New species related to Coenobita violascens(EN)

Image©Taniya Morris

Available Information

Below articles point out that specimens in East Africa (Kenya, Madagascar, Mozambique, Tanzania, Zanzibar, Mayotte) may belong to Coeonbita cavipes or Coenobita violascens.

1990

According to < Coastal Hermit Crabs (Decapoda: Anomura) from Kenya, with a Review and Key to East African Species > in 1990, Coenobita violascens (= C. cavipes) noted by Hilgendorf (1869) from Mombasa.

1997

① According to < Notes on the Macro-benthos of Kenyan mangroves > in 1997, Coenobita cavipes (below image) occasionally in mangrove sandy area.

② According to < Ecology of tropical hermit crabs at Quirimba Island, Mozambique: vertical migration (tree climbing) > in 1997, Coenobita cavipes occurs only in or close mangrove forests.

2001

According to < Reappraisal of hermit crab species (Crustacea: Anomura: Paguridea) reported by Camille Heller in 1861, 1862 and 1865 > in 2001, Hilgendorf (1869) identified specimens from Mombasa, Kenya and Zanzibar as Coenobita violascens. The male specimen from Mombasa, after re-examination by one of the authors (McLaughlin P. A) has been shown to actually represent Coenobita cavipes. Hilgendorf did not identify his illustrated specimen, but the convexity of the lower margin of the left chea suggests that it was the specimen of Coenobita cavipes and not Coenobita violascens that was depicted.

2002

According to < Ecology of subtropical hermit crabs in SW Madagascar: Refuge-use and dynamic niche overlap > in 2002,  table 2 show the habitat of Coenobita cavipes is mangrove. 

2013

① According to < Land, Mangrove and Freshwater Decapod Crustaceans of Mayotte Region (Crustacea Decapoda) > in 2013, Coenobita cavipes has been sometimes considered a junior synonym of Coenobita violascens. Mayotte specimens (below images) are tentatively attributed to Coenobita cavipes on the basis of key characters given by Nakasone (1988) and previous WIO records.

② According to < Kloiber U., 2013. Chumbe Island Coral Park – Conservation and Education, Status report 2013. 1-43, Zanzibar, Tanzania >  in 2013, named this speices as Coenobita violascens.

2014

A Japanese blog mentioned that Coenobita pseudorugosus was foiund in Madagascar. But I think it is juvenile of Coenobita violascens. I found adult size of Coenobita violascens in Madagascar on the web. That mean Madagascar may have Coenobita violascens.

2016

According to the report < new species of land hermit crab in the genus Coenobita Latreille, 1829 from Singapore, Malaysia and Indonesia, previously confused with C. cavipes Stimpson, 1858 (Crustacea: Decapoda: Anomura: Coenobitidae) >published on 29 June 2016, specimens examined from Madagascar and Mayotte also correspond to Coenobita violascens (unpublished morphological and molecular data).

My Opinion

Coenobita cavipes has been confused with Coenobita violascnes by some authors. According to < A Catalog of The Hermit Crabs (Paguroidea) of Taiwan >, it seems that McLaughlin P. A incorrectly identified the specimens of Coenobita cavipes as Coenobita violascens. Firstly, we need to identify if specimens in above artciles is Coenobita cavipes or Coenobita violascens? In fact, red antennule of Coenobita violascens could be easily distinguished from Coenobita cavipes

Secondly, mangrove habitat show this species should be Coenobita violascens, not Coenobita cavipes which occur in inland area. So, specimens in above articles should be related to Coenobita violascens.

In 2016, I found some images from East Africa that should be refer to this specimens. Their body colour is from light beige to dark beige with orange brown stripe on both cheliped and walking legs. ‘S’ shape darker colour stripes on carpus of left cheliped may be one of a key character of this specimens. The antennule of the specimens are red which same as Coenobita violascens.

I think it is because of different habitat (East Africa), their body color is different with normal Coenobita violascens. So that this specimens should be more likely related to species of Coenobita violascens? Or new species?

Let’s wait the authors of < new species of land hermit crab in the genus Coenobita Latreille, 1829 from Singapore, Malaysia and Indonesia, previously confused with C. cavipes Stimpson, 1858 (Crustacea: Decapoda: Anomura: Coenobitidae) > to publish the result they examined in East Africa later.

Kenya

Madagascar

Mozambique

Tanzania

Zanzibar

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Mayotte

Status (Updated on Sep 2021)

According to < A Guide to, and Checklist for, the Decapoda of Namibia, South Africa and Mozambique. Vol. 2 >  in 2017, and < Contributions to the taxonomy of South African hermit crabs (Crustacea: Decapoda: Paguroidea) > in 2018, confirmed specimens from East Africa are actually Coenobita violascens. This species is also recorded from Southern Africa and South Africa.

Reference articles

  • Barnes D. K. A., 1997. Ecology of tropical hermit crabs at Quirimba Island, Mozambique: vertical migration (tree climbing)
  • Barnes D. K. A., 2002. Ecology of subtropical hermit crabs in SW Madagascar: Refuge-use and dynamic niche overlap
  • Bouchard J. M., Poupin J., Cleva R., Dumas J., Dinhut V., 2013. Land, Mangrove and Freshwater Decapod Crustaceans of Mayotte Region (Crustacea Decapoda)
  • Chumbe Island Coral Park Conservation and Education Status Report 2013. Zanzibar, Tanzania
  • Dwi Listyo Rahayu, Hsi-Te Shih, Peter K. L. Ng, 2016. A new species of land hermit crab in the genus Coenobita Latreille, 1829 from Singapore, Malaysia and Indonesia, previously confused with C. cavipes Stimpson, 1858 (Crustacea: Decapoda: Anomura: Coenobitidae)
  • Emmerson W. D., 2017. A Guide to, and Checklist for, the Decapoda of Namibia, South Africa and Mozambique. Vol. 2. Cambridge Scholars Publishing, Newcastle upon Tyne
  • Jannes Landschoff., 2018. Contributions to the taxonomy of South African hermit crabs (Crustacea: Decapoda: Paguroidea) – integrating microCT scanning and barcoding
  • Kloiber U., 2013. Chumbe Island Coral Park – Conservation and Education, Status report 2013. 1-43, Zanzibar, Tanzania
  • McLaughlin P. A., Dworschak P. C., 2001. Reappraisal of hermit crab species (Crustacea: Anomura: Paguridea) reported by Camille Heller in 1861, 1862 and 1865
  • McLaughlin P. A., Rahayu D. L., Komai T., Chan-Tin Yam, 2007. A Catalog of The Hermit Crabs (Paguroidea) of Taiwan, National Taiwan Ocean University, Keelung
  • Nakasone Y., 1988. Land hermit crabs from the Ryukyus, Japan, with a Description of a New Species from the Philippines (Crustacea, Decapoda, Coenobitidae)
  • Reay P. J., Haig J., 1990. Coastal Hermit Crabs (Decapoda: Anomura) from Kenya, with a Review and Key to East African Species
  • Vannini M., Cannicci S., 1997. Notes on the Macro-benthos of Kenyan mangroves

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