Triodopsis juxtidens robinae subsp. nov.

Diagnosis. Shell distinguished by a relatively wide peristome, markedly constricted behind; an aperture periphery that is more triangular rather than round or oval, tallest just to the right of its attachment to the body whorl, with the palatal edge not high and round, widest below an imaginary horizontal midline (viewed with spire up, in the plane of the aperture), wider than tall; a strong parietal lamella that is curved toward the palatal denticle, not pointing above or below (for the three distinct shell accretions on the peristome, here “lamella” refers to that on the parietal wall, while “denticle” refers to those on the palatal and basal walls); a palatal denticle that is often (but not always) wide at the distal end, with the apex of the denticle pointing inward of the parietal lamella; and a basal buttress with a denticle that is deeper than wide, transverse upon the buttress. No other described taxon has a triangular aperture along with a parietal lamella pointing at the palatal denticle and a basal denticle upon a buttress.