Species related to Coenobita carnescens

 

Species related to Coenobita carnescens Dana, 1851

紫陸寄居蟹
ムラサキオカヤドカリ

 

Published on 4-April-2017

Published on 1-July-2017

Published on 14-July-2017

Published on 15-September-2017

Published on 5-January-2018

Published on 13-April-2018

Published on 9-January-2019

Published on 15-March-2019


Description

According to information from Worms Database, this species was accepted and may be found in French Polynesia. Joseph Poupin's comment is that Coenobita carnescens could be in fact the juvenile form of C. perlatus according to the drawings provided by Dana.

Thank you to Joseph Poupin for the drawing. We can see the specimen in the drawings (1855) with transverse band on walking legs. This drawing is black and white, we do not know the colour of transverse band.

Scientific name carnescens mean covered in white; hoary, is it refer to the white body colour with transverse band in gray tone on walking legs?





In fact, we can found images from website that some specimens is in white body colour with transverse band in gray tone on both cheliped and walking legs

In 2012, I wrote an article (In Chinese) and analyzed that they may be Coenobita pseudorugosus(Page 25~27)

http://www.tonycoenobita.com/CommentOnSpeciesDelimitationByTony_TradChi2.pdf


However, it is most likely that Coenobita pseudorugosus is merely a synonym or a variety of Coenobita rugosus, and according to the meaning of scientific name. It is possible that this specimens is Coenobita carnescens, please see below some points.

1. This specimens can be found in Samoa, Cook Islands, French Polynesia, Tahuata. From the images, we can see not only individual, but also in group, so I guess they are well represented within these areas.






----------------------------------------------------------------------------------------------------------------------------------------------------------

Images from Samoa:






Other images from Samoa:


----------------------------------------------------------------------------------------------------------------------------------------------------------

Images from Cook Islands:













































Other images from Cook Islands:

Movies from Cook Islands:

hermit crab


----------------------------------------------------------------------------------------------------------------------------------------------------------

Images from French Polynesia:

























Other images from French Polynesia:


----------------------------------------------------------------------------------------------------------------------------------------------------------

Images from Tahuata:





----------------------------------------------------------------------------------------------------------------------------------------------------------

2. The distribution of this specimens and Coenobita perlatus are same, so they has usually been misidentified as juvenile of Coenobita perlatus.

For example, we can found both of them in Cook Islands and French Polynesia.
http://www.hanway.co.uk/curiosities-cook-islands-hermit-crabs/
https://www.aitutaki-vacation.com/wp-content/uploads/2017/08/Aitutaki-Hermit-Crab-Photo-4.jpg
http://www.svsilhouette.com/2012/08/exploring-atoll.html
http://www.svbintalkhamseen.org/blog/2010/05
http://www.smallanimaltalk.com/2013/12/three-things-i-learned-about-hermit.html




The slightly different between both of them may be the colour of transverse band. Transverse band on both cheliped and walking legs of juvenile of Coenobita perlatus is in brownish-red colour. Shield of most of juvenile of Coenobita perlatus with brownish-red marks.




While shield of this specimens is usually in white, same as body colour.




3. Below image from Cook Islands show that juvenile on left hand side and adult on right hand side are same, with gray transverse band on both cheliped and walking legs. It means that there is no different between juvenile and adult during the growth. Some individuals of juvenile of Coenobita perlatus are almost white or pale orange. As they grow larger, the red orange colour gradually appear.





4. I checked with Joseph Poupin that specimens collected in Tahuata did not do any DNA test to confirm if they are actually Coenobita perlatus. Also, is male coxae of 5th legs same as Coenobita perlatus?


5. According to the information of < Poupin J., 1996. Crustacea Decapoda of French Polynesia (Astacidea, Palinuridea, Anomura, Brachyura) >, the distribution of this species is Tuamotu. Tuamotu Islands is a chain of islands and atolls in French Polynesia.



Images from Tuamotu:





6. This specimens also can be found in Vuvalu - Fuadatu Island & Tepuka Island, not only individual, but also in group.








7. This specimens also can be found in Tonga and Kiritimati (Christmas Island). To sum up, it seems that this specimens are distributed in the islands in between Pacific Ocean and South Pacific Ocean.Images from Tuamotu:
http://yachterica.blogspot.hk/2007/10/
http://www.travel-tour-guide.com/kiribati/01_christmas_island.htm
http://www.leeabbamonte.com/oceania/kiritimati-the-other-christmas-island.html#comment-315098



Images from Tanga:






Status

To be confirmed.

Only found one article < The effect of isolation on the behavioral interaction of juvenile land hermit crab (Coenobitidae) from the Motus of Mo'orea French, Polynesia > reported that this speices as juveniles Coenobita perlatus.




Reference link

http://crustiesfroverseas.free.fr/


http://travel2unlimited.com

Reference article

Dana J. D., 1955. Atlas. Crustacea

Poupin J., 1996. Crustacea Decapoda of French Polynesia (Astacidea, Palinuridea, Anomura, Brachyura)

Van Zerr, Vanessa E., 2008. The effect of isolation on the behavioral interaction of juvenile land hermit crab (Coenobitidae) from the Motus of Mo'orea French, Polynesia