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

SUPAROEK WATANASIT

ABSTRACT: Sperm competition was examined in the non-territorial damselfly, Xanthagrion erythroneurum (Selys) (Odonata: Zygoptera: Coenagrionidae) in a small freshwater la lee (Forrestdale Lake reserve), which is close to city Perth, Western Australia. Mating pairs were collected along the shores of lalee 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-lilee structure covered with small spines. These structures suggest that the male scoops sperm from the bursa copu/atrix before or during deposition of its own sperm. After removing the sperm from the previousmatings, new sperm is discharged through a channel which opens on the tip of penis.

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Department of Biology, Prince of Songlela University, Haad Yai, Songlela, Thailand 90112.

Received June 20, 1997