Ramellogammarus similimanus is a crustacean species in the family Anisogammaridae. Because this amphipod only resides in the Portland metropolitan area, in Oregon, United States, it has been given the common name "Stumptown scud."[1]
R. similimanus is about the size of a pinky nail.[1] It has a curled outer shell of a golden color[1] and long antennae.[1] Its appearance has been described as a "cross between a prawn and a potato bug."[2] Similar to marsupials, females have a pouch in which they carry their eggs.[2]
The species is believed to only exist within the boundaries of the Portland metropolitan area.[1] It lives in small freshwater creeks and tributaries.[1] "Stumptown" is a nickname applied to Portland and several other locations in the United States.[3][4][5]
R. similimanus is difficult to observe as it prefers to remain hidden under the organic material on which it feeds.[1][6] It can only move via connected waterways, limiting its geographic scope.[1] Scavenged dead and decaying material makes up its diet.[1] It is consumed by amphibians and fish.[1]
Mating involves a complex ritual.[2] Males search for maturing females who are nearly ready to molt out of their shells.[2] The males then ride the backs of the females to secure them and prevent other males from stealing their chosen mate.[2]
The species was first described by Edward L. Bousfield in 1961.[7] The Oregon Zoo funded research conducted by Oregon State University through the "Oregon Zoo Foundation's Future for Wildlife program".[8] The researchers have used the environmental DNA methodology in order to minimize impact on a small and vulnerable population.[1]
Ramellogammarus similimanus is a crustacean species in the family Anisogammaridae. Because this amphipod only resides in the Portland metropolitan area, in Oregon, United States, it has been given the common name "Stumptown scud."