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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Tubifex

Tubifex Lamarck, 1816 (ref. ID; 1257, 3692, 6913, 6972)

Family Tubificidae (ref. ID; 1257, 1928, 5813, 5876, 5939, 6208, 7254, 7854)

Family Tubificidae: Subfamily Tubificinae Eisen, 1879 (ref. ID; 6913) reported author and year? (ref. ID; 5857, 6648, 7201)

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 30 to 100 mm long. It has the anterior end imbedded in mud bottoms, sometimes in a special tube, and waves the posterior end about in the water for aeration. Especially common in polluted waters. Sometimes present in enormous numbers. (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 widely divergent; length of atrium and penis combined much shorter than the remainder of the sperm duct. (ref. ID; 1923)

ref. ID; 5945

Type species

Tubifex tubifex (Muller) (ref. ID; 5945)
  1. Tubifex acapillatus Finogenova, 1972 (ref. ID; 7201) reported year? (ref. ID; 5945)
    See; Tasserkidrilus acapillatus (ref. ID; 7924)
  2. Tubifex acuticularis Mart-An. & Giani (ref. ID; 6609)
  3. Tubifex albicola (Michaelsen, 1901) (ref. ID; 6208)
    See; Psammoryctes albicola in Brinkhurst, 1960 (ref. ID; 1257)
    Syn; Lophochaeta albicola Michaelsen, 1903 (ref. ID; 6208); Psammoryctes illustris Ditlevsen, 1904 (ref. ID; 6208)
  4. Tubifex alpinus Bretscher, 1900
    See; Tubifex tubifex (ref. ID; 6208)
  5. Tubifex americanus Brinkhurst and Cook, 1966
    See; Tasserkidrilus americanus (ref. ID; 7924)
  6. Tubifex barbatus (Grube, 1861) (ref. ID; 6208) reported year? (ref. ID; 1928)
    Syn; Psammoryctes barbatus Vejdovsky, 1883 (ref. ID; 6208); Psammoryctes umbellifer Vejdovsky, 1875 (ref. ID; 6208)
  7. Tubifex bazikalovae Cekanovskaya, 1975 (ref. ID; 7201) or Chekanovskaya, 1975 (ref. ID; 6660)
  8. Tubifex benedeni Udekem, 1855 (ref. ID; 5945) reported year? (ref. ID; 1928)
    See; Tubificoides benedeni (ref. ID; 5945)
  9. Tubifex bergi Hrabe, 1935 (ref. ID; 3692)
  10. Tubifex blanchardi Vejdovsky, 1891 (ref. ID; 6618)
  11. Tubifex bonneti Claparede, 1862
    See; Tubifex tubifex (ref. ID; 6208)
  12. Tubifex cameranoi De Visart, 1901
    See; Ilyodrilus hammoniensis (ref. ID; 6208)
  13. Tubifex costatus Claparede, 1863 (ref. ID; 1257, 3692) reported year? (ref. ID; 1928, 5945)
    Syn; Tubifex thompsoni Southern, 1909 (ref. ID; 1257)
  14. Tubifex excavatus (Harabe, 1982) n. comb. (ref. ID; 7201)
    Syn; Isochaetides excavatus Harabe, 1982 (ref. ID; 7201)
  15. Tubifex ferox Eisen. (ref. ID; 1928)
  16. Tubifex harmani Loden (ref. ID; 6560)
  17. Tubifex hattai (ref. ID; 6643)
  18. Tubifex hrabei Sokolskaja, 1973
    See; Tasserkidrilus hrabei (ref. ID; 7924)
  19. Tubifex ignota (Stolc, 1886) (ref. ID; 1257)
    Syn; Tubifex nerthus Michaelsen in Brinkhurst (1960) (ref. ID; 1257)
  20. Tubifex ignotus (Stolc, 1886) (ref. ID; 3692, 6208) reported author and year? (ref. ID; 5939)
  21. Tubifex inflatus Michaelsen, 1901
    See; Baikalodrilus inflatus (ref. ID; 7201)
  22. Tubifex kessleri Hrabe, 1962 (ref. ID; 3692, 6582, 7201, 7924)
    Syn; Limnodrilus infundibuliferus Isossimov, 1972 (ref. ID; 7201)
  23. Tubifex kessleri americanus Brinkhurst & Cook (ref. ID; 6913) reported authour and year? (ref. ID; 5939)
  24. Tubifex kessleri baicalensis Semernoy, 1982 (ref. ID; 7924)
  25. Tubifex kessleri variabilis Semernoy, 1982 (ref. ID; 7924)
  26. Tubifex litoralis Erseus (ref. ID; 5945)
  27. Tubifex longipenis Brinkhurst, 1965
    See; Tubificoides longipenis (ref. ID; 5945, 7248)
  28. Tubifex longipenis Cook, 1971
    See; Tubificoides longipenis (ref. ID; 7248)
  29. Tubifex marinus Ditl. (ref. ID; 5945)
  30. Tubifex maritimus Hrabe, 1973 (ref. ID; 5945)
    See; Tubificoides maritimus (ref. ID; 5945)
  31. Tubifex minor Sokol'skaja, 1961 (ref. ID; 6651, 7854)
  32. Tubifex minutus Cekanovskaya, 1975 (ref. ID; 7201)
  33. Tubifex mirandus Snimschikova, 1982
    See; Tasserkidrilus mirandus (ref. ID; 7924)
  34. Tubifex montanus Kowalewski, 1919 (ref. ID; 7924) reported year? (ref. ID; 4491)
    See; Tasserkidrilus montanus (ref. ID; 7924)
  35. Tubifex montanus parvus Giani & al. (ref. ID; 6609)
  36. Tubifex nerthus Michaelsen, 1908 (ref. ID; 1257, 3692, 6208) reported year? (ref. ID; 5945) reported author and year? (ref. ID; 5939)
    Syn; Tubifex newfei Pickavance & Cook (ref. ID; 5945)
  37. Tubifex newaensis (Michaelsen, 1903) (ref. ID; 6618, 7201) reported author and year? (ref. ID; 5939)
    Syn; Limnodrilus newaensis Michaelsen, 1903 (ref. ID; 7201)
  38. Tubifex newfei Pickavance & Cook, 1971 (ref. ID; 5939) reported year? (ref. ID; 5945)
    See; Tubifex nerthus (ref. ID; 5945)
  39. Tubifex plicatus Michaelsen, 1900
    See; Peloscolex ferox (ref. ID; 6208)
  40. Tubifex postcapillatus Cook, 1974
    See; Tubificoides postcapillatus (ref. ID; 5945)
  41. Tubifex pseudogaster (Dahl, 1959) (ref. ID; 1257) or (Dahl) Brinkhurst, 1962 (ref. ID; 5945, 7248)
    See; Tubificoides pseudogaster (ref. ID; 5945)
  42. Tubifex rivulorum Lamarck, 1816
    See; Tubifex tubifex (ref. ID; 6208)
  43. Tubifex sarnensis Pierantoni, 1901
    See; Peloscolex velutinus (ref. ID; 6208)
  44. Tubifex smirnovi Lastockin, 1927 (ref. ID; 3692)
  45. Tubifex siolii (Marcus, 1947) (ref. ID; 6616)
  46. Tubifex superiorensis (Brinkhurst & Cook, 1966) (ref. ID; 7201)
  47. Tubifex taediosus Cekanovskaya, 1975 (ref. ID; 7201) or Chekanovskaya, 1971 (ref. ID; 6660)
  48. Tubifex tempeltoni Southern, 1909 (ref. ID; 1257, 1928 original paper)
  49. Tubifex templetoni Southern, 1909 (ref. ID; 3692)
  50. Tubifex thompsoni Southern, 1909 (ref. ID; 1928 original paper)
  51. Tubifex tubifex (O.F. Muller, 1773) (ref. ID; 3692) or 1774 (ref. ID; 1257, 1663, 1861, 1923, 5813, 6208, 6648, 6651, 6913, 7254, 7852) reported year? (ref. ID; 1928, 3446, 3704, 3955, 4415, 7817) reported author and year? (ref. ID; 5855, 5900, 5939, 6583)
    Syn; Nais filiformis in Williams (1851) (ref. ID; 1928); Tubifex alpinus Bretscher, 1900 (ref. ID; 6208); Tubifex globulatus Friend, ? (ref. ID; 1257); Tubifex ignotus (Stolc) in Brinkhurst, 1960 (ref. ID; 1257); Tubifex bonneti Claparede, 1862 (ref. ID; 6208); Tubifex rivulorum Lamarck, 1816 (ref. ID; 6208); Tubifex tubifex var.heterochaeta Cernosvitov, 1925 (ref. ID; 6208)
  52. Tubifex tubifex f. blanchardi Vejdovsky, 1891 (ref. ID; 6601)
  53. Tubifex tubifex var. heterochaeta Cernosvitov, 1925 (ref. ID; 6208) reported author and year? (ref. ID; 3446)
    See; Tubifex tubifex (ref. ID; 6208)

Tubifex acapillatus Finogenova, 1972 (ref. ID; 7201) reported year? (ref. ID; 5945)

See

Tasserkidrilus acapillatus (ref. ID; 7924)

Descriptions

The vas deferens entered the atrium apically, and showed that most of the vas deferens was quite similar in width to the atrium (34-42 µm versus 38 µm to the nearest micrometre). (ref. ID; 7201)

Tubifex albicola (Michaelsen, 1901) (ref. ID; 6208)

See

Psammoryctes albicola in Brinkhurst, 1960 (ref. ID; 1257)

Synonym

Lophochaeta albicola Michaelsen, 1903 (ref. ID; 6208); Psammoryctes illustris Ditlevsen, 1904 (ref. ID; 6208)

Descriptions

A species having a small number of large, characteristic chaetae. There are 1-3 hair chaetae in the dorsal bundles, with fine hairlets. The dorsal crotchets (1-3 per bundle) are large, with the lower tooth larger and slightly longer than the upper, and at a more pronounced angle to the shaft than is usual. There is a small number of distinct intermediate teeth in the anterior segments, but in the posterior segments these are missing and the chaetae strongly resemble those of the ventral bundles (also 1-3 in number) in having the upper tooth much reduced. The spermathecal chaetae (segment 10 ventral) are straight with a hollow distal end. (ref. ID; 6208)

Tubifex barbatus (Grube, 1861) (ref. ID; 6208) reported year? (ref. ID; 1928)

Synonym

Psammoryctes barbatus Vejdovsky, 1883 (ref. ID; 6208); Psammoryctes umbellifer Vejdovsky, 1875 (ref. ID; 6208)

Descriptions

This species is found in fresh water. (ref. ID; 1928)

The hair chaetae in this species are simple, 2-3 in number. The anterior crotchets are characteristic in shape having a large number of equal sized teeth forming a fan. There are 7-8 of these chaetae in segments 2-10, thereafter they changes through a series of intermediate teeth until the form is attained where the upper tooth is thinner and shorter than the lower and there are no intermediate teeth. There are as few as 2-3 chaetae in the posterior dorsal bundles. The ventral chaetae (3-5 in anterior bundles, 2-3 in posterior) have the upper tooth longer and thinner than the lower anteriorly but resemble the dorsal crotchets posterior. The spermathecal chaetae is similar to that of T. albicola. (ref. ID; 6208)

Tubifex bazikalovae Cekanovskaya, 1975 (ref. ID; 7201) or Chekanovskaya, 1975 (ref. ID; 6660)

Descriptions

The dorsal setae are bifid from II to IV, V or VI but the hair setae begin from V or VII and are found to XV-XVII, accompanied by pectinate setae. The atria are of the classic Tubifex form. The vasa deferentia enter opposite to the prostate stalks. The spermatozeugmata are short. While the penes are sharply conical, it is not clear from the illustration if the penis sheath covers all or part of the conical penis. (ref. ID; 7201)

Type material

ZIAS (Zoological Institute, Academy of Sciences, Leningrad) 1/38361. (ref. ID; 7201)

Tubifex costatus Claparede, 1863 (ref. ID; 1257, 3692) reported year? (ref. ID; 1928, 5945)

Synonym

Tubifex thompsoni Southern, 1909 (ref. ID; 1257)

Descriptions

16 mm. Dorsal bundles of segments 5-13 (or 12 or 14) with 5-11 pectinate chaetae. Dorsal chaetae of segments 2-5. Posterior dorsal crotchets simply bifid with teeth of equal length. Ventral bundles with 1-4 bifid crotchets with the upper tooth longer than the lower. Penis sheath resembling that of T. pseudogaster but narrower at distal end, but shorter. (ref. ID; 1257)

Tubifex excavatus (Harabe, 1982) n. comb. (ref. ID; 7201)

Synonym

Isochaetides excavatus Harabe, 1982 (ref. ID; 7201)

Notes

This species has characteristics Tubifex-shaped atria but is excluded from the genus by Hrabe (1982) because it lacks hair and pectinate setae. The penis sheaths are widely basally, but deeply excavated on one side, more so than in T. kessleri. All the setae are bifid and there are no spermathecal setae. Hrabe (1982) compared it to various species which he includes in Isochaetides. (ref. ID; 7201)

Tubifex ignota (Stolc, 1886) (ref. ID; 1257)

Synonym

Tubifex nerthus Michaelsen in Brinkhurst (1960) (ref. ID; 1257)

Descriptions

According to Stolc 40-200 mm long- clearly an error. Specimens of Brinkhurst indicate that the worm is long and thinner than most Tubificidae. Dorsal bundles with 1-3 hair chaetae with lateral hairs, those of the segments around the clitellum being exceptionally long. 2-3 pectinate chaetae in anterior dorsal bundles, 2-5 ventral chaetae per bundle with the upper tooth a little longer than the lower. Penis sheath as in T. tubifex. (ref. ID; 1257)

Tubifex ignotus (Stolc, 1886) (ref. ID; 3692, 6208) reported author and year? (ref. ID; 5939)

Descriptions

This species is rather difficult to identify from the poor original description. Stolc's figures of the chaetae are highly stylised as can be seen from his impression of the clothing of fine hairs on the hair chaetae, but the following description agrees with his written account. The worm is closely similar to T. tubifex except in the following features: - Many, but not all, of the hair chaetae are beset with fine hairlets. The dorsal crotchets frequently have the main teeth divided or multiplied. There are fewer chaetae in the anterior segments viz: - Dorsal bundles with 2-4 (mostly 3) hair chaetae and 2-5 (mostly 4) crotchets. Ventral bundles anteriorly with 3-5 (mostly 4) crotchets and with 2 crothcets in all posterior bundles, 1-0 hair chaetae in the dorsal bundles. Although duplication of the dorsal chaetal teeth has been observed in other Tubificids it seems wisest at this stage to regard this as a separate species, recognising its close affinity to T. tubifex. (ref. ID; 6208)

Tubifex kessleri Hrabe, 1962 (ref. ID; 3692, 6582, 7201, 7924)

Synonym

Limnodrilus infundibuliferus Isossimov, 1972 (ref. ID; 7201)

Descriptions

  • Forms with hair and pectinate setae: Typical T. kessleri specimens have penis sheaths that conform quite well to those of the original form. A few appear to lack the narrow distal part and to be somewhat broader, but they cannot otherwise be distinguished from the typical form. Dr. V. Semernoj (personal communication) identifies the former as an endemic subspecies of T. kessleri which he will name. My specimens have 4 or 5 hair setae and 4 or 5 pectinates in anterior dorsal bundles, the latter with long, quite narrow teeth and many intermediates. There are 4-6 bifid ventral setae, the upper teeth much longer than the lower. The spermathecae have two separate ampullae. (ref. ID; 7201)
  • Forms with bifid setae: This form is more abundant than the above. There are 4-6 or even 8 setae per bundle, all bifid with long, thin upper teeth. This indicates that setal number remains close to that of the typical forms in dorsal bundles, only the form is changed. Penis sheaths, atria, and spermatozeugmata are essentially the same as those other typical form. (The spermathecae have two separate ampullae.) I belive these to be identifiable as L. infundibuliferus, which V. Semmernoj regards as a subspecies to T. kessleri. (ref. ID; 7201)

    Comments

    Before describing the new material, the identity of the specimens should be clarified, since some specimens have hair and pectinate setae, and some do not. These various taxa will be described as subspecies of T. kessleri by Dr. V. Semernoj, who was kind enough to inspect the illustrations of my specimens that do have hair and pectinate setae. He also indicates that, as I suspected, Limnodrilus infundibuliferus Isoss. (with only bifid setae) is also a member of this complex, the penis sheaths being very similar to those of T. kessleri. The question of the status of specimens of great similarity that differ in regard to the degree of development of the hair and pectinate setae has been the subject of some debate. Hrabe (1931) described two "forms" of Psammoryctides ochridanus from the preglacial balkan Lake Ohrid, one with hairs and pectinates (typica), one without (variabilis). By 1966 he recognized five subspecies (rather than forms) of T. tubifex, based on setal form, including T. t. bergi and T. t. blanchardi. Finogenova (1972) accepted my earlier suggestion that Psammoryctides deserticola and P. lastoschkini were similarly related, but preferred a subspecific status to my use of the term "form". Drs. T. Timm and V. Semernoj (personal communication) refer to similar variation in the T. kessleri complex as constituting a series of sympatric subspecies. Giani and Martinez-Ansemil (1981) use the subspecific nomenclature for T. t. blanchardi, and only Poddubnaja (1980) prefers to regard T. bergi as a species distinct from T. tubifex. She states that two subspecies cannot share the same habitat, so that T. bergi must either be a "morph" of T. tubifex (as expressed in translation, presumably a synonym for form or variety) or an independent species. I have preferred to use the them "form" for this degree of variation, whether the taxa are sympatric or not, in order to be consistent. It is worth noting that environmental effect on a gene or gene complex controlling setal form may act quite differently on individuals that may be heterozygous or homozygous, recessive or dominant in terms of the key gene or genes, resulting in phenotypic polymorphism within a single population. These oddities are usually observed in old or deep lakes (Baikal, Ohrid, Issyk-kul) or in saline water (see Giania and Martinez-Ansemil 1981, for example): I have seen the bergi and blanchardi forms of T. tubifex with typical specimens in a collection from Sahara ponds (courtesy of Dr. S. Woods.) (ref. ID; 7201)

    New material examined

    New collection, more than 100 with hair and pectinate setae, 500 with only bifid setae. (ref. ID; 7201)

    Type materials

    HOCB (Hrabe, Brno) 845-51-VI (kessleri), ZIAS (Zoological Institute, Academy of Sciences, Leningrad) 38627 (acapillatus, also HOCB1737-3, 14, 95, 102/3 for Lake Baikal material). Type of L. infundibuliferus unknown. (ref. ID; 7201)

    Tubifex minutus Cekanovskaya, 1975 (ref. ID; 7201)

    Type material

    ZIAS (Zoological Institute, Academy of Sciences, Leningrad) 1/38363. (ref. ID; 7201)

    Tubifex nerthus Michaelsen, 1908 (ref. ID; 1257, 3692, 6208) reported year? (ref. ID; 5945) reported author and year? (ref. ID; 5939)

    Synonym

    Tubifex newfei Pickavance & Cook (ref. ID; 5945)

    Descriptions

    15-30 mm. 52 or more segments. 3-4 pectinate chaetae in dorsal segments, 1-2 hair chaetae with lateral hairs. Ventral bundles mostly with 4 chaetae, the upper tooth twice as long as the lower and a little thinner, lower tooth becoming progressively reduced until in the penial chaetae it is weak or missing. Penis sheath as in T. tubifex. (ref. ID; 1257)

    The hair chaetae in this species also have a covering of fine hairlets. All the chaetae are small and thin with the nodulus median in the ventral chaetae but more distal in the dorsal crotchets. The teeth of the dorsal crotchets are equal in size, forming a somewhat U-shaped end to the chaetae, with a few well-defined intermediate teeth. In the ventral chaetae the upper tooth ist longer and thinner than the lower tooth in the anterior segments but thinner and shorter in the posterior segments. The penial chaetae (segment II ventral appear to be normal, although Michaelsen describes them as being almost simple-pointed with a reduced lower tooth. However, only a small number of specimens have been examined so far. There are 3-4 crotchets per bundle with 1-2 hair chaetae in addition in the dorsal bundles. The penis is again small and tub-shaped. The worms are very thin and up to 3 cm long. (ref. ID; 6208)

    Tubifex newaensis (Michaelsen, 1903) (ref. ID; 6618, 7201) reported author and year? (ref. ID; 5939)

    Synonym

    Limnodrilus newaensis Michaelsen, 1903 (ref. ID; 7201)

    Notes

    Specimens of a tubificine tubificid thought to be attributable to this species by Brinkhurst (1981) were found among the type set of Clitellio korotneffi (ZMUH V6589-90). As T. newaensis has not been recorded from Lake Baikal, Brinkhurst considered that the specimens had accidentally been included in the C. korotneffi set. This problem faces biologists using the Michaelsen collection because of the exceedingly difficult cicumstances involved in the curation of the material, and it is remarkable that so much of the fluid collection remains intact. It now seems more likely that these aberrant specimens are attributable to I. baicalensis. Hrage (1982) place T. newaensis in Isochaetides largely on the basis of the absence of hair setae. While the redescription of the type species of Isochaetides narrows the apparent gap between that genus and Tubifex, Isochaetides species have spermathecal setae and very thin (if any) cuticular penis sheaths, in contrast to Tubifex. It should be noted that Hrabe (1982) says that I. excavatus "has no modified spermathecal setae on the 10th segment as do I. newaensis (Mich., 1902), I. neotropicus (Cern., 1939), I. acapillatus (Fin., 1972) and I. pusillus (Timm, 1977)". I belive we may assume that Hrabe means to say that none of these species have spermathecal setae rather than the implication that they differ from I. excavatus in this respect. None of them do, in fact, and this is a major (but not the sole) reason of excluding all of them from Isochaetides. (ref. ID; 7201)

    Type material

    ZMUH (Zoological Museum of the University of Hamburg) V5843. (ref. ID; 7201)

    Tubifex newfei Pickavance & Cook, 1971 (ref. ID; 5939) reported year? (ref. ID; 5945)

    See

    Tubifex nerthus (ref. ID; 5945)

    Remarks

    This species is said to differ from T. nerthus Michaelsen, 1908, in three basic ways: nerthus was reported to have penial setae, to be a brackish water form, and to have thin penis sheaths, the penial setae were not found by an subsequent student, and would be a unique atribute for a Tubifex species, where penial setae usually, but not invariably, drop out of the male segment of mature worms. The species, like many brackish water forms, is essentially coastal, being found in a wide range of salinities. Tubifex newferi was located in the Rennies River, St. John's, Newfoundland, with the two most tolerant freshwater tubificids in a coastal habitat. The penis sheaths of newfei are irregularly thickened, the reference to thin penis sheaths in the original description of T. nerthus being presumed to refer to a contrast with Limnodrilus species, there being very few species described in 1908. Specimens attributed by me to T. nerthus have been found in the St. John River estuary, New Brunswick (collected by G. Gillis) in fresh water, as well as in Great Britain. (ref. ID; 5939)

    Tubifex pseudogaster (Dahl, 1959) (ref. ID; 1257) or (Dahl) Brinkhurst, 1962 (ref. ID; 5945, 7248)

    See

    Tubificoides pseudogaster (ref. ID; 5945)

    Descriptions

    12-13 mm. 50-85 segments. Dorsal and ventral bundles with simple bifid crotchets 3-4 or 6 in dorsal bundles, 2-3 in anterior ventral bundles. Penis sheath elongate. (ref. ID; 1257)

    Tubifex superiorensis (Brinkhurst & Cook, 1966) (ref. ID; 7201)

    Descriptions

    Among the large number of specimens with bifid setae and long cuticular penis sheaths were three with quite cylindrical penes. These penes together with the atria closely resemble those of T. superiorensis. All the animals have nothing but bifid setae, in contrast to the North American forms. The latter have 4 or 5 hairs and about 4 pectinate setae dorsally, the vental bundles having 4-6 setae. The three specimens from Lake Baikal differ slightly in respect to setal number, but as they have been in preservative for a long time most of the setal tips have broken off and setal form is difficult to evaluate. The few setae left have slightly longer, thinner upper teeth than the lower. The extreme range of preclitellar setal number is 4-8; most bundles have 5. The postclitellar setae are similar in form and number, though all three specimens are incomplete and a reduction in setal number posteriad might be anticipated. While these specimens have the same bipartite spermathecal ampullae noted in T. kessleri, the spermatozeugmata are several times longer than broad, unlike those of the latter. (ref. ID; 7201)

    New material examined

    New collection, three specimens; one in Canada balsam, two in polyvinyl lactophenol. (ref. ID; 7201)

    Type materials

    USNM (Smithsonian Institution, Washington) 32993-4. (ref. ID; 7201)

    Tubifex taediosus Cekanovskaya, 1975 (ref. ID; 7201) or Chekanovskaya, 1971 (ref. ID; 6660)

    Descriptions

    This species has hair setae accompanied by bifids with very long upper teeth but rudimentary (or absent) pectination. The ventral setae also have very long upper teeth. The atria, with their apical vasa deferentia and thin, cylindrical penis sheaths, are not of Tubifex form but do not support any other clear attribution. (ref. ID; 7201)

    Type material

    ZIAS (Zoological Institute, Academy of Sciences, Leningrad) 1/38362. (ref. ID; 7201)

    Tubifex tempeltoni Southern, 1909 (ref. ID; 1257, 1928 original paper)

    Descriptions

    10-14 mm. 3-4 pectinate chaetae, 1-4 hairs chaetae in anterior dorsal bundles, the former like those of T. tubifex. 3-4 ventral crotchets per bundle with the upper tooth longer and a little thinner than the lower. (ref. ID; 1257)

    This is a very small species of Tubifex, being only 10-14 mm long. It is pink in colour, and of a soft consistency. The anterior dorsal bundles contain 3-4 bifid and 1-4 capilliform setae. These anterior bifid setae have three fine intermediate teeth. The capilliform setae are very thin and flexible. The ventral bundles have 3-4 setae. The upper lip is longer and thinner than the lower one. There are no ventral setae in the 11th segment, and no genital setae are present. The girdle occupies segments 11 and 12, and is formed of cells with very granular contents. The front segments are formed of a narrow anterior; and a broad posterior ring. The pharynx reaches to the back of the 5th segment. From the 6th segment the intestine is covered with dark cells. The brain is deeply indented behind, with a median flap. It projects prominently in front. The nerve-cord has wing-like expansions in each segment, resembling the copulatory glands of the Enchytraeidae. These are present in very young forms, and are not glandular, but mere expansions of the nerve-cord. These are paired contractile hearts in segments 8 and 9. The nephridia are enveloped in large bladder-like cells, such as are found in some species of Limnodrilus. The spermathecae are composed of an irregularly spherical sac with a sharply defined duct. In one specimen, long and slender spermatophores were observed in the spermathecae. The male efferent apparatus consists of a cup-shaped funnel, a long duct which is dilated at its distal end, just before the entrance of the prostate gland. The dilation is ciliated internally; and from the position of the prostate, it must be regarded as the proximal part of the atrium. The atrium is almost as long as the narrow portion of the sperm-duct. At its distal end is a well-developed chitinous sheath. The latter is slightly curved; and its proximal end is much wider than its distal. It is about twice as long as its greatest width. This species is chiefly characterized by the brain and penis-sheath. (ref. ID; 1928)

    Tubifex thompsoni Southern, 1909 (ref. ID; 1928 original paper)

    Descriptions

    These worms are of a bright-red colour. The length is about 20 mm, The anterior dorsal setae closely resemble those of T. costatus. They are found in segments 5-18, whilst those of T. costatus only occur in segments 5-13. There are 7-10 of them in a bundle. The remaining dorsal bundles contain only bifid setae, having two equal teeth. In segments 2-4 there are 3 or 4 in each bundle; behind the 18th segment there are only 2 in a bundle. The ventral bundles contain 3-5 bifid setae. In the anterior bundles the teeth are nearly equal; but further back the lower tooth becomes smaller. The brain is concave in front and behind. The nephridia are large, without a covering of bladder-like cells and the cavity of the duct is swollen into a sac near the external pore. The spermatheca is sac-shaped and long, extending into the 9th segment. The sperm-duct terminates in a chitinous penis-sheath of characteristic shape. The proximal half is broad and cylindrical, whilst the distal half is narrow and curved. Near the external pore there is a sac containing a nail-shaped penial seta. This apparatus is quite different from the penis-sheath of T. costatus, and easily serves to distinguish the species from all others. (ref. ID; 1928)

    Tubifex tubifex (O.F. Muller, 1773) (ref. ID; 3692) or 1774 (ref. ID; 1257, 1663, 1861, 1923, 5813, 6208, 6648, 6651, 6913, 7254, 7852) reported year? (ref. ID; 1928, 3446, 3704, 3955, 4415, 7817) reported author and year? (ref. ID; 5855, 5900, 5939, 6583)

    Synonym

    Nais filiformis in Williams (1851) (ref. ID; 1928); Tubifex alpinus Bretscher, 1900 (ref. ID; 6208); Tubifex globulatus Friend, ? (ref. ID; 1257); Tubifex ignotus (Stolc) in Brinkhurst, 1960 (ref. ID; 1257); Tubifex bonneti Claparede, 1862 (ref. ID; 6208); Tubifex rivulorum Lamarck, 1816 (ref. ID; 6208); Tubifex tubifex var. heterochaeta Cernosvitov, 1925 (ref. ID; 6208)

    Descriptions

    20-100 mm. 34-120 segments. Anterior dorsal bundles with 3-5 pectinate chaetae and 1-3 or 4 hairs chaetae, most of which bear fine lateral hairs. The pectinate chaetae have three or more fine intermediate teeth between two equal sized lateral teeth; posterior dorsal crochets with the upper tooth thinner and longer than the lower. Ventral bundles with 3-5 chaetae (2 posteriorly) each with the upper tooth as long as but thinner than the lower, rarely with a small intermediate tooth. No modified genital chaetae. (ref. ID; 1257)

    T. tubifex is well known as a species of grossly polluted habitats, and also a characteristic species in oligotrophic and alpine lakes. (ref. ID; 1861)

    T. tubifex is very common in polluted waters. The anterior end is imbedded in mud tubes while the posterior end waves about. (ref. ID; 1923)

    Probably the commonest Tubificid worm, this species has been found in almost every collection so far made. The chaetae are probably variable (a detailed analysis of the amount of variation in this species will be made at a later date) but have proved sufficiently diagnostic for certain identifications, which have been verified by reference to be genitalia of fully mature specimens. The hair chaetae are long, thin and do not bear the fine hairlets described in other species (T. ignotus et al.). They vary in number from 3-6 (commonly 4) in the anterior segments to 1-2 in mid and posterior segments. The dorsal crotchets are of moderate size, sigmoid, with approximately equal teeth, the upper being a little thinner, and a varying number of intermediate theeth which are stout compared with those in other species. In the posterior segments the upper tooth is thinner and shorter than the lower, and the intermediate teeth are fewer in number and thinner. These more posterior chaetae resemble the ventral chaetae in that the teeth diverge more widely, up to 45 degrees, becoming more widely separated in the posterior ventral chaetae. Intermediate teeth occur rarely in the ventral chaetae. There are 3-4 crotchets in the anterior dorsal bundles, 4-6 in the ventral, falling to 1-3 in all postclitellar bundles. There are only 2 chaetae in each of the ventral bundles in segments 10 and 11. The penis is a small barrel shaped or thimble shaped structure as in T. ignotus. The vas deferens is long and coiled, and the spermatophores long and vermiform. (ref. ID; 6208)

    Lake Biwa material: In mature and fixed state, body 10-23 mm long, 0.4-0.6 mm wide in anterior segments except clitellum where it measures up to 0.8 mm wide. Segments 65-110. Dorsal chaetal bundles composed of hairs and pectinate chaetae. Dorsal hairs slightly to heavily hispid distally, 1-3 per bundle, 250-560 µm long preclitellarly, while 0-1 per bundle, 180-200 µm long postclitellarly. Dorsal pectinate chaetae in preclitellar segments 2-5 per bundle, 90-144 µm long, with upper tooth as long as or a little longer and as thick as lower, and with several distinct club-shaped intermediate teeth; those in postclitellar segments 1-3 per bundle, 110-130 µm, upper tooth thinner and intermediate teeth becoming absent. Aberrant modification of distal teeth often found in anterior dorsal pectinates. Ventral chaetae in preclitellar segments 2-4 per bundle, 95-142 µm long, upper tooth a little longer and thinner than lower, sometimes with short intermediate spine; those in postclitellar segments 2-3 per bundle, 110-124 µm long, upper tooth nearly as long as and thinner than the lower. Clitellum whitish, occupying from 1/2 X to end of XII. Vasa deferentia very long (up to 3900 µm) and coiled in XI-XIII, composed of narrow and ciliated proximal part (22-26 µm wide) and wide and non-ciliated distal part (40-45 µm wide), entering atria subapically. Atria tubular and bent proximally and distally, 450-600 µm long, 100-120 µm wide in maximum; inner epithelium thick and glandular. Prostate glands nearly as large as atria, connected with atria at the concave side of proximal portion of atria through a short stalk. Penes in penial poach about 100 µm long, protrusible, opening in XI ventrally. Penis sheath very thin, granular and plastic, usually tub-shaped. Spermathecae in X; ampullae ovoid in shape, 500 µm long by 380 µm and ducts thin and about 450 µm long, well marked off from ampullae. (ref. ID; 6648)

    Remarks

    Within the T. tubifex species several forms are known, differing only in chaetae structure. These forms have been variously classified by taxonomists as separate species, subspecies, varieties or mere forms. Particularly for T. tubifex, these is reduction and sometimes loss of the hair and pectinate chaetae are induced, producing individuals similar to the 'bergi' and 'blanchardi' forms. The latter differs from the normal form in that the hair and pectinate chaetae in dorsal bundles are replaced by forked chaetae, similar to the ventral ones. The 'blanchardi' form is uncommon. It was first found by Vejdovsky (1891) in two streams in a Algeria. Then Hrabe (1931) observed it in a stream in Corfu and in Lake Ochrida and Stephenson (1931) observed it in Paraguay. (ref. ID; 5900)

    This is the most dominant taxon in the macrozoobenthos of the profundal region of the northern lake, whereas so far the species has never been recorded from the littoral zone of the northern lake or from the shallow southern lake (Nishino et al. unpubl.). This species was formerly recorded under the name Tubifex sp. (Ohtaka 1993; Ohtaka & Nishino 1995); the present examination reveals that it is ascribable as Tubifex tubifex on the basis of chaetal and genital morphology. However, as already noted by Ohtaka & Nishino (1995), the Lake Biwa form is noticeable in having an aberrant modification of distal teeth in anterior dorsal pectinate chaetae. The modification involves a split or multiplication of lateral teeth, and the frequency of occurrence in the precilitellar bundles was found to be 50% in mature worms, whereas the modification was rare in young ones. Similar chaetal abnomalities in Tubifex tubifex were demonstrated to be induced by mercury and salinity stress by Chapman & Brinkhurst (1987), and has also been reported for anthor tubificid, Potamothrix hammoniensis, from a mercury-polluted Swedish lake (Milbrink 1983). In the profundal of Lake Biwa, however, the concentration of mercury in the sediment is lower than 0.3 mg kg-1 dry mud (Shiga Prefectural Institute of Public Health & Environmental Science, 1990) and the electric conductivity in the bottom water is lower than 125 uS cm-1 at 25 degrees C (Kumagai et al. 1995), which is much lower than the level for induction of chaetal abnormarities recorded by the above authors. Thus the modification of dorsal chaetae in the Lake Biwa form is caused by a more sensitive nature against these environmental factors, or by some other, unknown mechanism. (ref. ID; 6648)

    Localities

    Like L. hoffmeisteri this is a very common species in all types of habitat. There are indications that it can tolerate conditions of extreme oxygen depletion slightly better than can L. hoffmeisteri as it is often found alone close to the source of a gross organic pollution whereas both occur together throughout most of the Sphaerotilus zone. (ref. ID; 6208)

    Material examined

    Thirty-five mature individuals, off Wani (the northern lake), 70-74 m depth, 14th October, 1982, 25th October, 1993, 13th April, 1993; Seven mature individuals, off Hayasaki (the northern lake), 90 m depth, 14th February, 1995. (ref. ID; 6648)