epigynum

The term "epigynum" refers to a specific anatomical structure found in female spiders. It is an external genital organ, typically a hardened plate located on the underside of the spider's abdomen. This structure features one or two openings that are crucial for sperm transfer from the male during mating.1

The shape and size of the epigynum are highly variable among different spider species and are characteristic of each species, though not necessarily related to general classification. During mating, the male spider inserts his pedipalps (leg-like appendages) into the epigynum's openings to transfer sperm. This sperm then travels to receptacles (spermathecae) that connect to the oviducts, where eggs are fertilized as they pass through the gonopore.12

The word "epigynum" originates from Greek and Latin roots meaning "situated in relation to a female organ". It is important to note that "epigynous" also exists as an adjective, primarily used in botany to describe floral organs that appear to grow from the top of the ovary.13