Polytopic-variation
Guides
Crossidius
Crossidius is a genus of longhorned beetles (Cerambycidae) endemic to western North America, containing 11 described species and numerous subspecies. The genus exhibits exceptional polytopic variation, with geographically isolated populations showing marked differences in coloration, size, and elytral pattern. Unlike most cerambycids, which develop in dead wood, Crossidius species are root borers in living perennial shrubs of the Asteraceae family. Adults are diurnal and strongly associated with host plant flowers, where they feed, mate, and shelter.
Crossidius coralinus ruficollis
Crossidius coralinus ruficollis is a subspecies of longhorned beetle (Cerambycidae) endemic to the southern San Joaquin Valley of California. It is one of several geographically isolated subspecies of C. coralinus characterized by red and black coloration. Adults are active in late summer and early fall, feeding on flowers of Isocoma acradenia var. bracteosa (burrobrush). Historically isolated from the nominate subspecies by the now-dry Tulare Lake, this population exhibits distinct coloration with individuals ranging from tan to dark red depending on locality.
Crossidius pulchellus
Beautiful Longhorned Beetle
Crossidius pulchellus is a longhorned beetle (family Cerambycidae) first described by John Lawrence LeConte in 1861. Unlike most cerambycids that develop in dead wood, this species has evolved a root-boring lifestyle in living perennial shrubs of the family Asteraceae. Adults are strongly associated with flowers of their host plants, where they feed, mate, and shelter. The species exhibits the dense vestiture (hair covering) characteristic of the genus and shows geographic variation across its range in the Great Plains and southern Rocky Mountains.
Crossidius testaceus
Crossidius testaceus is a long-horned beetle in the family Cerambycidae. The species occurs in western North America and Central America. Like other members of its genus, it develops as larvae in living roots of perennial shrubs in the Asteraceae family. Two subspecies are recognized: C. t. testaceus and C. t. maculicollis.