Epeorus (Caucasiron) znojkoi (Tshernova, 1938), sensu lato

Hrivniak, Ľubos, Sroka, Pavel, Bojkova, Jindriska & Godunko, Roman J., 2020, Identification guide to larvae of Caucasian Epeorus (Caucasiron) (Ephemeroptera, Heptageniidae), ZooKeys 986, pp. 1-53 : 1

Epeorus (Caucasiron) znojkoi (Tshernova, 1938), sensu lato Figs 6 , 7 , 8

Iron znojkoi Tshernova, 1938

Epeorus (Iron) znojkoi (Tshernova, 1938); in Tshernova (1974)

Iron caucasicus (Tshernova, 1938); in Sinitshenkova (1976) partim

Iron znojkoi Tshernova, 1938; in Sinitshenkova (1976) partim

Epeorus (Caucasiron) znojkoi (Tshernova, 1938); in Kluge (1997b)

Type locality.

Azerbaijan, Nakchivan Autonomous Republic, Giljan-tshaj (Gilljak) (2000-2100 m a.s.l.).

Distribution.

Georgia, south-western Russia, Azerbaijan, Armenia, Turkey, northern Iran (Fig. 6 ). The most widespread species in the Caucasus.

Habitat.

Larvae inhabit streams and rivers of various sizes, from larger braided low altitude rivers to small streams at high altitude. Altitudinal range of sampling sites -6-2453 m a.s.l. (Fig. 6 ). Most frequently found in low and middle altitudes. Often syntopic with E. (C.) magnus .

Main morphological diagnostics of larvae.

(i) abdominal terga II-IV with triangular medial macula and terga V-VII with T shaped medial macula (Fig. 7A, G-I ); (ii) abdominal sterna intensively red or reddish (Fig. 7B, L, M ), with a pair of reddish oblique stripes (Fig. 7K, a ) and/or reddish medio-lateral stripes (Fig. 7K, b ), or with reddish to brownish longitudinal stripe on all sterna or at least on sterna VIII and IX (Fig. 7N-P ) (iii); tergum X with short postero-lateral projections (Fig. 8M , arrow) or without postero-lateral projections (Fig. 8N ); (iv) femora without medial hypodermal spot (Fig. 7F ); (v) gill plates VII (in natural position from ventral view) wide (Figs 7J, L-P , 8H-L ); (vi) denticles along posterior margin of tergum VII strongly sclerotized and dense (Fig. 8E ); (vii) gill plates III with well-developed projection (Fig. 8G ); (viii) shape of head sharply trapezoidal in males (Fig. 7D ).

Remarks.

Morphology. The reduction of reddish coloration of abdominal sterna observed particularly in specimens collected from Turkey (Fig. 7N ) and northern Iran (Fig. 7O, P ). Similar coloration pattern of sterna as present in E. (C.) insularis (Fig. 31J ).

Taxonomy. This species was described based on male and female subimagines and imagines from the Nakchivan Autonomous Republic ( Tshernova 1938). The type series is deposited in IZ ( Kluge 1995). The larva was described by Sinitshenkova (1976) based on material collected in Georgia, Russia (the central Greater Caucasus), Armenia and the type locality. Larvae were identified as species znojkoi , based on the proximity of its type locality and the similarity of markings on abdominal terga. However, the description of larva is confusing, because the larva of E. (C.) znojkoi was erroneously described under the name E. (C.) caucasicus by Sinitshenkova (1976) (Braasch, 1980). Therefore, the larva described by Sinitshenkova (1976) as E. (C.) znojkoi should belong to a different species. Its diagnostic characters correspond to those of E. (C.) magnus that was later described by Braasch (1978). These characters include: (i) body length: Tshernova (1938) noted 9.5-12 mm for imagines of species E. (C.) znojkoi ; contrary to Sinitshenkova (1976) who noted 14-19 mm for the larvae. Larvae of species magnus exhibit 20-24 mm as described by Braasch (1978); (ii) shape of head: trapezoidal head with rounded edges as figured by Sinitshenkova (1976) is typical for E. (C.) magnus (Fig. 10D, E ), not to E. (C.) znojkoi with more angular edges of head (Fig. 7D ); (iii) setation of labrum: the shape of labrum and dense setae on its dorsal surface as figured by Sinitshenkova (1976) is characteristic for E. (C.) magnus (Fig. 11A ); (iv) coloration of abdominal sterna: an absence of coloration on abdominal sterna as described by Sinitshenkova (1976) is typical for E. (C.) magnus (Fig. 10J ); E. (C.) znojkoi possess reddish sterna and gills.

Distribution. E. (C.) znojkoi is considered as a species complex containing several lineages ( Hrivniak et al. 2020b). They are distributed in the Pontic Mts. in Turkey ( Caucasiron sp. 5 in Hrivniak et al. 2020b), the Alborz Mts. in Iran ( Caucasiron sp. 4 in Hrivniak et al. 2020b), and the Lesser Caucasus in Georgian Adjara ( Caucasiron sp. 6 in Hrivniak et al. 2020b). The lineages are not formally described now and fall into the group E. (C.) znojkoi s. l. in this identification guide.

Figures

Figure 6. Geographical (left) and vertical (right) distribution of Epeorus (Caucasiron) znojkoi.

Figure 7. Epeorus (Caucasiron) znojkoi, 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 middle leg in dorsal view G-I abdominal terga J gills VII (in natural position from ventral view) K abdominal sterna II-VI (a, position of oblique stripes b, position of medio-lateral stripes) L-P abdominal sterna, variability in coloration pattern (L Georgia M, O, P Iran N Turkey).

Figure 8. Epeorus (Caucasiron) znojkoi, 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 and its variability F gill I G gill III H gill VII (flattened on slide) I-L gill VII (in natural position from ventral view), variability in shape M, N abdominal segments VIII-X in lateral view (arrow points on postero-lateral projection) O sternum IX of female with observed variability.

Figure 10. Epeorus (Caucasiron) magnus, 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, G middle leg in dorsal view H, I abdominal terga J abdominal sterna II-VI K gills VII (in natural position from ventral view).

Figure 11. Epeorus (Caucasiron) magnus, larva: A labrum (left half in dorsal view right half in ventral view) with detail of bristle-like seta 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, J gill VII (in natural position from ventral view) variability in shape K-M abdominal segments VIII-X in lateral view (arrow points on postero-lateral projection) N sternum IX of female with observed variability.

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).