226
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
region of the tegument are shed early in development, only the narrow inner
dense cytoplasm, with the now external fingerlike projections of cytoplasm,
being retained throughout life. An uninterrupted basement membrane is
also retained. The external fingerlike projections of protoplasm are very
elongate and unbranched in C . dichotoma and are thus remarkably similar in
appearance to vertebrate microvilli.
17. Cercaria hueti sp. inq.
(Superorder Anepitheliocystidia; order Strigeatoidea; suborder Azygiata;
As mentioned above, Pelseneer (1906) has expressed the opinion
that the unnamed cercaria described by Huet (188823) in Cardium
edule from Normandy is Cercaria dichotoma. But, as Stunkard and
Uzmann (1958) have pointed out, Huet’s figures indicate that this
cercaria, although a gymnophallid, is not C. dichotoma since the latter
possesses a bifid tail at maturity while Huet’s cercaria loses its tail
prior to escaping from the sporocyst. Furthermore, Huet’s description
of the sporocyst generation, as far as I have been able to determine,
differs from any of the known gymnophallid sporocysts, and hence I
am designating Huet’s cercaria as Cercaria hueti sp. inq. until further
information indicates otherwise.
Description of stages in mollusc. Sporocyst short, compact, spherical
to pyriform, with anterior end elongated to form a “ neck ”, covered
with ‘‘ cilia ”, and free swimming. Immature sporocyst 0.2 mm long,
grayish ; older sporocysts 0-3 mm long, yellowish, with birthpore at
anterior end surrounded by five tubercles ; crown of “ verrucosities ”
below tubercles ; intervening area covered with fine still bristles ;
mature sporocyst, 0.5 mm long, yellow, contains few distomate cercariae with bifid tails; mature cercariae shed their tails prior to
emergence from sporocysts.
Other information. No other information is available on this species.
superfamily Fellodistomatidea; family Fellodistomatidae)
18. Metacercaria 1 of Stunkard and Uzmann, 1958. (Fig. 137)
(Superorder Anepitheliocystidia; order Strigeatoidea; suborder Azygiata;
superfamily Fellodistomatoidea ; family Fellodistomatidae)
Stunkard and Uzmann (1958) reported the occurrence of a species
of metacercaria which they designated as Metacercaria I in about 25%
of the Mya arenaria collected at Boothbay Harbor, Maine, and Woods
Hole, Massachusetts. The soft clams were uniformly IightIy infected,
each harboring one to twelve metacercariae. The metacercariae are
unencysted and are found on the mantles of their hosts. Their morphology suggests that they are gymnophallids.
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
region of the tegument are shed early in development, only the narrow inner
dense cytoplasm, with the now external fingerlike projections of cytoplasm,
being retained throughout life. An uninterrupted basement membrane is
also retained. The external fingerlike projections of protoplasm are very
elongate and unbranched in C . dichotoma and are thus remarkably similar in
appearance to vertebrate microvilli.
17. Cercaria hueti sp. inq.
(Superorder Anepitheliocystidia; order Strigeatoidea; suborder Azygiata;
As mentioned above, Pelseneer (1906) has expressed the opinion
that the unnamed cercaria described by Huet (188823) in Cardium
edule from Normandy is Cercaria dichotoma. But, as Stunkard and
Uzmann (1958) have pointed out, Huet’s figures indicate that this
cercaria, although a gymnophallid, is not C. dichotoma since the latter
possesses a bifid tail at maturity while Huet’s cercaria loses its tail
prior to escaping from the sporocyst. Furthermore, Huet’s description
of the sporocyst generation, as far as I have been able to determine,
differs from any of the known gymnophallid sporocysts, and hence I
am designating Huet’s cercaria as Cercaria hueti sp. inq. until further
information indicates otherwise.
Description of stages in mollusc. Sporocyst short, compact, spherical
to pyriform, with anterior end elongated to form a “ neck ”, covered
with ‘‘ cilia ”, and free swimming. Immature sporocyst 0.2 mm long,
grayish ; older sporocysts 0-3 mm long, yellowish, with birthpore at
anterior end surrounded by five tubercles ; crown of “ verrucosities ”
below tubercles ; intervening area covered with fine still bristles ;
mature sporocyst, 0.5 mm long, yellow, contains few distomate cercariae with bifid tails; mature cercariae shed their tails prior to
emergence from sporocysts.
Other information. No other information is available on this species.
superfamily Fellodistomatidea; family Fellodistomatidae)
18. Metacercaria 1 of Stunkard and Uzmann, 1958. (Fig. 137)
(Superorder Anepitheliocystidia; order Strigeatoidea; suborder Azygiata;
superfamily Fellodistomatoidea ; family Fellodistomatidae)
Stunkard and Uzmann (1958) reported the occurrence of a species
of metacercaria which they designated as Metacercaria I in about 25%
of the Mya arenaria collected at Boothbay Harbor, Maine, and Woods
Hole, Massachusetts. The soft clams were uniformly IightIy infected,
each harboring one to twelve metacercariae. The metacercariae are
unencysted and are found on the mantles of their hosts. Their morphology suggests that they are gymnophallids.