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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Pottsia

Pottsia Chatton & Lwoff, 1927 (ref. ID; 3476)

[ref. ID; 3476]
The genus Pottsia was created by Chatton & Lwoff (1927) for P. infusoriorum Chatton & Lwoff which is ectoparasitic on Folliculina and Cothurina. The suctorian has been found in Manoca, Woods Hole and Samoa, but no further species has been added to the genus. (ref. ID; 3476)
  1. Pottsia infusoriorum Chatton & Lwoff, 1927 (ref. ID; 3476)
  2. Pottsia parasitica Nozawa, 1939 (ref. ID; 3476 original paper)

Pottsia parasitica Nozawa, 1939 (ref. ID; 3476 original paper)

Descriptions

It is attached to the stalk and the body, especially near its posterior end, of the host. The body is spherical, and enveloped by a thin pellicle. Neither test nor stalk is present. There is a single tentacle inserted into the plasm of the shot, working as the organelle both for attachment and nutrition. The tentacle is thick and short for the body, rugged markedly on its surface, and provided with a distinct internal canal which is widest at the distal end, and, becoming gradually narrow, terminates in the body. The macronucleus is single, ellipsoidal, and large for the body; it contains relatively large chromatin granules. The contractile vacuole is single, small, and placed on the side of the body away from the tentacle. The reproduction is probably by the internal budding. The embryo is monaxial, and ellipsoidal, with three ciliary bands around the equatorial region. The macronucleus is ellipsoidal and central. The contractile vacuole is single, small, and placed on the posterior side of the nucleus, i.e. on the side away from the tentacle, in the adult individual. (ref. ID; 3476)

Comments

The present suctorian is a small, spherical form ectoparasitic on the stalk or body of zoothamnia, and looks like a swelling of the latter. The rate of infection is not very great usually one, rarely two, parasits are found on a large colony of the host. The organelle of attachment is the relatively thick tentacle which is hardly visible even under a comparatively high magnification. The fine structure of the tentacle can be seen only by an oil-immersion lens. The surface of the tentacle is much rugged; this seems to be a kind of adaptive character for strengthening the power of fixation to the host. The tentacle is pierced by a distinct internal canal which is widest at the distal end, and enters the body beyond the proximal end of the tentacle. Thus, the tentacle resembles in structure that of Choanophrya infundibulifera (Hartog) (Collin 1912-13, p.114, Fig.23), and seems to be mainly suctorial, drawing the plasm of the short through the internal canal. According to Chatton & Lwoff (1927), the tentacles of P. infusoriorum are two to four in number, slightly capitated distally, and have no internal canal. Thus they are of opinion that the nutrition of P. infusoriorum is "uniquement par osmose". The nutrition of another ectoparasitic suctorian, Pseudogemma, in Collin's view (1912-13), is performed also by osmosis through its rudimentary stalk. Thus, the new suctorian differs in its mode of nutrition from both of these ectoparasitic suctorians. The embryo is monaxial, and more or less elongated in the direction of the principal axis. Three ciliary bands are placed in the middle of the body in a small angle with the short axis, instead of subdividing the body into four equal parts as in the embryo of P. infusoriorum. The embryo has no tentacle at all, while that of P. infusoriorum is provided with two tentacles at the anterior end of the body. The suctorian has a small contractile vacuole, while none is present in P. infusoriorum. The contractile vacuole is placed on the posterior side, while the tentacle is situated generally on the anterior side of the body. The reproduction has been observed in a few individuals, and seems to be performed by the internal budding. However, it is somewhat questionable weather this is a typical one or not. (ref. ID; 3476)

Type locality

The new species is also ectoparasitic, and found on Zoothamnium sp. occurring in Lake Biwa. (ref. ID; 3476)

Measurements

Diameter of body 25-30 um, length of tentacle 8-9 um, its thickness 3-4 um. (ref. ID; 3476)