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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. Body creamy-white to bluish-creamy-white. Two fine blue lines in the centre, which are usually so close to one another that they appear to be one solid blue line. In between the two fine blue lines, is the body colour. Has a pair of pseudotentacles made up of simple folded edges of the body.

Sometimes mistaken for similar flatworms. Here's more on how to tell apart small flatworms with one central line and three central lines.

Good mother: One study has found this worm to display long-term parental care.

Sentosa, May 08

Pseudotentacles simple fold.

Two fine blue lines in the centre.
Pulau Semakau, Sep 05
Blue-lined flatworm (Pseudoceros concinnus)
Blue-lined flatworm (Pseudoceros concinnus)

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

Blue-lined flatworms on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores


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

Changi, Aug 19
Shared by Jianlin Liu on facebook.


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

Beting Bronok, Jul 20
Photo shared by Vincent Choo on facebook.

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


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.


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

East Coast (PCN), May 21
Photo shared by Vincent Choo on facebook.


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

Berlayar Creek, Feb 20
Shared by Loh Kok Sheng on facebook


Sentosa Tg Rimau, Apr 21
Shared by Vincent Choo on facebook.

Sentosa Serapong, Jul 21
Shared by JIanlin Liu on facebook.


Lazarus Island, Nov 20
Photo shared by Vincent Choo on facebook.

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

St. John's Island, Apr 21
Shared by Jianlin Liu on facebook.


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

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


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

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

Big Sisters Island, Jan 20
Shared by Jianlin Liu on facebook.


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

Cyrene, Apr 21
Photo shared by Vincent Choo on facebook.

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


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

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


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

Pulau Hantu, Apr 21
Photo shared by Jianlin Liu on facebook.

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


Terumbu Bemban, Apr 11

Photo shared by Loh 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.


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.

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


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, Apr 21
Photo shared by Loh Kok Sheng on facebook.

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.
Grateful thanks to Rene Ong for sharing details and identifying the flatworms on this page.

References
  • Mating behavior, spawning, parental care, and embryonic development of some marine pseudocerotid flatworms (Platyhelminthes: Rhabditophora: Polycladida) in Singapore. Samantha Jia Wen Tong and Rene S.L. Ong. 27 June 2020. Invertebrate Biology.
  • Rene S.L. Ong and Samantha J.W. Tong. 29 October 2018. A preliminary checklist and photographic catalogue of polyclad flatworms recorded from Singapore. Nature in Singapore 2018 11: 77–125.
  • 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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