Main Content
< Top page

The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Parakahliella

Parakahliella Berger, Foissner & Adam, 1985 (ref. ID; 7423, 7751 redescribed paper) or Berger et al., 1985 (ref. ID; 2129)

Family Parakahliellidae Eigner, 1997 (ref. ID; 7423)

[ref. ID; 7751]
Diagnosis; Kahliellidae with caudal cirri and more than one right and one left somatic ("marginal") cirral row. Some parts of the parental left somatic (marginal) infraciliature are preserved in the post-dividers. (ref. ID; 7751)
Notes; Foissner et al. (1982) described another peculiar lower hypotrich, Kahliella marina, with an evolved frontal ciliature but an apomorph morphogenetic pattern. A comparison with Kahliela, Parakahliella, Psilotricha , and Parastrongylidium (Tuffrau 1969; Fleury and Fryd-Versavel 1982, 1984; Foissner 1983) shows that this character pair justifies the establishment of a new genus. (ref. ID; 7751)
Type species; Parakahliella macrostoma (Foissner, 1982) nov. comb. (Paraurostyla macrostoma Foissner, 1982) (ref. ID; 7751)
  1. Parakahliella haideri (ref. ID; 191, 4751)
  2. Parakahliella macrostoma (Foissner, 1982) Berger, Foissner & Adam, 1985 (ref. ID; 7423, 7751 redescribed paper) reported author and year? (ref. ID; 191, 4751)
    Basionym; Paraurostyla macrostoma (ref. ID; 7423, 7751)

Parakahliella macrostoma (Foissner, 1982) Berger, Foissner & Adam, 1985 (ref. ID; 7423, 7751 redescribed paper) reported author and year? (ref. ID; 191, 4751)

Basionym

Paraurostyla macrostoma (ref. ID; 7423, 7751)

Descriptions

The in vivo aspect of the alpine population (140-160x50-55 um; n=2) agrees largely with the type material (Foissner 1982). However, during diastole the contractile vacuole possesses a posterior as well as an anterior channel, and the small crystals, which are dumb-bell-shaped, do not only occur close beneath the pellicule but also in the remaining cytoplasm. Feeds on Desmidiaceae (Cylindrocystis sp.), ciliates, etc. The ciliates were caught while P. macrostoma is swimming and ingested very rapidly. The cortical pattern of this population is very similar to that of the type material. Nevertheless, we give a characterization, since study of morphogenesis reveals morphogenetically recognizable differences in the uniform infraciliature. Adoral zone of membranelles usually formed like a question mark, about 1/3 of body length. Paroral membrane shorter than the endoral one. Three hypertrophied obliquely arranged frontal cirri. Cirri of the buccal and frontal row slightly enlarged. Left fronto-ventral row in a line, but clearly separated from the short frontal one, begins anteriorly at the level of the posterior region of the adoral zone of membranelles, usually terminates near the posterior end of the cell. Right fronto-ventral row arises at the level of the right frontal cirrus, usually terminates more anteriorly than the left one. Often, additional short rows occur to the right or to the left of the right fronto-ventral row. Posterior ends of marginal rows sometimes nearly confluent. Outer row of right marginal cirri usually longer than the inner one, often extending onto the dorso-lateral surface anteriorly. Inner left marginal row J-shaped, extends from the level of the posterior edge of the buccal cavity to the cell's end. Next row usually shorter. The outer marginal rows are most frequently parental fragments with enlarged distances between the cirri. (ref. ID; 7751)
  • Morphogenesis: The first morphogenetic event is the formation of an oral primordium just left of the middle and posterior region of the left frontal-ventral row. At the right anterior part of this area the development of membranelles has already started. Just anteriorly a small heterogeneous anarchic field is formed. This and some disorganized cirri of the middle part of the left fronto-ventral row shape a ramified primordium. The second cirrus behind the right hypertrophied frontal one also commences with the development of a primordium. From about this level posteriorly just to the end of the adoral zone of membranelles some cirri of the right fronto-ventral row are modified to a streak. Membranelles of the opisthe's adoral zone organize in a posteriad direction. Simultaneously, the proliferation of new basal bodies occurs at 2 levels in the dorsal kineties 1, 2, and 3. The nuclear apparatus is unchanged. Some cirri behind the anteriormost one of the outer right and the anteriormost cirri of the inner left marginal row are modified to the proter's marginal primordia. The middle regions of the same rows are already incorporated in the primordia of the opisthe. The oral primordium is not far advanced in the formation of membranelles. Division continues with the maturation of the primordia. Both in the proter and in the opisthe 5 fronto-ventral anlagen are recognizable. Occasionally, an additional small streak occurs to the right or to the left of streak V. Presumably it forms those cirri that appear between or on the right of the ventral rows. The marginal primordia become longer due to incorporation of parental cirri. However, none originate within the inner right and the outer left marginal rows. The macronucleus fragments begin to fuse. A conspicuous morphogenetic event is the occurrence of additional streaks within each marginal primordium. They form the inner right and the outer left marginal row respectively. About a quarter of the opisthe's adoral zone of membranelles is still unstructured. The fusion of the macronucleus fragments is almost completed. Cortical morphogenesis proceeds with the cirral segregation from the fronto-ventral and marginal primordia. The undulating membranes are fused in both filial products. The right half of the primordium of the adoral zone is clearly modified to the final number of membranelles, while the posterior region of the left one is still undifferentiated. The anteriormost parental cirrus of the outer right marginal row and the one in front of the opisthe's right marginal primordium are modified to primordia of dorsal kineties; it is striking that no further dorsal anlagen can be observed. Subsequently, these streaks migrate onto the dorsal surface while continuing with the proliferation of new basal bodies. Caudal cirri develop from the posterior ends of dorsal kineties 1 and 2. The macronucleus and the micronuclei begin stretching. By the time the segregation of new cirri is finished, the adoral zone of membranelles of the opisthe has its definitive shape. The new cirral rows start the extension and migration to form the mature cortical pattern. Some of the new marginal rows are still fragmentary. The parental inner right and outer left marginal row(s) -they do not produce primordia!- and short fragments of the parental ventral rows are still preserved. The old dorsal kineties 1, 2, and 3 are nearly completely resorbed, while the kineties 4 and 5 are fully maintained. Presumably they form the new kinety 4 of the opisthe and the proter respectively. Both the cell and the macronucleus are distinctly dumb-bell-shaped. The divided micronuclei are still connected by a thin filament. The last conspicuous process is the migration of the left fronto-ventral row to its definitive site behind the short frontal row of primordium III. In both filial products the streak of the undulating membranes begins to separate. A cytopharynx is not recognizable either in the proter or in the opisthe. Both possess 2 new right and 2 new left marginal rows. Occasionally, additional short new marginal rows can be oberved. Most of the parental left marginal infraciliature is resorbed, but a variable fraction is preserved in the post-division specimens. The division of the macronucleus fragments and the mitosis of the micronuclei is still going on. (ref. ID; 7751)

    Morphogenesis of Parakahliella macrostoma and Histriculus muscorum

    The cortical morphogenesis of the frontal and somatic ciliature of P. macrostoma shows 4 remarkable features: a) The primordium III originates from the third anteriormost cirrus of the short frontal row. It is evident from evident from Table 4 that in H. muscorum and some other oxytrichids streak III arisis from cirrus III/2, which has nearly the same position as that of P. macrostoma. This suggests a homology of these cirri. b) The migration of the cirri of primordium IV in a posteriad direction to form of the left fronto-ventral row of non-dividers. Rows B5 of Kahleilla sp. (Fleury and Fryd-Versavel, 1982), but also the analgen IV and especially V of H. muscorm show a similar displacement. The right frontal rows of P. macrostoma and the rows B6 of Kahliella sp. and the cirri of the anlage VI of H. muscorum commence uniformly at the level of the hypertrophied frontal cirri. These conformities in the formation of the frontal ciliature imply a close lineage of the Kahliellidae and Oxytrichidae. c) The formation of each 2 left and right marginal rows and the preservation of parts of the parental left marginal ciliature in the filial products. The latter feature explains the high variability of this character complex. This interesting and apomorphic feature also occurs in species of Kahliella (Horvath 1932; Tuffrau 1969; Fleury and Fryd-Versavel 1982) and Engelmanniella (Foissner unpubl.). d) The conservation of the parental dorsal kineties 4 and 5 as new kinety 4. To get the typical infraciliature of a non-dividing specimen both parental dorsal kineties have to migrate in a posteriad direction. This is the only way we can explain the origin of the "new" dorsal kinety 4 in both filial products. The arithmetic mean of the number of basal body pairs in dorsal kinety 4 is significantly smaller (P<0.001; one-sided t-test) than that of kinety 5. This indicates the resorption of some few units. In many other species -e.g., H. muscorum, O. granulifera, and P. weissei- the kinety 4 arises by early fragmentation of the primordium of the leftmost unshortened row, in the middle stages of division. Thus the proter of P. macrostoma possesses 3 (adoral zone of membranelles, left marginal cirri, dorsal kinety 5) and the opisthe 2 (left marginal cirri, dorsal kinety 4) parts of the parental infraciliature. Previously Euplotes had been the only hypotrich in which fragments of the old dorsal kineties have been found to be preserved in post-dividers (Foissner and Adam 1983). However, the morphogensis of the dorsal infraciliature of Euplotes proceeds very differently from that of Parakahliella (Heckmann and Frankel 1968). Comparative analyis of some typical oxytrichids reveals that the origin of the 6 fronto-ventral-transverse primordia is very similar. It is evident that H. muscorum is in the very close lineage of Stylonychia sp. Additionally, morphogenesis shows clearly that in H. muscorum caudal cirri originate at the posterior ends of the dorsal kineties 1, 2, and 4. Hence, the rows of left and right marginal cirri are not confluent posteriorly, as already supposed by Foissner (1982). Wallengren (1900) stated that reduction of fronto-ventral-transverse cirri within the oxytrichids commences in the anterior part of the cell. These is true for the step Gastrostyla - Stylonychia or Oxytricha. However, a further decrease in the line Stylonychia - Histriculus - Urosomoida is due to the resorption of the left transverse cirri (II/1, III/1, IV/1) and the ventral cirrus V/2 (Buitkamp 1975; Foissner and Adam 1983; Wirnsberger et al. 1985). (ref. ID; 7751)

    Comparative morphology of Parakahliella macrostoma and related species

    Parakahliella macrostoma was originally described in Paraurostyla, which is now considered to be a member of Oxytrichidae because of similarities in the morphogenetic pattern (Borror 1979; Foissner 1982). The most closely related species is Paraurostyla terricola Buitkamp, 1977, which must also be trasferred into the genus: Parakahliella terricola (Buitkamp, 1977) nov. com. Unfortunately, nothing is known about the variability of this soil hypotrich. Hence a modified t-test was used to compare the data (Sokal and Rohle 1981). The only significant differences from both populations of P. macrostoma so found were in body width and number of cirri in the left front-ventral row; there were additional differences from the type-material in body length, number of adoral membranelles, and cirri in the right fronto-ventral row. Our criteria for the discrimination of the type species from its very similar congener are the mean number of adoral membranelles (nearly twice as high, and even the minimum value is considerably higher), the less fragmented fronto-ventral and right marginal rows, and the possession of small crystals (Foissner 1982). (ref. ID; 7751)

    Remarks

    Morphogenesis: Similar developments as in Neogeneia hortualis: N1 still develops in the rightmost row seven. The dorsomarginal kinety already migrates to the right and to the dorsal side, respectively and survives one generation as an old ciliary row like in some other parakahliellids. The additional row seven in N. hortualis is not present any more and the rows six in both species are most likely homologous. Both rows six produce according to the neokinetal wave the old cirri to their left. Row five in P. macrostoma generates additionally a N1 development already at the usual position, i.e. in the second ventral cirral row from right (if considering the row seven as RM). The left marginal row L1 generates a third N1 development. Variability of cirral pattern in P. macrostoma is great. (ref. ID; 7423)

    Sampling site

    11.8.1982; graded ski trail (0-2 cm), Schlossalm, alt. 1950 m, Bad Hofgastein, Salzburg. (ref. ID; 7751)