Neolithodes
| Neolithodes | |
|---|---|
| Neolithodes crab at the Davidson Seamount off California | |
| Scientific classification Edit this classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Clade: | Pancrustacea |
| Class: | Malacostraca |
| Order: | Decapoda |
| Suborder: | Pleocyemata |
| Infraorder: | Anomura |
| Family: | Lithodidae |
| Subfamily: | Lithodinae |
| Genus: | Neolithodes A. Milne-Edwards & Bouvier, 1894 |
| Type species | |
| Neolithodes grimaldii (A. Milne-Edwards & Bouvier, 1894)
| |
Neolithodes is a genus of king crabs in the subfamily Lithodinae.[1]
Description
Neolithodes has a pyriform carapace which does not cover the bases of its walking legs.[2] Of its three pairs of walking legs, the rearmost are the longest, and all of them have a similar form.[3] At the very front center of the carapace, its rostrum consists of a median spine and a pair of upward-slanted (dorsal) spines.[3] Behind the rostrum sits the elevated gastric region, followed by a deep groove separating it from the triangular cardiac region.[3] The cervical groove behind that is shallow and indistinct.[3] When measuring the carapace's length without including the rostrum,[a] the carapace is always shorter than the walking legs.[3]
Its second abdominal segment consists of five plates: a median plate and paired submedian and marginal (outer) plates.[3] As in all king crabs, males have a symmetrical abdomen, but females' abdomens are skewed – enlarged on the left side and reduced on the right.[5] In males, the third through fifth abdominal segments are composed of spine-like nodules, while in females, these are composed of well-developed plates on the left and well-developed plates or simply spine-like nodules on the right.[3] In front of the abdomen is a deep, logitudinal sternal fissure between the frontmost pair of walking legs;[3] this fissure is also present in Lithodes and readily distinguishes the two genera from other king crabs.[6]
Distribution
Although there are records from water as shallow as 70 m (230 ft) in cold regions, most records are much deeper, typically 700–2,000 m (2,300–6,600 ft).[7] [8] [9] Neolithodes grimaldii has been reported to a depth of 5,238 m (17,185 ft).[10]
Ecology
Various sessile organisms such as barnacles are sometimes attached to their carapace and legs,[10] [11] and small commensal amphipods may live in their carapace.[12] They are occasionally the victims of parasitic snailfish of the genus Careproctus , which lay their egg mass in the gill chamber of the crab, forming a mobile "home" until they hatch.[7] Conversely, some juvenile Neolithodes have a commensal relationship with Scotoplanes sea cucumbers. To protect itself from large predators, the young king crab hides under the sea cucumber.[13]
Taxonomy
Neolithodes was described in 1894 by carcinologists Alphonse Milne-Edwards and Eugène Louis Bouvier.[14] They initially placed the new species they found, Neolithodes grimaldii , in the closely related genus Lithodes , but they shortly thereafter constructed the genus Neolithodes based on the new species' distinctive abdomen, which they compared to the monotypic genus Dermaturus .[14] The word Neolithodes derives from the Greek neo, meaning "new", and Lithodes.[15] The name of the latter genus originates from the Latin lithodes, meaning "stone-like".[15] No known Neolithodes fossils exist.[16] Neolithodes' relationship to other king crabs can be seen in the following cladogram:[17]
Lithodidae cladogram
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