On the family- and genus-series nomina in Gyrinidae Latreille, 1810 (Coleoptera, Adephaga) Gustafson, Grey T. Miller, Kelly B. Zootaxa 2013 3731 1 77 105 Dejean, 1833 Dejean 1833 [151,486,476,501] Insecta Gyrinidae Trigonocheilus GBIF Animalia Coleoptera 21 98 Arthropoda genus  The nomen  Trigonocheiluswas first published by Dejean (1833) associated with the specific nomen  T. rostratus DeHaan, but there is no such publication by DeHaan and this species nomen is a nomen nudum. Therefore, the original publication of  Trigonocheilusdoes not contain an appropriate indication to a previously described species and does not meet the requirements of Article 12.2.5, and  TrigonocheilusDejean, 1833is a nomen nudum. Agassiz (1846) emended the spelling of  Trigonocheilusto  Trigonochilus. This emendation is unjustified according to Article 33.2.3 of the Code, but as  TrigonocheilusDejeanis a nomen nudumand an unavailable nomen, so is its emendation. Nevertheless, this emendation is a distinct nomen with its own author and date, as are all unjustified emendations. There is a homonym of the unavailable nomen  TrigonochilusAgassiz, 1846, the ruteline scarab genus  TrigonochilusBrenske, 1896. As  TrigonochilusAgassiz, 1846is unavailable this should prevent any need for action to remove the homonomy between these two nomina.