Mating Behavior of the Endemic Hawaiian Cricket Leptogryllus elongatus (Orthoptera: Gryllidae: Oecanthinae)

Abstract

Hawaiian tree crickets are remarkably speciose and phenotypically diverse and yet we know very little about their behavior. I present the first description of courtship and mating in a member of this group. Leptogryllus elongatus Perkins inhabit the hollow fronds of giant tree ferns on the windward slope of Mauna Kea, on the Big Island of Hawaii. Unlike all other tree crickets, except for the closely related genus Thaumatogryllus, Leptogryllus lack a stridulum to produce song and have no auditory tympanum. In the absence of song, courtship in L. elongatus appears to be vibratory and tactile, in the form of tremulation and tapping of the male cerci against the body of the female. Tremulation by male L. elongatus takes the form of a rhythmic “push-up” beginning at first contact and continuing until the postcopulatory dismount. During courtship, the male maneuvers his abdomen beneath the female and the female dorsally mounts the male. As in other tree crickets, copulation results in transfer of a small spermatophore composed on a external sperm sack and a tube running inside the genitalia of the dorsally mounted female. The rate of tremulation is relatively constant from first contact until copulation. Tremulation rate decreases after spermatophore transfer but increases dramatically when the female begins to move off the male. Another key difference is the lack of metanotal gland feeding in L. elongatus. Nevertheless, L. elongatus display prolonged postcopulatory mounted courtship which delays removal of the spermatophore by the female.