Colpocephalum bicolor Piaget, 1880: 561, pl. 47, fig. 1.
Baja California: Arenaria melanocephala, San Martin Island, 1897, R.C. McGregor (Kellogg & Mann 1912); Calidris virgata, San Gerónimo Island, Island1897, R.C. McGregor (Kellogg & Mann 1912). Note: Kellogg & Mann (1912) described the above samples of A. bicolor as “ Colpocephalum tigrum n. sp. ”. The record from the Surfbird (Calidris virgata) is most likely the result of a contamination because A. bicolor is a regular and natural parasite of only two species of Arenaria (see Price et al. 2003).