Cinygmula tetramera, Tiunova, Tatiana M. & Gorovaya, Ekaterina A., 2013

Tiunova, Tatiana M. & Gorovaya, Ekaterina A., 2013, New species of Cinygmula McDunnough, 1933 and larval description of Cinygmula irina Tshernova & Belov, 1982 from the Russian Far East (Ephemeroptera: Heptageniidae), Zootaxa 3691 (1), pp. 135-144 : 136-140

Cinygmula tetramera sp. nov.

( Figs.1–29 )

Material examined. Holotype male imago (reared from larva), RUSSIA, Khabarovskiy Kray, Okhotskiy region, spring without name near mount Three Brothers, approximately 3 km from the city of Okhotsk, 21.VIII.1998, T.Tiunova. Paratypes: collected together with the holotype: 1 male and 2 female imagines (reared), 11 mature larvae; second spring from the station “Orbit,” approximately 3 km from the city of Okhotsk, 22.VIII.1998, T.Tiunova.

Description. Male imago (in alcohol). Length (mm): body 9.7; forewings 9.7; cerci 17.8. Head: eyes noncontiguous ( Fig. 1 ), black tinged greenish. Medial and lateral ocelli white. Thorax: Medioscutum and submedioscutum light brown but submedioscutum darker; anteronotal protuberance brown; medial longitudinal suture narrow and brown, well expressed in base of thorax only. Scutellum light brown; scuto-scutellar impression dark brown. Forelegs light brown; joint brown; middle and hind legs yellowish; joint darker.

Length (mm) of foreleg segments: femora 2.4; tibia 3.1; tarsal segments 0.7, 1.1, 0.9, 0.7, and

0.4. Wings hyaline, all veins brown ( Figs. 2–3 ). Veins of forewings more contrasting than hind wings. Abdomen: terga without maculation; tergum I brown; terga II–IV translucent, dirty white with brownish lateral corner near posterior margin; terga V–VI dirty white, lateral margins brown; terga VII–IX dirty brown. Sterna whitish, translucent; sterna II–VIII with ganglionic markings; sterna VII–IX brownish. Styliger brown; gonostyli with five segments ( Figs.4 , 9 ). First and second segments of gonostylus dark brown; third and fourth segments light brown; fifth segment brown with light brown inner margin ( Figs. 4 , 10 ). Penes lobes brown; tops dark brown, widely separated, with grooves at apices ( Figs. 5–6 ); penes lobes each with long lateral spine; spine wide throughout, evenly narrowing to top, with pointed tips ( Figs. 5, 7 ). Titillators long and strong with pointed tips, almost reaching top, strongly curved laterally ( Figs. 5, 7 ). Cerci brown at the base and lighter distally.

Female imago. Length (mm): body 8.2–10.0; forewings 9.4; cerci 12.5–13.0. Overall color brown. Thorax: Mesonotum brown. Forelegs brown; middle and hind legs light brown. Length (mm) of foreleg segments: femora 1.8–2.2; tibia 2.0–2.3; tarsal 1.2–1.4. Color of wings as in male. Abdomen: terga brown, unicolorous. Sterna I–V brown (abdomen with eggs) or yellowish (without eggs), without maculation. Subanal plate with smooth and shallow depression ( Fig. 8 ). Cerci brownish, darker at base.

Mature larva. Length (mm): body 8.0–10.1; cerci 6.5–8.5. Head: brown, with shallow apical incision ( Fig. 11 ). Labrum light brown, posterior and lateral margins darker; width 2.5 times as long ( Fig. 12 ). Glossae with rounded tops ( Figs. 13–14 ). Thorax: pronotum light brown with pale large triangular spots at anterior margin and outer edges light ( Fig. 15 ). Mesonotum brown or light brown with unclear light maculation on lateral corners at anterior margin ( Fig. 15 ). Legs light brown; femur of forelegs with wide pale longitudinal stripe; strong brown setae nearly evenly cover dorsal surface of femur ( Fig. 16 ). Claws of foreleg with five subapical denticles ( Fig. 17 ). Length (mm) of leg segments as follows. Foreleg: 1.8–2.2; tibia 2.0–2.3; and tarsus 0.7–0.8. Middle leg: femur 2.0–2.2; tibia 1.7–2.2; and tarsus 0.6–0.7. Hind leg: femur 2.2–2.5; tibia 1.8–2.1; and tarsus 0.6–0.7. Abdomen: terga brown or light brown with pale lateral sides; terga I–VII with dark pair curved strokes in middle and dropshaped dark spots on sides; terga I–III lighter than others; tergum IX brown with pale median stripe ( Fig. 18 ). Sterna brown with pale lateral sides; sternum I with white middle and pair of brown strokes at anterior margin, and pair of round spots nearer to posterior margin; sterna II–V also with light middle, pair of brown strokes at anterior margin, pair of brown spots at posterior margin and pair of oval-shaped brown spots near lateral edges; sterna VI– VII darker than others; sterna VII with pair of brown spots on middle; sterna VIII brown with wide white spot in middle; sterna IX brown with darker lateral margin ( Fig. 19 ); abdominal sternum IX with deep posteromedian emargination ( Fig. 20 ). Gills white; gill I large with extended inner edge and almost right angle on outer margin, width 1.3 times as long as wide; 2-3 short gill filaments ( Fig. 21 ); gills II–V each with distinct angle on outer margin and 2–3 gill filaments; gill II wider than gill III ( Fig. 22 ); gill IV and V same shape and size ( Figs. 23– 24 ); gill VI ovate with one short gill filament ( Fig. 25 ); gill VII narrow with elongated pointed tip ( Fig. 26 ); length is 2.5 times width. Cerci light brown at base and brown on proximal portion.

Eggs. General egg form cylindrical, with length of 152–169 μm and width of 101–110 μm ( Fig. 27 ). Surface of chorion rugose, with clear granular structure; composed of numerous round granules of two sizes (small and medium) ( Fig. 28 ). Small KCT (knob-terminated coiled thread) attachment structures evenly spaced over entire surface of chorion ( Fig. 28 ); large and round knobs arranged on one pole ( Fig. 29 ). One or two round micropiles located in equatorial area; sperm guide round; micropylar rim well expressed.

Etymology. The epithet tetramera (meaning four-segmented) is an allusion to the forceps structure.

Distribution and biology. The species is known only from the type locale habitat in northern Khabarovskiy Kray. Mature larvae were collected from a spring with a width of approximately 80 cm, more than one meter into the ground and overgrown with grass. The temperature during the day (July 21) ranged from 6.4 to 6.6°C.

Discussion. The male imago of C. tetramera sp. nov. is similar to C. irina but can be distinguished from that species, and all other Cinygmula , by the number of distal segments of the forceps. C. tetramera sp.

nov. has imaginal forceps with three distal segments. The larvae of C. tetramera sp. nov. differ from C. irina larvae in regards to the form and the ratio of the length to the width of gills I and VII. In C. tetramera sp. nov., gill I has almost a right angle on the outer margin, and its width is 1.3 times as long; gill VII is narrow with an elongated pointed tip. In C. irina , gill I is heart-shaped, with an extended inner edge, and its width is almost equal to the length. Gill VII is narrow and uniformly tapers to a rounded tip.

Figures

FIGURES 1 – 8. Cinygmula tetramera sp. nov., male imago: 1. Head, dorsal view. 2. Fore wing. 3. Hind wing. 4. Sternum IX, styliger and gonostyli. 5. Penes, ventral view. 6. Penes, dorsal view. 7. Penes, lateral view. 8. Subgenital plate, female, ventral view.

FIGURES 9 – 10. Cinygmula tetramera sp. nov., male imago: 9. Gonostyli. 10. Fourth and fifth segments of gonostyli.

FIGURES 11 – 26. Cinygmula tetramera sp. nov., larva: 11. Head, dorsal view. 12. Labrum, dorsal view. 13 – 14. Labium: 13 — ventral view, 14 — dorsal view. 15. Pro- and meso-notum. 16. Femur of fore leg. 17. Tarsal claw of fore leg. 18. Abdominal terga. 19. Abdominal sterna. 20. Abdominal sternum IX (female). 21 – 26. Gills: 21. Gill I, 22. Gill II, 23. Gill III, 24. Gill V, 25 Gill VI, 26. Gill VII.

FIGURES 27 – 29. Cinygmula tetramera sp. nov., egg: 27. General view. 2. Structure of chorion and small knob-terminated coiled threads. 29. Large knobs. The arrow shows the micropiles (mp).