Photo by Britt Griswold
Helogenes Gunther, 1863
Helogenes is readily distinguished from all other cetopsid genera in having teeth of the anterior portion of outer row of dentary much larger and more widely spaced apart than remaining teeth of the jaw; and the dorsal fin is located on the posterior half of SL. In addition, a large suite of osteological characters that are unique within the Cetopsidae are found in all species of Helogenes.
KEY TO THE SPECIES OF HELOGENES
| 1. | Caudal fin with 15 principal rays (8 principal rays on ventral lobe) | 2 |
| Caudal fin with 16 principal rays (9 principal rays on ventral lobe) | 3 | |
| 2. | Anal fin with 43 to 49 rays; distance from tip of snout to origin of rayed dorsal fin base 0.57 to 0.60 of SL; Snout length 0.36 to 0.40 of HL; distance between rayed dorsal fin and adipose dorsal fin 0.16 to 0.19 of SL | Helogenes gouldingi |
| Anal fin with 39 to 43 rays; distance from tip of snout to origin of rayed dorsal fin base 0.65 to 0.71 of SL; Snout length 0.27 to 0.36 of HL; distance between rayed dorsal fin and adipose dorsal fin 0.11 to 0.15 of SL | Helogenes castaneus | |
| 3. | Anal-fin rays 32-37 | Helogenes uruyensis |
| Anal-fin rays 38-48 | Helogenes marmoratus |