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1969 Journal of the Lepidopterists Society 189
AN EXTREME PHENOTYPE OF PIERIS PROTODICE (PIERIDAE)
Arthur M. Shapiro
Department of Entomology & Limnology, Cornell University, Ithaca, N. Y.
Vernal phenotypes in Pieridae are described by Klots (1951) as "paler, with reduced dark borders or spots" relative to the summer phenotypes. This characterization applies only to the upper surface of the wings; beneath, the hindwing is generally more or less melanized in the vernal phenotype. This redistribution of black pigment may fulfill a thermoregulatory function (Clench, 1966).
The "cold weather" phenotype of Fieris protodice Boisduval & LeConte (f. vern. vemails Edwards) occurs in late autumn and early spring throughout the range of the species (Rawson, 1945; Bean, 1877). Lutz (1948) characterized it as possessing "so much greenish gray on the hind wings that the white is reduced to narrow triangular spots; spots on the upper side are much reduced, or even absent." Shapiro (1968) has demonstrated
Fig. 1. Fieris protodice f. vern. vernalis, females. Upper surface at left, lower at right. Above: normal, Camden, N. J., March 29, 1968. Below: extreme, Tinicum Wildlife Preserve, Phila. Co., Pa., March 30, 1968.
190
Shapiro: Rare common white
Vol. 23, no. 3
that the vernalis phenotype may be induced by exposure of the larvae to long nights, regardless of temperature. Specimens obtained by photoperiodic manipulation in the laboratory are similar to wild Philadelphia, Pennsylvania butterflies exposed to equivalent photoperiods in late larval life.
An extreme specimen of vernalis taken at the Tinicum Wildlife Preserve, Philadelphia County, Pennsylvania, March 30, 1968, is illustrated in figure 1, along with a normal vernalis. The Tinicum specimen, a female, is darker on the lower surface than the darkest female grade figured by Abbott, Dillon, and Shrode (1960). The dark vein-lines are even broader and more confluent than is usual in the spring phenotype (calyce Edwards) of the western, montane sibling species, Pieris occidentalis Reakirt. The specimen differs from calyce also in the intensity of the melanization, which obscures the underlying yellow pigment almost completely and presents a black, rather than a brownish green effect.
No photoperiod or photoperiod-temperature combination yet tested will induce such extreme melanization in the lower surface. In the Cornell culture of P. protodice, which has been maintained through seventeen generations for genetic studies, heritable variations in expression of the vernalis phenotype under standardized conditions have been observed. However, a brood of 39 reared from the Tinicum female (already mated to an unknown male) in an inducing photoperiod of fourteen hours darkness produced only normal vernalis.
Acknowledgments
The photographs were taken by Mr. James D. Biggs, of Department of Entomology & Limnology, Cornell University. Mr. Edward L. Ritter-shausen assisted in the laboratory rearing.
Literature Cited
Abbott, W., L. S. Dillon and R. R. Shbode, 1960. Geographic variation in Pieris protodice Boisduval and LeConte. Wasmann J. Biol., 18: 103-127.
Bean, T. E., 1877. Pieris vernalis a variety of Pieris protodice. Canad. Ent., 9: 201-203.
Clench, H. K., 1966. Behavioral thermoregulation in butterflies. Ecology, 47: 1021-1034.
Klots, A. B., 1951. Field Guide to the Butterflies. Houghton-Mifflin, Boston; 349 pp.
Luttc, F. E., 1948. Field Book of Insects. G. P. Putnam's Sons, New York; 510 pp.
Rawson, G. F., 1945. Interesting problems connected with the checkered white butterfly, Pieris protodice Bdv. & Lee. Bull. Brooklyn Ent. Soc, 40: 49^-54.
Shapibo, A. M., 1968. Photoperiodic induction of vernal phenotype in Pieris protodice Boisduval & LeConte (Lepidoptera: Pieridae). Wasmann J. Biol., 26(1): 137-149.