Dichromadora Kreis, 1929

Venekey, Virag, Gheller, Paula F., Kandratavicius, Noelia, Cunha, Beatriz Pereira, Vilas-Boas, Ana Carolina, Fonseca, Gustavo & Maria, Tatiana F., 2019, The state of the art of Chromadoridae (Nematoda, Chromadorida): a historical review, diagnoses and comments about valid and dubious genera and a list of valid species, Zootaxa 4578 (1), pp. 1-67 : 36-38

Genus Dichromadora Kreis, 1929

The genus Dichromadora was first established by Kreis (1929) as part of Chromadorinae to accommodate D. microdonta Kreis, 1929 and six species of Chromadora : Chromadora cephalata Steiner, 1916 (the type species), Chromadora cricophana Filipjev, 1922 , Chromadora geophila (de Man, 1876) , Chromadora parapoecilosoma , Chromadora sabulicola Filipjev, 1918 and Chromadora setosa Bütschli, 1874 . Kreis (1929) distinguished Dichromadora from Chromadora based on the cuticle with two longitudinal rows of dots, the presence of a spherical pharyngeal bulb, reflexed and symmetrical paired ovaries. Later, Dichromadora was differentiated by having a dorsal triangular and acute tooth, different from the S-shaped tooth known for Hypodontolaimus ( Wieser 1954) . Gerlach & Riemann (1973) presented a list of sixteen species, including D. serrata , renamed later to Chromadora serrata by Timm (1978).

After Gerlach & Riemann (1973), D. antarctica ( Cobb, 1914) was transferred from Spilophora , and other 13 valid species were described ( D. cucullata Lorenzen, 1973 ; D. amphidiscoides Kito, 1981 ; D. abyssalis Bussau, 1993 ; D. gathuai Muthumbi & Vincx, 1998 ; D. loiseae Muthumbi & Vincx, 1998 ; D. longicaudata Muthumbi & Vincx, 1998 ; D. quadripapillata Muthumbi & Vincx, 1998 ; D. parasimplex Dashchenko, 2002 ; D. parva Vermeeren, Vanreusel & Vanhove, 2004 ; D. polaris Vermeeren, Vanreusel & Vanhove, 2004 ; D. polarsternis Vermeeren, Vanreusel & Vanhove, 2004 ; D. southernis Vermeeren, Vanreusel & Vanhove, 2004 and D. weddellensis Vermeeren, Vanreusel & Vanhove, 2004 ). Huang & Zhang (2010) described D. major , D. multisetosa and D. sinica and reviewed Dichromadora , considering 32 valid species. D. abyssalis was described by Bussau (1993) in his PhD thesis and despite its description being of good quality it should be considered as nomen nudum following the International Code of Zoological Nomenclature. The last addition to Dichromadora was the description of D. rigida by Thanh et al. (2016). Today we recognize 32 valid species.

Diagnosis (modified from Huang & Zhang 2010 and Tchesunov 2014): Cuticle with homogeneous ornamentation and a pronounced lateral differentiation of two longitudinal rows of enlarged dots. Six outer labial papillae and four cephalic setae in separate circles. Amphideal fovea transverse slit-like and loop shaped. Buccal cavity with a triangular hollow dorsal tooth or a large dorsal tooth and two additional ventrosublateral ones; denticles can be present. Peribuccal pharyngeal tissue not swollen anteriorly or with an asymmetrical dorsal swelling; a distinct posterior pharyngeal bulb. Precloacal supplements present or absent. Marine.

Number of valid species: 32

Genus Dichromadora Kreis, 1929

VALID SPECIES

1. Dichromadora abnormis Gerlach, 1953 ( Italy, San Rossore and Tirrenia beaches)

2. Dichromadora amphidiscoides Kito, 1981 ( Japan, Oshoro Bay)

3. Dichromadora antarctica ( Cobb, 1914) Timm , 1 978 (Cape Royd, Antarctica)

Syn. Spilophora antarctica Cobb, 1914

4. Dichromadora apapillata Timm , 1 961 (Indian Ocean, Bay of Bengal)

5. Dichromadora arcospiculum Timm, 1961 (Indian Ocean, Bay of Bengal)

6. Dichromadora cephalata ( Steiner, 1916) Kreis, 1929 (Arctic Ocean, Barents Sea)

Syn. Chromadora cephalata Steiner, 1916

Chromadora cricophana Filipjev, 1922

7. Dichromadora cucullata Lorenzen, 1973 (North Sea, Baltic Sea, Helgoland)

8. Dichromadora dissipata Wieser, 1954 ( Chile, Seno de Reloncaví)

9. Dichromadora gathuai Muthumbi & Vincx, 1998 (Indian Ocean, Kenyan coast)

10. Dichromadora geophila (de Man, 1876) Kreis, 1929 (North Sea, Netherlands)

Syn. Chromadora canadensis ( Cobb, 1914) Micoletzky, 1922

Chromadora geophila (de Man, 1876) Micoletzky, 1922

Hypodontolaimus geophilus (de Man, 1876) Wieser, 1954

Spiliphera geophila de Man, 1876

Spiliphera canadensis Cobb, 1914

Spiliphera spectabilis Allgén, 1929

11. Dichromadora gracilis ( Kreis, 1929) Wieser, 1954

Syn. Spilophorella gracilis Kreis, 1929

12. Dichromadora hyalocheile De Coninck & Schuurmans Stekhoven, 1933 ( Belgium, Oostende) 13. Dichromadora islandica Kreis, 1963 ( Iceland, Eyjafjörður)

14. Dichromadora loiseae Muthumbi & Vincx, 1998 (Indian Ocean, Kenyan coast)

15. Dichromadora longicaudata Muthumbi & Vincx, 1998 (Indian Ocean, Kenyan coast)

16. Dichromadora major Huang & Zhang, 2010 ( China, Yellow Sea, intertidal sandy sediment)

17. Dichromadora microdonta Kreis, 1929 ( France, English Channel)

18. Dichromadora multisetosa Huang & Zhang, 2010 ( China, Yellow Sea)

19. Dichromadora parasimplex Dashchenko, 2002 (New Guinea, Astrolabe Bay)

20. Dichromadora parva Vermeeren, Vanreusel & Vanhove, 2004 (Antarctic Sea, Halley Bay)

21. Dichromadora polaris Vermeeren, Vanreusel & Vanhove, 2004 (Antarctic Sea, Halley Bay)

22. Dichromadora polarsternis Vermeeren, Vanreusel & Vanhove, 2004 (Antarctic Sea, Halley Bay) 23. Dichromadora punctata Schuurmans Stekhoven, 1950 (Mediterranean, Villefranche Bay)

24. Dichromadora quadripapillata Muthumbi & Vincx, 1998 (Indian Ocean, Kenyan coast)

25. Dichromadora rigida Thanh, Tu & Gagarin, 2016 ( Vietnam)

26. Dichromadora scandula Lorenzen, 1966 (North Sea)

27. Dichromadora simplex Timm, 1961 (Indian Ocean, Bay of Bengal)

28. Dichromadora sinica Huang & Zhang, 2010 ( China, Yellow Sea)

29. Dichromadora southernis Vermeeren, Vanreusel & Vanhove, 2004 (Antarctic Sea, Halley Bay) 30. Dichromadora strandi Allgén, 1940 ( Norway, Knivskjaerodden)

31. Dichromadora tobaensis Schneider, 1937 (Sumatra)

32. Dichromadora weddellensis Vermeeren, Vanreusel & Vanhove, 2004 (Antarctic Sea, Halley Bay)

NOMEN NUDUM

1. Dichromadora abyssalis Bussau, 1993 (SE Pacific, Peru Basin)