Polystoma integerrimum Froelich, 1791; Rudolphi, 1808.
OTHER COMMON NAMES
Adult about 0.39 in (10 mm) in length. Haptor has six muscular suckers, one pair of hamuli and 16 hooklets, each sucker containing one hooklet. Oral sucker around mouth. Testis follicular.
Likely to be present wherever its specific host, the brown frog, Rana temporaria, occurs, but not systematically mapped.
Bladder of Rana temporaria. BEHAVIOR
Nothing is known for adult.
FEEDING ECOLOGY AND DIET
Feeds on blood.
Adult parasite accumulates reserves, but assembles no eggs while frog is living on land during most of year. When frogs enter water to spawn in spring, the parasite assembles and lays its eggs. Hormonal changes in the host may control parasite reproduction; parasites feed on blood and would have access to hormones circulating in the blood. Ciliated oncomiracidia invade frog tadpole gills. If attached to young tadpole, parasites become precociously sexually mature and lay a few eggs. On-comiracidia infecting older tadpoles remain immature; when the host undergoes metamorphosis, they migrate via the digestive tract and possibly the skin to the host's bladder where they mature. Single egg retained in uterus of adult develops and hatches; larva remains in host of its parent, increasing the host's parasite burden by autoinfection. In Polystoma nearcticum, which infests North American tree frogs, the parasite's egg assembly switches on and off abruptly as sexual activity of host switches on and off during nocturnal spawning episodes on successive nights.
CONSERVATION STATUS Not threatened.
SIGNIFICANCE TO HUMANS None known. ♦
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