|Basic info||Taxonomic history||Classification||Relationships|
|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|J. M. Malinky 2009||Species of Orthotheca having narrow longitudinal ribs with steeply dipping sides separated by spaces that are flat at the bottom; concave transverse lines divide the ribs into segments; the lines vary in spacing and intensity from place to place on the dorsum, such that some areas appear to be smooth on certain individuals.
Dorsum inflated and having a central tightly rounded ridge; flanks are straight and lateral edges sharp. Apertural rim on dorsum nearly planar although a slight concavity may be seen along the ventral edge. Conch seemingly orthoconic and with up to seven septae in apical region; septae are transverse and each appears widest in middle region, thinning toward wall of conch. Cross section has weakly developed kidney-shaped outline.
Dorsum with prominent narrow, longitudinal ribs whose sides dip steeply and appear nearly straight; width of spaces between ribs varies from width of one to six ribs, and intervening spaces are flat at bottom; ribs best developed near aperture, gradually becoming finer near apex. Venter smooth in some areas but with faint transverse, concave lines that possess a shallow flexure toward apex in other areas.
Operculum with broad, low folds and broad shallow sulcus; width of sulcus at the margin of the aperture equal to about 40% width of operculum; operculum has radiating lines most clearly developed along the margins; lines are of both irregular intensity and spacing as well; superimposed on these are faint concentric lines also of seemingly irregular intensity and spacing.