a condition in which males and females of the same species are morphologically different, usually indicated in unionoids by an expanded posterior marsupial area in the female in contrast to a more pointed or bluntly rounded area in the male. (Parmalee and Bogan 1998)
A marked difference in size and appearance between males and females of a species.
Refers to species that have noticeable physical differences between males and females (e.g. Heteropteryx dilatata, Extatosoma tiaratum).