Main Content

The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ilyodrilus

Ilyodrilus Eisen, 1879 (ref. ID; 3692)

Family Tubificidae (ref. ID; 5876, 5939, 6208, 7854)

ref. ID; 1663

Dorsal and ventral setae different. Ventral setae bifurcate, dorsal setae bifurcate or mixture of two or three types. Four bundles of an indeterminate number each per segment. Worm usually reddish. Coelomocytes sparse or absent. Without gills. Single solid prostates attached to atria by narrow stalk. Vasa deferentia as long as or longer than atria. Atria much wider than vasa deferentia. Penis sheaths never thick-walled, without spiral muscles. Body not papillate. Atria without a long internal duct. Living worm 10 to 30 mm long. (ref. ID; 1663)

ref. ID; 1923

Ventral setae ordinarily cleft; spermatheca if present usually open on segment 10; usually reddish in appearance, commonly more than 25 mm in length, many live in tubes. Body surface not covered with many cuticular papillae. Dorsal bundles with hair setae. Two lateral teeth of dorsal pectinate setae not widely divergent; length of atrium and penis combined at least 2/3 that of the remainder of the sperm duct. (ref. ID; 1923)
  1. Ilyodrilus asiaticus Chen, 1940 (ref. ID; 3692, 6208)
  2. Ilyodrilus bavaricus Oeschmann, 1913 (ref. ID; 3692)
  3. Ilyodrilus bedoti (Piguet, 1913) (ref. ID; 3692)
  4. Ilyodrilus caspicus Lastockin, 1937 (ref. ID; 3692)
  5. Ilyodrilus coccineus Stolc., 1886
    See; Rhyacodrilus coccineus (ref. ID; 6208)
  6. Ilyodrilus danubialis Hrabe, 1941 (ref. ID; 3692, 6208)
  7. Ilyodrilus fragilis Eisen, 1879 (ref. ID; 1923)
  8. Ilyodrilus frantzi Brinkhurst, 1965 (ref. ID; 5939)
  9. Ilyodrilus frantzi f. capillatus Brinkhurst, 1965 (ref. ID; 5939, 6582)
  10. Ilyodrilus frantzi f. typica Brinkhurst, 1965 (ref. ID; 5939, 6582)
  11. Ilyodrilus grimmi Hrabe, 1950 (ref. ID; 3692, 6208)
  12. Ilyodrilus hammoniensis (Michaelsen, 1901) (ref. ID; 3692, 6208)
    Syn; Psammoryctes fossor Ditlevsen, 1904 (ref. ID; 6208); Tubifex cameranoi De Visart, 1901 (ref. ID; 6208)
  13. Ilyodrilus heuscheri Bretscher, 1900 (ref. ID; 3692)
  14. Ilyodrilus isochaetus Hrabe, 1931 (ref. ID; 6208)
  15. Ilyodrilus mastix Brinkhurst, 1978 (ref. ID; 5939 original paper)
  16. Ilyodrilus mrazeki Hrabe, 1941 (ref. ID; 3692, 6208)
  17. Ilyodrilus moldaviensis mitropolskiji Harbe, 1950 (ref. ID; 3692)
  18. Ilyodrilus moldaviensis moldaviensis (Vejdovsky & Mrazek, 1902) (ref. ID; 3692)
  19. Ilyodrilus perrierii Eisen, 1879 (ref. ID; 1923) or perrieri (ref. ID; 5939)
  20. Ilyodrilus sodalis Eisen, 1879 (ref. ID; 1923)
  21. Ilyodrilus sokolskayae Brinkhurst, 1970 (ref. ID; 6651, 7854)
  22. Ilyodrilus swirenkoi Lastockin, 1937 (ref. ID; 3692)
  23. Ilyodrilus templetoni (Southern, 1909) (ref. ID; 6651, 7854) reported year? (ref. ID; 6607, 7817) reported author and year? (ref. ID; 1861, 5939, 6583)
  24. Ilyodrilus vejdovskyi Hrabe, 1941 (ref. ID; 3692)

Ilyodrilus bavaricus Oeschmann, 1913 (ref. ID; 3692, 6208)

Descriptions

This species differs from I. hammoniensis and I. isochaetus in the following details: The dorsal crotchets of the anterior segments have a large number of fine intermediate teeth, whereas the intermediate teeth in I. hammoniensis are fewer in number. The ventral chaetae are only rarely armed with intermediate teeth but are otherwise similar, the upper teeth being a little longer. The spermathecal chaetae are flatter, broader and altogether more spear-shaped than in other Ilyodrilus species. (ref. ID; 6208)

Ilyodrilus fragilis Eisen, 1879 (ref. ID; 1923)

Descriptions

Spermathecae not bent, but globular and inflated. (ref. ID; 1923)

Ilyodrilus frantzi Brinkhurst, 1965 (ref. ID; 5939)

Remarks

The original specimens of this species had only bifid setae, but had characteristic atria and unique spermatozeugmata best described as shaped like frying pans. Specimens with hair setae in some bundles beyond V or even more posteriad were found in Suisun Bay, California. In the Fraser River there are typical I. frantzi (stations 6-9) and the capillatus form with hair setae (stations 5-9). The distribution is the same for I. mastix, i.e. these species are found between Mission and Vancouver, but not at the four river-mouth stations (1-4) where brackish-water species are found along with L. hoffmeisteri. The new specimens of the capillatus form sometimes have hair setae from II, III, or IV, and have some pectinate setae in the dorsal bundles, which may be made up of as many as seven setae plus two to four hairs. The ventral setae may also reach seven per bundle. One specimens had a curious mixture of normal bifid setae and few thinner setae, still with bifid tips, which could be thought to be transitional in form between hairs and normal bifids. The setae and prostomia of both forms of I. frantzi are illustrated with those of I. mastix. The ventral setae of f. capillatus seem to be slightly ornamented, but this needs confirmation by scanning electron microscopy. Specimens have been deposited in the U.S.N.M., catalogue number 55378 and 55379 (capillatus) in addition to the type series (holotype 32996, paratype 32995). (ref. ID; 5939)

Ilyodrilus hammoniensis (Michaelsen, 1901) (ref. ID; 3692, 6208)

Synonym

Psammoryctes fossor Ditlevsen, 1904 (ref. ID; 6208); Tubifex cameranoi De Visart, 1901 (ref. ID; 6208)

Descriptions

There are 3-5 hair chaetae in the dorsal anterior bundles, with 3-5 broad crotchets. These have an angle of approximately 45 degrees between the two equal sized main teeth and several large intermediate teeth. There are 3-6 ventral teeth in which the upper tooth is thinner and longer than the lower which is frequently armed with from 1-3 extra teeth. The spemathecal chaetae are large, with a hollow head shaped like a marrow-scoop, frequently 2 per bundle (on segment 10). (ref. ID; 6208)

Ilyodrilus isochaetus Hrabe, 1931 (ref. ID; 6208)

Descriptions

I. isochaetus was originally described from Lake Ochrid, in which most species are endemic, only I. hammoniensis among the Tubificidae is known from the rest of Europe. I. danubialis (recorded first from the Danube in 1941) differs from this in that it has rather more segments, is thinner, and has fewer chaetae per bundle (Hrabe 1950). These two (possibly one?) species differ from other Ilyodrilus species without hair chaetae in having a prostate gland (absent in I. grimmi Hr. and I. moldaviensis (Vejd. and Mr.) and specialised spermathecal chaetae like those of I. hammoniensis (absent in I. caspicus Last and I. mrazeki Hr.) but lacking specialised penial chaetae (present in I. moldaviensis (Vejd. and Mr.). The species is therefore described as: hair chaetae and intermediate teeth in crotchets absent, dorsal and ventral chaetae similar, 7-9 per bundle anteriorly, to 3 posteriorly. The upper tooth is longer, and thinner distally, than the lower, and the teeth are more pointed than in I. claparedeanus. The nodulus is distal. Penis large and muscular. (ref. ID; 6208)

Ilyodrilus mastix Brinkhurst, 1978 (ref. ID; 5939 original paper)

Descriptions

Prostomium small, as broad as long, mouth large with enlarged eversible pharynx. Dorsal and ventral setae of II usually single, with short thin upper tooth. Setae of III often missing. Other ventral setae with upper tooth thinner and slightly longer than the lower, two to four or five per bundle, other dorsal setae two to three or even five short hair setae, two to three bifid setae with upper tooth thinner than but about as long as lower. Atria muscular, with moderate-sized stalked prostates on posterior face, penes without cuticular penis sheaths, vasa deferentia thin, relatively short from apices of atria. Spermathecae absent? (ref. ID; 5939)

Remarks

The species is clearly identifiable by virtue of its greatly enlarged mouth and eversible pharynx which presumably consists of the roof of the pharynx as usual although it appears bilobed when everted. If the floor of the pharynx is involved this would be unique (the ventral pharyngeal bulb of other annelids being external). The setae are often missing in segment III or even IV, and consist of single dorsal and ventral setae in II. The atria appear quite rigid, the prostates and penes quite distinct. The vasa deferentia are initimately associated with the large ovaries seen in all the dissected specimens, and are only about twice the length of the atria. The gut is often distended with large quantities of granular substrate, there being no sign of any specialized diet associated with the enlarged mouth and pharynx apart, perhaps, from a tolerance for coarse substrates. No spermathecae were observed. No coelomocytes were observed. The species is clearly a member of the Tubificinae but the exact generic placement is dubious. The penes lack cuticular sheaths and the atria are robust, both in contrast with the usual Ilyodrilus condition. The prostates are posterior on the atria, the short vasa deferentia arising apically. There is no other genus with this form of atrium and associated structures, the closest approximation being found in Ilyodrilus and some members of the Peloscolex complex. The genus Ilyodrilus consists of the type species, I. perrieri, together with I. templetoni and the dubious entity I. fragilis and I. frantzi. The penis sheaths were not developed in the type specimens of I. perrieri with may have been partially mature and were thin in I. fragilis types. Both of these species are Californian. The cosmopolitan I. templetoni has distinctive setae and long conical penis sheaths. None of these species, nor I. frantzi, have the unusual modified mouth and pharynx of I. mastix which derives its name from this peculiar characteristic. (ref. ID; 5939)

Type locality

Fraser River, British Columbia, stations 5-9 (Northcote et al. 1976), seen once at station 2. (ref. ID; 5939)

Type deposited

  • Holotype: U.S.N.M. 55374. (ref. ID; 5939)
  • Paratype: U.S.N.M. 55375. (ref. ID; 5939)

    Ilyodrilus perrierii Eisen, 1879 (ref. ID; 1923) or perrieri (ref. ID; 5939)

    Descriptions

    With a double oviduct. (ref. ID; 1923)

    Ilyodrilus sodalis Eisen, 1879 (ref. ID; 1923)

    Descriptions

    With a single oviduct. (ref. ID; 1923)

    Ilyodrilus templetoni (Southern, 1909) (ref. ID; 6651, 7854) reported year? (ref. ID; 6607, 7817) reported author and year? (ref. ID; 1861, 5939, 6583)

    Descriptions

    This species is indicative of eutrophic conditions. (ref. ID; 6607)