Geoplana

The genus Geoplana was erected in 1857 by William Stimpson and included most land planarians with several eyes distributed along the body.[1] Species with only two eyes were placed in the genus Rhynchodemus, while species with a crescent-shaped head were placed in Bipalium.

In the same year, apparently unaware of Stimpson's paper, the naturalist Max Schultze, based on published information and new species collected in Brazil by the naturalist Fritz Müller, also erected a genus named Geoplana, but included all land planarians in it.[2] However, Stimpson's system prevailed.

During most of the 20th century, many new land planarian species, mostly from Australia and South America, were placed in Geoplana. In 1955, Eudóxia Maria Froehlich defined that Geoplana vaginuloides would be the type-species of Geoplana, as it was the first species listed by Stimpson.[3]

In 1990, Robert E. Ogren and Masaharu Kawakatsu published a review of the classification of land planarians and divided Geoplana in four genera: Geoplana, Gigantea, Notogynaphallia and Pasipha. Geoplana retained all species with dorsal testes, a protrusible penis and a female canal entering the genital antrum dorsally. Species with ventral testes, without a protrusible penis or with a female canal entering the genital antrum ventrally were placed in other genera.[4]

During the 21st century, molecular studies revealed that Geoplana sensu Ogren & Kawakatsu was still heterogeneous. A study published in 2013 by Carbayo et al.,[5] based on molecular data, divided Geoplana in 6 genera: Geoplana, Barreirana, Cratera, Matuxia, Obama, and Paraba. Only three species remained as Geoplana,[6] along with several incertae sedis.

Currently, the genus Geoplana is characterized by having the features described by Ogren & Kawatasu (dorsal testes, a protrusible penis and a female canal entering the genital antrum dorsally) plus several others, such as a slender body with nearly parallel margins, a strongly convex dorsum, monolobulated eyes (i.e., simple and circular, with only one lobe), and a strong muscle tube around the intestine.[5][6]

There are currently only thirteen species certainly belonging to Geoplana:

Also, there are several species currently considered incertae sedis: