Phenology and biology of harvestmen in and near Sapporo, Hokkaido, Japan, with some taxonomical notes on Nelima suzukii n. sp. and allies (Arachnida: Opiliones)

[摘要] References(50)Cited-By(8)Phenology and biology of a total of 11 opilionid species were surveyed in and near Sapporo, Hokkaido. Most of the species showed an annual life cycle with overwintering in egg stage. Exceptions were Paraumbogrella pumilio having an annual cycle with adult hibernation and Sabacon makinoi with overwintering in both egg and juvenile stages. Compared to the phenological patterns of opilionid assemblage in Shikoku, southwestern Japan, those in Hokkaido were characterized by the absence of species with overwintering in juvenile stage. Among the species overwintering as eggs, species whose juveniles emerge earlier in spring tended to have longer juvenile period. Furthermore, in most of the species females reached adulthood earlier than males (protogyny). The protogyny seems to be rather prevalent in harvestmen of the superfamily Phalangioidea including Phalangiidae and Sclerosomatidae, although it has been only rarely documented in insects and other arachnids. Long reproductive period and multiple mating by females connected with presumable last sperm precedence might explain protogeny in harvestmen. Except for three soil-dwelling species (Sabacon makinoi, S. imamurai, and Paraumbogrella pumilio), all species changed their diurnal microhabitat preference from soil litter on the ground to upward herbaceous layer or tree trunks before they reach adulthood. Even in sexually reproducing species, adult sex ratios in the field often deviated from 1:1. Relative abundance between male and female changed also temporally, probably as a result of sexual difference in microhabitat preference and in reproductive behavior. Data on fecundity of some species and egg size of ten species were presented. Mucous egg sacs produced by two Sabacon species are described and illustrated for the first time. In addition, a new name Nelima suzukii is proposed for one of the two species of the genus Nelima, with some notes on their taxonomy and biology.

[学科分类] 动物科学

[关键词] life cycle;phenology;protogyny;sex ratio;thelytoky;Opiliones;Nelima suzukii n. sp