Synonym: Pentatrichomonas gallinarum auct.
Hosts: Chicken, turkey, guinea fowl.
Location: Ceca, liver.
Geographic Distribution: Probably worldwide.
Morphology: Pentatrichomonas sp. resembles T. gallinarum morphologically except that it has 5 anterior flagella. Four of these are of equal length and the fifth is about half as long as the others. The body is usually spherical, sometimes more or less pear-shaped, fixed specimens measuring 3 to 7 by 5 to 8 u with a mean of 5 by 7 u. The undulating membrane extends the full length of the body, with a free flagellum at its end. A costa is present (Allen, 1940 called it a parabasal body). A row of paracostal granules runs between the costa and the undulating membrane. The axostyle is slender, projecting from the posterior end, but not discernible in rounded-up specimens. A cytostome is present. The blepharoplast is composed of a group of small granules.
Pathogenesis: As mentioned in the discussion of Trichomonas gallinarum, Allen and others isolated this form from turkey liver lesions resembling those of histomonosis and attributed the disease to it. However, post hoc reasoning is not enough, and there is as yet no acceptable proof that this trichomonad is pathogenic.
Remarks: Allen (1936) first assigned this species to the genus Pentatrichomonas without naming it. She later (1940) described it as a five-flagellate "Trichomonas gallinarum Martin and Robertson, 1911". Later authors such as Morgan and Hawkins (1952) called it Pentatrichomonas gallinarum. The species described by Martin and Robertson has 4 anterior flagella, as does the form described by McDowell (1953). Further study is needed to determine the relationship between the two forms.