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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Baikalodrilus

Baikalodrilus Holmquist, 1978 (ref. ID; 7201)

Family Tubificidae (ref. ID; 6660)

ref. ID; 7201

Holmquist (1979) included the type species B. kozovi (Hrabe, 1969) and B. digitatus in the genus, but referred two other taxa to a list of species of uncertain position (Peloscolex werestschagini Michaelsen, 1933 and P. inflatus (Mich., 1901)). Brinkhurst (1981) indicated the similarity in male ducts and other characters normally used to define tubificid genera among these four and placed them all in the genus. (ref. ID; 7201)
  1. Baikalodrilus cristatus (ref. ID; 6660)
  2. Baikalodrilus digitatus (ref. ID; 6660, 7201)
  3. Baikalodrilus inflatus (Michaelsen, 1901) (ref. ID; 7201)
    Syn; Peloscolex inflatus (Mich.): Cekanovskaya 1962; Brinkhurst & Jamieson 1971; Hrabe 1982 (ref. ID; 7201); Tubifex inflatus Michaelsen, 1901 (ref. ID; 7201)
  4. Baikalodrilus intermedius Cernoschikova, 1991 (ref. ID; 6660)
  5. Baikalodrilus kozovi (ref. ID; 7201)
  6. Baikalodrilus malevici (ref. ID; 6660)
  7. Baikalodrilus werestschagini (ref. ID; 7201)

Baikalodrilus digitatus (ref. ID; 6660, 7201)

Type materials

See Baikalodrilus kozovi. (ref. ID; 7201)

Baikalodrilus inflatus (Michaelsen, 1901) (ref. ID; 7201)

Synonym

Peloscolex inflatus (Mich.): Cekanovskaya 1962; Brinkhurst & Jamieson 1971; Hrabe 1982 (ref. ID; 7201); Tubifex inflatus Michaelsen, 1901 (ref. ID; 7201)

Descriptions

The anterior end is characteristically broad and the inflated appearance is presumably the basis of the specific epithet. The posterior end is often short and much thinner than the relatively short midsection, strongly suggesting that it gets cropped by predators in the manner described (for T. newaensis) by Poddubnaya (1962). The dense covering of the tail with stalked protozoans suggests that the tail is frequently protruded in the manner thought typical for tubificids. The setae are frequently broken. The dorsal setae are hairs plus thin penctinates, with short but relatively broad lateral and intermediate teeth. There are up to four of each on II-VI, one of each beyond VII. The ventral setae are both simple-pointed and bifid, and may reach five per bundle (Hrabe 1982). The spermathecae have voluminous ampullae and contain several very elongate spermatozeugmata. The body wall is covered in a readily detachable cuticular layer with rings of foreign matter. Some specimens are more obviously papillate than others, a variation common among species with such body walls (see old Peloscolex assemblage), comfirmed by Hrabe (1982). The species is clearly allied to Baikalodrilus Holmquist according to Brinkhurst (1981), even though the body forms is "very different" (Holmquist 1979). In fact, the swollen anterior end approaches the condition of the types species, B. kozovi and the two others (B. digitatus, B. werestschagini), but it retains the tail-like posterior end. In the original description of B. werestschagini the similarity of the male ducts of that species and B. inflatus was noted. There are more dorsal setae anteriorly in B. inflatus than in others (3 or 4 hairs, 3 or 4 pectinates versus 1 hair and 1 bifid or perhaps 2 hairs in the others). (ref. ID; 7201)

Type materials

Typus amissus (Reynolds and Cook 1976), but many specimens located: ZMUH (Zoological Museum of the University of Moscow) V5606, 5609, 6952, 6593, 9961, 10450, 11947 (Brinkhurst 1981) and also ZIAS (Zoological Institute, Academy of Sciences, Leningrad) (two) ZMUH (three) according to Homquist (1978). (ref. ID; 7201)

Baikalodrilus kozovi (ref. ID; 7201)

Type materials

The types of B. kozovi and B. digitatus were located by Holmquist (HOCB (Hrabe, Brno), ZMUM (Zoological Museum of the University of Moscow)) but the single type and only specimen of B. werestschagnini found by Brinkhurst (1981) in Hamburg consisted of the tail end (ZMUH (Zoological Museum of the University of Humburg) V11948). The head end, presumably sectioned, was undoubtedly destroyed along with other slide material. The material identified as werestschagini by Soviet biologists and lent to Dr. C. Holmquist was described by her as B. digitatus. The possible shedding of papillae that happens in all these papillate oligochaetes should be noted as it might reduce the apparent differences between these three taxa. All three are based on very few specimens. (ref. ID; 7201)

Baikalodrilus werestschagini (ref. ID; 7201)

Type materials

See Baikalodrilus kozovi. (ref. ID; 7201)