After

<==o Sipunculidae Rafinesque 1814
   |--o Sipunculus Linnaeus, 1766 [Syrinx Bohadesh, 1761; Lumbricus Linnaeus, 1758]
   |  |--o (Sipunculus) Linnaeus, 1766
   |  |  |-- S. (S.) lomonossovi Murina, 1968
   |  |  |-- S. (S.) longipapillosus Murina, 1968
   |  |  |-- S. (S.) marcusi Ditadi, 1976 [?Lumbricus phalloides Pallas, 1774]
   |  |  |-- S. (S.) norvegicus Danielssen, 1868 [Sipunculus aequabilis Sluiter, 1902; Sipunculus priapuloides americanua Gerould, 1913; Sipunculus infrons Sluiter, 1902; Sipunculus  nitidus Sluiter, 1900; Sipunculus priapuloides Koren & Danielssen, 1877]
   |  |  |-- S. (S.) nudus Linnaeus, 1766 [Syrinx tesselatus Rafinesque, 1814; Sipunculus balanophorus Delle Chiaje, 1823; Sipunculus gigas de Quatrefages, 1856; Sipunculus eximioclathrathus Baird, 1868; Sipunculus titubans Selenka & Balow, 1883; Sipunculus titubans diptychus Fischer, 1895; Sipunculus delphinus Murina, 1967]
   |  |  |--o S. (S.) phalloides (Pallas, 1774) [Lumbricus phalloides Pallas, 1774]
   |  |  |  |-- S. (S.) p. phalloides (Pallas, 1774) [Lumbricus phalloides Pallas, 1774; Sipunculus galapagensis Fischer, 1947; Sipunculus multisulcatus Fischer, 1913]
   |  |  |  `-- S. (S.) p. inclusus Sluiter, 1902 [Sipunculus sp. Cutler & Cutler, 1985]
   |  |  |-- S. (S.) polymyotus Fischer, 1947 [Sipunculus natans Fischer, 1954]
   |  |  `-- S. (S.) robustus Keferstein, 1865 [Sipunculus angasii Baird, 1868; Sipunculus gravieri Hrubel, 1904]
   |  `--o (Austrosiphon) Fischer, 1954 [Xenosiphon (Austrosiphon) Fischer, 1954; Xenosiphon (Xenopsis) Johnson, 1969; Sipunculus (Contraporus) Cutler & Cutler, 1985]
   |     |-- S. (A.) indicus Peters, 1850 [Sipunculus porrectus Selenka, 1888; Sipunculus discrepans Sluiter, 1898]
   |     `-- S. (A.) mundanus (Selenka & Balow, 1883) [Xenosiphon mundatus Selenka & Balow, 1883; Sipunculus maoricus Benham, 1904]
   |--o Xenosiphon Fischer, 1947
   |  |-- X. absconditus Saiz, 1984 [Xenosiphon branchiatus nudud Cutler & Cutler, 1985]
   |  `--- X. branchiatus (Fischer, 1895) [Sipunculus mundanus branchiatus Fischer, 1895; Xenosiphon caribaceus Fischer, 1954]
   |--o Siphonosoma Spengel, 1912 [Siphonosoma (Damosiphon) Fischer, 1950; Siphonosoma (Hesperosiphon ) Fischer, 1950]
   |  |-- S. arcassonense Cuenot, 1902
   |  |--o S. australe (Keferstein, 1865) [Phascolosoma australe Keferstein, 1865]
   |  |  |-- S. s. australe (Keferstein, 1865) [Phascolosoma australe Keferstein, 1865; Siphonosoma aeneus Baird, 1868]
   |  |  `-- S. s. takatsukii Sati, 1939 [Siphonosoma pescadolense Sati, 1939]
   |  |-- S. boholense (Selenka, de Man & Balow, 1883) [Sipunculus boholense Selenka, de Man & Balow, 1883]
   |  |-- S. cumanense (Keferstein, 1867) [Phascolosoma cumanense Keferstein, 1867; Lumbricus edulis Pallas, 1774; Sipunculus deformis Baird, 1868; Sipunculus cumanensis vitreus Selenka & Balow, 1883; Phascolosoma semirugosum Grabe, 1868; Sipunculus billitonensis Sluiter, 1886; Sipunculus claviger Sluiter, 1902; Sipunculus novaepommeraniae Fischer, 1926; Physcosoma hebes Sluiter, 1902; Siphonosoma carolinense Fischer, 1928; Siphonosoma hataii Sati, 1935; Siphonosoma cumanense yapense Sati, 1935; Siphonosoma formosum Sati, 1939; Siphonosoma koreae Sati, 1939; Siphonosoma opacum (Selenka & Balow, 1883); Siphonosoma marchadi Stephen, 1960]
   |  |-- S. dayi Stpehen, 1942
   |  |-- S. funafuti (Shipley, 1898) [Sipunculus funafuti Shipley, 1898; Sipunculus amamiense Ikeda, 1904]
   |  |-- S. ingens (Fischer, 1947) [Sipunculus ingens Fischer, 1947]
   |  |-- S. mourense Sati, 1930
   |  |-- S. rotumanum (Shipley, 1898) [Sipunculus rotumanum Shipley, 1898; Siphonosoma eniwetoki Fischer, 1950; Siphonosoma hawaiense Edmonds, 1966]
   |  `-- S. vastum (Selenka & Balow, 1883) [Sipunculus vastus Selenka & Balow, 1883; Sipunculus (Phascolosomum) violaceus de Quatrefages, 1865; Siphonosoma crassum Spengel, 1919; Sipunculus parvum Fischer, 1928; Siphonosoma vastum album (Shipley, 1899); Siphonosoma vastum obscurum (Shipley, 1899)]
   |--o Siphonomecus Fischer, 1947
   |  `-- S. multicinctus Fischer, 1947
   `--o Phascolopsis Fischer, 1950 [Golfingia (Phascolopsis) Fischer, 1950]
      `-- P. gouldii (Pourtales, 1851) [Sipunculus gouldii Pourtales, 1851]

Reference(s):

Special thanks to:

Jos H. M. Dols, for gathering additional information and species of these animals.