Reproductive performance of the New Zealand flatworm Arthurdendyus triangulatus in earthworm species-poor and -rich habitats at Benmore, Scotland

This study of the terrestrial flatworm Arthurdendyus triangulatus at Benmore in Scotland focuses upon egg capsule weight and the number/weight of juveniles within the capsule in relation to food resources available at an earthworm-poor site (botanic garden) and an earthworm-rich site (pastureland). Significant differences in flatworm parameters were evident between sites. In the resource-rich pastureland, egg capsules were heavier and contained more juvenile mass and more individuals, though the weight of the average juvenile in the potential hatchling population was lower. A complex relationship between egg capsule weight, the number of juvenile siblings and their weight was revealed. In general, individual juvenile weight increased with decreasing sibling number and with increasing egg capsule weight. Controlling for these parameters, a higher average individual juvenile weight was found for pastureland. Our study highlights earthworm prey availability as a key factor affecting flatworm reproductive performance.