Does it matter that Lesson also named C. manurus in the sub-genus?
Lesson included only one
taxonomic species (his species #429) in the sub-genus, for which he cited three names, "
Caprimulgus enicurus, Vieill.", "
Ibijau cola extrana,
azara" (vernacular, hence not eligible to be the type) and "
Caprimulgus manurus, Vieill.". When only one taxonomic species is included in a new genus, if no type is explicitly designated, the nominal species denoted by the name that is adopted as the
valid name of the single species is automatically the type. (This is called a type fixation by original monotypy.) In other words, the synonyms don't count.
If you interpret the first name cited for each species in Lesson's list as the one that he adopted as valid, the type of
Tetroura is
enicurus by original monotypy. A potential problem, though, is that Lesson simply listed several names separated by semicolons, without giving an evidently distinct treatment or status to the first one in the list. Thus it might probably be argued that all the listed names are in fact given equal status, with none being clearly 'the' valid name. In this case,
manurus might be seen as a candidate type as well, the type might be seen as not fixed in the OD and a subsequent designation might be required.
Ultimately, however, in the present case, it doesn't matter, because Gray 1849 designated
enicurus as well: both interpretations give the same type species.
Ridgway & Friedmann in 1914 "Type, Caprimulgus enicurus Vieillot=unidentified species"!!
The bird described by Azara, which Vieillot named
e[p/n]icurus, had a peculiar tail shape, with the four central feathers of the same length, and shorter than the immediately following feathers, which were the longest ones. On this base the bird has been tentatively treated as an unidentified/unkown member of the genus
Hydropsalis.
Smith 2017 makes it a Little Nightjar in moult, with growing central tail feathers.
(Of course Ridgway & Friedmann's citation of the name (as a possible invalid synonym of
Hydropsalis) does not amount to using it as valid.)
