6. THE PHYLA PORIFERA, CNIDARIA AND PLATYHELMINTHES
249
35. Lepocreadium album Stossich, 1890. (Figs. 159 and 160)
(Superorder Epitheliocystidia; order Plagiorchiida ; suborder Plagiorchiata;
Adults of Lepocreadium album were originally described by Stossich
(1 890) from the intestine of the marine fish Cantharus orbicularis
collected at Trieste. Later (1904), he found adults of the same species
in C. Zineatus and Oblata melanura and in that report placed this trematode in the genus Lepocreadium. This trematode has been shown by
Palombi (1931a, 1932, 1937) to be the adult of Cercaria setifera which
had been described by Monticelli (1888) in Nassa mutabilis and has
since been reported by Odhner (1914), Dollfus (1926) and Palombi
(1931a). Palombi (1934a, 1937) has shown that this cercaria utilizes
Tapes decussatus, T. aureus and Aplysia punctata as the second intermediate host. Experimental infection of Blennius gattoruginae and other
fishes by feeding them encysted metacercariae has been successfully
accomplished.
Description of metacercaria (the stage found in commercially
important molluscs). Metacercaria (Fig. 159) encysted in cutaneous
tissue of Aplysia punctata and in gill and mantle tissues of Tapes
decussatus and T . aureus. The cyst may be surrounded by a gelatinous
outer coat of host origin which is impregnated with calcium carbonate
granules. Cysts without this outer wall average 0.30 mm in diameter.
Metacercaria elongate, oval, measurements not available ; anterior
sucker connected to prepharynx which in turn is connected to large
pharynx ; esophagus short ; intestinal caeca reaching to near posterior
end of body; cercarial eye-spots on each side of pharynx; excretory
vesicle tubular, extending to level of ventral sucker ; ventral sucker
smaller than anterior sucker ; genital primordia, situated in intercaecal
space, in posterior half of body.
Life cycle. Within the first intermediate host, Nassa mutabilis, the
straight-tailed cercariae (not the trichocercous cercaria referred to aB
C. setijera by J. Miiller) develop in rediae located in the gastropod's
hepatopancreas. The escaping cercariae encyst in the superficial tissues
of Aplysia punctata, Tapes decussatus or T . aureus. When the second
intermediate host is ingested by a suitable fish, the adult stage (Fig. 160)
is attained in its intestine (Palombi, 1937).
36. Metacercaria acherusiae Palombi, 1934. (Fig. 161)
superfamily Allocreadioidea ; family Allocreadiidae)
superfamily Allocreadioidea ; family Allocreadiidae)
(Superorder Epitheliocystidia; order Plagiorchiida; suborder Plagiorchiata ;
Palombi (1934a) described Metacercaria acherusiae based on one
specimen found encysted in Tapes decussatus collected at Fusaro.
249
35. Lepocreadium album Stossich, 1890. (Figs. 159 and 160)
(Superorder Epitheliocystidia; order Plagiorchiida ; suborder Plagiorchiata;
Adults of Lepocreadium album were originally described by Stossich
(1 890) from the intestine of the marine fish Cantharus orbicularis
collected at Trieste. Later (1904), he found adults of the same species
in C. Zineatus and Oblata melanura and in that report placed this trematode in the genus Lepocreadium. This trematode has been shown by
Palombi (1931a, 1932, 1937) to be the adult of Cercaria setifera which
had been described by Monticelli (1888) in Nassa mutabilis and has
since been reported by Odhner (1914), Dollfus (1926) and Palombi
(1931a). Palombi (1934a, 1937) has shown that this cercaria utilizes
Tapes decussatus, T. aureus and Aplysia punctata as the second intermediate host. Experimental infection of Blennius gattoruginae and other
fishes by feeding them encysted metacercariae has been successfully
accomplished.
Description of metacercaria (the stage found in commercially
important molluscs). Metacercaria (Fig. 159) encysted in cutaneous
tissue of Aplysia punctata and in gill and mantle tissues of Tapes
decussatus and T . aureus. The cyst may be surrounded by a gelatinous
outer coat of host origin which is impregnated with calcium carbonate
granules. Cysts without this outer wall average 0.30 mm in diameter.
Metacercaria elongate, oval, measurements not available ; anterior
sucker connected to prepharynx which in turn is connected to large
pharynx ; esophagus short ; intestinal caeca reaching to near posterior
end of body; cercarial eye-spots on each side of pharynx; excretory
vesicle tubular, extending to level of ventral sucker ; ventral sucker
smaller than anterior sucker ; genital primordia, situated in intercaecal
space, in posterior half of body.
Life cycle. Within the first intermediate host, Nassa mutabilis, the
straight-tailed cercariae (not the trichocercous cercaria referred to aB
C. setijera by J. Miiller) develop in rediae located in the gastropod's
hepatopancreas. The escaping cercariae encyst in the superficial tissues
of Aplysia punctata, Tapes decussatus or T . aureus. When the second
intermediate host is ingested by a suitable fish, the adult stage (Fig. 160)
is attained in its intestine (Palombi, 1937).
36. Metacercaria acherusiae Palombi, 1934. (Fig. 161)
superfamily Allocreadioidea ; family Allocreadiidae)
superfamily Allocreadioidea ; family Allocreadiidae)
(Superorder Epitheliocystidia; order Plagiorchiida; suborder Plagiorchiata ;
Palombi (1934a) described Metacercaria acherusiae based on one
specimen found encysted in Tapes decussatus collected at Fusaro.