Females become adults about ten days earlier than males in a phalangiid harvestman Odiellus aspersus (Opiliones: Eupnoi: Phalangiidae)

The reproductive phenology of a species of phalangiid harvestmen, Odiellus aspersus, was studied at Maruyama Park, Sapporo, Hokkaido, for the difference in adult emergence between males and females. At the timepoint in which 50% of the population had matured to adulthood, more females were represented than males, and adult females developed about 10 days earlier on average than males. There was no difference in adult body size between males that had matured earlier and males that were collected later in the season. This fact would conflict with a plausible hypothesis that males should mature slowly to attain larger body size in this species. Elongation of spermatheca in females of the species may explain the marked difference in the adult emergence in the species, by enhancing sperm priority of the males that copulated with females last.