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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Quadricoma

Quadricoma Filipjev, 1922 (ref. ID; 878, 3571)

Desmoscolecida Filipjev, 1929: Family Desmoscolecidae Shipley, 1896: Subfamily Desmoscolecinae Shipley, 1896 (ref. ID; 3571)

ref. ID; 878

Filipjev (1922) erected the genus Quadricoma. The original diagnosis is of little use, but on the basis of the type species Q. loricata the genus can be recognized. Over the years a number of nematologists rejected Quadricoma as a valid genus and synonymized with Tricoma. From the 48 species ever described or considered as Quadricoma-species, 50% nowadays belongs to other genera. Among the remaining species only 15 have a clear inversion ring. However, the differences between Quadricoma and Tricoma are relatively small and even intermediate forms are known. The main difference between Quadricoma and Tricoma lies 1) in the shape of the main rings: always quadricomoid in Quadricoma, rounded or partially quadricomoid in Tricoma and 2) in the single ring of inversion: present in Quadricoma, always absent in Tricoma. A second difference lies in the shape of the endring and spinneret and a third difference is given by the shape of the head. 1. A single inversion ring is never found in Tricoma-species. However, some Quadricoma-species without a clear inversion ring, e.g. Q. noffsingerae has specimens with and without an inversion ring and Tricoma bathycola Freudenhammer, 1975 and T. beata Freudenhammer, 1975 represent presumably Quadricoma-species without a clear inversion ring. The type specimens are no longer available. Consequently the shape of the main rings together with the presence or absence of an inversion ring is not decisive enough to allow the separate genus state for Quadricoma. 2. The shape of the endring and spinneret as taxonomic features are not of conclusive validity. The fine naked offset spinneret is not always present in Quadricoma-species (50%), it depends on the species and even on the individual itself. The cylindrical tricomoid shape of the endring, typical for the majority of Tricoma-species, was once found in a Quadricoma-specimen with an inversion ring; the fine offset spinneret does also occur in some Tricoma-species. 3. The head-shape may represent an additional feature in the characterization of the genus e.g. the broad wide triangular head-shape with the peduncles of insertion of the cephalic setae at the base is never observed in Quadricoma. However, the more rounded head shape with broad anterior end may be present in both Quadricoma and Tricoma. The three features (shape of main rings and inversion ring, shape of endring and spinneret, and head-shape) together define quite well the Quadricoma-group. However, by the presence of intermediate forms, the overlapping of some of the features Quadricoma is considered as a subgenus of Tricoma. The acquistion of quadricomoid rings and a clear inversion ring is an apomorphous character defining a monophyletic subgroup with the genus Tricoma. (ref. ID; 878)

ref. ID; 3571

Type species

Quadricoma loricata Filipjev, 1922 (ref. ID; 3571)
  1. Quadricoma arctica (Kreis, 1963)
    See; Quadricoma scanica (ref. ID; 3571)
  2. Quadricoma bahamensis Timm, 1970 (ref. ID; 3571)
  3. Quadricoma cobbi (Steiner, 1916) Filipjev, 1922 (ref. ID; 878, 3571)
    Syn; Tricoma cobbi Steiner, 1916 (ref. ID; 3571)
  4. Quadricoma crassicauda Timm, 1970 (ref. ID; 3571)
  5. Quadricoma crassicoma (Steiner, 1916) Filipjev, 1922 (ref. ID; 3571)
    Syn; Tricoma crassicoma Steiner, 1916 (ref. ID; 3571)
  6. Quadricoma crassicomoides Timm, 1970 (ref. ID; 878, 3571)
  7. Quadricoma desmoscolecoides Timm, 1970 (ref. ID; 3571)
  8. Quadricoma eurycricus (Filipjev, 1922) Timm, 1970 (ref. ID; 3571)
    Syn; Desmoscolex eurycricus Filipjev, 1916 (ref. ID; 3571)
  9. Quadricoma falklandiae (Allgen, 1952) Timm, 1970 (ref. ID; 3571)
    Syn; Desmoscolex falkalndiae Allgen, 1952 (ref. ID; 3571)
  10. Quadricoma filipjevioides Timm, 1970 (ref. ID; 3571)
    Syn; Tricoma filipjevioides (ref. ID; 3571)
  11. Quadricoma freudenhammeri Decraemer, 1976 (ref. ID; 878)
  12. Quadricoma frontalis (Gerlach, 1952) Timm, 1970 (ref. ID; 3571)
    Syn; Desmoscolex frontalis Gerlach, 1952 (ref. ID: 3571)
  13. Quadricoma granulata Kreis, 1934
    See; Quadricoma loricata (ref. ID; 3571)
  14. Quadricoma greeffii (Reinhard, 1881) Filipjev, 1922 (ref. ID; 3571)
    Syn; Desmoscolex greffii Reinhard, 1881 (ref. ID; 3571)
  15. Quadricoma hupferi (Steiner, 1916) Timm, 1970 (ref. ID; 3571)
    Syn; Desmoscolex hupferi Steiner, 1916 (ref. ID; 3571)
  16. Quadricoma intermedia (Steiner, 1916) Filipjev, 1922 (ref. ID; 3571)
    Syn; Tricoma intermedia Steiner, 1916 (ref. ID; 3571)
  17. Quadricoma longicauda Timm, 1970 (ref. ID; 3571)
  18. Quadricoma loricata Filipjev, 1922 (ref. ID; 878, 3571)
    Syn; Quadricoma granulata Kreis, 1934 (ref. ID; 3571)
  19. Quadricoma magna Timm, 1970 (ref. ID; 3571)
  20. Quadricoma media (Reinhard, 1881) Filipjev, 1922 (ref. ID; 3571)
    Syn; Desmoscolex medius Reinhard, 1881 (ref. ID; 3571)
  21. Quadricoma noffsingerae (ref. ID; 878)
  22. Quadricoma parva Timm, 1970 (ref. ID; 3571)
  23. Quadricoma pontica Filipjev, 1922 (ref. ID; 3571)
  24. Quadricoma reinhardi Filipjev, 1922
    See; Quadricoma tenuis (ref. ID; 3571)
  25. Quadricoma scanica (Allgen, 1935) Timm, 1970 (ref. ID; 3571)
    Syn; Desmoscolex scanicus Allgen, 1935 (ref. ID; 3571); Neoquadricoma arctica Kreis, 1963 (ref. ID; 3571)
  26. Quadricoma steineri Filipjev, 1922 (ref. ID; 3571)
    Syn; Tricoma filipjevi Stammer, 1935 (ref. ID; 3571)
  27. Quadricoma suecica (Allgen, 1930) Timm, 1970 (ref. ID; 3571)
    Syn; Tricoma suecica Allgen, 1930 (ref. ID; 3571)
  28. Quadricoma tenuis (Steiner, 1916) Filipjev, 1922 (ref. ID; 3571)
    Syn; Quadricoma reinhardi Filipjev, 1922 (ref. ID; 3571); Tricoma tenuis Steiner, 1916 (ref. ID; 3571)
  29. Quadricoma trigintatres Timm, 1970 (ref. ID; 3571)
  30. Quadricoma vittata (Lorenzen, 1969) Timm, 1970 (ref. ID; 3571)
    Syn; Desmoscolex vittatus Lorenzen, 1969 (ref. ID; 3571)