1. a) Scales in horizontal scale row 22-25 ... 2
b) Scales in horizontal scale row 26-28 ... 4
2. a) Bright blue stripes along flanks conspicuous; conspicuous pattern of dots or small stripes on unpaired fins ... 3
b) Bright blue stripes along flanks hardly visible; colour pattern of unpaired fins faint, without conspicuous dots or stripes ... Gg. setequedas
3. a) Dorsal and anal fins with well-defined circular dots ... Gg. meridionalis
b) Dorsal and anal fins with small stripes ... Gg. rhabdotus
4. a) Dorsal fin with 12-15 soft rays; caudal fin almost completely scaled, with lateral line branch on the lower lobe ... Gg. balzanii
b) Dorsal fin with 8-12 branched rays; caudal fin width scales only on the proximal third or half, without lateral line branch on the lower lobe ... 5
5. a) Dark band extends posteroventrally from the dorsal fin origin; well-defined circular dots on dorsal, anal and especially caudal fins ... 6
b) Dark band from nape to cheek crossing the eye instead of the band described above; dorsal and especially caudal fins with rather small stripes ... 7
6. a) Dorsal profile of body anterior to dorsal fin origin very steep; soft dorsal fin scaly; caudal peduncle depth 0.9 in its length ... Gg. australis
b) Dorsal profile of body anterior to dorsal fin origin not as steep; soft dorsal fin rarely scaled; caudal peduncle depth 1.0-1.4 in its length ... Gg. gymnogenys
7. a) Lips thick, extremely well developed, lower lip deeply notched medially ... Gg. labiatus
b)Lips normal, not excessively developed or notched ... Gg. lacustris
