One of these subfamilies is called Ieraglaucinae.
I checked James Jobling's Dictionary, and Ieraglaux is listed as a synonym for Ninox, so I guess the subfamily name comes from here. However, according to the checklist there are currently no species belonging to the genus Ieraglaux (all members of the subfamily are placed in the genus Ninox or Uroglaux). Shouldn't there be at least one species matching the subfamily name?
It used to be the case, but not any more. (And it was not really 'formal', as the creation of formal rules governing family-group names is a quite recent evolution.) The general rule now is that the oldest family-group name formed from a genus-group name included in the family must be used.
(With a significant number of exceptions, though.
If the name of the type genus was suppressed partially or completely by the Commission, the family-group name cannot be used.
If the name of the type genus is a junior homonym, the family-group name cannot be used.
If a family-group name which is not the oldest is in prevailing use for a taxon that includes a subtaxon for which the oldest name is in prevailing use (e.g., Phasianidae Horsfield 1821, in prevailing use for a family that includes a subfamily Tetraoninae Leach 1819), the younger name must be maintained for the broader taxon.
If the oldest family-group name was replaced before 1961 by a younger name as a result of the type genus of the oldest name having been synonymized with the type genus of the new name (= the old rule), and if this younger name is in prevailing use, this younger name must be maintained (and is deemed to take precedence from the date of publication of the older name).
If a family-group name which is not the oldest is in wide use, and the oldest name has not been used at all after 1899, the name is wide use must be maintained.)
(Beware, however, that a
new family-group name cannot be proposed in a work where the genus-group name it is formed from is not treated as the valid name of a full genus.)
"Ieraglaucinae" is formed from "
Ieraglaux", which is a subsequent spelling of
Hieracoglaux Kaup 1848 (Kaup JJ. 1848. Uebersicht der Eulen (Strigidae). Isis (Oken), Jahrgang 1848: 753-774.; p. 768;
https://www.biodiversitylibrary.org/page/13256491 ; originally included nominal species:
Ninox connivens,
N. strenuus; type:
Falco connivens Latham 1801 by subsequent designation in: Gray GR. 1855. Catalogue of the genera and subgenera of birds contained in the British Museum. British Museum, London.; p. 8;
https://www.biodiversitylibrary.org/page/17136628 ; OD of type: Latham J. 1801. Supplementum indicis ornithologici, sive systematis ornithologiae. G Leigh, J & S Sotheby, London.; p. xii;
https://www.biodiversitylibrary.org/page/33261386 ). The variant spelling was introduced by Kaup himself in 1849, in:
https://www.biodiversitylibrary.org/page/13705874 ; the change may have been intentional, but Kaup did not make this clear, hence under the current Code it must be treated as an error.
This family-group name is attributable to Bonaparte 1854 (who spelled it "Ieroglauceae": Bonaparte CL. 1854. Conspectus systematis ornithologiae. Ann. Sci. Nat. (Zool.), sér.4, 1: 105-152.; p. 112;
https://www.biodiversitylibrary.org/page/35982397 ).
Family-group names formed from a subsequent spelling must be corrected to match the stem of the original spelling of the name of their type genus (unless the change of spelling was mandatory under the Code, or is conserved for some other reason): "Ieraglaucinae" as such is unacceptable, as is Bonaparte's "Ieroglauceae" (from "
Ieroglaux", another subsequent spelling of
Hieracoglaux); if used for a subfamily, the name must be corrected to Hieracoglaucinae.