sibling species Species that are identical in outward appearance or very nearly so. Despite the similarity, however, they qualify as species by being reproductively isolated. See reproductive isolating mechanisms.

sibling species Species that are identical in outward appearance or very nearly so. Despite the similarity, however, they qualify as species by being reproductively isolated. See REPRODUCTIVE ISOLATING MECHANISM.

sibling species (cryptic species) Two or more groups of organisms that cannot be readily distinguished by their appearance or other traditional taxonomic criteria but whose members cannot interbreed successfully. For example, many North American species of cricket, occupying the same geographical range, can be distinguished only by their song.