Preferences of the Proctodrilus species (Lumbricidae: Oligochaeta) on a slope of the lower 'Kokel' uplands in Romania.

Romania. On a slope in the 'Kokel' uplands in Romania (Transylvanian Piedmont at the foot of the eastern Carpathians) the earthworm species Proctodrilus tuberculatus (Černosvitov, 1935), P. thaleri Höser & Zicsi, 2009 and P. opisthoductus Zicsi, 1985 were found at different points in the soil catena. The colluvial soil clearly has the distinctive characteristics of an inverse profile. P. tuberculatus occurs at the top of the slope and in the colluvial soil, while P. thaleri was found exclusively in the area at the foot of the slope towards the valley, in the section of greater colluvial horizon diversity. P. opisthoductus occurs towards the valley floor, in the relatively humus-rich mineral layer of the inverse profile. The pedological findings indicate that P. tuberculatus prefers the leached horizons of the lessived soils. Where P. thaleri occurs is a colluvial soil with a probable tendency to a soil-type interference of lessive soil and brown loam (terra fusca), where these two types are within one and the same soil profile. Possibly the sedimentary lessivage complexes of a terra fusca character (plasma flow) make it easier for the Proctodrilus species to move through the solum