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worms > Phylum Platyhelminthes > Class Turbellaria > Order Polycladida
Blue-lined flatworm
Pseudoceros concinnus*
Family Pseudocerotidae
updated Feb 2020

Where seen? This small pale flatworm elegantly edged in blue with a central blue stripe is regularly encountered on many of our shores, on coral rubble near living reefs. 'Concinnus' means 'elegant' in Latin.

Features: 2-4cm long. There is a pair of pseudotentacles made up of simple folded edges of the body.

Grouped in this entry are flatworms with a body that is white, beige or pale bluish, edged with a bright blue margin and one central blue stripe along the length of the body. The central line ends with a tiny blue circle-dot near the head.

From Rene Ong:

Pseudoceros concinnus: central line is all solid blue

Yellow striped flatworm Pseudoceros sp. 3: central line is yellow with dark blue border

Braided stripe flatworm Pseudoceros sp. 4: resembles Pseudoceros sp. 3 but has a golden-speckled yellow line that looks intermittent by some dull orange and ends in front.

Racing stripe flatworm Pseudoceros bifurcus - Bluish body with central stripe that is white or yellow becoming orange or red near the head, the stripe is edged with a thin dark purple border.

Pulau Jong, Jun 17*
Photo shared by Liz Lim on facebook.

Changi, Aug 19*
Photo shared by Loh Kok Sheng on facebook.

Pulau Sekudu, Jul 19*
Photo shared by Loh Kok Sheng on facebook.

Pulau Jong, Jun 19*
Photo shared by Loh Kok Sheng on facebook.

Beting Bronok, Jul 19*
Photo shared by Loh Kok Sheng on facebook.

Pulau Tekukor, Sep 18
Photo shared by Dayna Cheah on facebook.

Labrador, Sep 19
Photo shared by Shawne Goh on facebook.

With a solid blue line.
Sentosa, May 08

Little blue circle-dot at the head.

With a blue-and-yellow line.
Pulau Semakau, Sep 05

Sentosa, Sep 11
Photo shared by Marcus Ng on flickr.

With a blue-and-yellow line.
Chek Jawa, Oct 03

*
Species are difficult to positively identify without close examination.
On this website, they are grouped by external features for convenience of display.

Elegant flatworms on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores


Changi, Aug 19
Shared by Jianlin Liu on facebook.

Pulau Sekudu, Jul 16
Photo shared by Loh Kok Sheng on his blog.


Chek Jawa, Oct 10
Photo shared by Neo Mei Lin on her blog.

Chek Jawa, Jan 14
Photo shared by Loh Kok Sheng on his blog.

Chek Jawa, Jul 13
Photo shared by Loh Kok Sheng on his blog.


Chek Jawa, Jul 16*
Photo shared by Loh Kok Sheng on facebook.

Chek Jawa, Jul 18
Photo shared by Jianlin LIu on facebook.


Sentosa Serapong, May 17
Shared by Jianlin Liu on facebook.

Seringat-Kias, Aug 15
Shared by Loh Kok Sheng on his blog.


Lazarus, Feb 09
Shared by Loh Kok Sheng on his blog.

Lazarus, Jul 11
Shared by Loh Kok Sheng on his blog.

Lazarus, Jul 11
Shared by Loh Kok Sheng on his blog.


Kusu Island, May 16
Photo shared by Loh Kok Sheng on facebook.

Kusu Island, Jan 14
Photo shared by Loh Kok Sheng on his blog.


St. John's Island, Feb 11
Photo shared by Loh Kok Sheng on his blog.

St. John's Island, Sep 07
Photo shared by Loh Kok Sheng on his blog.


St. John's Island, Sep 07
Photo shared by Toh Chay Hoon on her flickr.

Big Sisters Island, Feb 19
Photo shared by Abel Yeo on facebook.

Pseudoceros sp. 5*
Pulau Tekukor, Jun 16
Photo shared by Loh Kok Sheng on facebook.


Pulau Jong, May 10
Photo shared by James Koh on his blog.

Terumbu Hantu, Jun 16
Photo shared by Rene Ong on facebook.


Pulau Hantu, Jun 10
Photo shared by Loh Kok Sheng on his blog.

Pulau Hantu, Jul 07
Photo shared by Loh Kok Sheng on his blog.

Raffles Lighthouse, Nov 16
Photo shared by Jianlin Liu on facebook.


Terumbu Bemban, Apr 11

Photo shared by Loh Kok Sheng on his blog.

Terumbu Pempang Tengah, May 11
Photo shared by Loh Kok Sheng on his blog.

Terumbu Pempang Laut, Apr 11
Photo shared by Loh Kok Sheng on his blog.


Pulau Semakau, Aug 11
Photo shared by Lok Kok Sheng on his blog.

Terumbu Semakau, May 10
Photo shared by James Koh on his blog.

Beting Bemban Besar, May 11
Photo shared by Loh Kok Sheng on his blog.


Pulau Biola, Dec 09

Pulau Biola, Dec 09
Photo shared by Loh Kok Sheng on his flickr.

Pulau Biola, Dec 09
Photo shared by Loh Kok Sheng on his flickr.


Pulau Salu, Jun 10

Pulau Biola, May 10

Pulau Senang, Jun 10
Photo shared by Loh Kok Sheng on his flickr.

blue-lined flatworm @ pulau hantu 17Apr2010 from SgBeachBum on Vimeo.


Blue-lined flatworm gliding (Cyrene), Jun 12
Blue-lined flatworm gliding

Blue-lined flatworm gliding (Cyrene)

Posted by Singapore Reef Watch on Thursday, 21 June 2012

Acknowledgement
With grateful thanks to Leslie H. Harris of the Natural History Museum of Los Angeles County for comments on this worm and its identification.

References
  • D. M. Bolaños, B. Q. Gan & R. S. L. Ong. 29 Jun 2016. First records of pseudocerotid flatworms (Platyhelminthes: Polycladida: Cotylea) from Singapore: A taxonomic report with remarks on colour variation.(pdf) The Raffles Bulletin of Zoology Supplement No. 34: 130-169  Pp. 130-169.
  • Newman, Leslie and Lester Cannon. 2003. Marine Flatworms: The World of Polyclads. CSIRO Publishing. 97pp.
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