(previously Thiodina sylvana)
Three species of Colonus occur in North America (see C. puerperus). Both C. sylvanus and T. puerperus occur in the eastern part of N.A. Distinguishing between the adult males of the three species is relatively easy. The central white mark on the cephalic (head) plate is diagnostic. This shape is elongate in C. puerperus and more roundish in the present species. Males of these two species also show white lines along the length of the abdomen roughly parallel to the mid-line; these lines are absent in C. hesperus. Females and immatures are less reliably identified using non-genetalic characteristics. As its name implies C. sylvanus is associated with woodlands; C. puerperus is a grassland species.
Bustamante, Maddison, and Ruiz, 2015