Yukikoa, M. Sato, 1976

Nakamura, Ryo & Kubota, Kôhei, 2023, Taxonomic study of the Japanese endemic genus Yukikoa M. Satô (Coleoptera, Cantharidae) with descriptions of two new species, Zootaxa 5351 (5), pp. 581-589 : 587-588

Key to species of the genus Yukikoa (for males only)

1 Dorsal plate of male genitalia with length more than twice as long as ventral process in lateral view........... Y. onzuiensis

- Dorsal plate of male genitalia with length less than twice as long as ventral process in lateral view..................... 2

2 Dorsal plate of male genitalia with little or shallow incision (of less than 1/5 of the total length of dorsal plate) in the anterior margin.............................................................................................. 3

- Dorsal plate of male genitalia with deep U-shaped or V-shaped incision (of more than 1/5 of the total length of dorsal plate) in the anterior margin.................................................................................... 6

3 Elytra shorter (EL/MEW <1.65, EL/HEW <2.40)........................................................... 4

- Elytra longer (EL/MEW> 1.80, EL/HEW> 2.40)........................................................... 5

4 Dorsal plate of male genitalia with lateral sides somewhat broadened anteriorly; ventral process of male genitalia with its 1/5 length exceeding laterophyse in lateral view; each laterophyse of male genitalia wide in ventral and dorsal view..................................................................................................... Y. maniwana

- Dorsal plate of male genitalia with lateral sides weakly narrowed anteriorly; ventral process of male genitalia not exceeding laterophyse in lateral view; each laterophyse of male genitalia slender in ventral and dorsal view...... Y. mashimai sp. nov.

5 Terminal antennomere shorter than any of the 5 to 9 segments; genitalia elongate; each laterophyse of male genitalia about 3.5 times as long as wide and distantly located in ventral and dorsal view.................................... Y. kanekoi

- Terminal antennomere longer than any of the 5 to 9 segments; genitalia broad; each laterophyse of male genitalia about 2.5 times as long as wide and closely located in ventral and dorsal view....................................... Y. akitai

6 Each laterophyse of male genitalia significantly dilated toward the apex in ventral or dorsal view, with the inner margin approaching toward the apex................................................................... Y. watanabei

- Each laterophyse of male genitalia moderately widened toward the apex in ventral or dorsal view, with the inner margin almost parallel or becoming distant toward the apex................................................................ 7

7 Elytra longer (EL/HEW> 2.70); head and pronotum entirely blackish brown; apex of ventral process of male genitalia with blunt tip............................................................................ Y. nishimotoi sp. nov.

- Elytra shorter (EL/HEW <2.55); head and pronotum reddish brown for the most part; apex of ventral process of male genitalia with sharply pointed tip................................................................................ 8

8 Antennomere 2 not so short, more than 0.7 times as long as 3; dorsal plate of male genitalia with somewhat V-shaped incision ................................................................................................... 9

- Antennomere 2 short, less than 0.66 times as long as 3; dorsal plate of male genitalia with U-shaped incision........... 10

9 Each laterophyses of male genitalia about 2.2 times as long as wide in ventral and dorsal view; ventral process of male genitalia shorter than laterophyse in lateral view; dorsal plate of male genitalia with sharper tip V-shaped incision......... Y. mizunoi

- Each laterophyses of male genitalia about 2.5 times as long as wide in ventral and dorsal view; ventral process of male genitalia as long as laterophyse in lateral view; dorsal plate of male genitalia with rounder tip V-shaped incision.......... Y. wittmeri

10 Laterophyses of male genitalia exceeding the tip of ventral process in lateral view........................ Y. kamezawai

- Laterophyses of male genitalia not reaching the tip of ventral process in lateral view...................... Y. masatakai