254
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
similar to that of Parvatrema homoeotecnum as reported by James
(1964) and speculated on by Cable (1965) and Cheng (1967). It is
certainly in need of verification. It should be pointed out that this
unusual ( ( sporocyst ” may not be a larval trematode at all, but is a
viviparous rhabdocoel turbellarian as suggested by Linton (1910).
According to Nicoll, this parasite is commonly found in Cardium
edule and Mytilus edulis but not as frequently in Mactra stultorum.
There is rarely more than six in each cockle.
41. Acanthoparyphium spinulosum Johnston, 1917
(Superorder Anepitheliocystida; order Echinostomida; suborder Echinostomata; superfamily Echinostomatoidea; family Echinostomatidae)
Since the completion of this section, Mr. John W. Little of the
Texas A & M University has informed me that he has found the larval
stages of Acanthoparyphium spinulosum in Crassostrea uirginica near
Port Isabel, Texas. A research note (Little et aZ., 1966) reporting this
finding has since appeared. In this note, the authors reported that
A. spinulosum metacercariae have been found in nearly 1 0 0 ~ ’ of the
oysters examined, embedded along the mantle. Of the fifty oysters
examined in detail, each contained an average of forty-five metacercariae. Metacercariae were used to infect chicks and sexually mature
adults were recovered on the eighth day. The adult of A. spinulosum
is normally an intestinal parasite of shore birds and has been reported
from Australia, Japan and California. Its life cycle has been studied by
Martin and Adams (1961) and Bearup (1960) who found metacercariae
encysted in marine gastropods.
C. Class Cestoidea
Molluscs as a group are not common hosts for cestode parasites. In
the exceptional cases where molluscs have been reported to serve as
hosts for cestodes, their role is that of intermediate hosts. As far as I
can determine, only three orders of cestodes, members of the subclass
Eucestoda, include members which have been found in molluscs.
Specifically, the order Tetraphyllidea includes two genera, Phyllobothrium and Pelichnibothrium, which in turn include species the larvae of
which have been reported from cephalopods. The larva of P. speciosum
has also been reported from teleost fishes. What has been identified
as the larva of a species of a third tetraphyllid genus, Echeneibothrium,
has been found by Sparks and Chew (1966) in Venerupis staminea, a
pelecypod.
The second order which includes ‘( species ” with larvae found in
molluscs is the Lecanicephala. Among the members of this order, the
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
similar to that of Parvatrema homoeotecnum as reported by James
(1964) and speculated on by Cable (1965) and Cheng (1967). It is
certainly in need of verification. It should be pointed out that this
unusual ( ( sporocyst ” may not be a larval trematode at all, but is a
viviparous rhabdocoel turbellarian as suggested by Linton (1910).
According to Nicoll, this parasite is commonly found in Cardium
edule and Mytilus edulis but not as frequently in Mactra stultorum.
There is rarely more than six in each cockle.
41. Acanthoparyphium spinulosum Johnston, 1917
(Superorder Anepitheliocystida; order Echinostomida; suborder Echinostomata; superfamily Echinostomatoidea; family Echinostomatidae)
Since the completion of this section, Mr. John W. Little of the
Texas A & M University has informed me that he has found the larval
stages of Acanthoparyphium spinulosum in Crassostrea uirginica near
Port Isabel, Texas. A research note (Little et aZ., 1966) reporting this
finding has since appeared. In this note, the authors reported that
A. spinulosum metacercariae have been found in nearly 1 0 0 ~ ’ of the
oysters examined, embedded along the mantle. Of the fifty oysters
examined in detail, each contained an average of forty-five metacercariae. Metacercariae were used to infect chicks and sexually mature
adults were recovered on the eighth day. The adult of A. spinulosum
is normally an intestinal parasite of shore birds and has been reported
from Australia, Japan and California. Its life cycle has been studied by
Martin and Adams (1961) and Bearup (1960) who found metacercariae
encysted in marine gastropods.
C. Class Cestoidea
Molluscs as a group are not common hosts for cestode parasites. In
the exceptional cases where molluscs have been reported to serve as
hosts for cestodes, their role is that of intermediate hosts. As far as I
can determine, only three orders of cestodes, members of the subclass
Eucestoda, include members which have been found in molluscs.
Specifically, the order Tetraphyllidea includes two genera, Phyllobothrium and Pelichnibothrium, which in turn include species the larvae of
which have been reported from cephalopods. The larva of P. speciosum
has also been reported from teleost fishes. What has been identified
as the larva of a species of a third tetraphyllid genus, Echeneibothrium,
has been found by Sparks and Chew (1966) in Venerupis staminea, a
pelecypod.
The second order which includes ‘( species ” with larvae found in
molluscs is the Lecanicephala. Among the members of this order, the