Visible genetic markers for the color of external body structures and eyes in the scarab Canthon cyanellus cyanellus (Coleoptera: Scarabaeidae)

Abstract

Two new body color mutations are described in both a wild-type, usually green (GG), and a red strain (gg) of Canthon cyanellus cyanellus LeConte, a scarab from the tropical forest in Los Tuxtlas, Veracruz, Mexico. One mutation changed the testaceous (TT) color of mouthparts, antennae, palpi, and tarsi in the red and wild-type strains to a piceous (tt) color, retaining the red and green body color, respectively. Specimens with this mutation were reared in laboratory to determine whether the genetic behavior of the character was controlled by a single autosomal recessive allele. Specimens of the new strain, recessive homozygous (gg/tt), were crossed with wild-type beetles. The phenotype of F2 offspring from these crosses segregated in a ratio of 9:3:3:1 according to a dihybrid cross. Specimens of the GG/TT genotype were intercrossed, and in F1 a second mutation changed the brown (BB) eye color to nonmelanin (bb), retaining the green body color. Crosses were made between beetles with this character (GG/bb) and the wild-type (GG/BB). The nonmelanin eye mutation also was controlled by a single autosomal recessive allele. The new mutations tt and bb showed uniform expression in both sexes. The red beetles with the piceous character were not as reproductively successful as wild-type beetles, whereas the other strains showed reproductive success similar to that of the wild type. © 2004 Entomological Society of America.