Genus Petaloproctus Quatrefages, 1865: 247. Type species: Petaloproctus terriculus Quatrefages, 1865. Maldane Grübe, 1860: 92; Lumbriclymene Sars 1872: 413; Nicomachella Levinsen, 1883: 146.
24. Petaloproctus borealis Arwidsson, 1907: 118 –122, pl. 3, figs. 85–90, pl. 8, 268–272. Type: NSMT K 97 – 11–125 (1). Type locality: North Sea.
Petaloproctus tenuis var. borealis Arwidsson, 1907: 118 –122, pl. 3, figs. 85–90, pl. 8, 268–272.
Petaloproctus borealis: Hartman 1948: 42; Uschakov 1955: 339, figs. 125 h; Hartmann-Schröder 1971: 413 – 412, figs. 151 a–d; Hobson and Banse 1981: 76, fig. 17 f; Imajima and Shiraki 1982: 44 –46, figs. 19 a–k; Buzhinskaja 1985: 163; Imajima 2001: 86.
Geographic distribution: North Sea, Japan (Suruga Bay to Korea Strait), Okhotsk Sea, Pacific coast of North America.
Remarks: Imajima and Shiraki (1982) elevated the taxonomic status of the variety Petaloproctus tenuis var. borealis Arwidsson, 1907 to the specific rank Petaloproctus borealis, emphasizing that the variety is clearly distinguishable, by having 20 setigerous segments and an anal plate with a crenulated margin, while P. tenuis has 21 setigerous segments and an anal plate with a smooth margin.
26. Petaloproctus dentatus Imajima and Shiraki, 1982: 42 –44, figs. 18 a–n. Holotype: NSMT –Pol. H 159. Paratypes: NSMT –Pol. 160, NSMT K 97 – 11-250 (19), NSMT K 97 - 11–300 (2), NSMT K 98 – 1–250 (3). Type locality: Japan.
Petaloproctus dentatus: Imajima 2001: 87.
Geographic distribution: Known only from the type locality.
27. Petaloproctus macrodentatus Lee and Paik, 1986: 23, fig. 7 a–g. Holotype: 1009 KORDI. Type locality: Yellow Sea, Korea.
Geographic distribution: Known only from the type locality.
28. Petaloproctus neoborealis Hartman, 1969: 471, figs. 1–3. Holotype: not mentioned in description. Type locality: Off San Diego, California, USA, (32 ° 3112 N; 11808 30 W).
Geographic distribution: Known only from the type locality.
29. Petaloproctus ornatus Hartman, 1969: 473, figs. 1–4. Holotype not mentioned in description. Type locality: Palos Verdes Point, California, USA, (334800 N; 11832 0 0 W).
Petaloproctus ornatus: Hartman 1955: 19.1, fig. 46.
Geographic distribution: Known only from the type locality.
30. Petaloproctus socialis Andrews, 1891: 295 –296, pl. 7, figs. 36–41. Type: EL–ECOSUR 2782. Type locality: North Carolina.
Petaloproctus socialis: Hartman 1945: 40, pl. 8, figs. 3–4; Jimnez-Cueto and Salazar-Vallejo 1997: 1463, figs. a–c; Amaral, Nallin and Steiner 2006: 6, catalogue.
Geographic distribution: Northwestern Caribbean to North Carolina and South America, Brazil.
31. Petaloproctus tenuis (Théel, 1879): 57, figs. 52–54. Type: NMG, number not mentioned; CNRS St. 1425 (5), 426 (2), 451 (4); USNM 10486. Type locality: Cape Cod Bay, Massachusetts, USA.
Maldane tenuis Théel, 1879: 57, figs. 52–54.
Maldane filifera Verrill, 1880: 179.
Lumbriclymene filifera (Verrill, 1880) Verrill 1900: 659.
Petaloproctus filifer (Verrill, 1880) Arwidsson, 1907: 141
Petaloproctus tenuis: Eliason 1920: 66; Annenkova 1937: 181; Hartman 1942: 42; 1948: 42; Berkeley and Berkeley 1952: 56, figs. 114–116; Pettibone 1954: 306 –307, figs. 34 l–m; Rullier 1965: 194; Amoureux 1982: 198; Buzhinskaja 1985: 163; Lee and Paik 1986: 23, tab.
Geographic distribution: Off Cape Cod, Massachusetts; East Greenland; Spitsbergen; north Japan Sea; Novaya Zelmya; British Columbia to southeastern Alaska; Arctic, (Pettibone 1954; Lee and Paik 1986).
32. Petaloproctus terriculus Quatrefages, 1865: 247. Syntypes: USMN – POLY – TYPE 281–284. Type locality: France.
Petaloproctus terriculus: Fauvel 1927: 194, fig. 68; Day 1955: 429; 1967: 622–623, figs. 30.2a–d; Rullier 1965: 194, without figs.; Solis-Weiss et al. 2004: appendix S 7.
Nicomache macintosh Marenzeller, 1887: 19, pl. 1, fig. 8.
Petaloproctus macintosh Augener, 1918: 491.
Geographic distribution: East Atlantic from Angola to the English Channel.