''Lethenteron reissneri'', the Far Eastern brook lamprey, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

lamprey Lampreys (sometimes inaccurately called lamprey eels) are a group of Agnatha, jawless fish comprising the order (biology), order Petromyzontiformes , sole order in the Class (biology), class Petromyzontida. The adult lamprey is characterize ...

. Immature ''L reissneri'' are

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...

, but shift to a non-parasitic feeding strategy upon reaching maturity. It is found in lakes and rivers in China, Japan, Korea, Mongolia, and the Russian Far East. It may be identical to the Siberian brook lamprey, ''

Lethenteron kessleri ''Lethenteron'' is a genus of lamprey in the family Petromyzontidae. Species There are currently 7 recognized species in this genus: * ''Lethenteron alaskense'' Vladykov & Kott, 1978 (Alaskan brook lamprey) * '' Lethenteron appendix'' ( DeKay, ...

'', but molecular evidence suggests they are

cryptic species In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

References

reissneri {{jawless-fish-stub