202
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
6. Hoploplana inquilina thaisana Hyman, 1940
Originally described as Hoploplana thaisana by Pearse (1938), this
polyclad, which has been found in Apalachicola Bay, Florida, was
given its present designation by Hyman (1940b) who stated:
Insofar as can be determined from the available data and material, H .
thaisana differs from H . inquilina only in its smaller size and in its commensalism with a different snail host. I am therefore of the opinion that it is at
best a geographical subspecies and hence should be named H . inquilina
thaisana.
It is being briefly mentioned here since this turbellarian, generally a
commensal ” of the snail Thais Jloridana Jloridana, has also been
found associated with oysters and barnacles in Florida.
7. Paravortex gemellipara (Linton, 1910)
(Order Polycladida; suborder Acotylea; family Hoploplanidae)
< <
(Order Rhabdocoela; suborder Lecithophora; family Graffillidae)
This viviparous rhabdocoel was originally described by Linton
(1910) as Grafilla gemellipara. He found it on the gill surfaces of the
ribbed mussel, Modiolus demissus. The relationship between this
turbellarian and its host is not clear although Linton inferred in the
title of his paper that it is a commensal. Ball (1916), who studied the
development of this worm, demonstrated why it properly belongs to
the genus Paravortex.
According to Linton (1910), P. gemellipara is generally found in
mussels which are exposed to fairly free tidal currents rather than in
those confined to coves. Furthermore, large mussels appear to harbor
more specimens than smaller ones. First discovered in the Woods
Hole, Massachusetts, area, it has been also found in mussels from New
Haven, Connecticut. Although Linton has stated that it is only found
associated with Modioks demissus in Massachusetts, he did point out
that a form found in Cardium edule by Nicoll (1906b) “ . . . and
identified as a sporocyst is very near, if not identical with this species ”.
Furthermore, Uzmann (unpublished) has reported it in Mya arenaria
on the Atlantic coast of the United States. It would thus appear that
P. gemellipara is not host-specific.
B. Class Trematoda
A comparatively large number of larval stages of digenetic trematodes have been recorded from commercially important marine molluscs.
These have been either in the form of germinal sacs (rediae and sporocysts) enclosing cercariae or as metacercariae, either encysted or
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
6. Hoploplana inquilina thaisana Hyman, 1940
Originally described as Hoploplana thaisana by Pearse (1938), this
polyclad, which has been found in Apalachicola Bay, Florida, was
given its present designation by Hyman (1940b) who stated:
Insofar as can be determined from the available data and material, H .
thaisana differs from H . inquilina only in its smaller size and in its commensalism with a different snail host. I am therefore of the opinion that it is at
best a geographical subspecies and hence should be named H . inquilina
thaisana.
It is being briefly mentioned here since this turbellarian, generally a
commensal ” of the snail Thais Jloridana Jloridana, has also been
found associated with oysters and barnacles in Florida.
7. Paravortex gemellipara (Linton, 1910)
(Order Polycladida; suborder Acotylea; family Hoploplanidae)
< <
(Order Rhabdocoela; suborder Lecithophora; family Graffillidae)
This viviparous rhabdocoel was originally described by Linton
(1910) as Grafilla gemellipara. He found it on the gill surfaces of the
ribbed mussel, Modiolus demissus. The relationship between this
turbellarian and its host is not clear although Linton inferred in the
title of his paper that it is a commensal. Ball (1916), who studied the
development of this worm, demonstrated why it properly belongs to
the genus Paravortex.
According to Linton (1910), P. gemellipara is generally found in
mussels which are exposed to fairly free tidal currents rather than in
those confined to coves. Furthermore, large mussels appear to harbor
more specimens than smaller ones. First discovered in the Woods
Hole, Massachusetts, area, it has been also found in mussels from New
Haven, Connecticut. Although Linton has stated that it is only found
associated with Modioks demissus in Massachusetts, he did point out
that a form found in Cardium edule by Nicoll (1906b) “ . . . and
identified as a sporocyst is very near, if not identical with this species ”.
Furthermore, Uzmann (unpublished) has reported it in Mya arenaria
on the Atlantic coast of the United States. It would thus appear that
P. gemellipara is not host-specific.
B. Class Trematoda
A comparatively large number of larval stages of digenetic trematodes have been recorded from commercially important marine molluscs.
These have been either in the form of germinal sacs (rediae and sporocysts) enclosing cercariae or as metacercariae, either encysted or