Neolithodes


Neolithodes is a genus of king crabs in the subfamily Lithodinae.

Description

Neolithodes has a pyriform carapace which does not cover the bases of its walking legs. Of its three pairs of walking legs, the rearmost are the longest, and all of them have a similar form. At the very front center of the carapace, its rostrum consists of a median spine and a pair of upward-slanted spines. Behind the rostrum sits the elevated gastric region, followed by a deep groove separating it from the triangular cardiac region. The cervical groove behind that is shallow and indistinct. When measuring the carapace's length without including the rostrum, the carapace is always shorter than the walking legs.
Its second abdominal segment consists of five plates: a median plate and paired submedian and marginal plates. 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. 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. In front of the abdomen is a deep, logitudinal sternal fissure between the frontmost pair of walking legs; this fissure is also present in Lithodes and readily distinguishes the two genera from other king crabs.

Distribution

Although there are records from water as shallow as in cold regions, most records are much deeper, typically. Neolithodes grimaldii has been reported to a depth of.

Ecology

Various sessile organisms such as barnacles are sometimes attached to their carapace and legs, and small commensal amphipods may live in their carapace. 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. 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.

Taxonomy

Neolithodes was described in 1894 by carcinologists Alphonse Milne-Edwards and Eugène Louis Bouvier. 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. The word Neolithodes derives from the Greek, meaning "new", and Lithodes. The name of the latter genus originates from the Latin lithodes, meaning "stone-like". No known Neolithodes fossils exist. Neolithodes relationship to other king crabs can be seen in the following cladogram:

Species

Neolithodes contains the following species:
ImageScientific nameCommon nameDistributionReferences
Neolithodes agassizii Western Atlantic
Neolithodes asperrimus Barnard, 1947Rough stone crabSouth Africa to Mauritania
Neolithodes brodiei Dawson & Yaldwyn, 1970Brodie's king crabNew Zealand and adjacent waters
Neolithodes bronwynae Ahyong, 2010Rock crabBay of Plenty, Lord Howe Rise, eastern Australia, possibly New Caledonia, Hawaiian–Emperor seamount chain
Neolithodes capensis Stebbing, 1905Cape stone crabSouthern Ocean, Indian Ocean, Bellingshausen Sea
Neolithodes diomedeae Eastern Pacific, Southwestern Atlantic, Southern Ocean
Neolithodes duhameli Macpherson, 2004Crozet Islands
Neolithodes flindersi Ahyong, 2010Southeastern Australia
Neolithodes grimaldii Porcupine crabNorth Atlantic
Neolithodes indicus Padate, Cubelio & Takeda, 2020Southeastern Arabian Sea
Neolithodes nipponensis Sakai, 1971Japanese spiny crabJapan and Taiwan
Neolithodes vinogradovi Macpherson, 1988Arabian Sea to the Coral Sea
Neolithodes yaldwyni Ahyong & Dawson, 2006Ross Sea

Works cited

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