Soil containing the earthworms (Alma nilotica), host of the target ciliate Dicoelophrya nkoldaensis Fokam, 2012, was dug monthly for six months. Worms where counted in situ to establish earthworm’s volumic density (VD) and subsequently dissected to evaluate ciliate abundance (AB). Ten soil physicochemical parameters were analyzed: Cation Exchange Capacity (CEC), Mg2+, Ca2+, Available Phosphorus (AP), K+, Na+, organic carbon (OC), organic matter (OM), total nitrogen (TN), Moisture (M), and pH. The studies reveal that, the mid gut was noticed to be the preferential zone of for Dicoelophrya nkoldaensis. Correlations between mean ciliate abundance in the worm’s foregut and physicochemical parameters demonstrated a significant negative correlations with TN (r = -0.360; P < 0, 05), AP (r = -0.328; P < 0, 05), K+ (r = -0.334; P < 0, 05) and pH (in H2O) (r = -0.401; P < 0, 05). In the mid gut, a significant positive correlation with (M) (r = 0.356; P < 0, 05), a highly significant positive correlation with Ca2+ (r = 0.553; P < 0, 01) and a negative highly significant correlation with TN (r = -0.4277; P < 0, 01). In the hind gut, a negative significant correlation was observed with TN (r = -0.564; P < 0, 05) and a positive highly significant correlation with Ca2+ (r = 0.456; P < 0, 05). Correlations of soil physico-chemical properties with worm VD demonstrated a highly significant positive correlation with CEC (r = 0.634; P < 0, 01) and Mg2+ (r = 0.443; P < 0, 01) a significant negative correlation with both OC (r = -0.314; P < 0, 05) and OM (r= -0.312; P < 0, 05) and a significant positive correlation with potassium (r = 0.350; P < 0, 05). These results suggest that the preferential zone of Dicoelophrya nkoldaensis in the digestive tract of earthworms, considered as a microhabitat, is influenced by the physicochemical parameters of the soil ingested.
