Cratera boja is a species of land planarian belonging to the subfamily Geoplaninae.[1] It is known from specimens found in Serra da Bocaina National Park in Brazil.
Cratera boja is a flatworm around 34 mm in length and 4–4.5 mm in width. The body is elongate, with parallel margins, a rounded front tip, and a pointed back tip. The dorsal side of the body is an olive gray base color, spotted with black patches. The patches concentrate in a median band that may be divided by a thin midline. The ventral side of the body is olive gray, turning gray at the front end.[2]
Aside from its coloration and length, it is distinguished from other members of Cratera by having marginal eyes, a bell-shaped pharynx, the distal portion of the ejaculatory duct being widened to occupy around half of the penis papilla, a narrowing that separates the male and female atria, a postero-dorsally oriented penis papilla that is shorter than the male atrium, a prostatic vesicle with an inverted-U shape in a lateral view, several cyanophil cell necks that pierce the male atrium roof, a female atrium that is half the length of the male, and the lack of a common glandular ovovitelline duct.
The specific epithet is derived from the Tupi language word, "intermediate, middle", in reference to the intermediate size of the ejaculatory duct's distal dilation.