I found a few online sources for Ralf’s suggestion that may facilitate discussion:
Original description of Nebela gracilis by Penard can be found here http://www.biodiversitylibrary.org/page/10712428#page/1001/mode/1up
This link will take straight to figure 6 and 7 in plate 8 at the end of book, for description navigate back to page 934.
The variety described by Wailes is on page 157 here http://www.biodiversitylibrary.org/page/32143949#page/209/mode/1up
I paste the text here:
N. gracilis, Penard. (Rev. Suisse Zool. 1910.)
Var. STOMATA, var. nov. (PL 12. figs. 41 & 42.)
This variety differs from the type in the possession of two evaginated
pores, one on either side of the neck. Similar protuberances occur on other
Nebelae, i. e. N. tuberosa and N. americana. Individuals also occur here of a
more slender form than shown in figs. 41 & 42, with a long, slender neck ;
they are below the average size, measuring about 90 um in length.
Length 90-130 um; breadth about half the length or less ; thickness two-
thirds of the breadth ; aperture oval, about 20 um by 13um, slightly notched in narrow view.
Distribution. Peru (l. 107-130 um) ; Long Island, U.S.A. (l. 100-116 um).
If you scroll down a few pages you’ll get to the figures.
Hope this helps.
