Taxon classification Animalia Stylommatophora Orthalicidae

Subgenus Sultana (Metorthalicus) Pilsbry, 1899

Orthalicus (Metorthalicus) Pilsbry 1899: 187.

Sultana (Trachyorthalicus) Strebel 1909: 151 (syn. n.).

Type species.

Bulimus yatesi Pfeiffer, 1855, by original designation.

Diagnosis.

Shell conic-ovate, solid, yellowish coloured with a pattern of brown, sinuous streaks, protoconch sculptured with axial riblets, becoming more zigzag on the last part, suture sharply ascending in front, aperture ovate, peristome thickened, columellar margin with a (indistinct) fold entering the aperture.

Distribution.

Colombia, Ecuador, Peru.

Habitat.

Not known.

Remarks.

The main distinction between Sultana (Metorthalicus) and Sultana (Trachyorthalicus) -type species Bulimus fraseri Pfeiffer, 1858, by original designation (Strebel 1909: 103)-is a slight difference in the protoconch scultpture, which in the latter subgenus consists of “schräge sich kreuzenden Reihen von Grübchen” (Strebel 1909: 151). The two subgenera are here synonymized after examination of the protoconch sculpture in the type specimens of the two type species; this sculpture proved to be nearly identical.

Most species in this group are represented in museum collections by a low number of specimens, which hampers an in-depth study of their variation. Also the lack of anatomical and phylogenetical data is currently a bottle-neck to fully understand their systematic position.