On the abundance and phenology of palpigradi (Arachnida) from Central Amazonian upland forests

Abstract

The 745 palpigrads (micro-whip scorpions) collected in a 12 month period in the soil (0-7 cm depth) of a secondary upland forest (120.1 ± 50.8 ind./m2/month) and of a primary upland forest (29.4 ± 20.2 ind./m2/month) near Manaus all belong to the species Eukoenenia janetscheki Condé 1993. About 75% of all specimens inhabited the mineral subsoil (3.5-7 cm depth) where monthly catches were negatively correlated with temperature and moisture content of the soil. Females were almost twice as abundant as males. The lack of a distinct reproductive period and the presence of juveniles and adults (both sexes) throughout the year indicate a plurivoltine mode of life. No specimens were caught on or above the soil surface. Abundances of E. janetscheki are compared with those of the Schizomida (tartarids) and Thelyphonida (vinegaroons) from the same study sites. E. janetscheki also represented the palpigrads obtained from the soil of three other upland forest types in Central Amazonia (0-14 cm depth) and accounted for 0.1-0.3% of the total arthropod fauna.