VI as on Fig. 34J–L	E. (C.) bicolliculatus (NE Turkey, W Caucasus, Armenia), p. 36
–	Abdominal terga without postero-medial protuberances; terga V–VII with well-defined triangular maculae (Fig. 19H, I); sterna not intensively pigmented, pattern of sterna II–VI as on Fig. 19J, K	E. (C.) soldani (W and central Greater Caucasus), p. 24
3	Postero-lateral projections on tergum X distinct (Fig. 41K, arrow); abdominal sterna II–VI with circular medial macula (Fig. 40L–N); gill plates VII wide (Figs 40J, K; 41H–J)	E. (C.) alborzicus (N Iran), p. 41
–	Postero-lateral projections on tergum X absent or indistinct, coloration pattern of abdominal sterna different	4
4	Abdominal sterna II–VI yellowish, with a pair of black oblique stripes or brownish rounded medial macula	5
–	All or at least abdominal sterna VIII–IX intensively red (Fig. 7L), with reddish to brownish maculation (Fig. 7M) including a longitudinal stripe (Figs 7N–P; 31J) and a pair of reddish oblique (Fig. 7K, a) and/or medio-lateral stripes (Fig. 7K, b)	6
5	Abdominal sterna II–VI with a pair of black oblique stripes (Fig. 4J); abdominal terga V–VII with crown-like medial macula (Fig. 4I)	E. (C.) caucasicus (widespread in the Caucasus, E Turkey), p. 11
–	Abdominal sterna II–VI with brownish rounded medial macula (Fig. 16I); abdominal terga V–VII with narrow stripe-like medial macula (widened on terga VIII–IX, Fig. 16G, H, arrows)	E. (C.) alpestris (W and central Greater Caucasus), p. 23
6	Gill plate VII wide (Figs 7J, L–P; 8H–L); denticles along posterior margin of tergum VII relatively long, strongly sclerotized and dense (Fig. 8E); postero-lateral projections on tergum X present or absent (Fig. 8M, N)	E. (C.) znojkoi s. l. (widespread in the Caucasus, Turkey), p. 13
–	Gill plates VII narrow (Figs 31K; 32H, I); denticles along posterior margin of tergum VII relatively short and poorly sclerotized (Fig. 32E); postero-lateral projections on tergum X absent (Fig. 32J)	E. (C.) insularis (Samos Island, Greece), p. 35
subgroup B2
1	Postero-lateral projections on tergum X present (Fig. 11K–M); dorsal surface of labrum with dense bristle-like setae (Fig. 11A); gill plates VII wide or slightly narrowed (Figs 10K; 11H–J)	E. (C.) magnus (widespread in the Caucasus, Turkey), p. 18
–	Postero-lateral projections on tergum X absent (Figs 20L, 26L); gill plates VII distinctly narrowed (Figs 19L; 20H–K; 25J; 26H–K); dorsal surface of labrum with sparse hair-like setae (Figs 20A; 26A)	2
2	Abdominal terga V–VII with narrowed triangular medial macula and a pair of anterolateral spots (Fig. 25H; arrows); gill plates III without distinct projection (Fig. 26G); setae on terga not distinctly widened at base, often elongated (Fig. 26E)	E. (C.) sinitshenkovae (W and central Greater Caucasus), p. 30
–	Abdominal terga V–VII with well-defined triangular medial maculae, without a pair of anterolateral spots (Fig. 19H, I); setae on terga wide at base (Fig. 20E); gill plates III with well-developed projection (Fig. 20G)	E. (C.) soldani (W and central Greater Caucasus), p. 24