Monotypic decapod genera

Sculptolithodes is a monotypic genus of king crab. Its only species is Sculptolithodes derjugini.

Austropenaeus is a monotypic genus of deepwater prawn. Its only species is Austropenaeus nitidus which is native to the deep water surrounding South Africa.

Davusia glabra, commonly called the shiny bait crab, Sowrie crab or Sourie crab is the sole species of crab in the genus Davusia. It lives around the low tide area on rocky ocean shores on the eastern coast of Australia (southern Queensland to Victoria), in crevices and rock pools and on rock platforms. Its distribution is stated differently in different sources; some have described the crab's habitat as from Queensland to as far south as the NSW-Victorian border, while others have stated it can be found as far south as Wilson's Promontory (Southern Victoria). Its carapace is grey to fawn-colored with very small green spots, resulting in Davusia glabra having a greenish appearance. The width of the carapace is around 30-40 mm across and is smooth without hair, slightly wider than long, with 3 distinct spines at each edge.

Migmathelphusa olivacea is a species of freshwater crab found in Lake Poso on the Indonesian island of Sulawesi. It is the only species in its genus. It is listed by the IUCN as Endangered, given "its extent of occurrence and area of occupancy is less than 500 square kilometres (190 sq mi)", and its individuals being found in less than five locations. There is also a "decline in the extent and quality of its habitat and it is not found in a protected area". Being found around a lake, "present and future threats to this species include human-induced habitat loss/degradation due to population increases and industrial and agrarian development".

Troglocambarus is a monotypic genus of troglobitic crayfish, endemic to Florida. Troglocambarus maclanei is found underground in Hernando, Marion, Alachua, Columbia, Gilchrist and Suwanee counties, and is named after Mr. William A. McLane who first collected it. It is commonly called the North Florida Spider Cave crayfish.

Trypaea australiensis, known as the (marine) yabby or ghost nipper in Australia, or as the one-arm bandit due to their occasional abnormally large arm, and as the Australian ghost shrimp elsewhere, is a common species of mud shrimp in south-eastern Australia, and may be the only extant species in the genus Trypaea. T. australiensis is a popular bait used live or frozen by Australians targeting a range of species. It grows to a length of 6 centimetres (2.4 in) and lives in burrows in mudflats or sandbanks, especially in or near estuaries.

Palibythus magnificus, sometimes called the musical furry lobster, is a species of furry lobster found in Polynesia. It is generally included in the family Palinuridae, although it has also been separated from that family with the genus Palinurellus to form the family Synaxidae in the past. The species is known in Samoan as ula moana, a name which also covers the deep-water shrimp Heterocarpus laevigatus.

Hymenocera picta, commonly known as the harlequin shrimp, is a species of saltwater shrimp found at coral reefs in the tropical Indian and Pacific Oceans. It is usually considered the only species in the genus Hymenocera, but some split it into two species: H. picta from the central and east Pacific, where the spots are deep pinkish-purple with a yellow edge, and H. elegans from the Indian Ocean and west Pacific, where the spots are more brownish and have a blue edge. They reach about 5 cm (2.0 in) in length, live in pairs, and feed exclusively on starfish, including crown-of-thorns starfish. They do seem to prefer smaller, more sedentary starfish, but as these generally are not sufficiently numerous for their needs, they commonly attack crown-of-thorns starfish, both reducing its consumption of coral while under attack, and killing it within a few days.

Thymops birsteini, the Patagonian lobsterette, is a species of lobster found around the coasts of South America, particularly the South Atlantic. It belongs to the monotypic genus Thymops.

Parapylocheles scorpio is a species of hermit crab in the family Pylochelidae. It lives at depths from 200 to 925 meters in the Indo-West Pacific, in Indonesia and the Philippines, although it may live in water as shallow as 100 meters, in wood fragments, tusk shells, and pieces of bamboo. It is the only member of the genus Parapylocheles.