Tumidotheres maculatus

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Tumidotheres maculatus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Infraorder: Brachyura
Family: Pinnotheridae
Genus: Tumidotheres
Species: T. maculatus
Binomial name
Tumidotheres maculatus
(Say, 1818)
Synonyms [1]
  • Cancer parasiticus Linnaeus, 1763
  • Cancer pinnophylax Linnaeus, 1767
  • Pinnotheres maculatus Say, 1818

Tumidotheres maculatus is a species of crab that lives commensally or parasitically in the mantle cavity of molluscs. It is found along much of the western Atlantic Ocean and was first described by Thomas Say in 1818.


Tumidotheres maculatus has a wide range in the western Atlantic Ocean, extending from the seas of Martha's Vineyard (United States) to San Matías Gulf (Argentina).[1]


There is conspicuous sexual dimorphism in T. maculatus which corresponds with the differing ecology of the two sexes. Males are typically less than 6 millimetres (0.24 in) in carapace width, and are able to leave the host. Females grow up to 16 mm (0.63 in) wide,[2] and, having reached adulthood, spend their entire lives in the host.[3]


Tumidotheres maculatus is an endosymbiont of molluscs; it is unclear whether the host is harmed by the crabs presence, that is whether the relationship is commensal or parasitic.[3] It is associated with a wide range of mollusc hosts, most of which are bivalves. They include Argopecten irradians, Atrina rigida, Modiolus americanus, Mytilus edulis[3] and Flexopecten felipponei.[4] It has also been found in a tunicate of the genus Molgula, in the tubes of the tubeworm Chaetopterus variopedatus and on the asteroid (starfish) Asterias rubens.[5]

In molluscan hosts, T. maculatus uses its legs to cling to the gills of its host, and feeds on strands of food aggregated by the host.[3] Reported rates of infestation of T. maculatus on mollusc hosts vary widely, from 0%–20% on Argopecten irradians at St. Joseph Bay, Florida, to 97.6% on Mytilus edulis at Quicks Hole, Massachusetts.[3]


Tumidotheres maculatus was first described by Thomas Say in 1818, under the name Pinnotheres maculatus. It was transferred to the new genus Tumidotheres, alongside T. margarita by Ernesto Campos in 1989.[6] It may be the species referred to by Carl Linnaeus as Cancer parasiticus in his 1763 work Centuria Insectorum, and the one he called Cancer pinnophylax in the 1767 12th edition of Systema Naturae.[7]


  1. ^ a b Peter Davie (2010). "Tumidotheres maculatus (Say, 1818)". World Register of Marine Species. Retrieved March 7, 2011. 
  2. ^ Maite Andrea Narvarte & María Natalia Saiz (2004). "Effects of the pinnotherid crab Tumidotheres maculatus on the Tehuelche scallop Aequipecten tehuelchus in the San Matías Gulf, Argentina". Fisheries Research. 67 (2): 207–214. doi:10.1016/j.fishres.2003.09.041. 
  3. ^ a b c d e Karen Kane & Gregory S. Farley (2006). "Body size of the endosymbiotic pea crab Tumidotheres maculatus: larger hosts hold larger crabs" (PDF). Gulf and Caribbean Research. 18: 27–33. 
  4. ^ Florencia Cremonte, Antonio Figueras & Eugene M. Burreson (2005). "A histopathological survey of some commercially exploited bivalve molluscs in northern Patagonia, Argentina". Aquaculture. 249 (1–4): 23–33. doi:10.1016/j.aquaculture.2005.01.024. 
  5. ^ Laura Schejter & Claudia S. Bremec (2007). "Epibionts on Flexopecten felipponei (Dall, 1922), an uncommon scallop from Argentina". American Malacological Bulletin. 22 (1): 75–82. doi:10.4003/0740-2783-22.1.75. 
  6. ^ Ernesto Campos (1989). "Tumidotheres, a new genus for Pinnotheres margarita Smith, 1869, and Pinnotheres maculatus Say, 1818 (Brachyura: Pinnotheridae)". Journal of Crustacean Biology. 9 (4): 672–679. doi:10.1163/193724089x00674. JSTOR 1548597. 
  7. ^ Peter K. L. Ng, Danièle Guinot & Peter J. F. Davie (2008). "Systema Brachyurorum: Part I. An annotated checklist of extant Brachyuran crabs of the world" (PDF). Raffles Bulletin of Zoology. 17: 1–286. 

External links[edit]

  • Enrique E. Boschi. "Tumidotheres maculatus" (PDF). Atlas de Sensibilidad Ambiental de la Costa y el Mar Argentino: Crustáceos estomatópodas y decápodos del Mar Argentino (in Spanish).