Epeorus (Caucasiron) caucasicus (Tshernova, 1938)

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) caucasicus (Tshernova, 1938) Figs 3 , 4 , 5

Cynigma caucasica Tshernova, 1938

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

Iron fuscus Sinitshenkova, 1976; jun. syn.; in Braasch (1979)

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

Type locality.

Azerbaijan, The Nakhchivan Autonomous Republic, a stream in the vicinity of the upper Sakarsu River (3000 m a.s.l.).

Distribution.

Georgia, south-western Russia, Azerbaijan, Armenia, eastern Turkey (Fig. 3 ). One of the most widespread species in the Caucasus.

Habitat.

Larvae inhabit small streams and rivers at middle and high altitude, most frequently found above 1000 m a.s.l. Altitudinal range of sampling sites 496-2474 m a.s.l. (Fig. 3 ).

Main morphological diagnostics of larvae.

(i) abdominal sterna II-VI with a pair of oblique stripes; nerve ganglia often with stripes or spots (Fig. 4B, J ); (ii) abdominal terga V-VII with crown-like medial macula (Fig. 4A, I , arrow); (iii) femora with medial hypodermal spot (Fig. 4G, H ), sporadically absent or poorly visible (Fig. 4F ); (iv) setae on abdominal terga hair-like (Fig. 5E ); (v) gill plates III with well-developed projection (Fig. 5G ); (vi) tergum X with poorly developed postero-lateral projections (Fig. 5M , arrow) or without postero-lateral projections (Fig. 5L ).

Remarks.

Morphology. Coloration pattern of abdominal sterna as in E. (C.) iranicus (Figs 22I, J ), similar pattern in E. (C.) zagrosicus (Fig. 46I ). Lateral stripes on abdominal terga sporadically dorso-posteriorly extended as in E. (C.) nigripilosus (Fig. 13H, I , arrows). A projection on gill plates III usually well-developed, a slight reduction observed in specimens collected from central Armenia.

Taxonomy. This species was described based on male imagines from the Nakchivan Autonomous Republic (upper Sakarsu River) ( Tshernova 1938). The type series is deposited in the Institute of Zoology, Russian Academy of Sciences, Saint Petersburg (IZ) ( Kluge 1995). Female imago not described; the larva described by Sinitshenkova (1976) from several localities in Russia, Armenia, and Azerbaijan. Larvae and imagines were associated based on the same sampling sites (a part of the larval material originated from the vicinity of the type locality) and a similarity in the coloration of abdomen of the larva and imagines. The description and validity of larval diagnostic characters were discussed by Braasch (1979, 1980). According to him, Sinitshenkova (1976) described the larva of E. (C.) znojkoi under the name E. (C.) caucasicus by mistake. This opinion was supported by the investigation of imagines reared from larvae corresponding to E. (C.) caucasicus described by Sinitshenkova (1976). Imagines corresponded to E. (C.) znojkoi as were described by Tshernova (1938). The larva belonging to E. (C.) caucasicus was also described in Sinitshenkova (1976), but under erroneous attribution to newly proposed species E. (C.) fuscus . Later, E. (C.) fuscus was considered as a synonym of E. (C.) caucasicus ( Braasch 1979; Braasch and Soldán 1979).

Figures

Figure 3. Geographical (left) and vertical (right) distribution of Epeorus (Caucasiron) caucasicus.

Figure 4. Epeorus (Caucasiron) caucasicus, 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 (arrow points on medial macula) J abdominal sterna II-VI K, L gills VII (in natural position from ventral view).

Figure 5. Epeorus (Caucasiron) caucasicus, larva: A labrum (left half in dorsal view, right half in ventral view) with detail of hair-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 with detail of hair-like seta F gill I G gill III (arrow points on distinct projection on costal margin) H gill VII (flattened on slide) I-K gill VII (in natural position from ventral view), variability in shape L, M abdominal segments VIII-X in lateral view (arrow points on postero-lateral projection) N sternum IX of female with observed variability.

Figure 13. Epeorus (Caucasiron) nigripilosus, 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 (arrows point on dorso-posteriorly extended lateral stripes) J abdominal sterna II-VI K gills VII (in natural position from ventral view).

Figure 22. Epeorus (Caucasiron) iranicus, 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, H abdominal terga (arrows point antero-lateral stripes of medial macula) I, J abdominal sterna II-VI K gills VII (in natural position from ventral view).

Figure 46. Epeorus (Caucasiron) zagrosicus, 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, H abdominal terga (arrows point on dorso-posteriorly extended lateral stripes) I abdominal sterna II-VI J, K gills VII (in natural position from ventral view).