L. Forró - É. Murai szerk.: Miscellanea Zoologica Hungarica 5. 1989 (Budapest, 1989)

Murai, É., Tenora, F.; StanÄ›k, M.: Atypical strobilocercus (Cestoda: Taeniidae) – a parasite in experimental stocks of Ondatra zibethicus (Rodentia)

The examination of 18 died muskrats revealed not only the presence of single cysts with one strobilocercus in the liver parenchyma but also massive infestation characterized as polystrobilocercus cases. Three formations of strobilocercosis were observed: 1) Normal bladderworms with one strobilocercus only; situated on the liver surface or in the liver parenchyma. 2> Some of the cysts hang in the abdominal cavity in transparent common capsule, originate from the liver surface, contained more than 20 strobilocerci, every one are covered individually with an envelope (Fig. 1). 3) Common cysts approximately 5 cm in diameter hang between the liver lobes or inside the liver tissue (Figs 2 to 5) ). These large cysts contain different numbers of strobilocerci (6-16) and they do not have envelope, and are situated freely in them. 41 In seven cases combined attacks were observed: single bladderworms and common cyst with many strobilocerci in the same liver are presented in the Figs 3 and 4. The external morphology of this polystrobilocercus cysts have little variability: saclike formations of unusual size, i.e. more than 5 cm in diameter. The connective tissue of the cyst-wall was transparent elastic membrane, which was in some cases firmly attached to the liver lobes on the visceral surface. The bases of these cysts were situated between the liver lobes. In another case, a large cyst was present inside the liver parenchyma and only a part of the cyst-wall was visible on the liver surface. The inner morphology of polystrobilocercus cysts is similar to that or the bladderworm of Hydatigera taeniaeformis

: All cysts under study contained a clear fluid in which the strobilocerci were situated. These strobilocerci were of different age as it is indicated by their body length, form and size of hooks. Some of them were undeveloped, several centimeter long (i.e. 3-7 cm! while some others were fully developed measuring 12 to 24 em in length. In the caudal end of the strobilocerci a bladder of 2 to 4 mm in diameter, could always be found. The well developed strobilocerci characterized by a pseudosegmented body with a scolex identical to that of the adult H. taeniaeformis. The scolex is protruded, 1-1.3 mm in diameter; the rostellum is 0.6 mm, the suckers are 0.40 to 0.44 mm in diameter. Rostellar hooks - 30-36 in numberare situated in two circles. The large hooks measure 0. 385 to 0. 466 mm and the smaller ones 0.253 to 0.278 mm. The shape of rostellar hooks is illustrated in Figs 6 to 10. Some of the strobilocerci, are situated freely within the cyst, and are attached to the inner surface of the connective tissue envelope by their caudal part. Short and badly developed ones were damaged with vacuolized and necrotized tegument, particularly in the germinative zone behind the scolex. The endbladders of these specimens were crammed with calcareous bodies. It is possible, that these physiological phenomena are signs of immunological attack of the intermediate hosts. Fig. 1. Massive liver invasion of Hydatigera taeniaeformis in Ondatra zibethicus. Common cyst contained more than 20 strobilocerci, are covered individually with an envelope. Fig. 2. Polystrobilocercus cyst between the liver lobes: contained strobilocerci they do not have envelope, situated freely in the cyst. Figs 3^4. Combined attacks of H. taeniaeformis in muskrat: single bladderworms ( •=*> 1 and polystrobilocercus cysts in the same liver. Fig. 5. A sample of metacestodes from one polystrobilocercus cyst'Figs 1-5: Photo STANEK). Fig. 6. Hook crown of H. taeniaeformis from domesticated cat, Czechoslovakia 'SEM photograph by LOVAS). Figs 7-10. Rostellar hooks of H. taeniaeformis (7= whole hook crown from O. zibethicus. Fertő Lake, Collection SEY; 8= whole hook crown from O. zibethicus in polystrobilocercus cyst, Farm Pilnikov, Collection STANEK; 9= whole hook crown of the adult worm from Felis catus dorn., Apátfalva, Collection HNHM; 10= form of the rostellar hooks 'detail of No 8). Figs 11-12. Rostellar hooks of Taenia parva '11= whole hook crown of the metacestodes from Apodemus sylvaticus, Granada, Pinos Genii, Spain, Collection VAUCHER; 12 = form of the rostellar hooks, detail of No 111 (Figs 7-12: Photo MURAI.Scale bar 0.2mm)