5 . THE PHYLUM PROTOZOA
1 G 1
7. Hyaloklossia pelseneeri LBger, 1897
(Subclass Coccidia; order Eucoccida; suborder Eimeriina; family AggreHyaloklossia pelseneeri was reported by LBger (1897) from the
nephridia of the marine pelecypods Tellina sp. and Donax sp. Although
Kudo (1966) lists Hyaloklossia as a valid genus, Grass6 (1953) is of the
opinion that it should be transferred to the genus Pseudoklossia since
it appears to be more closely related to the known species of that genus
in marine pelecypods than it is to H . lieberkhilhni, a renal parasite of
frogs which has since been shown by Laveran and Mesnil (1902) to be
a species of Diplospora. Some minor differences, however, do exist
between H . pelseneeri, Pseudoklossia pectinis and P. glomerata, the
most conspicuous one being that there are two types of spores within
the oocysts of H . pelseneeri (see Lbger, 1897). For this reason, until
further evidence to the contrary becomes available, I am in agreement
with Kudo that H . pelseneeri should be considered to be generically
distinct from Pseudoklossia.
Description of stages in mollusc. Oocysts, 75-8Op in diameter, in
renal cavity of molluscan host ; each oocyst includes two types of spores,
the smaller, 8 p in diameter, includes spirally coiled sporozoites, while
the larger, 11-12 p in diameter, includes four to six sporozoites.
Life cycle. Sporogony occurs in the molluscan host. How the
pelecypods become infected and where schizogony occurs remain
unknown.
Other information. Pathological changes in pelecypods parasitized
by H . pelseneeri have not been studied; however, there is no reason
to believe that this parasite is seriously detrimental to its host.
gatidae)
D. Subphylum SPOROZOA
Class Haplosporea"
Included in the sporozoan class Haplosporea are two parasites of
Crassostrea virginica and one of Mytilus californianus. Minchinia
costalis is believed to cause a disease in oysters which may lead to
death while the mysterious MSX, now known as Minchinia nelsoni,
which continues to evade the protozoan taxonomist, is believed to be
the primary mortality factor among oysters along the mid-Atlantic
coast of the United States. The third species, Haplosporidium tume* For another interpretation of the taxonomic position of the Haplosporea, see
A.M.B.-5
11
Sprague (1966).
1 G 1
7. Hyaloklossia pelseneeri LBger, 1897
(Subclass Coccidia; order Eucoccida; suborder Eimeriina; family AggreHyaloklossia pelseneeri was reported by LBger (1897) from the
nephridia of the marine pelecypods Tellina sp. and Donax sp. Although
Kudo (1966) lists Hyaloklossia as a valid genus, Grass6 (1953) is of the
opinion that it should be transferred to the genus Pseudoklossia since
it appears to be more closely related to the known species of that genus
in marine pelecypods than it is to H . lieberkhilhni, a renal parasite of
frogs which has since been shown by Laveran and Mesnil (1902) to be
a species of Diplospora. Some minor differences, however, do exist
between H . pelseneeri, Pseudoklossia pectinis and P. glomerata, the
most conspicuous one being that there are two types of spores within
the oocysts of H . pelseneeri (see Lbger, 1897). For this reason, until
further evidence to the contrary becomes available, I am in agreement
with Kudo that H . pelseneeri should be considered to be generically
distinct from Pseudoklossia.
Description of stages in mollusc. Oocysts, 75-8Op in diameter, in
renal cavity of molluscan host ; each oocyst includes two types of spores,
the smaller, 8 p in diameter, includes spirally coiled sporozoites, while
the larger, 11-12 p in diameter, includes four to six sporozoites.
Life cycle. Sporogony occurs in the molluscan host. How the
pelecypods become infected and where schizogony occurs remain
unknown.
Other information. Pathological changes in pelecypods parasitized
by H . pelseneeri have not been studied; however, there is no reason
to believe that this parasite is seriously detrimental to its host.
gatidae)
D. Subphylum SPOROZOA
Class Haplosporea"
Included in the sporozoan class Haplosporea are two parasites of
Crassostrea virginica and one of Mytilus californianus. Minchinia
costalis is believed to cause a disease in oysters which may lead to
death while the mysterious MSX, now known as Minchinia nelsoni,
which continues to evade the protozoan taxonomist, is believed to be
the primary mortality factor among oysters along the mid-Atlantic
coast of the United States. The third species, Haplosporidium tume* For another interpretation of the taxonomic position of the Haplosporea, see
A.M.B.-5
11
Sprague (1966).