Pseudofertilization in the Genus Lumbricillus (Enchytraeidae)

NATURAL populations of the common enchytraeid worm Lumbricillus lineatus Müll., occurring in decaying seaweed, contain diploid (2n= 26) and triploid (3n = 39) individuals. The Enchytraeidae are normally hermaphrodite but the triploid form of L. lineatus reproduces parthenogenetically and is distinguishable from the diploid type by the absence of seminal vesicles. Spermatogenesis in the partheno-genetic form does not proceed beyond the spermatid stage and no mature spermatozoa are produced1. In spite of this, the spermathecæ of triploid worms from natural populations always contain spermatozoa. Experiments were designed to determine the origin of these spermatozoa as well as their possible role in the activation of cleavage in triploid eggs. The triploid form will be referred to as L. lineatus 3 × and the diploid as L. lineatus 2 ×.