6. THE PHYLA PORIFERA, CNIDARIA AND PLATYHELMINTHES
203
non-encysted. From what. is known about the life cycles of the Digenea,
those molluscs which harbor the germinal sacs and cercariae are first
intermediate hosts while those which harbor metacercariae are second
intermediate hosts. Instances are known, however, where cercariae
and metacercariae of the same species are found in the same mollusc.
In such cases, the mollusc is serving both as the first and second
intermediate hosts.
Given in this section are those species of trematodes which have
been recorded from commercially important marine molluscs. Unfortunately, in attempting an adequate description of each species, it was
found in many instances that the original descriptions were rather
inadequate by modern standards and, as the result, the descriptions
given below reflect the inadequacies of certain of the original descriptions.
I n still other instances, for example in Gutsell's (1930) report of
parasites of the scallop Aequipecten ( = Pecten) maximus, the descriptions
of the trematodes encountered are so inadequate that these are not
even being considered here.
The familial designations used are those of the original author
unless more recent evidences suggest otherwise. The higher taxonomic
designations are those of LaRue (1957).
1. Bucephalus haimeanus Lacaze-Duthiers, 1854. (Figs. 110 and 111)
(Superorder Anepitheliocystidia; order Strigeatoidea; suborder Azygiata;
Bucephalus haimeanus was originally described by Lacaze-Duthiers
(1854) based on sporocysts and cercariae found in the oyster, Ostrea
edulis, and the cockle, Cardium tuberculatum (=C. rusticum), from the
Mediterranean Sea. Nicoll (1914) renamed this parasite Bucephalopsis
haimeanus, basing his decision on Tennent's (1906) report that the
adult of Bucephalus haimeanus (actually B. cuculus) is without a cephalic
hood or papilla like that which occurs in Bucephalus polymorphus, the
genotype. But, as Hopkins (1954a, 1957a) has correctly pointed out,
the life cycle of B. haimeanus, as reported by Tennent, was in error
due to a lack of validly controlled experiments and what Tennent
considered to be stages in the life history of his parasite may well
represent two or more bucephalid species. For this reason, until
further indisputable evidences become available, the designation
Bucephalus haimeanus is being retained.
This larval trematode appears to be the common one in Ostrea
edukis and Cardium tuberculatum in European waters (Huet, 1888~1,
1893 ; and others). It has been repeatedly reported in the European
literature as " Bucephalopsis gracilescens ", '' Gasterostomum gracisuperfamily Bucephaloidea; family Bucephalidae)
203
non-encysted. From what. is known about the life cycles of the Digenea,
those molluscs which harbor the germinal sacs and cercariae are first
intermediate hosts while those which harbor metacercariae are second
intermediate hosts. Instances are known, however, where cercariae
and metacercariae of the same species are found in the same mollusc.
In such cases, the mollusc is serving both as the first and second
intermediate hosts.
Given in this section are those species of trematodes which have
been recorded from commercially important marine molluscs. Unfortunately, in attempting an adequate description of each species, it was
found in many instances that the original descriptions were rather
inadequate by modern standards and, as the result, the descriptions
given below reflect the inadequacies of certain of the original descriptions.
I n still other instances, for example in Gutsell's (1930) report of
parasites of the scallop Aequipecten ( = Pecten) maximus, the descriptions
of the trematodes encountered are so inadequate that these are not
even being considered here.
The familial designations used are those of the original author
unless more recent evidences suggest otherwise. The higher taxonomic
designations are those of LaRue (1957).
1. Bucephalus haimeanus Lacaze-Duthiers, 1854. (Figs. 110 and 111)
(Superorder Anepitheliocystidia; order Strigeatoidea; suborder Azygiata;
Bucephalus haimeanus was originally described by Lacaze-Duthiers
(1854) based on sporocysts and cercariae found in the oyster, Ostrea
edulis, and the cockle, Cardium tuberculatum (=C. rusticum), from the
Mediterranean Sea. Nicoll (1914) renamed this parasite Bucephalopsis
haimeanus, basing his decision on Tennent's (1906) report that the
adult of Bucephalus haimeanus (actually B. cuculus) is without a cephalic
hood or papilla like that which occurs in Bucephalus polymorphus, the
genotype. But, as Hopkins (1954a, 1957a) has correctly pointed out,
the life cycle of B. haimeanus, as reported by Tennent, was in error
due to a lack of validly controlled experiments and what Tennent
considered to be stages in the life history of his parasite may well
represent two or more bucephalid species. For this reason, until
further indisputable evidences become available, the designation
Bucephalus haimeanus is being retained.
This larval trematode appears to be the common one in Ostrea
edukis and Cardium tuberculatum in European waters (Huet, 1888~1,
1893 ; and others). It has been repeatedly reported in the European
literature as " Bucephalopsis gracilescens ", '' Gasterostomum gracisuperfamily Bucephaloidea; family Bucephalidae)