Rhithrogena klugei, Tiunova, Tatiana M., 2010

Tiunova, Tatiana M., 2010, A new species of Rhithrogena Eaton, 1881 from the Far East of Russia with notes on this genus in this area (Ephemeroptera: Heptageniidae), Zootaxa 2639, pp. 1-18 : 2-5

Rhithrogena klugei sp. nov.

( Figs. 1–23 )

Holotype. Male imago, RUSSIA, Khabarovskiy Kray, Bikin River, 50 m below motor-car bridge, line Vladivostok-Khabarovsk, 16.VI 2005, T Tiunova.

Paratypes. Collected with holotype: Russia, Khabarovskiy Kray, Bikin River, 50 m below motor-car bridge, line Vladivostok-Khabarovsk, 16.VI 2005, together with holotype, 70 male imagines, 3 larvae; T Tiunova; same place, 18.VI 2005, T Tiunova, 2 male imagines; same place, 2.VII 2005, T Tiunova, 16 male imagines.

Other material examined. Russia: Chitinskaya Oblast’: Selenga River, 65 km upper mouth, 25.VI 2007, N Bazova, 1 male imago; Selenga River, Iljinka Village, 13.VI 2007, N Bazova, 1 male, 2 female imagines; same place, 25.VI 2007, N Bazova, 2 male imagines; Selenga River, Sutoj Village, 9.VI 2008, N Bazova, 3 male, 1 female imagines; Selenga River, Ust’-Kehta Village, 9.VI 2008, N Bazova, 1 male imago; Selenga River, Utes Tologoj, 10.VI 2009, N Bazova, 1 male, 2 female imagines. Amurskaya Oblast’: Burunda River, 800 m upper mouth, tributary Nora River (Selemdzha River Basin), 16.VI 2004, T Tiunova, 7 male imagines; Zeya River, near Krasnoyarovo Village, 24.VI 2004, T Tiunova, 27 male imagines. Primorskiy Kray: Ussuri River, 3 km below Novomikhailovka Village, 27.V 1991, T Tiunova, 3 larvae; Ussuri River, Saratovka Village, 29.V 1991, T Tiunova, 12 larvae; Ussuri River, 6 km below Koksharovka Village, 28.V 1992, T Tiunova, 1 male imago; Ussuri River, Stepanovka Village, 15.VI 2005, T Tiunova, 1 male imago; Razdol’naya River, Pokrovka Village, 1.VI 1991, T Vshivkova, 3 male imagines; Razdol’naya River, Fadeevka Village, 30–31.V 1998, T Tiunova, 1 male imago; Komissarovka River, Komissarovo Village, 28.V 1998, T Tiunova, 12 male imagines, 4 larvae; Bolshaya Ussurka River, 2 km below Zvenigorodka Village, 8.VI 2004, T Tiunova, 1 male imago.

Description. Male imago (in alcohol). Dimensions: length (mm): body 7.7–10.0; forewings 8.7–11.2; cerci 18.5–24.0. Total color of living imago brown. Head: upper portion of eyes from pinkish-grey to dark grey. Eyes contiguous dorsally. Thorax: medioscutum brown, submedioscutum light brown, scutellum and sublateroscutum dark brown ( Fig. 1 ); median longitudinal suture well expressed, light yellow. Mesosternum brown. Femora and tibia of forelegs brown, darker than the middle and hind legs, with dark brown joints. Tarsal segments from light brown to yellowish, last segments and claw brownish. Femora of all legs with a contrasting black coloration. Length (mm) of foreleg segments: femora 1.9–2.3; tibia 2.6–3.2; tarsal segments 0.3–0.4, 1.5–1.9, 1.3–1.8, 1.0–1.5, 0.4–0.5. Wings hyaline; longitudinal veins brownish or whitish; crosssectional veins colorless; pterostigma whitish. Abdomen: terga from brown to light brown, hyaline; terga 2–6 having a poorly defined pair of bow-shaped light colored strokes. Sterna 1–7 brownish, sterna 8–9 whitish, opaque. Forceps dark brown, styliger plate brown. Penis lobes from light brown to yellow, having a contrasting pattern with dark forceps and styliger plate. Penis lobes jut out to the edge of the styliger plate; tops of penis lobes are rounded externally, with an inner apical tooth that is long and pointed ( Fig. 2 ). Laterodorsoventral tooth on the penis lobes is absent ( Figs. 5–7 ). Titillators curved and pointed ( Figs. 4–5 ). Cerci: proximal third brown, distally from light brown to yellow, base of each segment dark brown.

Female imago. Dimensions: length (mm): 6.5–8.8; forewings 7.2–11.0; cerci 11.0–11.5. Total color of living imago yellow. Terga 2–6 light brown with a pair of white spots. Legs yellow, joints of tarsal segments and claw brown.

Subimagines. Unknown.

Mature larva. Dimensions: length (mm): body 9–12, cerci 6–8. Head: frons brown, frequently with a light medial longitudinal spot. Posterior part of the head having a pair of small white spots in the middle area ( Fig. 9 ). Labrum slightly concave in the middle of the anterior margin, width 3.2 times longer than the length ( Fig.12 ). Labium with U-shaped separation of glossae; tips of glossae slightly narrowed and rounded ( Fig. 10 ). Lower tooth of mandible 1/3 times the length of the upper tooth ( Fig. 11 ). Hypopharynx with apex slightly convex ( Fig. 13 ). Maxilla with 9 comb-shaped setae at the apical margin ( Fig. 18 ). Thorax: pronotum with white anterior margin and lateral corners; mesonotum brown with a light colored median longitudinal stripe and a pair of white spots at the base of the wing pads. Femur of each leg with dark spot in the middle of the light central area; setae on the dorsal surface of the fore-femora of three different types: 1—elongated with a rounded apex, 2—with distinct divergent margins and a truncated apex, 3—with distinct divergent margins and a rounded apex ( Fig. 19 ). Claws of fore- and middle legs with four subapical denticles ( Fig. 22–23 ). Length (mm) of leg segments are the following. Foreleg: femur 1.6–1.9, tibia 1.4–1.7, tarsus 0.5–0.6; middle leg: femur 1.6–2.1, tibia 1.4–1.7, tarsus 0.4–0.6; hind leg: femur 2.2–2.8, tibia 1.6–2.1, tarsus 0.5–0.6. Femora of the hind leg is 1.4 times longer than the femur of the middle and hind legs. Abdomen: terga brown, usually monotonous, sometimes lighter in the posterior area; central portion of the posterior margin of terga 5 having long and pointed teeth of uniform sizes ( Fig. 20 ); sterna from light brown to brownish-yellow, sternum 9 darker than the others; abdominal sternum 9 in females with deep posteromedian emargination ( Fig. 21 ). Gills white; gill I large with a wavy outer margin ( Fig. 14 ); gills II–VI approximately 1.3 times as long as they are wide ( Fig. 15–16 ); gill VII broadens in its middle area ( Fig. 17 ). Cerci light brown, darker on the proximal portion with yellow tips.

Etymology. The new species is named in honor of ephemeropterologist Nikita Kluge, who has been a long-time investigator of mayflies in Russia.

Distribution and biology. This species was found during an excursion to investigate mayfly species in the Russian Far East and in southwestern Siberia. The imagines were collected in light traps and in the grass and leaves of trees near the water. Larvae of this species were found in gravel and pebbles in the centers of large rivers that can be characterized as hyporhithral and potamal.

Discussion. Male imago of R. klugei sp. nov. can be distinguished from all other members of lepnevae species group by the following characteristcs: Titillators of R. lepnevae are wide, with 3–5 teeth apically ( Fig. 46 ), while titillators of R. klugei sp. nov. narrow to a single point apically ( Fig. 4–5 ) and are similar to R. bajkovae , R. ingalik and R. piechockii . However R. bajkovae ( Fig. 25–29 ) and R. ingalik [ Fig. 3 ( Randolph and McCafferty 2005)] have latero-dorsoventral teeth on penis lobes in contrast to R. klugei sp. nov. ( Fig. 5– 7 ). Tops of penis lobes of R. klugei sp. nov. are rounded externally ( Fig. 6 ) and smoothly passes an inner apical tooth that is straight and pointed ( Fig. 8 ), whereas the tops of penis lobes of R. piechockii have a deep groove in the middle and at the base of inner apical tooth it is curved and arched [ Fig. 6 ( Braasch 1977)]. The larvae of R. klugei sp. nov. differ from those of R. bajkovae and R. lepnevae the form of gills I and the ratio of the length to the width of gills III–IV. In R. klugei sp. nov., gill I has a wavy inner margin ( Fig. 14 ); gills III– IV are approximately 1.3 times as long as they are wide; in contrast to R. bajkovae and R. lepnevae , gill I has an inner marginal ( Figs. 34 , 51 ); gills III–IV are elongated, being approximately 1.5–1.7 times as long as they are wide. The larva of R. klugei sp. nov. differ from those of R. sibirica in the absence of a rounded ledge on the inner margin of gills III–IV ( Fig. 70–71 ), in the form of the setae on the dorsal surface of the fore-femora ( Fig. 73 ) and in the number of subapical denticles on the claws.

Figures

FIGURES 1 – 8. Rhithrogena klugei sp. nov., male imago: 1. Mesonotum, dorsal. 2. Genitalia, ventral. 3. Penis, ventral. 4. Penis, dorsal. 5. Penis lobes, semi-lateral. 6. Penis lobes, view from above. 7. Apex of penis lobes, dorsal. 8. Apex of penis lobes, ventral. Scale (mm): 1 = 1.0, 2 = 0.5, 3 – 8 = 0.2.

FIGURES 9 – 23. Rhithrogena klugei sp. nov., larva: 9. Head, dorsal. 10. Labium, dorsal. 11. Teeth of left mandible, dorsal. 12. Labrum, dorsal. 13. Hypopharynx, dorsal. 14. Gill I. 15. Gill III. 16. Gill IV. 17. Gill VII. 18. Comb-shaped setae the maxilla. 19. Setae on the dorsal surface of fore femora. 20. Posterior margin of terga 5. 21. Abdominal sternum 9 (female). 22. Tarsal claw of fore leg. 23. Tarsal claw of middle leg. Scale (mm): 9,14 = 1.0; 10,12 – 13,15 – 17 = 0.5; 11,18 = 0.01; 19 – 20 = 0.05; 21 = 0.2; 22 – 23 = 0.1.

FIGURES 43 – 47. Rhithrogena lepnevae, male imago: 43. Mesonotum, dorsal. 44. Penis, ventral. 45. Penis, dorsal. 46. Titillators, lateral. 47. Penis lobes lateral. Scale (mm): 43 = 1.0; 44 – 45,47 = 0.2; 46 = 0.05.

FIGURES 24 – 29. Rhithrogena bajkovae, male imago: 24. Mesonotum, dorsal. 25. Penis, ventral. 26. Penis, dorsal. 27. Penis lobes lateral. 28. Penis lobes, view from above. 29. Apex of penis lobes, dorsal. Scale (mm): 24 = 1.0; 25 – 29 = 0.2.

FIGURES 30 – 42. Rhithrogena bajkovae, larva: 30. Head, dorsal. 31. Labrum, dorsal. 32. Teeth of left mandible, dorsal. 33. Comb-shaped setae of the maxilla. 34. Gill I. 35. Gill III. 36. Gill IV. 37. Gill VII. 38. Setae on the dorsal surface of fore femora. 39. Abdominal sternum 9 (female). 40. Tarsal claw of fore leg. 41. Tarsal claw of middle leg. 42. Posterior margin of terga 5. Scale (mm): 30 = 0.1; 31 = 0.2; 32,40 – 41 = 0.01; 33,38,42 = 0.05; 34 = 1.0; 35 – 37,39 = 0.5.

FIGURES 48 – 59. Rhithrogena lepnevae, larva: 48. Head, dorsal. 49. Labrum, dorsal. 50. Comb-shaped setae of the maxilla. 51. Gill I. 52. Gill III. 53. Gill IV. 54. Gill VII. 55. Setae on the dorsal surface of fore femora. 56. Tarsal claw of fore leg. 57. Tarsal claw of middle leg. 58. Posterior margin of terga 5. 59. Abdominal sternum 9 (female). Scale (mm): 48,51 = 1.0; 49 = 0.2; 50,55,58 = 0.05; 52 – 54, 59 = 0.5; 56 – 57 = 0.1.

FIGURES 65 – 77. Rhithrogena sibirica, larva: 65. Head, dorsal. 66. Labrum, dorsal. 67. Teeth of left mandible, dorsal. 68. Comb-shaped setae of the maxilla. 69. Gill I. 70. Gill III. 71. Gill IV. 72. Gill VII. 73. Setae on the dorsal surface of fore femora. 74. Abdominal sternum 9 (female). 75. Tarsal claw of fore leg. 76. Tarsal claw of middle leg. 77. Posterior margin of terga 5. Scale (mm): 65,69 = 1.0; 66,74 = 0.2; 67 – 68,75 – 76 = 0.01; 70 – 72 = 0.5; 73,77 = 0.05.