Isonychia sexpetala Tiunova et al., 2004

Qiang, Xin-He & Zhou, Chang-Fa, 2023, A preliminary review of Isonychia Eaton, 1871 from Chinese mainland with a re-description of I. kiangsinensis Hsu, 1936 (Insecta, Ephemeroptera, Isonychiidae), ZooKeys 1178, pp. 115-141 : 115

Isonychia sexpetala Tiunova et al., 2004

Isonychia (Isonychia) sexpetala Tiunova et al., 2004: 10 (nymph and adults). Types from Russia and China; Zhou 2013: 196; Zhou et al. 2015: 245.

Material examined.

1 male imago, Nenjiang , Liuyuan, Qiqihar City, Heilongjiang Province, China, 1-VIII-2007, collected by Shilei Wang, Changfa Zhou.

Diagnosis.

The male of this species is smaller than most congeners but similar to I. ussurica . It has no pigments on wings, MP of hindwings forked more apically than MA, but two forking points are close (Fig. 12A, B ), segment II of forceps with straight inner margin, penes nearly cylindrical with convex distal margins and membranous processes with pigmented or sclerotized tip (Fig. 12C-E ).

The males of I. ivani Tiunova et Gorovaya, 2010 and I. sexpetala Tiunova et al., 2004 are alike because they have similar cylindrical penes (Fig. 12D ) and the basal 1/2 of their foretarsi is usually pale (Fig. 1D ), but their membranous processes beneath penes are different. The processes of I. sexpetala have a rounded apex (Fig. 12E ) while those of I. ivani are tapered. The nymphs of these two species can be separated by their color pattern of abdominal terga and gills: (1) the pale median longitudinal line of I. sexpetala is shorter than that of I. ivani ( Tiunova et al. 2004; Tiunova and Gorovaya 2010), (2) gills of I. ivani have apical small dark dots while those of I. sexpetala are transparent.

Description.

See Tiunova et al. (2004).

Distribution.

China (Heilongjiang province); Russia ( Tiunova et al. 2004).

Figures

Figure 1. Imaginal structures of I. guixiensis A forewing of male B hindwing of male C subanal plate of female (ventral view) D foreleg of male E abdomen of male (dorsal view) F male genitalia (ventral view) G penes (dorsal view) H membranous processes (ventral view).

Figure 12. Male structures of I. sexpetala A forewing B hindwing C genitalia (ventral view) D penes (dorsal view) E membranous processes (ventral view).