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98
Vol.16: no.2
A MOSAIC MELANIC MALE OF PAPILIO GLAUCUS
J. A. Ebner reported a melanic male of Papildo glaucus canadensis Rothschild & Jordan in the March, 1961, issue of this Journal. Another melanic male of this subspecies was caught by E. M. S. on June 27, 1961, on Gorge Creek where it is crossed by Highway 11 north of Nipigon, Ontario. The specimen settled down amidst a score of normal males on a wet spot of the sandy bank of the creek. It was at once recognized as a melanic mutation and easily netted. It is a perfect specimen much resembling in general distribution of the black scales the specimen figured in the issue quoted above.
Papilio glaucus canadensis $, upper surface at left, lower surface at right. The bilateral asymmetry is conspicuous, the left wings being much more heavily blackened than the right wings.
However, the striking difference between the more heavily melanic left wings, on the upper as well as under side, characterize this specimen as a bilateral genetic mosaic. An explanation for the exact mechanism of its formation can not of course be given, without breeding work. The chromosome or part of it carrying a modifier for one of the several (?) genes responsible for melanism could have been lost during this mitosis; or such a modifier gene could have been lost or shifted by an abnormal crossing over. Another possibility could be a differential expression of the melanic gene caused by differences in the physiological (genome) en-viroment on the two sides.
Harry Sicher, School of Dentistry, Loyola University, Chicago 12, 111., U. S. A.