Coenobita violascens(EN)

Image©Stefanie Schwing

Common name

Viola, Komurasaki Land Hermit Crab.

*Red data status from Japan Ministry of the Environment: Near threatened

Size

Shield length can reach 20mm.

Distribution

From Indian to Pacific Ocean, Thailand, Malaysia, Philippines, India, Indonesia, Taiwan, Japan(Ogasawara Islands) etc.

Habitat

Mainly live in inner bay or estuarine of river, usually found near mangrove forest of inner bay.

Larval stages

Four zoeal stages.

Characteristics

Adult
Body colour is light lavender, dark violet, violet, blackish green.

Eyestalks
Eyestalks are compressed in shape, completely black.

*The bottom part of antenna are blue or orange brown.

Antenna
Antennal acicles are fused with the second segment of peduncle.

Antennule (1st antennal) are red, some specimen are in dark red.

Cheliped
Left cheliped is bigger than right cheliped. No series of ridge (////) on upper outer surface of palm of left cheliped.

Upper margins of both cheliped with brush of setae.

Lower margin of palm of left cheliped straight or slightly concave in middle portion, lower proximal angle produced in to lobe-like projection. Dactylus and fixed finger of left cheliped in purple. Lower outer surface of palm smooth, with dark brown patch.

Walking legs
Propodus of 3rd walking leg is relatively strong. Inner margin of propodus of left 3rd walking leg strongly projecting inwards and inner surface strongly concave.

Outer surface of propodus of left 3rd walking leg separated from dorsal surface by a very small and indistinct well-marked longitudinal crest(B).

Abdomen
The abdomen is long.

Male coxae of 5th legs
Coxae of 5th legs of both sides thick and short, a sternal protuberance between both coxae of 5th legs very small.

Juvenile
Body colour is red brownish, there is dark brown band on the lower surfaces of the eyestalks. As they grow larger, the dark violet colour gradually appear.

Below images are the growth record from same crab.

Remark

Is the specimens found in East Africa refer to related species of Coenobita violascens? Please go to New species related to Coenobita violascens.

Gallery

Reference links

coenobita.e-monsite.com
coenobitaspecies.com
http://crustiesfroverseas.free.fr/
Taiwan Biodiversity Information Facility (台灣生物多樣性資訊入口網)

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)
Hung-Li Yuan, 2008. Morphological and Molecular Evidence for a Stepwise Terrestrial Evolution and Species Delimitation on the Coenobita Phylogeny
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., Komai T., Lemaitre R., Rahayu D. L., 2010. Annotated checklist of anomuran decapod crustaceans of the world (exclusive of the Kiwaoidea and families Chirostylidae and Galatheidae of the Galatheoidea) Part I. Lithodoidea, Lomisoidea and Paguroidea
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
有馬啓人, 2014. ヤドカリ (ネイチャーウォッチングガイドブック), 誠文堂新光
朝倉彰, 2004. ヤドカリ類の分類学，最近の話題－オカヤドカリ科 (Asakura A., 2004. Recent topics on taxonomy of hermit crabs from Japanese waters – family Coenobitidae)
仲宗根幸男, 1987. 「あまん」オカヤドカリ生息実態調査報告, 沖縄教育委員会
大澤正幸, 藤田喜久, 2016. 宮古諸島伊良部島･下地島から得られた口脚目および十脚目 (アナエビ下目, アナジャコ下目, 異尾下目) 甲殻類 (Osawa M., Fujita Y., 2016. Stomatopods and decapods of Axiidea, Gebiidea and Anomura (Crustacea: Malacostraca) from Irabu-jima and Shimojijima Islands, Miyako Group, southern Ryukyus, Japan)
豊田幸詞, 関慎太郎, 2014. 日本の淡水性エビ．カニ: 日本産淡水性・汽水性甲殻類102種(ネイチャーウォッチングガイドブック), 誠文堂新光社

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