Lamprops fuscatus Sars, 1865: 192; 1900: 20, pl. 11.
Type material. Deposition unknown. Lofoten Islands, Norway. Not seen. Diagnosis. Carapace without lateral ridges, antennal notch weak, pseudorostrum pointed,eyelobe small. Telson
1.1 length of uropod peduncles, 2 pairs lateral setae, 5 terminal setae. Uropod peduncle with 5 medial setae. Adult male smaller than female, eyelobe larger than in female.
Depth. 4–112 m.
Distribution. Northern boreal Pacific, Arctic, northern boreal Atlantic.
Remarks. The recorded distribution is very large, and unlikely to represent a single species. It is likely that specimens from the North Pacific and Arctic ascribed to L. fuscatus by Hart (1930), Derzhavin (1929), Lomakina (1955, 1958), and Given (1965) are L. northwindae, a species with a very similar carapace, or possibly several species. Lamprops northwindae from the Laptev Sea can be differentiated from L. fuscatus by the lack of an antennal notch, blunt pseudorostrum, and large eyelobe. In L. fuscatus, the antennal notch is weak but present, the pseudorostrum is pointed, and the the eyelobe is small.
In the genus Alamprops, the most similar species are A. affinis, A. carinatus, A. obfuscatus, and A. serratus. In Lamprops fuscatus, the telson is longer than the uropod peduncles, while in A. affinis, A. carinatus and A. obfuscatus the telson is shorter than or equal to the uropod peduncles. The most similar species A. serratus, which has a strongly serrate anterolateral corner on the carapace, and the telson terminal setae have the outermost pair long, and the central three setae are equal in length and short. In L. fuscatus, the anterolateral corner of the carapace is smooth, and the telson terminal setae are all long, with the outermost pair slightly longer than the central three setae.