A new species and new synonym in Camelobaetidias demoulin (Ephemeroptera: Baetidae)

Based on the examination of type material, we recognize a new synonym for Camelobaetidius warreni [=C. similis, NEW SYNONYM]. Published records of C. similis have been based either on misidentifications of C. mexicanus or are referable to a previously undescribed species, C. maidu Jacobus and McCafferty, n. sp. Camelobaetidius maidu is described based on male and female larvae from the far western United States and Mexico. It is distinguished from congeners by having a combination of osmobranchiae present on the forecoxae and absent on the midcoxae; claws with relatively few denticles; and a labrum with relatively few setae in the dorsal, submarginal anterior line and relatively many sublateral setae. Diagnoses are provided for the larvae of C maidu, C. mexicanus, and C. warreni.