About Prophysaon andersonii (J.G.Cooper, 1872)
Description: Adults of this slug species reach around 50 mm in length when active, and can grow longer than 60 mm. Body color can be grayish brown, reddish brown, or yellowish. The dorsum has furrows forming a reticulated mesh-like pattern of diamond shapes. The mantle has two dark lateral bands. The slug's mucus is yellow or orange. One of the most common body colorations is plain gray, which is found mostly in populations off the coast. This species has no dark bands on its foot, only reticulation. Inland populations toward California are more brown in color. This species can also be identified by its male genitalia: the genitalia are always smaller than the muscular epiphallus. This characteristic is generally not used for identification, because the species already has a very distinctive reticulated pattern.
Distribution: This slug species is found on the West Coast of North America, occurring in California, Oregon, Idaho, and part of Montana.
