Rugogaster hydrolagi Schell, 1973, vicinity of San Juan Island, Washington, United States.
OTHER COMMON NAMES None known.
Adults have an elongated body 0.27-0.59 in (7-15 mm) long and 0.039-0.078 in (1-2 mm) wide without spines, but with a row of 17-25 transverse ridges or rugae on a small ventral sucker. It also has numerous testes and two caeca (large intestine) rather than the one caecum and one or two testes characteristic of other members of its subclass.
Southeastern coast of Australia; northwestern coast of United States and British Columbia.
Hosts include the ratfish (Hydrolagus colliei). The parasite inhabits the coecal glands, sometimes protruding into the rectum.
Adult flatworms infect the rectal glands of holocephalan fishes. (chimaeras).
FEEDING ECOLOGY AND DIET
These parasites rely for their nutritional needs on their host fishes, but little else is known about their feeding ecology.
A large uterus contains numerous amber-colored eggs, which are oval and operculate, ranging from 0.006-0.0066 in (154-168 pm) long and 0.0036-0.004 in (92-102 pm) wide. The larvae, which do not reproduce, are 0.0104-0.011 in (265-288 pm) by 0.0027-0.0032 in (70-82 pm), and leaf-shaped with a rounded anterior end and a pointed posterior end. They have no cilia, but do have a posterior sucker.
Not listed by IUCN
SIGNIFICANCE TO HUMANS None known. ♦
I Fasciola hepatica I Rugogaster hydrolagi
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