The Genus Megalobulimus (Gastropoda: Strophocheilidae) from Peruvian Andes: Re-Description of Megalobulimus leucostoma and Description of Two New Species

A major taxonomic problem around the genus Megalobulimus Miller,1878, the largest land snails in the Neotropics, is plasticity of conchological characters. Here we re-describe Megalobulimus leucostoma (Sowerby, 1835) and describe two new species of Megalobulimus from Southern Peru, Megalobulimus tayacajus sp.nov. and Megalobulimus inambarisense sp.nov. These descriptions are based on both conchological and soft anatomical characters. Megalobulimus leucostoma is characterized by the presence of a retractor muscle with two insertions to the buccal mass, two small bulges on pre-rectal valve, and a geographical distribution appears limited to Cusco. Megalobulimus tayacajus sp.nov. is characterized by the presence of a retractor muscle that divides near the buccal mass, two lobed bulges on pre-rectal valve, and to date, has been found only in Huancavelica. Megalobulimus inambarisense sp.nov. is characterized by the presence of a retractor muscle with one insertion to the buccal mass, two big bulges on pre-rectal valve, and a distribution appears limited to Puno. The digestive system appears to serve as useful characters to discriminate these species and, when combined with shell and reproductive characters, may help to understand better the evolution and ecology of these snails.