Opisthogender

 is a faunagender associated with sea slugs/cucumbers.

Definitions

 * Opisthogender: a gender associated (visually, spiritually, as a kingender, etc.) with sea slugs/cucumbers - xeno-aligned, 2019

History
Opisthogender was coined on August 20, 2019 by Tumblr user xeno-aligned. The flag was made on July 3, 2021 by Tumblr user neopronouns.