This study tested the possibility that detritus stabilimenta of Cyclosa octotuberculata affect prey capture rate. Field experiments showed that there was no significant difference in prey capture rate between webs with and without detritus stabilimenta even after controlling for factors likely to affect foraging success. Thus, detritus stabilimenta appear to have no visual effects on insect prey despite their conspicuous appearance.
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.
New taxonomic conclusions on some species of the genus Zelotes (Gnaphosidae) are reported. Z. tintinnus Paik 1986 is synonymized with Z. kimwha Paik 1986. It was detected that the females associated with Z. hayashii Kamura 1987 correctly belong to Z. bifukaensis Kamura 2000, and true female of Z. hayashii is described. Although male Z. flexuosus Kamura 1999 has not been reported, it became clear that a part of the males formerly associated with Z. ryukyuensis Kamura 1999 belongs to Z. flexuosus.
A new species of oribatid mite, Dolicheremaeus ohmensis sp. nov., was described from Ohme in the western forest area of Tokyo. The new species is distinguishable from the known species of the genus Dolicheremaeus by the lack of median notogastral condyles, the short sensilli with a strongly swollen head and the notogaster with short and long setae.
As a result of a series of faunal surveys of spiders of Okinawa Prefecture, southernmost Japan, following seven species were recognized to occur in the family Pisauridae: Hygropoda higenaga (Kishida 1936), Perenethis venusta L. Koch 1878, Dolomedes yawatai Ono 2002, D. orion n. sp., D. zatsun n. sp., D. horishanus Kishida 1936, and Pisaura bicornis Zhang & Song 1992. Descriptions of the two new species, Dolomedes orion and D. zatsun, are presented. Dolomedes horishanus and Pisaura bicornis are the species whose occurrences in Japan were recognized for the first time. Redescriptions of those two species based on the specimens collected from Okinawa Prefecture are also provided. Dolomedes mizhoanus Kishida 1936 known from Taiwan is newly synonymized with D. horishanus. D. yawatai, which was described from Ishigaki-jima Island, was found to occur also in Iriomote-jima Island. D. okinavensis Kishida 1924 is considered as nomen dubium and hence removed from the species list of Japanese Pisauridae.
Three closely related species, Pardosa azerifalcata sp. n. (SE Azerbaijan), P. jergeniensis Ponomarev 1979 (northern Ciscaspia) and P. falcata Schenkel 1963 (northern China and Mongolia), represent a separate species group. Illustrated descriptions of the three species are given. P. donabila Roewer 1955 (Iran) may belong to this group as well. P. falcata was found to be a senior synonym of P. crucifera Schenkel 1963 syn. II. P. falcata was reported from Mongolia for the first time.
A new medium-sized species of Cybaeus (Araneae: Cybaeidae) from the westernmost part of Honshu, Japan, is described under the name C. akiensis. The species most resembles C. kuramotoi Yaginuma 1963, which is sympatrically found with C. akiensis n. sp., and C. ashikitaensis (Komatsu 1968) inhabiting Kyushu. Local species assemblage of the genus Cybaeus in western Honshu consists of 5 to 6 species with different body sizes. Cybaeus akiensis n. sp. is the second largest species in the five-species assemblage found in the distributional range of the species. Collecting records revealed that the species overwinters as both adults and juveniles and two years are needed from hatching to maturity. Silken retreat of the species bears two terminal openings and a loophole at the bottom, the latter is a feature only rarely found among Japanese species of Cybaeus.