PROC. ENTOMOL. SOC. WASH. 96(3), 1994, pp. 566-578 THE VARIOUS TAXA AND HOSTS OF THE NORTH AMERICAN CELASTRINA (LEPIDOPTERA: LYCAENIDAE) Gordon F. Pratt, David M. Wright, and Harry Pavulaan (GFP) Department of Entomology, University of California, Riverside, California 9252 1 ; (DMW) Department of Pathology and Laboratory Medicine, University of Pennsylvania, 1 00 Medical Campus Dr., Lansdale, Pennsylvania 1 9446; (HP) 494 Fillmore St., Hemdon, Virginia 22070. Abstract.— T\\e genus Celastrina (Lepidoptera: Lycaenidae) includes Holarctic small blue butterflies whose larvae feed on the flowers, fruits, leaves, and galls of a diverse variety of plants. In North America the Celastrina ladon species complex presently con-tains three recognized species (ladon. neglectamajor, and nigra). The versatile Celastrina ladon consists of eight subspecies and several seasonal forms. Many of these forms are biologically distinct allochronic races. The hosts and distributions of the species, subspe-cies, and races of the C ladon complex in North America are presented. In the West, the Celastrina have segregated into seven subspecies, while in the East they have reached greater evolutionary diversity and formed several species and several seasonal races. It appears that host shifts, associated with changes in adult season or habitat preference, may have played a major role in the historical evolution of the species and races of the C ladon complex. Key Words: Host races, Lycaenopsis, distribution, asynchronous, evolution, phytoph-agous, Polyommatini, sympatric speciation Host plant adaptation is believed to have had a major role in the evolution of phy-tophagous insects (Walsh 1 864, Jermy 1 984, Strong et al. 1984). Some insect host races feature differences in rates of adult matu-ration, which result in asynchronous mating periods and genetic isolation (Wood and Guttman 1983, Bush 1969, PhiHips and Barnes 1975, Knerer and Atwood 1973, Smith 1988). Such allochronic examples may be incipient species. Seasonal isolation therefore may play as important a role as host differences in the evolution of species in sympatry (Smith 1988, Wood and Keese 1990, Wood etal. 1990). Celastrina are small blue butterflies whose larvae feed mainly on the flowering parts of a broad variety of plants. Three North American species are currently recognized: Celastrina ladon (Cramer, Celastrina ne-glectamajor Opler & Krizek, and Celastrina nigra (Forbes) (= ebenina Clench) (see Cra-mer 1 780, Forbes 1960, Clench 1972, Opler and Krizek 1 984, Scott and Wright, in press). These taxa are considered bonafide species, since they exhibit discrete morphological and host differences in sympatry. Celastrina nigra larvae likewise feed exclusively on Aruncus dioicus (Wagner and Mellichamp 1978); C. neglectamajor larvae feed exclu-sively on Cimicifuga racemosa (Edwards 1878, 1883b); however C. ladon larvae feed on a wide variety of plants (56 species, 19 families) (Scott 1986). Eight North American subspecies of C ladon are currently recognized: argentata
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