Londinimola williamsi (Collins & Saward, 2006)

Londinimola williamsi is a very rare crab found in the London Clay. Only a few examples have ever been found.

It has been found at Steeple Bay, Aveley, Seasalter and Tankerton, an example of the crab can be seen below along with another specimen with claws preserved which is very rare.

Description: Carapace subovoid, longer than wide, widest across metabranchial lobes, from four fifths to almost as long as carapace; orbital margin less than half carapace width; rostrum triangular, sulcate bounded by pseudorostral spines; dorsal regions well defined, anterogastric lobes weakly tumid and spinose, mesogastric lobe subtriangular; urogastric lobe with median spine and lateral ridges; elongated cardiac lobe with weak spines; two spines on epibranchial lobes, mesobranchiallobes spinose, becoming smoother as growth advances; nodes on meso-posterior angles of metabranchial lobes; lineae homolicae well defined.

(Description from: A guide to the fossil Decapoda (Crustacea: Axiidea, Anomura, Brachyura) of the British Isles)

Kingdom: Animalia

Phylum: Arthropoda

Subphylum: Crustacea

Superclass: Multicrustacea

Class: Malacostraca

Subclass: Eumalacostraca

Superorder: Eucarida

Order: Decapoda

Suborder: Pleocyemata

Infraorder: Brachyura

Section: Homoloida

Superfamily: Homoloidea

Family: Homolidae (Closest living relatives)

Genus: Londinimola

Species: Londinimola williamsi

Londinimola Williamsi

Photos permission granted by Thomas Wells

Londinimola Williamsi

Photos permission granted by Thomas Wells

Photo from and premission granted by Martin Rayner

Londinimola Williamsi

Photos permission granted by Thomas Wells

Londinimola Williamsi

Photos permission granted by Thomas Wells

Londinimola williamsi is extinct, with its closest living relatives being from the family Homolidae commonly refered to as carrier crabs or porter crabs.

Members of the Homolidae have their fifth pereiopods (last pair of walking legs) in a sub-dorsal position, which allows them to hold objects in place over the rear half of the carapace. The objects carried include sponges, black corals and gorgonians, and this behaviour may be a defence mechanism against predators. Some species have been observed carrying living sea urchins in a symbiotic relationship which allows them to benefit from the protection of the urchin's dangerous spikes. (Currently Londinimola Williamsi has not been preserved carrying any objects).

Another crab from the family Homolidae which may have looked similar to Londinimola williamsi.

Image from:

https://www.gbif.org/occurrence/4138976311

Acknowledgments:

Thank you very much Thomas Wells and Martin Rayner for allowing usage of the images on this page.

References:

https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=221032&is_real_user=1

https://www.marinespecies.org/traits./aphia.php?p=taxdetails&id=1615533

https://en.wikipedia.org/wiki/Homolidae

https://www.gbif.org/occurrence/4138976311