Dr. Murai Éva - Gubányi András szerk.: Parasitologia Hungarica 28. (Budapest, 1995)

Taking into consideration the fact that developmental cycle of P. medians is dependent upon two transitional hosts such as Bithynia tentacuiata and some species of Aranea, Odonata, Coleoptera, Megaloptera, or Lepidoptera (ova, 1974), frequent occurrence of this species in the region under investigation is expected. A detailed morphometric analysis of samples collected from three different types of aquatic ecosystems showed highly significant differences in the values of six measured characters. An evident variability was found in the dimensions of the abdominal sucker, ovary length, and width of the left and right testes. The variation of these characters certainly depends upon habitat conditions, primarily upon the species of transitional host and also upon the nourishment regime of the definitive host. For instance, in the diet of R. lessonae from Koviljski Rit Coleoptera and larvae Table 1 Morphometric characters of the species P. medians from Obedska bara Morphometric characters x (mm) SEM (mm) Min. (mm) Max. (mm) n Body length 791.35 19.15 529.30 1177.10 40 Body width 477.20 15.49 253.00 505.60 Oral sucker length 83.05 2.33 63.20 110.60 40 Oral sucker width 88.45 2.45 63.20 134.30 Abdominal sucker length 79.40 2.82 47.40 118.50 40 Abdominal sucker width 77.22 2.33 47.40 118.50 Ovary length 114.02 3.40 55.30 150.10 40 Ovary width 87.70 2.99 47.40 126.40 Left testis length 116.50 3.53 71.10 158.00 40 Left testis width 102.35 3.23 71.10 158.00 Right testis length 127.17 5.06 86.90 158.00 40 Right testis width 110.82 4.99 79.00 158.00 Egg length 25.73 0.65 20.5 32.50 26 Egg width 13.63 0.27 11.25 15.00 Table 2 Morphometric characters of the species P. medians from Stari Begej Morphometric characters x (mm) SEM (mm) Min. (mm) Max. (mm) n Body length 642.50 10.46 521.40 837.40 40 Body width 329.97 5.39 244.90 410.80 Oral sucker length 78.65 1.63 55.30 94.80 40 Oral sucker width 89.47 2.60 55.30 118.50 Abdominal sucker length 56.80 2.24 31.60 79.00 31 Abdominal sucker width 52.16 2.27 31.60 79.00 30 Ovary length 87.16 3.79 63.20 173.80 31 Ovary width 83.86 2.78 63.20 134.30 30 Left testis length 88.06 3.10 71.10 126.40 31 Left testis width 81.67 2.32 63.20 118.50 Right testis length 88.00 3.02 63.20 134.30 31 Right testis width 81.19 2.81 63.20 126.40 Egg length 25.10 0.44 20.00 28.75 18 Egg width 12.50 0.23 11.25 15.00