Cinygmula levanidovi Tshernova & Belov, 1982

Tiunova, Tatiana M., 2020, Description of the larva of Cinygmula levanidovi Tshernova & Belov, 1982 (Ephemeroptera, Heptageniidae) with redescription of the male adult from the Russian Far East, Zootaxa 4772 (2), pp. 371-378 : 371-378

Cinygmula levanidovi Tshernova & Belov, 1982

( Figs 1–34 )

Tshernova & Belov 1982:289, figs18–20, 62 (Holotype, male adult)

Material examined. RUSSIA: Primorskiy Kray, Khasanskiy region, Kedrovaya River, Kedrovaya Pad Reserve , upper Cordon , 4.VI.1990, T. Tiunova , 3 male, 3 female imagines (reared from larvae); Kedrovaya River basin, Vodopadnii Stream, 4.VI.1990, T. Tiunova, 4 female imagines (reared from larvae) ; Jewish Autonomous Region, Bastak Nature Reserve: Srednii Sorennak River , 11.VII.2018, T. Vshivkova , 2 male, 7 female imagines (light trap); Bastak River , 12.VII.2018, T. Vshivkova, 1 male, 12 female imagines; Bastak River Basin, Dubovii Stream, near Cordon, 12.VII.2018, T. Vshivkova, 9 female imagines; Bolshoi Sorennak River , on the road to Kunan, above and below bridge, 13.VII.1918, T. Vshivkova, 11 female imagines; Ikura River , upper reaches, Ryabinovii Cordon, 4.VIII.2019, T. Vshivkova, 13 larvae, 13 female imagines, 2 male, 4 female sub imagines; same place, 5.VIII.2019, T. Vshivkova, 9 larvae; Bastak River , ferry to the Tigrovii Cordon, 5.VIII.2019, T. Vshivkova, 17 larvae, 1 male imago .

Description. Mature larva. Length (mm) 7.6–9.2; cerci 5.8–8.7. Head: brown, with a somewhat lighter anterior margin and a deep apical incision; posterior area between eyes with two pairs of round and oval light spots, sometimes poorly visible ( Figs 1–2 ). Labrum with white or yellowish anterior area, posterior and lateral areas brown; 2.5 times as wide as long ( Figs 1, 3 ). Glossae wide with rounded tops ( Fig. 4 ). Thorax: pronotum brown with a white anterior area and light posterior edges ( Fig. 8 , 19 ). Mesonotum brown with a lighter median longitudinal stripe; antero- lateral corners with light shapeless spots; base of protoptera with a pair of large light spots and light oblique stripes ( Fig. 8 , 19 ). Legs brown; femur of foreleg with light inner margin and long oval pale stripe in the middle; posterior edge lighter ( Fig. 5 ); stout brown setae cover dorsal surface of femur ( Fig. 6 ); tibia and tarsus light brown or brown. Claws of forelegs with five subapical denticles ( Fig. 7 ). Lengths (mm) of the leg segments as follows. Foreleg:

femur 1.7–1.9; tibia 1.5–1.8; and tarsus 0.7–0.8. Middle leg: femur 1.7–2.0; tibia 1.5–1.6; and tarsus 0.6. Hind leg: femur 1.9–2.3; tibia 1.5–1.8; and tarsus 0.5–0.6. Abdomen: terga brown with a light maculation ( Figs 9 , 19– 20 ); terga I and II light with brown lateral sides ( Fig. 9 ); terga III–VI with pale lateral sides and with a pair of large light spots on sides and almost round light spot in the middle; terga III–VIII with a pair of light curved strokes and round spots on the sides; terga VI–VIII darker than others with light spots on the sides and a pair of triangular light spots near to the posterior margin ( Figs 9 , 19–20 ); tergum IX white with brown triangular spot in the media anterior area and lateral sides; tergum X white ( Figs 9 , 20 ). In some individuals, terga IX–X brownish and tergum IX of the same color as tergum VIII, while tergum X with a pair of wide light lateral spots, not reaching posterior margin ( Fig. 19 ). Posterior margins of tergites with small pointed teeth of different sizes ( Fig. 10 ). Sterna I–V brownish or yellowish; sterna IV–V sometimes with darker middle area; sterna VII–IX brown with somewhat lighter lateral sides and with pairs of light stripes and round spots at the middle; sternum X light brown or brown ( Figs 11 , 21 ), in female with a deep posteromedian emargination ( Fig. 18 ).Tergalii white, with poorly visible tracheation ( Fig. 19 ). Tergalii II–V with 2–3 short gill filaments; tergalius I heart-shaped, and nearly as wide as long, with a single short gill filament ( Fig. 12 ); tergalius II wide, almost oval, and only slightly tapering in distal half ( Fig. 13 ); tergalii III–IV similar in shape and size, almost oval ( Fig. 14 ); tergalius V rounded at the end, somewhat narrower than IV ( Fig. 15 ); tergalius VI with a drawn and pointed tip ( Fig. 16 ); tergalius VII long and narrow, 2.1 times as long as wide ( Fig. 17 ). Cerci brownish ( Figs 20–21 ).

Male imago (in alcohol). Length (mm): body 7.7–8.3; forewings 8.2–8.6; cerci 15.0–16.3. Head: eyes non-contiguous, black tinged greenish ( Figs 23–24 ). Medial and lateral ocelli white. Thorax: Medioscutum and submedioscutum brown, but submedioscutum lighter; anteronotal protuberance brown; medial longitudinal suture narrow and dark brown. Posterior scutal protuberance dark brown, with inner margins tinged dark; scutellum dark brown and tinged by darker; lateroparapsidal suture yellowish ( Fig. 23 ). Forelegs brownish or yellowish, tibia and tarsus lighter than femora; joins brown. Middle and hind legs yellowish; joins brown ( Fig. 22 ). Length (mm) of foreleg segments: femora1.7; tibia 2.1–2.2; tarsal segments 0.8–0.9, 1.1–1.2, 1.0–1.1, 0.9, and 0.3. Wings hyaline with brown veins ( Figs 23 , 25–26 ). Veins of forewings more contrasting than hind wings; pterostigma white on a dark background ( Figs 22–23 ) and brownish on a light background. Abdomen: Terga not transparent, dirty brown with maculations ( Fig. 23 ); tergum I brown; terga II–VII with light anterior areas and lateral corners, with two pairs of light covered strokes and rounded spots in the middle; terga VIII–IX dark brown, with maculations invisible; tergum X lighter. Sterna grayish and translucent; sterna VII–IX brownish. Styliger brown. First and second segments of gonostyli dark brown; third and fourth segments light brown or yellowish ( Fig. 27 ). Penes lobes brownish or yellowish, with a brown spot near to the upper part ( Fig. 28 ), widely separated with grooves at the apices ( Fig. 29 ); each lobe with a long lateral spine wide and strong, with long teeth on the top ( Fig. 30 ). Titillators long and strong, with large teeth on the inner edge near the top ( Fig. 31 ). Cerci brownish at the base and distally pale ( Fig. 22 ).

Female imago. Length (mm): body 8.0–9.7; forewings 9.5–12.0; cerci 11.7–16.0. Head: yellow with a pair of small brownish spots between the eyes. Thorax: Mesonotum yellow; prelateposcutum dirty brownish; median longitudinal and medioparapsidal sutures brownish. Forelegs brownish; joints of tarsal segments black; middle and hind legs brownish or yellowish; joints brown. Length (mm) of foreleg segments: femora 1.7–2.3; tibia 1.3–1.8; and tarsus 0.6–0.8. Color of the wings as in the male, but veins of hind wings pale. Abdomen (with eggs): terga brown as in the male; tergum II with light middle area, with dark brown anterior area and lateral sides; terga III–VII with light maculations as in the male; terga VIII–IX light brown; tergum X yellow. Sterna yellowish or whitish, not transparent. Female sterna without eggs brownish and translucent. Cerci pale with brownish joints.

Egg. General egg shape cylindrical, length of 131–137 μm and width of 89–113 μm ( Fig. 32 ). Surface of the chorion almost smooth, with a clear granular structure, composed of numerous round granules of two sizes (very small and small) ( Figs 33–34 ). One or two round micropyles located in the equatorial area; sperm guide round with a wrinkled bottom; micropylar rim well expressed ( Fig. 32 ).

Distribution and biology. Cinygmula levanidovi is an East Asian species that is distributed in the Russian Far East at Primorskiy Kray and Jewish Autonomous Region ( Tshernova & Belov 1982; Tiunova 2007, 2009). Larvae of this species are associated with stones, gravel, and pebbles in small rivers or streams, which are characterized as cold and moderately cold rivers. The emergence occurs in June in the rivers of southern Primorye, and from July to early August in the north.

Remarks. The larva of C. levanidovi is similar to the one of C. hirasana and C. kurenzovi , but it can be distinguished from these species and from all other Far Eastern Cinygmula by the shape of tergalius I, which is almost symmetric, heart-shape and bears a single short gill filament. Tergalius I of C. hirasana and C. kurenzovi has a similar shape, but there are no gill filaments on the first or on the other tergalii.

Figures

FIGURES 1–7. Cinygmula levanidovi, larva: 1–2. Head, dorsal view. 3. Labrum, dorsal view. 4. Labium, ventral view. 5. Femur of fore leg. 6. Setae on the dorsal surface of the femur 7. Claw of fore leg.

FIGURES 8–18. Cinygmula levanidovi, larva: 8. Pro- and mesonotum. 9. Abdominal terga. 10. Teeth at the posterior margin of abdominal tergite VI. 11. Abdominal sterna. 12–17. Tergalii, dorsal view: 12. Tergalius I. 13. Tergalius II. 14. Tergalius III. 15. Tergalius V. 16. Tergalius VI. 17. Tergalius VII. 18. Abdominal sternum IX (female).

FIGURES 19–21. Cinygmula levanidovi, larvae: 19–20, dorsal view. 19, female. 20, male. 21, male, ventral view. Scale bar: 1 mm.

FIGURES 22–23. Cinygmula levanidovi, male imago: 22, lateral view. 23, dorsal view. Scale bar: 1 mm.

FIGURES 24–31. Cinygmula levanidovi, male imago: 24. Head, dorsal view. 25. Fore wing. 26. Hind wing. 27. Styliger and gonostyli. 28. Penis, ventral view. 29. Penis, dorsal view. 30. Lateral spine of penes lobes. 31. Apex of titillator.

FIGURES 32–34. Cinygmula levanidovi, egg: 32. General view. 33–34. Structure of chorion. The arrows show the micropyles (mp). Scale bar: 10 μm