After Hulbert, 1997, McKenna & Bell, 1997, Candela, 2004, and Voss, Hubbard & Jansa, 2013, with Recent species from Nowak, 1991, and Wikipedia

<==o Erethizontidae Bonaparte, 1845 [taxonomic history] (New World Porcupines; puupiikkisiat)
   |-- Chaetomys subspinosus Gray, 1843 [Plectrochoerus Pictet, 1843] [Chaetomyinae Thomas, 1897] ()?
   `--+--o Erethizontinae Bonaparte, 1845 [taxonomic history] (Recent New World Porcupines; nykypuupiikkisiat)
      |  |?-o †Paradoxomys Ameghino, 1885; U.Mioc. SA. [has been treated as octodontid]
      |  |  `-- †P. cancrivorus
      |  |--o Erethizon F. Cuvier, 1822 [taxonomic history] U.Plioc.-R. NA. (puupiikkisiat)
      |  |  |-- †E. poyeri Hulbert, 1997
      |  |  |-- †E. bathygnathum R.W. Wilson, 1935 [taxonomic history]
      |  |  |-- †E. cascoensis (J. White, 1970) [taxonomic history]
      |  |  |-- †E. kleini Frazier, 1981
      |  |  `-- E. dorsatum (Linnaeus, 1758) (kanadanpuupiikkisika)
      |  `--o Coendou Lacépède, 1799 sensu Voss, Hubbard & Jansa, 2013 [incl. Echinoprocta Gray, 1865; Sphiggurus F. Cuvier, 1825] (koendut, kierteishäntäpiikkisiat)
      |     |?- C. baturitensis Feijó & Langguth, 2013
      |     |?- C. rothschildi (Thomas, 1902) (Rothschild's Porcupine, Gato de Espinas)
      |     |?- C. sanctamartae Allen, 1904 (Santa Marta porcupine)
      |     |?- C. speratus Pontes, Gadelha, Melo, Sá, Loss, Caldara jr, Costa & Leite, 2013
      |     |?- C. insidiosus (Olfers, 1818) [Sphiggurus insidiosus (Olfers, 1818)] (Bahi[']a Hairy Dwarf Porcupine, Ouric[,]o Cacheiro)
      |     |?- C. pallidus [Sphiggurus pallidus] (Lesser Antillean Indian Hairy Porcupine)
      |     |?- C. roosmalenorum Voss & da Silva, 2001 [Sphiggurus roosmalenorum (Voss & da Silva, 2001)] (Roosmalen's dwarf porcupine)
      |     |?- C. villosus (Cuvier, 1822) [Sphiggurus villosus (Cuvier, 1822)] (Orange-spined hairy dwarf porcupine; ruskopuupiikkisika)
      |     |-- C. ichillus (Voss & da Silva, 2001) [Sphiggurus ichillus Voss & da Silva, 2001] (Streaked dwarf porcupine)
      |     |-- C. melanurus (Wagner, 1842) [Sphiggurus melanurus (Wagner, 1842)] (Black-tailed hairy dwarf porcupine)
      |     |--+-- C. pruinosus (Thomas, 1905) [Sphiggurus pruinosus (Thomas, 1905)] (Frosted hairy dwarf porcupine)
      |     |  `-- C. vestitus (Thomas, 1899) [Sphiggurus vestitus Thomas, 1899] (Brown Hairy Dwarf Porcupine)
      |     |--+-- C. spinosus (Cuvier, 1822) [Sphiggurus spinosus (Cuvier, 1822)] (Paraguaian hairy dwarf porcupine; brasilianpuupiikkisika)
      |     |  `--+-- C. nycthemera (Olfers, 1818) [C. koopmani Handley & Pine, 1992] (Black dwarf porcupine; Koopman's porcupine)
      |     |     `--o C. bicolor (Tschudi, 1844) (Bicolored-spined porcupine; pohjankierteishäntäpiikkisika)
      |     |        |-- C. b. bicolor (Tschudi, 1844)
      |     |        |-- C. b. richardsoni Allen, 1913
      |     |        `-- C. b. simonsi Thomas, 1902
      |     `--+-- C. prehensilis (Linnaeus, 1758) (Brazilian porcupine; kierteishäntäpiikkisika, koendu)
      |        `--+-- C. mexicanus (Kerr, 1792) [Sphiggurus mexicanus (Kerr, 1792)] (Mexican hairy dwarf porcupine; meksikonpuupiikkisika)
      |           `--+-- C. rufescens (Gray, 1865) [Echinoprocta rufescens Gray, 1865] (Stump-tailed porcupine; amazoninpuupiikkisika)
      |              `-- C. quichua Thomas, 1899 [C. bicolor quichua Thomas, 1899] (Andean porcupine)
      `--o †Steiromyinae Ameghino, 1902 sensu Candela, 2004 (Giant New World Porcupine; jättipiikkisiat)
         |-- †Hypsosteiromys axiculus Patterson, 1958; L.Mioc. SA.
         `--+--o †Neosteiromys Rovereto, 1914; ?M.Mioc. U.Mioc. SA.
            |  |-- ?†N. tordillense
            |  |-- †N. bombifrons Rovereto, 1914
            |  `-- †N. pattoni Candela, 2004
            `--+-- †Erethizontidae genera et species indet. [Candela, 2004]
               `--+-- †Eosteiromys homogenidens Ameghino, 1902 [Eosteiromys Ameghino, 1901 (nomen nudum)] L.Mioc. ?M.Mioc. SA.
                  `--o †Steiromys Ameghino, 1887 [incl. Parasteiromys Ameghino, 1904 sensu Candela] L.Mioc. SA.
                     |-- †S. duplicatus
                     `-- †S. detentus

Erethizontidae incertae sedis:

[= taxons not listed by Candela, 2004]

Protosteiromys A.E. Wood & Patterson, 1959; U.Olig. SA.
        †P. medianusP. asmodeophilusParasteiromys Ameghino, 1904; L.Mioc. SA.
    †Disteiromys Ameghino, 1904; M.Mioc. SA.

After Voss, Hubbard & Jansa, 2013 (Recent species only)

<==o Erethizontidae
   |-- Chaetomys subspinosus
   `--+-- Erethizon dorsatum
      `--o Coendou
         |--+-- C. vestitus
         |  `-- C. pruinosus
         |-- C. melanurus
         |-- C. ichillus
         |--+-- C. spinosus
         |  `--+-- C. nyctimera
         |     `-- C. bicolor
         `--+-- C. prehensilis
            `--+-- C. mexicanus
               `--+-- C. rufescens
                  `-- C. quichua

Reference(s):

  • Voss, R. S., Hubbard, C. & Jansa, S. A., 2013: Phylogenetic Relationships of New World Porcupines (Rodentia, Erethizontidae): Implications for Taxonomy, Morphological Evolution, and Biogeography.
    –American Museum Novitates: Vol. #3769, pp. 1-36 [doi: 10.1206/3769.2]

Reference(s):