Source: FAO 2002.
| Family | Scientific Name | Author | Year | Common Name |
| Halosauridae | Aldrovandia affinis | (Gunther) | 1877 | Allied Halosaur |
All Halosaurs: Mouth inferior, overhung by snout. Dorsal fin short-based, on midtrunk, slightly closer to anus than to tip of snout. All rays segmented (the anteriormost ray reduced and unsegmented in Aldrovandia). Anal fin long, extending from just behind anus to tip of tail (FAO 2002).
All Aldrodvandia Species: First dorsal-fin ray much shorter than second and unsegmented. No scales on opercle. Sheath of lateral line unpigmented.
Aldrovandia affinis
Unique Characteristics: Anal opening white, surrounded by a dark field. Palatine tooth patches of the 2 sides in contact medially. 13-15 gill rakers on anterior arch. Preoral portion of snout about 2 times in total snout length. Dorsal origin over or very slightly behind base of pelvic fin.
Similar Species:
Aldrovandia gracilis, Slender Halosaur
Anal opening dark blue or black, surrounded by a white field.
Aldrovandia phalacra, Shortsnout Halosaur
Anal opening white, surrounded by a dark field. Palatine tooth patches of the 2 sides separated medially. 19-23 gill rakers on anterior arch. Preoral portion of snout about 3 times in total snout length. Dorsal origin distinctly behind base of pelvic fin.