SPERM DISPLACEMENT IN THE DAMSELFLY, XANTHAGRION ERYTHRONEURUM (ZYGOPTERA: COENAGRIONIDAE) - VARIANCE IN FEMALE SPERM COUNT AND GENITAL MORPHOLOGY

Abstract

Sperm competition was examined in the non-territorial damselfly, Xanthagrion erythroneurum (Selys) (Odonata: Zygoptera: Coenagrionidae) in a small freshwater lake (Forrestdale Lake reserve), which is close to city Perth, Western Australia. Mating pairs were collected along the shores of lake in 3 categories: precopula, interrupted copula and postcopula. Evidence of sperm removal in X. erythroneurum was found from two sources: counts of the number of sperm and penis/female genitalia morphology. Females captured during copulation had fewer sperm in their storage organ than pre- and post-copula females. These results suggest that male X. erythroneurum can remove rival sperm from a female's storage organ during copulation. The morphology of the penis shows that the distal appendage of the penis is a recurved flap-like structure covered with small spines. These structures suggest that the male scoops sperm from the bursa copulatrix before or during deposition of its own sperm. After removing the sperm from the previous matings, new sperm is discharged through a channel which opens on the tip of penis.