Comprehensive description of new and known stages of Americabaetis titthion Lugo-Ortiz & McCafferty (Ephemeroptera: Baetidae)

The male imago of Americabaetis titthion is described for the first time. It can be distinguished from other male imagos of the genus by the following combination of characteristics: turbinate portion of the eyes with upper surface ellipsoidal and separated by approximately the width of a lateral ocellus; costal area of fore wings tinged with reddish-brown; presence of pairs of soft, setose protuberances on the meso- and metasternum; subgenital plate slightly concave; forceps with segment I/II slightly tapering medioapically. Supplementary descriptions for the nymph and female imago are provided, as well as the first description of the eggs of a species of the genus.