Isonychia ignota (Walker, 1853)

Martynov, Alexander V., 2018, New records of some rare mayflies (Insecta, Ephemeroptera) from Ukraine, Ecologica Montenegrina 16, pp. 48-57 : 52

Isonychia ignota (Walker, 1853)

This species was given for Ukraine in Godunko & Kłonowska- Olejnik (2003) basing on data of Mikulski (1936). The latter article was devoted to Ephemeroptera of Poland that previously included some regions of modern Western Ukraine and Belarus. Mikulski (1936) declared I. ignota for tributaries of the Prypyat’ River without precise points. Basin of this river falls within territory of modern Ukraine and Belarus. During the revision of the collections housed at the Institute of Systematics and Evolution of Animals PAS (Kraków), where the materials of J.S. Mikulski is housed, none specimen of I. ignota from the basin of Prypyat’ River was found (Kłonowska- Olejnik et al. 2005; Godunko R.J. personal communication). Thus, up to know there were no confident records of I. ignota for Ukraine.

We registered I. ignota ( Fig. 9 ) in potamal zone of meddle-sized Horyn’, Styr and Sluch Rivers within Rivne Region ( Figs 3 , 14, 15 ). These rivers are the right tributaries of the Prypyat’ River of the first or second orders. We found fresh exuvia of I. ignota at the Styr River in the first decade of August; this confirms that a part of population of I. ignota emerges at this period.

Habitat: In all rivers the larvae were registered at microhabitats with sand, sometimes with small stones or/and pieces of bog iron ore, or silted sand bottom and current velocity from 0.2 to 0.3 m /s. Larvae were collected from bottom and vascular aquatic plants, Potamogeton natans Linnaeus, 1758 and P. pectinatus Linnaeus, 1758 mainly. The additional parameters of waterbodies in collecting places measured during the sampling were: water temperature 23–30°C, water hardness 210–270 ppm, pH 8.6–9.0.

Material: Ukraine, Rivne Region: 15 larvae, vicinity of Zbuzh village, Horyn’ River , 50.990300, 26.320683, h – 154 m a.s.l., Martynov A. V. leg., 7.07.2017 – IN Riv2Isoign/1–2; 1 larva, vicinity of Horodets’ village, Horyn’ River , 51.284421, 26.366363, h – 149 m a.s.l., Martynov A. V. leg., 2.08.2017 – IN Riv8Isoign; 1 larva, 1 exuviae, vicinity of Stara Rafalivka village, Styr River , 51.378866, 25.863339, h – 156 m a.s.l., Martynov A. V. leg., 2.08.2017 – IN Riv7Isoign; 1 larva, vicinity of Sarny town, Sluch River , 51.317445, 26.635826, h – 148 m a.s.l., Martynov A. V. leg., 2.08.2017 .

Threats and recommendations for conservation: Water pollution is the most obvious threat to I. ignota . In common with other Ephemeroptera , this species relies upon good water quality. Other concrete threats for I. ignota within Ukraine are not defined. We consider that it deserves to be included in the Red Data Book of Ukraine because of the restricted distribution within the country, its rarity within the whole areal and stenobiotic nature. Detailed investigation (also genetic affinity to other populations) of Ukrainian populations of the species continues.

Figures

Figures 9–13. Larvae and imago of some registered species: 9. – Isonychia ignota (Walker, 1853), total view of larva, scale bar 2 mm; 10. – Baetopus tenellus (Albarda, 1878), total view of larva, scale bar 1 mm; 11. – Metreletus balcanicus (Ulmer, 1920), total view of larva, scale bar 2 mm; 12. – the same species, genitalia and posterior part of abdomen, male imago, ventral view, scale bar 1 mm; 13. – Brachycercus harrisella Curtis, 1834, total view of larva, scale bar 2 mm.

Figures 1–4. Larva and subimago of Palingenia fuliginosa (Georgi, 1802) and its habitat: 1. – total view of larva, scale bar 10 mm; 2. – total view of subimago, male, scale bar 10 mm; 3. – Horyn’ River, vicinity of Zbuzh village (July 2017); 4. – microhabitats most preferred by P. fuliginosa larvae on Horyn’ River (July 2017).

Figures 14–18. New collection sites of the investigated species within Ukraine: 14. – map showing new sites (red circles – Palingenia fuliginosa (Georgi, 1802); yellow circles – Isonychia ignota (Walker, 1853); green circle – Baetopus tenellus (Albarda, 1878); blue circles – Brachycercus harrisella Curtis, 1834; red quadrates – Siphlonurus aestivalis Eaton, 1903; yellow quadrate – Metreletus balcanicus (Ulmer, 1920)); 15. – Styr River, (vicinity of Stara Rafalivka village, July 2017); 16. – Stvyga River (vicinity of Poznan’ village, July 2017); 17. – bay of Desna River (vicinity of Prydesnyans’ke village, May 2017); 18. – Salva River (territory of Bukove village, May 2017).