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worms > Phylum Platyhelminthes > Class Turbellaria > Order Polycladida
Dawn flatworm
Pseudobiceros hancockanus
Family Pseudocerotidae
updated Feb 2020

Where seen? This elegant flatworm is commonly seen on coral rubble near living reefs on many of our Southern shores. Like the first light of dawn, the dark to black flatworm has orange and white edges. Previously known as Pseudobiceros uniarborensis.

Features: 5-8cm long. Usually with deep ruffles. Body dark brown to black. Margin in three colours: thin white line on the outermost edge, a transparent greyish band in the middle and orange band innermost next to black body. Centre of the body is raised, with a short grey or white stripe on the head. Underside uniformly semi-translucent grey with same marginal markings as the upper side. It has a pair of pseudotentacles that are ear-like and pointed. The pseudotentacles are all black, bordered only by the opaque white rim (no orange) and has conspicuous white tips.

St. John's Island, Jan 06

Marginal band: orange, grey, white.
Pseudotentacles all black with white tips.
Grey or white stripe on the head.

Underside uniformly grey semi-translucent.
Dawn flatworm (Pseudobiceros hancockanus)


Pulau Hantu, Sep 08

Tanah Merah, Aug 09

Dawn flatworms on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores


East Coast PCN, Jul 20
Photo shared by Loh Kok Sheng on facebook.


Sentosa, Jan 10
Photo shared by Loh Kok Sheng on his flickr.

Sentosa Serapong, May 15
Photo shared by Loh Kok Sheng on his blog.


Lazarus, Mar 20
Photo shared by Vincent Choo on facebook.

St John's Island, Oct 20
Photo shared by Loh Kok Sheng on facebook.

Pulau Tekukor, May 10
Photo shared by Neo Mei Lin on her blog.


Terumbu Semakau, Apr 21
Photo shared by Marcus Ng on facebook.

Terumbu Raya, Aug 14
Photo shared by Jianlin Liu on facebook.

Terumbu Bemban, Jun 20
Photo shared by Dayna Cheah on facebook.


Terumbu Pempang Tengah, Sep 14
Photo shared by Loh Kok Sheng on his blog.

Pulau Biola, Jan 22
Photo shared by Vincent Choo on facebook.

Raffles Lighthouse, Jan 22
Photo shared by Vincent Choo on facebook.


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

Pulau Sudong, Dec 09


Pulau Salu, Apr 21
Photo shared by Toh Chay Hoon on facebook.

Pulau Senang, Aug 10

Terumbu Berkas, Jan 10
Photo shared by Loh Kok Sheng on his flickr.

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.

Links

References
  • 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, L.J. & Cannon, L.R.G. Nine new species of Pseudobiceros (Platyhelminthes: Polycladida) from Indo-Pacific. Pp. 341-368. in the Raffles Bulletin of Zoology vol 45.
  • Newman, Leslie and Lester Cannon. 2003. Marine Flatworms: The World of Polyclads. CSIRO Publishing. 97pp.
  • Humann, Paul and Ned Deloach. 2010. Reef Creature Identification: Tropical Pacific New World Publications. 497pp.
  • Kuiter, Rudie H and Helmut Debelius. 2009. World Atlas of Marine Fauna. IKAN-Unterwasserachiv. 723pp.
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