Neanura (Metanura) okinawana Yosii 1965 was redescribed with special reference to its chaetotaxy including some minute setae, which are overlooked in the original description. In addition, two new species of the subgenus Metanura were described from the Ryukyu Islands, Southwestern Japan. N. (M.) yonana sp. nov. can be separated from other consubgeneric species by having dorsal tubercles united into a large mass covering whole width of each of posterior three abdominal segments. N. (M.) amamiana sp. nov. can be identified by body setae extremely widened at apex.
The postembryonic development of Trigoniulus corallinus (Gervais) was surveyed using the specimens collected from the Okinawa Island in November 25, 1990. The specimens in younger stages were obtained by culture of their eggs. The number of abdominal segments, legs, ocelli and ocellar rows, the length and the width of body, the live weight, the male gonopod and the secondary sex characteristics were surveyed. Based on these observations, we distinguished ten postembryonic stages (Ist-IXth larval stadia and Xth adult studium). The adult (Xth stadium) specimens had 47-51 abdominal segments and about 40 ocelli in nine rows. The adult male was about 37 mm in length, 3.5 mm in width, and about 350 mg in live weight, and the adult and subadult females were about 40 mm, 3.6 mm and about 450 mg, respectively.
A small (60-70mm) semi-aquatic or limnic lumbricid earthworm from a creek in Hachioji, western Tokyo appears new to science and is named after the locality. It is tentatively attributed to the genus Helodrilus Hoffmeister, 1845 – characterized by lack of nephridial bladders – rather than Eisenia Malm, 1877 that holds the only other endemic lumbricid, E. japonica (Michaelsen, 1891). The current species is close to type Helodrilus oculatus Hoffmeister, 1845 but differs on its clitellum in segments 23-31 with tubercula pubertatis in 29, seminal vesicles in 9-12, and intramural calciferous glands in 11-12 extending into 13-14. Further lack of spermathecae is distinctive, whereas He. oculatus is not known for parthenogenesis in its European headquarters. Restricted distribution suggests endemicity, however discovery of a specimen in a rice paddy at Lake Biwa indicates at least partial transportation. Alternatively, its apparent rarity and restriction may relate to common sampling omission of small species.
The following four new species of oribatid mites are described from soil material of the gardens, grave yards and forests associated with 32 temples in Shikoku Island: Galumna (Galumna) cavernalis n. sp., Pergalumna filiformis n. sp., Pergalumna rima n. sp., Pergalumna virga n. sp.
Genomics is the structural and functional study of genomes, and the application of genomic technology to ecotoxicology is known as ecotoxicogenomics. Ecotoxicogenomics is receiving increasing attention because of its potential advantages in several applications, including the identification of pollutants. Because relatively little genetic information is available for Collembola, the identification and characterization of stress-responsive genes constitute the first steps toward using these organisms in ecotoxicogenomics. Field and laboratory studies are currently underway for Orchesella cincta and Folsomia candida, respectively．In O. cincta, a gene for the metal binding protein, metallothionein, was identified and the microevolution of its expression was documented in field populations. In F. candida, which is widely used for ecotoxicity testing, a DNA microarray is being developed for risk assessment in soil ecosystems, and the Collembase, a database of collembolan expressed sequence tags (ESTs), is being developed for F. candida together with O. cincta by the research group at the Vrije University. We have begun the search for stress-responsive genes in F. candida using high-coverage expression profiling (HiCEP). These activities are in their initial stages, but promise to lead to considerable advances in collembolan ecotoxicogenomics.