The proposed synonymy of Parakontikia ventrolineata (Dendy, 1892) and Kontikia mexicana (Hyman, 1939) - what is a penis papilla?

Geoplanid land planarians found near Johannesburg, South Africa, and in a hothouse in Liverpool, UK, could be identified either as Parakontikia ventrolineata (Dendy, 1892) or as Kontikia mexicana (Hyman, 1939). Comparison of the specimens with P. ventrolineata type specimens and other material and with published descriptions of K. mexicana shows no significant consistent difference between the species, other than the apparent presence of a penis papilla in K. mexicana. It is suggested that, in this case, the penis papilla is not a well-defined structure and that its presence in some specimens may be the result of differential contraction or eversion of the penial musculature at fixation. Accordingly it is proposed that the two species names are synonymous, and thus Parakontikia Winsor, 1991 is to be considered a junior synonym of Kontikia Froehlich, 1955. This is only the second geoplanid species to be recorded from Africa. It has also been found in Australia, New Zealand and the U.S.A.