Google search seems to think that Eulacestomatidae was used in October 1999 Schodde & Mason
DIRECTORY OF AUSTRALIAN BIRDS: PASSERINES. But I have not proved that. Also not necessary under the Code? I looked at the French version of the Code and did not find "again" "encore" type language in that version of that code section.
Any use of the name in a pre-2000 publication other than Stein 1936 would automatically make it available from the latter. But I don't think Schodde & Mason 1999 used it. (They had
Eulacestoma in Pachycephalidae and did not define subfamilies in this family, so far as I can assess from
Google Books.)
As I wrote above, Art. 13.2.1 is usually understood as if it included "again" -- even though it doesn't. (Without the "again", the requirement could only affect family-group names published without a description after 1930 and before 1961, not used as valid when first published, not subsequently used as valid before 2000, but treated as senior homonyms before 1961. This is at best an extremely rare situation (I know no actual examples), and one might be entitled to wonder why the Code would bother providing a special rule for it. In all the other cases, a name that fails to meet the requirement of Art. 13.2.1 as a result of not having been used
at all before 2000 (not even in the OD) is unavailable due to a failure to meet the provisions of Art. 11.5 or 11.6 in the first place, anyway : Art. 13.2.1 changes nothing to its status.)
Are both versions of the family name formed according to the Code Article 29?
Eulacestoma ends in the Greek word στομα (= mouth), genitive στοματος, stem στοματ-. Thus the stem of the genus-group name under Art. 29.3 (i.e., 29.3.1) is
Eulacestomat-.
The use of
Eulacestom- as the stem (i.e., Eulacestomidae as the name of the family) would be justified either if this stem had been originally used in a name proposed after 1999 (29.4; but Schodde & Christidis 2014 used Eulacestomatidae, so this could not possibly apply), or if this stem was in prevailing use (29.5).
Laurent said Stein merely used the name, without describing the taxon. He described the bird he saw as lanius-like. (Lanius-artig) Since there is only one species in the family this description of the subspecies is also a description of the family.
"Lanius-artig", as such, does not fulfill the requirement of Art. 13.1 "a description or definition that states in words characters
that are purported to differentiate the taxon". You cannot make a name available by describing the taxon as being merely "like" another taxon.