S. ecorne was initially identified by
Ferdinand von Mueller, but it was not specifically named until
Rica Erickson and
Jim Willis reviewed the taxonomy of
Stylidium calcaratum in 1956 and authored
S. calcaratum var. ecorne. Erickson and Willis decided to keep it at the variety level on the basis that it shared a similar morphology to that of
S. calcaratum with the exception of the nectary spur, which was reduced or absent in
S. calcaratum var.
ecorne.
Pauline G. Farrell and
Sydney Herbert James, in their 1979 review, based their decision to elevate the variety to species level on chromosomal and reproductive discontinuities. Farrell and James discovered that
S. ecorne has a
haploid chromosome number of 13, whereas
S. calcaratum has a haploid chromosome number of 11. Farrell and James reasoned that dysploid reduction (also called
aneuploidy) in the genus
Stylidium is frequent and probable in this case, meaning that
S. calcaratum is virtually certain to be derived from
S. ecorne. This reduction is also evident from the floral spur, reduced number of ovules, and increased tolerance of other habitats, which the authors cited as derived conditions in
S. calcaratum. Crosses between
S. ecorne and
S. calcaratum yielded very few seeds, indicating that the taxa are well isolated from each other. == Distribution ==