Species Crossing in Oncomelania 1

Abstract

Summary The four species of Oncomelania, namely, O. quadrasi, O. formosana, O. nosophora, and O. hupensis of the orient were successfully interbred in all 12 possible species-crossing combinations, including the male and female reciprocal matings. Fertile hybrids resulted from all the crossings. In addition, a male hybrid resulting from an O. formosana + O. hupensis cross was crossed to a female O. nosophora. The hybrids from the species crossings had characteristics which were intermediate to those of the parents as well as representing those of the parents. Although no dominant or recessive characters were evident, the bright yellow, coarse, compact “eyebrows” of O. quadrasi + O. formosana appeared more frequently than the light yellow, fine “eyebrow” pigment of the other species. The prominent shell ridges of O. hupensis appeared infrequently in the hybrids. The most successful crossing was obtained in the O. hupensis + O. formosana matings.