Spatial and Temporal Segregation Among Six Species of Coexisting Ophiogomphus (Odonata: Gomphidae) in the Aroostook River, Maine

Abstract Spatial and temporal segregation of six coexisting species of Ophiogomphus (O. anomalus, O. aspersus, O carolus, O. howei, O. mainensis, and O. rupinsulensis) were studied in a 137.7 km reach of the Aroostook River in northern Maine. Collections of exuviae showed that O. mainensis was most abundant and dominated the assemblage at sites in the upper reaches of the study area and was in low numbers and percent of total Ophiogomphus at sites in the lower reaches of the study area. Ophiogomphus rupinsulensis was most abundant and dominated the assemblage at sites in the lower reaches of the study area but was absent or in low numbers and percent of total Ophiogomphus at sites in the upper reaches. Ophiogomphus anomalus and O. carolus were present at all sites and O. anomalus was generally more abundant and made up a higher percent of the total Ophiogomphus spp. than O. carolus. Ophiogomphus howei and O. aspersus were present at only a few sites in low abundance and percent of the total Ophiogomphus. ...