Heydenius

Heydenius is a collective group genus of fossil mermithid nematodes from the Tertiary period that cannot be placed in extant genera.

Species

 * †H. antiquus (von Heyden, 1860) Taylor, 1935
 * †H. arachnius Poinar, 2012
 * †H. araneus Poinar, 2000
 * †H. brownii Poinar, 2001
 * †H. cecidomyae Poinar, 2011
 * †H. dipterophilus Poinar, 2011
 * †H. dominicus Poinar, 1984
 * †H. formicinus Poinar, 2002
 * †H. lamprophilus Poinar, 2011
 * †H. matutinus (Menge, 1866) Taylor, 1935
 * †H. myrmecophila Poinar, Lachaud, Castillo & Infante, 2006
 * †H. neotropicus Poinar, 2011
 * †H. phasmatophilus Poinar, 2012
 * †H. podenasae Poinar, 2012
 * †H. psychodae Poinar, 2011
 * †H. quadristriatus (Menge, 1872) Taylor, 1935
 * †H. saprophilus Poinar, 2011
 * †H. scatophilus Poinar, 2011
 * †H. sciarophilus Poinar, 2011
 * †H. simulphilus Poinar & Currie, 2019
 * †H. tabanae Poinar, 2011
 * †H. trichorosus Poinar, 2012