Dichromadora Kreis, 1929

Liang, Huixin, Guo, Wen & Wang, Chunming, 2024, Two new species of Hypodontolaiminae (Nematoda, Chromadorida, Chromadoridae) from the Yellow Sea with a phylogenetic analysis in the subfamily, ZooKeys 1190, pp. 281-302 : 281

Genus Dichromadora Kreis, 1929

Diagnosis

(based on Venekey et al. 2019). 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.

Remarks.

The genus Dichromadora was erected by Kreis in 1929 with the type species Dichromadora microdonta Kreis, 1929 with the genus characters the cuticle with two longitudinal rows of dots, small tooth, pharynx bulb big and round, ovaries paired symmetrical and reflexed, and males with or without precloacal supplements. Six species from the genus Chromadora ( C. cephalata Steiner, 1916, C. cricophana Filipjev, 1922, C. geophila de Man, 1876, C. parapoecilosoma Micoletzky, 1922, C. sabulicola Filipjev, 1918, C. setosa Bütschli, 1874) were transferred to Dichromadora by Kreis (1929). Later, D. hyalocheile De Coninck & Schuurmans Stekhoven, 1933, D. tobaensis Schneider, 1937, D. strandi Allgén, 1940, D. punctata Schuurmans Stekhoven, 1950, D. tenuicauda Schuurmans Stekhoven, 1950, and D. abnormis Gerlach, 1953a were described. Wieser (1954a) described D. dissipata Wieser, 1954a, revised the genus characters based mainly on tooth shape and provided new combinations. After Wieser (1954a), D. apapillata Timm, 1961, D. arcospiculum Timm, 1961, D. simplex Timm, 1961, D. islandica Kreis, 1963, D. scandula Lorenzen, 1966, and D. cucullata Lorenzen, 1973 were described and Gerlach and Riemann (1973) presented a list of sixteen species. Later, 12 species ( 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) were described. Huang and Zhang (2010) described three species from the China Sea, D. major , D. multisetosa , and D. sinica , and provided a short review of Dichromadora . Dichromadora abyssalis was considered as valid by Holovachov (2020) based on the high quality descriptions and illustrations despite not following the International Code of Zoological Nomenclature ( Venekey et al. 2019). With the addition of D. rigida Thanh, Tu & Gagarin, 2016 and D. agilis Long, Gagarin & Tu, 2022, 35 species are currently considered as valid (based on Venekey et al. 2019):

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

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

3. Dichromadora agilis Long, Gagarin & Tu, 2022 (Vietnam, Quảng Ninh)

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

5. Dichromadora antarctica (Cobb, 1914) (Antarctica, Cape Royd; = Spilophora antarctica Cobb, 1914)

6. Dichromadora apapillata Timm, 1961 (Indian Ocean, Bay of Bengal)

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

8. Dichromadora cephalata (Steiner, 1916) (Arctic Ocean, Barents Sea; = Chromadora cephalata Steiner, 1916, Chromadora cricophana Filipjev, 1922)

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

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

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

12. Dichromadora geophila (de Man, 1876) (North Sea, Netherlands; = Chromadora canadensis (Cobb, 1914), Chromadora geophila (de Man, 1876), Hypodontolaimus geophilus (de Man, 1876), Spiliphera geophila de Man, 1876, Spiliphera spectabilis Allgén, 1929)

13. Dichromadora gracilis (Kreis, 1929) (France, Trebeurden; = Spilophorella gracilis Kreis, 1929)

14. Dichromadora hyalocheile De Coninck & Schuurmans Stekhoven, 1933 (Belgium, Oostende)

15. Dichromadora islandica Kreis, 1963 (Iceland, Eyjafjörður)

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

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

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

19. Dichromadora media sp. nov. (China, Yellow Sea)

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

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

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

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

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

25. Dichromadora polarsternis Vermeeren, Vanreusel & Vanhove, 2004 (Antarctic Sea, Halley Bay)

26. Dichromadora punctata Schuurmans Stekhoven, 1950 (Mediterranean, Villefranche Bay)

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

28. Dichromadora rigida Thanh, Tu & Gagarin, 2016 (Vietnam, Yen River Estuary)

29. Dichromadora scandula Lorenzen, 1966 (North Sea, Schleswig-Holstein)

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

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

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

33. Dichromadora strandi Allgén, 1940 (Norway, Knivskjaerodden)

34. Dichromadora tobaensis Schneider, 1937 (Indonesia, Sumatra)

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