Isonychia ussurica ussurica Bajkova, 1970 (first record from China)

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 ussurica ussurica Bajkova, 1970 (first record from China)

Isonychia ussurica Bajkova, 1970: 148 (adults). Types from Khor River, Russia.

Isonychia sp. 1: Bajkova 1970: 153 (nymph) (named Isonychia (Isonychia) ussurica ussurica by Tiunova et al. 2004: 16 (male, female, and nymph)).

Material examined.

2 male imagos and 1 female imago, the river under No. 70 Bridge , Nancha County, Yichun City, Heilongjiang Province, China, 15-17-VII-2016, collected by Wei Zhang.

Diagnosis.

The male of this subspecies can be identified by its body smaller than other species (~ 10.0 mm), forewing with pigmented band, MP and MA of hindwing forked equally (Fig. 14A, B ), and nearly triangular penes and its membranous processes, slightly convex inner margin of forceps (Fig. 14D-F ). The body of it is also usually uniformly reddish to reddish brown. Female size and color pattern are similar to males but without pigment on wings. Sternum IX has a narrowed posterior half and free margin is shallowly concave (Fig. 14C ).

Description.

See Bajkova (1970) or Tiunova et al. (2004).

Distribution.

China (Heilongjiang province), Russia ( Tiunova et al. 2004), Korea ( Bae and Yoon 1997).

Remarks.

The size of brownish transverse band on forewing of our Chinese material seems smaller than that described by Bajkova (1970) and Tiunova et al. (2004) on Russian specimens (Fig. 14A ). We regard this difference as a population variation.

Tiunova et al. (2004) stated clearly that two subspecies are distributed in different parts of Russia: I. u. sibirica in the western part such as Siberia and Mongolia while I. u. ussurica is found in the eastern part, the Russian Far East. Consistently, our collections of these two subspecies from Heilongjiang province show that the distribution of I. u. sibirica is more western than that of I. u. ussurica .

Figures

Figure 14. Imaginal structures of I. ussurica ussurica A forewing of male B hindwing of male C subanal plate of female (ventral view) D male genitalia (ventral view) E penes (dorsal view) F membranous processes (ventral view).