Spermatophylax

Definition

A protein-rich, gelatinous mass that accompanies the spermatophore in the ejaculate of certain male insects, transferred to the female during copulation and consumed as a nuptial gift. The spermatophylax delays sperm transfer by occupying the female's attention while the spermatophore attaches to her reproductive tract, simultaneously providing nutritional resources that may increase female fecundity or influence paternity patterns.

Etymology

From Greek sperma (seed, sperm) + phylax (guard, protector), alluding to its role in protecting or facilitating sperm transfer.

Example

In decorated crickets (Gryllodes sigillatus), males produce a large spermatophylax that females consume immediately; males with larger spermatophylaces enjoy extended copulation durations and higher fertilization success because the female is occupied eating while sperm are transferred from the attached ampulla.

Synonyms

• Nuptial gift
• sperm-protection mass

Related Terms

• Spermatophore
• nuptial feeding
• Sexual selection
• cryptic female choice
• Aedeagus
• ampulla
• ejaculate

Usage Notes

Distinguished from the spermatophore proper: the spermatophylax lacks sperm and serves primarily as a physical barrier and nutritional offering, whereas the spermatophore contains the sperm ampulla. The term is most commonly applied in Orthoptera (crickets, katydids) and some Lepidoptera, though analogous structures occur in other insects. Some authors restrict 'spermatophylax' to cases where the structure is clearly detachable and consumed separately from the sperm-containing ampulla.