Isonychia guixiensis Wu et al., 1992

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 guixiensis Wu et al., 1992

Isonychia guixiensis Wu et al., 1992: 78 (male, female). Type from Jiangxi province, China; You and Gui 1995: 25 (male); Gui and Zhou 1999: 126.

Isonychia sinensis Wu et al., 1992: 79 (male, female). Type from Jiangxi province, China; You and Gui 1995: 27 (male); Su and Zhu 1997: 121 (egg) (synonymized by Zhou 2013: 196).

Material examined.

Holotype of I. guixiensis (male imago), Guixi City , Jiangxi Province, China, 4-6-VI-1990, collected by Lixin Tian, Lianfang Yang; paratypes of I. guixiensis : 10 male imagos and 12 female imagos, same data as the holotype . Holotype of I. sinensis (male imago), Guixi City , Jiangxi Province, China, 4-6-VI-1990, collected by Lixin Tian, Lianfang Yang; paratypes of I. sinensis : 5 male imagos and 13 female imagos, same data as the holotype .

Diagnosis.

The male of I. guixiensis has transparent wings (Fig. 1A, B ), dark brown forefemora, foretibiae, apical half of tarsal segment I-IV and tarsal segment V (Fig. 1D ). Its abdominal terga are brown with a pale median line and dark longitudinal submedian stripes (Fig. 1E ). The penes are nearly cylindrical with pointed apicolateral angles, and membranous processes beneath penes are clear (Fig. 1F-H ). The females are similar to the males, with concave sternum IX (Fig. 1C ).

This species and I. kiangsinensis can be found sympatrically in Jiangxi province, central China. They can be differentiated by the following characters: (1) I. guixiensis is smaller than I. kiangsinensis ; (2) the body of I. guixiensis is brown to dark brown (Fig. 1E ) while the body of I. kiangsinensis is usually pink to reddish; (3) I. guixiensis has distinct brown markings on abdomen (Fig. 1E ) while the I. kiangsinensis has none. (4) their penes are dissimilar: those of I. kiangsinensis are triangular but penes of I. guixiensis are nearly cylindrical with pointed apicolateral angles (Fig. 1G ).

Description.

See Wu et al. (1992).

Distribution.

China (Jiangxi province).

Remarks.

Wu et al. (1992) named two species, I. guixiensis and I. sinensis , in a single paper, with the penes of I. guixiensis appearing remarkably small. After checking all types of those two species, we found no difference between them, and their abdominal markings are absolutely less distinct than those in the original figures of Wu et al. (1992), and the synonymy of two species is confirmed here. Because the name of I. guixiensis is before I. sinensis in the same paper, the former is retained as the valid name.

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).