Třída: Chondrichthyes - paryby
Řád: Carcharhiniformes - žralouni
Čeleď: Triakidae - hladkounovití

Typový druh: Triakis scyllium Müller & Henle, 1839

Reference: Müller J. & Henle F. G. J. 1838. On the generic characters of cartilaginous fishes, with descriptions of new genera. Mag. Nat. Hist. [Charlesworth, ed.] (N. S.) v. 2. 33-37; 88-91.

Přehled druhů

• Triakis acutipinna Kato, 1968
  Hladkoun ostroploutvý
  Kato, S. 1968. Triakis acutipinna (Galeoidea, Triakidae), a new species of shark from Ecuador. Copeia 1968 (no. 2): 319-325.
• Triakis maculata Kner & Steindachner, 1867
  Hladkoun skvrnitý
  Kner, R. & F. Steindachner 1867. Neue Fische aus dem Museum der Herren J. Ces. Godeffroy & Sohn in Hamburg. Sitzungsber. Akad. Wiss. Wien v. 54 (pt 3): 356-395, Pls. 1-5.
• Triakis megalopterus (Smith, 1839)
  Hladkoun velkoploutvý
  Smith, A. 1838-47. Pisces. In: Illustrations of the zoology of South Africa; consisting chiefly of figures and descriptions of the objects of natural history collected during an expedition into the interior of South Africa in 1834-36. Illust. Zool. S. Africa v. 4: 77 unnumb. pp, accompanying Pls. 1-31.
• Triakis scyllium Müller & Henle, 1839
  Hladkoun žralokovitý
  Müller, J. & F. G. J. Henle. 1838-41. Systematische Beschreibung der Plagiostomen. Berlin. Plagiostomen: i-xxii + 1-200, 60 pls.
• Triakis semifasciata Girard, 1855
  Hladkoun leopardí
  Girard, C. F. 1855. Characteristics of some cartilaginous fishes of the Pacific coast of North America. Proc. Acad. Nat. Sci. Phila. v. 7 (no. 6): 196-197.

Statistické údaje

Počet druhů: 5