Chionomus, Fennah, 1971

Weglarz, Kathryn M. & Bartlett, Charles R, 2020, A revision of the planthopper genus Chionomus Fennah (Hemiptera: Fulgoroidea: Delphacidae), Zootaxa 4811 (1), pp. 1-63 : 10-11

Key to males of the Genus Chionomus

1. Armature of diaphragm distinctly bilobed ( Figures 6i, 28a, 29a).............................................. (2).

- Armature of diaphragm not distinctly bilobed, may be cordate, notched, or U-shaped ( Figures 19a, 25a, 30a)........... (5).

2. Armature of diaphragm hooked, lobes parallel; processes of segment X present but not particularly strong, specimens with carinae of the mesonotum lightened frequently forming a vitta ( Figures 6, 22, 13, 28)............................. (3).

- Armature of diaphragm not hooked, lobes distinctly diverging; processes distinct and directed ventrad, carinae of mesonotum concolorous ( Figures 5, 21, 14, 29)..................................................................... (4).

3. Armature of diaphragm hooked only in apical half, lobes only diverging in apical half; aedeagus with toothed flange on left side ( Figures 6, 22)............................................................................. C. bellicosus .

- Armature of diaphragm hooked along entire length, lobes diverging from point of origin; aedeagus without flange, with two rows of scattered teeth ( Figures 13, 28)........................................................... C. pacificus .

4. Lobes of armature of diaphragm small and closely approximated; processes of segment X parallel. Posterior edge of pronotum dark, only paranota white in color ( Figures 5, 21)................................................. C. banosensis .

- Lobes of armature of the diaphragm produced, diverging from point origin; processes of segment X diverging. Posterior edge of pronotum white, paranota also white ( Figures 14, 29)............................................... C. puellus .

5. Pygofer with prominent quadrate, dorsolateral process. Parameres not flattened at apex. ( Figures 12, 27)......... C. herkos .

- Pygofer without dorsolateral processes, if produced at dorsolateral margin, not quadrate. Parameres flattened at apex. ( Figures 19, 23, 26)......................................................................................... (6).

6. Segment X with a total of 4 processes ( Figures 23b, 24b, 25b, 30b)............................................ (7).

- Segment X with only 2 processes or processes vestigial ( Figures 19b, 20b, 26b, 31b)............................. (10).

7. Secondary processes of segment X small, spine-like. Armature of diaphragm shelf-like. Ventral margin of pygofer with caudally projecting median process ( Figures 9, 24)..................................................... C. dolonus .

- Secondary processes of segment X long, sinuate. Armature of diaphragm quadrate, quadrate and notched, or U-shaped. Ventral margin of pygofer lacking median process ( Figures 23, 25, 29)............................................... (8).

8. Armature of diaphragm quadrate or cordate/notched, toothed along vertical margins; aedeagus not distinctly enlarged at base ( Figures 23a, c, 25a, c)............................................................................... (9).

- Armature of diaphragm U-shaped, lacking teeth; aedeagus with distinctly enlarged, quadrate base ( Figures 29 a, b).............................................................................................. C. quadrispinosus .

9. Armature of diaphragm notched along ventral margin; aedeagus with slight enlargement apically. Parameres not produced opposite of basal angle. Posterior compartments of vertex and stem of Y-shaped carina dark ( Figures 10, 25)... C. gluciophilus .

- Armature of diaphragm quadrate, notch along ventral margin not evident; aedeagus tapering along entire length, not enlarged apically. Parameres with rounded projection opposite of basal angle. Posterior compartment of vertex light but with fuscous markings, stem of Y-shaped carina light ( Figures 8, 23)............................................. C. dissipatus .

10. Aedeagus nearly straight, may have slight dorsal curve ( Figures 19b, 20c, 26c)................................. (11).

- Aedeagus with distinct curve dorsad, nearly forming a right-angle apical hook on left, small teeth along length. Segment X with two rounded processes, lobe-like, arising from the middle of segment. Specimens frequently large for Chionomus , with wings infuscate ( Figures 17, 31)......................................................................... C. tenae .

11. Aedeagus with subapical and distinctly projecting flagellum, lacking teeth and hooks ( Figure 19b)............ C. havanae .

- Aedeagus without flagellum, with hooks and/or teeth ( Figures 20c, 26c)....................................... (12).

12. Aedeagus with large hooks on right side of aedeagus; apex of parameres anvil shaped ( Figures 20b,c).......... C. balboae .

- Aedeagus with small teeth in two scattered rows, lacking any sort of hook; apex of parameres quadrate ( Figures 26b,c)............................................................................................... C. haywardi .