Tringa Linnaeus 1758 originally included 13 spp :
Tringa pugnax,
T. vanellus,
T. gambetta,
T. interpres,
T. 'tobata' = lobata,
T. fulicaria,
T. alpina,
T. 'ocrophus' = ochropus (with 'Tringa' cited from Aldrovandus, Willughby and Ray, in its synonymy),
T. hypoleucos,
T. canutus,
T. glareola,
T. littorea,
T. squatarola. As you can probably see, these formed a ragtag assemblage of taxa, which are placed today in as much as 6 distinct genera (
Calidris,
Arenaria,
Vanellus,
Phalaropus,
Tringa and
Pluvialis).
Under current rules, the fact that a uninominal species name 'Tringa' was cited in the OD from pre-1758 works in the synonymy of
Tringa 'ocrophus' is seen as automatically making the latter the type species "by Linnean tautonymy", which is why we use the name for shanks. This method of type fixation, however, is a relatively recent invention (early 20th C), which was not used by earlier authors.
Early authors have restricted the scope of the name in various ways -- e.g.,
Cuvier 1798 and
1816, and
Illiger 1811 restricted it to lapwings and what they perceived to be their relatives;
Temminck 1815,
Vieillot 1816 and
1819,
Nilsson 1821, etc., restricted it to sandpipers/stints and their relatives.
Gray, in 1840, designated
Tringa canutus Linnaeus 1758 as the type; the type was also determined to be
Tringa canutus Linnaeus 1758 "by elimination" by the (primarily American) authors who applied this now entirely disused method of type fixation, e.g.
AOU 1886, see also
Allen 1907; this species was still accepted as the type by such authorities as the
AOU in 1910 and the
BOU in 1915.
These successive changes in the applications of the name, however, merely represented subsequent uses of Linnaeus' name (i.e.,
Tringa Linnaeus 1758
sensu various workers); they cannot be construed as successive introductions of different names, that could be attributed to different authors and treated as separately available.
...Thus my answer to your original question would be: one.
