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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Tylotrocha

Tylotrocha Harring & Myers, 1922

ref. ID; 1663

Foot annulated with single toe. Trophi highly specialized virgate. Retrocerebral sac absent. Body length 250 µm long. Single rare species in ponds and reservoirs. (ref. ID; 1663)

ref. ID; 3245

Notommatid rotifers with spindle-shaped, illoricate body, with a distinct constriction between the head and abdomen; two lateral, knoblike, retractile processes near mid-length; the tail is rudimentary, the foot fairly long and unjointed the toe is single, formed by the fusion of two originally separate toes. The dorsal antenna is double. The corona is slightly oblique and has a marginal row of moderately long cilia and two lateral, auricle-like tufts of long cilia; the buccal field is sparsely ciliated; on the apical plate are two unciliated, retractile elevations without definite form. The mastax is a specialized form of the virgate type; all the normal elements are fused into a dome-shaped structure, serving for the support of the walls of the mastax during the pumping action. At the posterior end of the ganglion is a lenticular pigment body, which is probably a rudimentary retrocerebral sac enclosing the eyespot. (ref. ID; 3245)
  1. Tylotrocha monopus (Jennings, 1894) (ref. ID; 1345, 1923, 2017, 2595, 2894, 3245, 3688)
    Syn; Notommata monopus Jennings, 1894 (ref. ID; 1345, 2017, 3245, 3688); Tylotrocha monopus Harring & Myers, 1922 (ref. ID; 1345, 3245, 3688)

Tylotrocha monopus (Jennings, 1894) (ref. ID; 1345, 1923, 2017, 2595, 2894, 3245, 3688)

Synonym

Notommata monopus Jennings, 1894 (ref. ID; 1345, 2017, 3245, 3688); Tylotrocha monopus Harring & Myers, 1922 (ref. ID; 1345, 3245, 3688)

Descriptions

It can be easily recognized by its reddish-purple or rusty colour, and the spindle-shaped body with two lateral retractable humps. The foot is long, conical, without joints but wrinkled, carrying a single toe. The internal organization agrees with the description of Harring & Myers (1924). (ref. ID; 2894)

The body of this peculiar species is spindle-shaped and slender; its greatest width is about one fourth of the total length. The integument is very flexible and the outline varies constantly in response to the contractions of the animal. The entire body is of a brilliant, translucent reddish-purple or crimson color. The head and abdomen are separated by a shallow constriction; there is no distinct transverse fold. The head segment decreases slightly in width towards the neck; its length is nearly equal to the width. The abdomen is fusiform, largest in the middle and tapering to the rudimentary tail. Near the middle are two knoblike lateral elevations, retractile at the will of the animal and constantly changing in form. The foot is relatively long and conical, continuing the outline of the body; it is without joints, but deeply wrinkled. The toe is single, slender and conical, slightly reduced at the base and apparently formed by the fusion of the two normal toes, are there are two well developed mucus glands; its length is one twentieth of the total length. There are two dorsal antennae, slightly elevated papillae with a minute tuft of sensory setae; they are on the posterior part of the head and about 15 µm apart. The lateral antennae are in the normal position and very small. The corona consists of a circumapical band of moderately long cilia; laterally there are two tufts of long cilia, resembling auricles. The buccal field is evenly and somewhat sparsely ciliated; on its upper edge there is a median tuft of long cilia or setae. The mouth is near the ventral edge. Near the lateral margins of the apical plate are two unciliated retractile elevations without any very definite form; they are constantly being thrust out and withdrawn, thus resembling the enigmatic lateral humps; when fully extended, they appear to be bluntly conical. The mastax is a highly specialized form of the virgate type; all the normal elements are firmly fused into a roughly dome-shaped structure. The outlines of the incus are still recognizable; a very slender, rodshaped fulcrum and two elongate triangular rami, separated by an elongate oval space. The mallei are no longer divisible in unci and manubria; a single, roughly semicircular lamella with a posterior, rodlike extension representing the posterior part of the median cell, is all that is actually present, and the ventral margin is firmly united to the rami. The animal has not been observed while feeding, and the operation of the mastax is unknown; the sclerified framework may act simply as a support to the walls of a pump, the piston moving in the cavity. The possibility is not excluded that it may serve as the real piston, as in the genus Lindia, and produce the vacuum necessary for suction by a rocking motion; this would, however, appear to require some form of an epipharynx, and no trace of this has been found. The oesophagus is long and slender. The stomach and intestine are separated by a deep constriction. The gastric glands are replaced by a cluster of small rounded bodies of high refractive index, apparently enclosed in a membranous investment; there highly refractive globules are also found floating freely in the body cavity, and there is always a cluster in the lateral humps; their nature and function are unknown. The bladder is a simple expansion of the cloaca. Two well developed foot glands are present, indicating that the single toe is of recent origin. The ovary is normal. The ganglion is large and nearly circular; at its posterior end is a lenticular, pigmented body which seems toe partly eyespot and partly a rudimentary retrocerebral sac. (ref. ID; 3245)

Type locality

Jennings found it in Lake Michigan, as well as in inland lakes in Michigan. (ref. ID; 3245)

Measurements

Total length 175-250; toes 18-24; trophi 18 µm. (ref. ID; 3245)