The mouse catshark (Galeus murinus) is a species of catshark and part of the family Scyliorhinidae. It is common in the northeastern Atlantic Ocean from Iceland to Western Sahara. There is much taxonomic confusion regarding this species in Icelandic waters, where it may be confounded with another species of Galeus or Apristurus. Probably not exceeding long, the mouse catshark has a uniformly brown body and is characterized by large, rounded pelvic fins and crests of enlarged dermal denticles along both the dorsal and ventral caudal fin margins. In addition, in adult males the inner margins of the pelvic fins are merged into an "apron". Demersal in nature, the mouse catshark inhabits continental slopes at a depth of . It preys mainly on benthic crustaceans, bony fishes, and cephalopods. Reproduction is oviparous, with females producing "furry" egg capsules. Although it is caught incidentally by commercial trawl fisheries, this species does not appear to be threatened by fishing activities and has been listed under Least Concern by the International Union for Conservation of Nature (IUCN). Taxonomy and phylogeny Norwegian zoologist Robert Collett originally described the mouse catshark as Pristiurus murinus, in a 1904 issue of the scientific journal Forhandlinger i Videnskabs-selskabet i Christiania; its specific epithet means "relating to a mouse" in Latin. The type specimen is an immature female long, collected northwest of the Hebrides at a depth of . Later authors have recognized Pristiurus as a junior synonym of Galeus. Some taxonomic confusion has arisen over Pristiurus jensenii, described from Iceland by Bjarni Sæmundsson in 1922, which has traditionally been considered the same species as G. murinus. Recently reported data for G. murinus have shown inconsistencies between sharks from Iceland and elsewhere, suggesting that P. jensenii may in fact be a valid species very similar to G. murinus. However, an alternate possibility is that some of the data may have been confounded with a species of Apristurus. The placement of G. murinus within Galeus is problematic as it does not much resemble the more typical members of the genus. On the other hand, a 2005 phylogenetic analysis by Samuel Iglésias and colleagues, based on mitochondrial and nuclear DNA, found that G. murinus forms a clade with G. melastomus, apart from the clade of G. eastmani, G. sauteri, and G. gracilis. Distribution and habitat Fairly common, the mouse catshark has recently been found to be more widespread in the northeastern Atlantic