Key to males of Neoperla species from Guangdong Province, China (excluding N. banksi (Illies, 1966), N. infuscata Wu, 1935, N. limbatella Navás, 1933, and N. tingwushanensis Wu, 1935)

1. Tergum 8 lacks a process (see figs. 24b–d in Mo et al. 2022).............................. N. cavaleriei (Navás, 1922)

- Tergum 8 possesses a process............................................................................ 2

2. Tergum 7 has a small, rounded posterior process (see fig. 13 in Li et al. 2012a).......... N. similiserecta Wang & Li, 2012

- Tergum 7 has a large, trapezoidal posterior process........................................................... 3

3. Tergum 7 has an anteromedian pair of sclerotized, nipple-shaped processes....................................... 4

- Tergum 7 lacks a pair of anteromedian processes............................................................ 5

4. Aedeagal sac is approximately twice as long as the tube (see fig. 7 in Li & Yan 2021).............. N. bicornua Wu, 1973

- Aedeagal sac is only slightly longer than the tube (see figs. 2a–e in Mo et al. 2021)... N. annulatispina Mo, Li & Wang, 2021

5. Aedeagal tube lacks a ventral lobe........................................................................ 6

- Aedeagal tube features a ventral lobe or lobes............................................................... 7

6. Aedeagal tube is fully sclerotized and distinctly longer than the sac (Figs. 5d, 6a).............. N. xiangtoushana sp. nov.

- Aedeagal tube is sclerotized only on the dorsal surface and is obviously shorter than the sac (see fig. 10 in Mo et al. 2021)........................................................................... N. maolanensis Yang & Yang, 1993

7. Aedeagal tube features a single, finger-like ventral lobe (see figs. 4c–d in Mo et al. 2021)... N. chebalinga Chen & Du, 2016

- Aedeagal tube features a bifurcated, Y-shaped ventral lobe..................................................... 8

8. Aedeagal sac is covered with a dense cluster of spines on the apical half (Figs. 2d, 3a–b).......... N. lianhuashana sp. nov.

- Aedeagal sac lacks a dense cluster of spines on the apical half.................................................. 9

9. The arms of the Y-lobe are approximately four times as long as its stalk on the aedeagal tube (see fig. 3 in Zeng et al. 2024b)..................................................................................... N. minor Chu, 1929

- The arms of the Y-lobe are either as long as or distinctly shorter than its stalk on the aedeagal tube.................... 10

10. Aedeagal sac is distinctly shorter than half the length of the tube (see fig. 8 in Zeng et al. 2024a)...... N. mnong Stark, 1987

- Aedeagal sac is longer than half the length of the tube (see figs. 5d–g in Mo et al. 2020b).... N. hubleyi Stark & Sivec, 2008