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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Lycodrilus

Lycodrilus Grube, 1873 (ref. ID; 3692, 7201)

ref. ID; 7201

Limnodrilus Claparede (in part), Michaelsen, 1926. Defined as for the sole species L. dybowskii. While these various species in Lycodrilus remained poorly described, their taxonomic position remained a matter of considerable doubt. Cekanovskaya (1962) placed them in a separate family, Lycodrilidae, based on unpublished work by P.G. Svetlov. At that time there were five species, all limited to Lake Baikal, none of which had been since 1905. The genus had been allied with Limnodrilus by Michaelsen (1926) and it is now clear that they are mostly tubificine tubificids, based on examination of two species in my material and the independent work of Hrabe (1982) on three of the species. One species (L. parvus Michaelsen, 1905) was shown to be a member of the Lumbriculidae by Hrabe, and this contested here. The lumbriculids in the new collection will be examined at a later date. Brinkhurst and Jamieson (1971) had loosely allied the genus Lycodrilus with Dorydrilus, but that is no longer tenable. (ref. ID; 7201)
  1. Lycodrilus dybowskii Grube, 1873 (ref. ID; 3692, 7201)
    Syn; Limnodrilus dybowskii (Grube) Michaelsen, 1926 (ref. ID; 7201)
  2. Lycodrilus dybowskii var. schizochaeta Michaelsen, 1901
    See; Lycodrilides schizochaetus (ref. ID; 7201)
  3. Lycodrilus grubei Michaelsen, 1905 (ref. ID; 3692)
    See; Lycodrilides grubei (ref. ID; 7201)
  4. Lycodrilus kraepelini Michaelsen, 1914 (ref. ID; 6578)
  5. Lycodrilus parvus Michaelsen, 1905 (ref. ID; 3692, 7201)
  6. Lycodrilus phreodriloides Michaelsen, 1905 (ref. ID; 3692, 7201)
  7. Lycodrilus schizochaetus Michaelsen, 1905 (ref. ID; 3692)
    See; Lycodrilides schizochaetus (ref. ID; 7201)

Lycodrilus dybowskii Grube, 1873 (ref. ID; 3692, 7201)

Synonym

Limnodrilus dybowskii (Grube) Michaelsen, 1926 (ref. ID; 7201)

Descriptions

Examination of the three specimens located in Hamburg, presumably not the type series, added little to our knowledge of the species. One was a tail fragment; the head, presumably having been sectioned, is now presumed lost with the other sectioned material. Another was semimature, with straplike gonads in X-XI, the latter being ovaries. Some traces of what appear to be a male duct were seen in X, and a female funnel in XI. The setae are simple pointed and hooked, and sequentially enlarged in anterior ventral bundles, but the two setae in each pair appear unequal in width. The broken specimens was about 20 mm long with 60 segments or more. The third specimen was similar, but the ventral anteriormost setae were bifid with short upper teeth, those of V curved with reduced upper teeth, and the progressive enlargement of ventral setae was noted from II to IX, after which the setal width was reduced. The large setae in IX were simple pointed. This specimen may well belong to Lycodrilides schizochaetus, originally described as a variety of L. dybowskii. The two specimens examined were very similar apart from differences in the nature of the setae. Hrabe (1982) obtained eight specimens, of which two were mature. His specimens resemble earlier descriptions of the species, with some differences. There is usually a single seta posterior to the immediate preclitellar region (somewhere between VIII and XI). Hearts were observed in VIII. The vasa deferentia are very long, and enter "spindle-shaped, crescent-curved" atria which gradually narrow. The long ejaculatory ducts enter penes with distinct cuticular sheaths bearing distal discs. The presumption is that these are attributable to L. dybowskii, despite my finding of the specimen with bifid setae in the vial labelled L. dybowskii in the Michaelsen collection. This is now the sole species in the genus. (ref. ID; 7201)

Type materials

Unknown. (ref. ID; 7201)

Material examined

Three species, ZMUH (Zoological Museum of the University of Hamburg) V5601, from Korontneff 1901 (plus one other specimen; also V6594, 9965, 11949, many specimens examined superficially). (ref. ID; 7201)

Lycodrilus parvus Michaelsen, 1905 (ref. ID; 3692, 7201)

Notes

Hrabe (1982) redescribed L. parvus Michaelsen, 1905 as Pseudolycodrilus parvus, a new genus of Lumbriculidae. My examination of one of six types in Hamburg (ZMUH (Zoological Museum of the University of Hamburg) V6597) confirmed the position of spermathecal pores in VIII, male pores in X behind the setae and associated glands. Michaelsen's original description identified the second pair of testes as ovaries and failed to note ovaries in the segment bearing the female funnels (XI). Hrabe did not see the type material. (ref. ID; 7201)

Lycodrilus phreodriloides Michaelsen, 1905 (ref. ID; 3692, 7201)

Notes

L. phreodriloides Michaelsen, 1905 has not been rediscovered. The setae are rather hairlike dorsally, the reproductive system is tubificine in arrangement according to the description. No specimens were located in Hamburg, though the types are listed as ZMUH (Zoological Museum of the University of Hamburg) V6619 (Reynolds and Cook 1976). The ejaculatory duct is short but there is no penis, so an alignment with either Lycodrilus or Lycodrilides seems problematic. The species should be regarded as a dubious taxon within the Tubificidae, but no certain position, i.e., incertae sedis in Lycodrilus for reference purposes. (ref. ID; 7201)