194
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
although a few also occurred in the gonads. No dramatic histopathological changes were observed by me although Burton (1961) has
reported observing abnormal histological appearance of the hosts’
tissues and unusual concentrations of leucocytes which he has attributed
to the presence of this ciliate among other parasites. It would appear
that this ciliate is a true endosymbiont. It may or may not be identical
with the ciliate identified as Ancistrocoma pelseneeri by Mackin (1960).
Unfortunately, because of its endosymbiotic nature, intact specimens
were not available for description. It should be noted that the possibility
exists that this is not a species of Ancistrocoma, but the dimensions
and what can be seen of its morphology in histological sections suggest
that it is.
15. Hypocornides mytili Chatton and Lwoff, 1922. (Figs. 103 and 104)
(Subclass Holotrichia; order Thigmotrichida; family Ancistrocomidae)
Chatton and Lwoff (1922a) erected the genus Hypocomides to include
two new species of ancistrocomid ciliates, H . rnytili from Mytilus
edulis, and H . modiolariae from Modiolaria, marmorata. Subsequently
(Chatton and Lwoff, 192213, 1924), brief mentions were made concerning
the morphology of H . mytili but they never illustrated it. Similarly,
Chatton and Lwoff (1926) published a sketchy diagnosis of a third
species, H . zyrphaeae from Zirfaea crispata. Basing his decision primarily
on differences between H . zyrphaeae and ciliates which he found on the
gills of Mytilus edulis, Raabe (1938) reported the finding of H . mytili
but he was not able to detect the structure referred to by Chatton and
Lwoff as “ vestige de frange adorale ” which is supposed to be bettex
developed in H . modiolariae than in H . mytili.
Later, Kozloff (194613) found ciliates on Mytilus edulis from San
Francisco Bay, California, which conformed to Raabe’s description of
H . mytili. He too was unable to detect a ( ( vestige de frange adorale ”.
Furthermore, Kozloff stated :
The position of the “ vestige de frange adorale ” in relation to other ciliary
structures in these species of Hypocomides ( H . mytili, H . modiolariae and
H . zyrphaeae) is entirely unclear . . . and it is altogether possible that, as
Raabe has pointed out, these authors (Chatton and Lwoff) used the term
“ vestige de frange adorale ” to indicate only a short segment of the distal
portion of one of the longer ciliary rows on the right side of the body. . .
The following description of H . mytili is based on the descriptions of
Raabe (1938) and Kozloff (1946b).
Body elongate, somewhat flattened dorsoventrally,
34-48p (average 40p) long x 16-22p (average 1 8 p ) wide x 13-18p
Description.
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
although a few also occurred in the gonads. No dramatic histopathological changes were observed by me although Burton (1961) has
reported observing abnormal histological appearance of the hosts’
tissues and unusual concentrations of leucocytes which he has attributed
to the presence of this ciliate among other parasites. It would appear
that this ciliate is a true endosymbiont. It may or may not be identical
with the ciliate identified as Ancistrocoma pelseneeri by Mackin (1960).
Unfortunately, because of its endosymbiotic nature, intact specimens
were not available for description. It should be noted that the possibility
exists that this is not a species of Ancistrocoma, but the dimensions
and what can be seen of its morphology in histological sections suggest
that it is.
15. Hypocornides mytili Chatton and Lwoff, 1922. (Figs. 103 and 104)
(Subclass Holotrichia; order Thigmotrichida; family Ancistrocomidae)
Chatton and Lwoff (1922a) erected the genus Hypocomides to include
two new species of ancistrocomid ciliates, H . rnytili from Mytilus
edulis, and H . modiolariae from Modiolaria, marmorata. Subsequently
(Chatton and Lwoff, 192213, 1924), brief mentions were made concerning
the morphology of H . mytili but they never illustrated it. Similarly,
Chatton and Lwoff (1926) published a sketchy diagnosis of a third
species, H . zyrphaeae from Zirfaea crispata. Basing his decision primarily
on differences between H . zyrphaeae and ciliates which he found on the
gills of Mytilus edulis, Raabe (1938) reported the finding of H . mytili
but he was not able to detect the structure referred to by Chatton and
Lwoff as “ vestige de frange adorale ” which is supposed to be bettex
developed in H . modiolariae than in H . mytili.
Later, Kozloff (194613) found ciliates on Mytilus edulis from San
Francisco Bay, California, which conformed to Raabe’s description of
H . mytili. He too was unable to detect a ( ( vestige de frange adorale ”.
Furthermore, Kozloff stated :
The position of the “ vestige de frange adorale ” in relation to other ciliary
structures in these species of Hypocomides ( H . mytili, H . modiolariae and
H . zyrphaeae) is entirely unclear . . . and it is altogether possible that, as
Raabe has pointed out, these authors (Chatton and Lwoff) used the term
“ vestige de frange adorale ” to indicate only a short segment of the distal
portion of one of the longer ciliary rows on the right side of the body. . .
The following description of H . mytili is based on the descriptions of
Raabe (1938) and Kozloff (1946b).
Body elongate, somewhat flattened dorsoventrally,
34-48p (average 40p) long x 16-22p (average 1 8 p ) wide x 13-18p
Description.