234
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
normal gametogenesis. Thus follicular development is either seriously
impaired or totally precluded. In addition, ‘‘ the vascular system of the
mantle eventually loses its organized continuity through the rupturing
of the lymph bearing vessels and appears finally as a more or less
continuous hemocoel with sporocysts pervading throughout.”
22. Zetacercaria (Proctoeces) ostreae Fujita, 1925. (Fig. 142)
(Superorder Anepitheliocystidia; order Strigeatoidea; suborder Azygiata;
This metacercaria was described by Fujita (1925) from the gonads
of Crassostrea gigas collected at Hiroshima, Japan.
Description. Unencysted, progenetic, with eggs measuring 0-04 mm
X 0.02 mm; body elongate, aspinous, approximately 3 mm long,
0.97 mm wide ; anterior sucker 0.27 mm in diameter ; ventral sucker,
0.47 mm x 0.42 mm, in anterior half of body ; prepharynx extremely
short, pharynx 0.18 mm x 0.15 mm; no esophagus; intestinal caeca,
each 2-35 mm long, extending to near posterior margin of body ; testes,
each approximately 0.17 mm x 0.13 mm, tandemly arranged in
posterior one-third of body; ovary, 0.11 mm x 0.07 mm, anterior to
testes ; ootype, Mehlis’ gland, cirrus pouch, seminal vesicle and internal
prostate glands present ; follicular vitelline glands scattered throughout
parenchyma, extending along entire length of body, limited primarily
to two lateral fields but may converge along midline; genital pore
immediately anterior to ventral sucker, posterior to caecal bifurcation ;
excretory vesicle Y-shaped, with tubular arms extending to level of
caecal bifurcation.
superfamily Fellodistomatoidea ; family Fellodistomatidae)
23. Cercaria brachidontis Hopkins, 1954. (Fig. 143)
(Superorder Anepitheliocystidia; order Strigeatoidea; suborder Azygiata;
Cercaria brachidontis, a parasite of Brachidontes recurvus (= Mytilus
recurvus, M . hamatus), was described by Hopkins (195413) from hosts
collected at Barataria Bay, Louisiana. He compared this cercaria to
Uzmann’s Cercaria milfordensis, which is now known to be the larva of
Proctoeces maculatus, among other similar cercariae and concluded that
“ it is not improbable that C. brachidontis also belongs to that family
(Fellodistomatidae). ’ ’
Sporocyst orange pigmented, in
gonads, mantle and other tissues of host. Cercaria (Fig. 143) elongate
oval, 0.33-0.43 mm long, 0.14-0.18 mm wide ; anterior sucker averaging
0.075 mm in diameter ; ventral sucker, 0.09 mm in diameter, slightly
superfamily Fellodistomatoidea; family Fellodistomatidae)
Description of stages in mollusc.
MARINE MOLLUSCS AS HOSTS FOR SYMBIOSES
normal gametogenesis. Thus follicular development is either seriously
impaired or totally precluded. In addition, ‘‘ the vascular system of the
mantle eventually loses its organized continuity through the rupturing
of the lymph bearing vessels and appears finally as a more or less
continuous hemocoel with sporocysts pervading throughout.”
22. Zetacercaria (Proctoeces) ostreae Fujita, 1925. (Fig. 142)
(Superorder Anepitheliocystidia; order Strigeatoidea; suborder Azygiata;
This metacercaria was described by Fujita (1925) from the gonads
of Crassostrea gigas collected at Hiroshima, Japan.
Description. Unencysted, progenetic, with eggs measuring 0-04 mm
X 0.02 mm; body elongate, aspinous, approximately 3 mm long,
0.97 mm wide ; anterior sucker 0.27 mm in diameter ; ventral sucker,
0.47 mm x 0.42 mm, in anterior half of body ; prepharynx extremely
short, pharynx 0.18 mm x 0.15 mm; no esophagus; intestinal caeca,
each 2-35 mm long, extending to near posterior margin of body ; testes,
each approximately 0.17 mm x 0.13 mm, tandemly arranged in
posterior one-third of body; ovary, 0.11 mm x 0.07 mm, anterior to
testes ; ootype, Mehlis’ gland, cirrus pouch, seminal vesicle and internal
prostate glands present ; follicular vitelline glands scattered throughout
parenchyma, extending along entire length of body, limited primarily
to two lateral fields but may converge along midline; genital pore
immediately anterior to ventral sucker, posterior to caecal bifurcation ;
excretory vesicle Y-shaped, with tubular arms extending to level of
caecal bifurcation.
superfamily Fellodistomatoidea ; family Fellodistomatidae)
23. Cercaria brachidontis Hopkins, 1954. (Fig. 143)
(Superorder Anepitheliocystidia; order Strigeatoidea; suborder Azygiata;
Cercaria brachidontis, a parasite of Brachidontes recurvus (= Mytilus
recurvus, M . hamatus), was described by Hopkins (195413) from hosts
collected at Barataria Bay, Louisiana. He compared this cercaria to
Uzmann’s Cercaria milfordensis, which is now known to be the larva of
Proctoeces maculatus, among other similar cercariae and concluded that
“ it is not improbable that C. brachidontis also belongs to that family
(Fellodistomatidae). ’ ’
Sporocyst orange pigmented, in
gonads, mantle and other tissues of host. Cercaria (Fig. 143) elongate
oval, 0.33-0.43 mm long, 0.14-0.18 mm wide ; anterior sucker averaging
0.075 mm in diameter ; ventral sucker, 0.09 mm in diameter, slightly
superfamily Fellodistomatoidea; family Fellodistomatidae)
Description of stages in mollusc.