186
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
7. Ancistrospiru veneris Chatton and Lwoff, 1926. (Fig. 92)
(Subclass Holotrichia; order Thigmotrichida; family Hemispeiridae)
This ciliate is found on the gill surfaces of Venusfasciata in European
waters. Its relationship with its host has not been examined although
some consider it t o be a commensal.
Body ovoid but with pointed anterior end, 50-6Op
x 22-28 p ; ciliary rows meridional ; thigmotactic cilia concentrated on
left side of body, sharply marked from body ciliature ; peristome with
right spiral.
Description.
Other information. Nothing else is known about this species.
8. Conchophthirus mytili De Morgan, 1925. (Fig. 93)
(Subclass Holotrichia; order Thigmotrichida; family Conchophthiridae)
This ciliate was originally described by De Morgan (1925) on the
foot of Mytilus edulis collected a t Plymouth, England. Its morphology
and nuclear cytology have been studied by Kidder (1933a,b) who also
considers it a member of Conchophthirus. However, Raabe (1933), in
a review of this and related ciliates, erected the genus Kidderia with
K . mytili as the type. Similarly, Kahl (1934) erected Morgunia with
M . mytili as the type. Although MacKinnon and Hawes (1961), who
recognized the great similarity between Conchophthirus and Kidderia,
referred to this ciliate as K . mytili, Corks (1961) has correctly pointed
out that both Kidderia and Morgania are junior homonyms and that
the correct designation is Conchophthirus mytili.
This ciliate can be found in relatively large numbers creeping on
the surface of the foot of Mytilus edulis. A single large specimen of
M . edulis may yield seventy-five ciliates although five to thirty ciliates
per host is more likely. The relationship of C. mytili with its mussel
host has not been studied. It may be a commensal, an epiphoront, or
an ec to parasi te ,
Description. Body reniform, 130-220 p x 76-161 p ; dorsal body
surface convex; ventral surface flat except posteriorly where it is
slightly concave ; numerous trichocysts located in pellicular ridges,
more numerous ventrally than dorsally; cytostome on right edge of
body ; buccal cavity shallow, with fundamentally similar ciliature ;
body cilia slightly longer posteriorly ; cilia on ventral body surface
generally used to adhere to host but no special thigmotactic area
visible ; numerous food vacuoles scattered throughout body ; macronucleus large and oval, in anterior half of body; two, rarely three,
micronuclei present.
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
7. Ancistrospiru veneris Chatton and Lwoff, 1926. (Fig. 92)
(Subclass Holotrichia; order Thigmotrichida; family Hemispeiridae)
This ciliate is found on the gill surfaces of Venusfasciata in European
waters. Its relationship with its host has not been examined although
some consider it t o be a commensal.
Body ovoid but with pointed anterior end, 50-6Op
x 22-28 p ; ciliary rows meridional ; thigmotactic cilia concentrated on
left side of body, sharply marked from body ciliature ; peristome with
right spiral.
Description.
Other information. Nothing else is known about this species.
8. Conchophthirus mytili De Morgan, 1925. (Fig. 93)
(Subclass Holotrichia; order Thigmotrichida; family Conchophthiridae)
This ciliate was originally described by De Morgan (1925) on the
foot of Mytilus edulis collected a t Plymouth, England. Its morphology
and nuclear cytology have been studied by Kidder (1933a,b) who also
considers it a member of Conchophthirus. However, Raabe (1933), in
a review of this and related ciliates, erected the genus Kidderia with
K . mytili as the type. Similarly, Kahl (1934) erected Morgunia with
M . mytili as the type. Although MacKinnon and Hawes (1961), who
recognized the great similarity between Conchophthirus and Kidderia,
referred to this ciliate as K . mytili, Corks (1961) has correctly pointed
out that both Kidderia and Morgania are junior homonyms and that
the correct designation is Conchophthirus mytili.
This ciliate can be found in relatively large numbers creeping on
the surface of the foot of Mytilus edulis. A single large specimen of
M . edulis may yield seventy-five ciliates although five to thirty ciliates
per host is more likely. The relationship of C. mytili with its mussel
host has not been studied. It may be a commensal, an epiphoront, or
an ec to parasi te ,
Description. Body reniform, 130-220 p x 76-161 p ; dorsal body
surface convex; ventral surface flat except posteriorly where it is
slightly concave ; numerous trichocysts located in pellicular ridges,
more numerous ventrally than dorsally; cytostome on right edge of
body ; buccal cavity shallow, with fundamentally similar ciliature ;
body cilia slightly longer posteriorly ; cilia on ventral body surface
generally used to adhere to host but no special thigmotactic area
visible ; numerous food vacuoles scattered throughout body ; macronucleus large and oval, in anterior half of body; two, rarely three,
micronuclei present.