Gyraulus parvus (Mollusca: Gastropoda) in the Czech Republic

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The number of catfish examined each month and the incidence of infection with S. minima isgiven in Tab. 3. They occurred in all size-groups of catfish, but it is evident from Tab. 2 thatinfection by this trematode is associated with the body size (age) of the fish; the highest prevalence(29%) and the lowest mean intensity (1.9) was in the smallest fish; the lowest prevalence and thehighest mean intensity was found in fish with a body length 16–19 cm. The smallest catfish harbouringS. minima measured 12 cm and the largest 28 cm.Seasonal changes in prevalence and mean intensity of infectionA survey of the monthly prevalence, intensity and mean intensity of S. minima infection of catfishis shown in Tab. 3. This trematode was found in catfish from June to October. The highest prevalence(40%) was in June, decreased (18–21%) in July-September, and again (13%) in October tozero in November, when only two fish were examined (Fig. 4). The mean intensity decreased (1) inJuly and then increased to attain its maximum (19) in September, followed by a decrease (13) inOctober.Seasonal changes in maturation of Stunkardiella minimaThe state of maturation of S. minima in each month is shown in Fig. 5. The first group of trematodesincludes young individuals (body length 0.4–0.7 mm) without eggs, the second group – smallindividuals (body length 0.7–0.8 mm) with only a few eggs in their uterus, and the third group –larger specimens (body length 1.3–2.2 mm) with many eggs.Fig. 4. Variation in the prevalence (triangle) and mean intensity of infection (square) of Stunkardiella minima(Stunkard) of Rhamdia guatemalensis (Günther) from the cenote Ixin-há over the period June to November1994.127
Tab. 4. Monthly survey of Rhamdia guatemalensis (Günther) from the cenote Ixin-há for infection with metacercariaeof Stunkardiella minima (Stunkard)month no. of fish examined no. of fish infected prevalence (%) intensity mean (range)June 20 2 10 60.5 (1–120)July 1 7 4 2 4 6.8 (1–15)August 14 3 21 6.3 (2–8)September 14 1 7 43.0 (43)October 15 3 20 8.0 (4–16)November 2 0 – –It is evident from Fig. 5 that S. minima containing eggs were present in all months exceptNovember, when only two fish were examined and no S. minima was found. The specimens withmany eggs (group III) made up 100% of the samples in September and October and prevailed inthose collected in June–August, in which trematode groups I and II were present. The proportionof specimens without eggs (group I) gradually increased from June to August, whereas of thosewith few eggs (group II) was somewhat greater in July compared to June and August.Monthly changes in the number of trematode groups are apparent from Fig. 6, which shows themean numbers of individuals in each of the size group of S. minima in each month. The highestFig. 5. Monthly changes in the occurrence and state of maturity of Stunkardiella minima (Stunkard) in Rhamdiaguatemalensis (Günther) from the cenote Ixin-há over the period June to November 1994. The data are expressedas percentages of the total number of trematodes found per month: small specimens without eggs – group I(unshaded), specimens with few eggs – group II (stippled) and fully mature specimens with numerous eggs – groupIII (blackened).128
Page 2: Acta Soc. Zool. Bohem. 66: 81-84, 2
Page 5 and 6: REFERENCESBERAN L. & HORSÁK M. 199
Page 7: Tab. 1. Nematodes studied with the
Page 10: Tab. 2. The dimensions (mm) of thir
Page 14 and 15: Family Acuariidae Railliet, Henry e
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Page 20 and 21: Acta Soc. Zool. Bohem. 66: 99-119,
Page 22 and 23: Figs 1-10. Harpalus (Harpalus) atra
Page 24 and 25: Figs 11-19. Harpalus (Harpalus) cis
Page 26 and 27: Figs 20-27. Harpalus (Harpalus) lut
Page 28 and 29: Figs 28-35. Harpalus (Harpalus) pic
Page 30 and 31: Figs 36-44. Harpalus (Harpalus) sax
Page 32 and 33: Figs 45-53. Harpalus (Harpalus) ser
Page 34 and 35: Figs 54-61. Harpalus (Harpalus) sol
Page 36 and 37: Figs 62-70. Harpalus (Harpalus) xan
Page 38 and 39: Based on the study of our larval ma
Page 40 and 41: EMDEN F. I. van 1942: A key to the
Page 44 and 45: and D. papillifera (Fuhrmann, 1908)
Page 46 and 47: about 1 mm) with only a few eggs in
Page 50 and 51: number (3.65) of trematodes with ma
Page 52 and 53: cestode was distinctly associated w
Page 54 and 55: from individual months. Tab. 2 show
Page 56 and 57: number (5.57) of males occurred in
Page 58 and 59: intermediate host, copepod, catfish
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Page 70 and 71: REFERENCESBACHMAYER F. 1952: Fossil
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Page 80 and 81: 4. The queen that was accepted was

Gyraulus parvus (Mollusca: Gastropoda) in the Czech Republic

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