Coenobita purpureus

 

Coenobia lila Rahayu, Shih & Ng, 2016

淡紫陸寄居蟹
ムラサキオカヤドカリ

 

Published on 19-June-2016

Updated on 4-July-2016

Updated on 17-July-2016


Description

In 2006, a land hermit crab enthusiast, Félix J. Wáng found Coenobita purpureus inhabit in Indonesia and named Indonesia/Kelomang Blueberry. Adult are in purple, burgundy, brown or greyish purple. There is black band on the lower surfaces of the eyestalks, no series of ridge (////) on upper outer surface of palm of left cheliped (Especially on the adult).




Overseas land hermit crab enthusiast also think that they are Coenobita purpureus. In 2010, I pointed out that Coenobita purpureus of Japan is different with Indonesia/Kelomang Blueberry in a forum
(HCA , Hermit Crab Association).


 

In 2011, I also discussed this with Félix J. Wáng.

http://coenobita.e-monsite.com/pages/especes-et-biotopes/coenobita-purpureus.html



In 2012, I also wrote an article (In Chinese) and analyze that they may be a new speices(Page 35~42)

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



From my study, this species may also inhabit in Singapore and Malaysia. Juvenile in very small size are in light orange.






I do not agree with Félix that they are Coenobita purpureus. Morphology is one of a marker in species delimitation. Besides above characteristics, I found a important evidence, the male coxae of 5th legs of this species is not same as Coenobita purpureus, right coxa is no produced into an elongate tube. So in my opinion, this may be a new species different from Coenobita purpureus. They are not real Coenobita purpureus. I think this species needs further investigation to proof if it is new species.






Status

In Singapore, information show that they are Coenobita violascens or Coenobita cavipes. But according to a seminar in Singapore at 29 Oct 2015, Dr Dwi Listyo Rahayu is now studying about this and got already the proof it is new species. The report will be published later.

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, a new species Coenobita lila is described from Singapore and adjacent countries.



Common name

Indonesia/Kelomang Blueberry.



Size

Shield length can reach 19mm.



Distribution

Singapore, Indonesia, Malaysia.



Habitat

Upper intertidal to 100m inland from the beach, under grass beds or under stones during the day. Also found in reef, at the edge of mangroves and estuarine habitats.



Larval stages

Unknown.



Characteristics

Adult
In general is violet, dark purple, purplish blue or brownish purple. Adult female is pale or light purple.





Shield transversely convex. Surface of shield with patch of dark purple or light brown anteriorly. Lateral surface slightly punctate, doral surface scattered with small and large tubercles.







Eyestalks

Eyestalks are compressed in shape, with dark brown band on the lower surfaces of the eyestalks.





 

Antenna

Antennal acicles are fused with the second segment of peduncle.

 

Flagellum of antennule and antenna are brown.






Cheliped

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




Upper margins of both cheliped with brush of setae.




Lower proximal part of palm of left cheliped angled, forming slightly oblique lobe-like projection, continued to slightly upright lower margin of fixed finger. Lower outer surface of palm covered with tubercles.






Walking legs
Lateral surface of propodus of left 3rd walking leg slightly flattened.





Carpus and Merus with longitudinal light brown streak on surface of walking legs.





Both 2nd & 3rd walking legs covered dark brown granules.




Outer surface of propodus of left 3rd walking leg not separated from dorsal surface by a well-marked longitudinal crest(A).







Abdomen
The abdomen is long.






Male coxae of 5th legs
Coxae of 5th legs thick, forming moderately long, calcified sexual tube, subtriangular, left tube slightly broader than right.






Juvenile
Young male is pale or light purple. Small females in light purple, greenish white or yellowish green.



Remark

1. Adult Coenobita lila has been misidentified as Coenobita purpureus because of purple body colour.

According to < 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) >, Coenobita purpureus is easily separated from Coenobita lila by the presence of ridges (////) on upper outer surface of palm of left cheliped and an asymmetrical sexual tube.




2. According to < 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) >, Coenobita lila differs from Coenobita violascens in the absence of prominent longitudinal ridge separated the dorsal and lateral surfce of propodus of 3rd walking legs and in the slightly elongated, subtriangular shape of the male sexual tube.




Nature Photo gallery

http://budak.blogs.com/the_annotated_budak/2010/12/hermits-and-robbers.html



Reference link

Lee Kong Chian Natural History Museum


Reference article


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)