Teratological Nymphal Ixodes scapularis (Acari: Ixodidae) From Wisconsin

Abnormalities of physiological development (teratological forms) in ticks are rare. The occurrence of gigantism, dwarfism, gynandromorphs, missing legs, extra legs, and asymmetries is most often reported from lab-reared specimens, but has been observed in field-collected specimens. All morphologically anomalous ticks (besides gynandromorphy) described to date are from species other than Ixodes scapularis Say (Acari: Ixodidae). Here we describe four teratological I. scapularis nymphs collected while dragging vegetation in Wisconsin in 2015, including two asymmetrical ticks, one with a missing leg, and one with an extra leg.