Hong Kong Plocamopherus ceylonicus

March 11, 2002
From: W.B. Rudman & B.W. Darvell

Here is some information and photos on Plocamopherus ceylonicus from Brian Darvell's Hong Kong collections.

The mantle is reduced to a head shield or veil around the anterior end and a set of three large papillae down each side of the body. There are about twelve arborescent papillae on the edge of the head shield and some or all of the large lateral papillae can have a large terminal sphere which can luminesce when the animal is disturbed. There are also scattered arborescent papillae on the sides of the body and the posterior end of the foot has a large crest in the dorsal midline.

Specimens from Hong Kong are a translucent white with a dark grey-brown irregular reticulate pattern and yellow spots. In Australia and the Indian Ocean the yellow spots become less prominent and the dark reticulate pattern becomes a heavy patching of brown or orange-brown.

Like other species of the genus, P. ceylonicus feeds on bryozoans and can swim when disturbed or dislodged by flattening its body dorso-ventrally and vigorously bending its body backwards and forwards laterally. It grows to approximately 45 mm in length.

PHOTO:
AM C139085, 2 specimens, 8 April 1983, Site 5.51, Heung Lo Po, Tolo Channel (Gruff Head), 5-10 m, Hong Kong. Photo: Brian Darvell.

Hong Kong Collection Records:
AM C139085, 2 specimens, 8 April 1983, Site 5.51, Heung Lo Po, Tolo Channel (Gruff Head), 5-10 m. AM C139086, 8 April 1983, Site 5.51, Heung Lo Po, Tolo Channel (Gruff Head), 5-10 m. AM C139087, 3 specimens, 11 April 1983, Site 4.60, Kong Chan (NW), Mirs Bay, 5-10 m. AM C139088, 2 specimens, 12 April 1983, Site 6.62, Flat Reef, Tolo Channel, 7-12 m. AM C139089, 5 specimens, 14 April 1983, Site 2.32, Round Is. (E), Mirs Bay, 3-10 m. AM C140154, 2 specimens, 8 May 1983, Site 2.66, Round Is. (W), Mirs Bay, 4-6 m. AM C140164, [not known]. AM C 1423 35, 1 0 June 1984, Site 9.108, Chi Chau (NW), Rocky Harbour, I m. AM C146972, 10 specimens, 5 May 1985, Site 9.159, 'Dolphin Reef', Rocky Harbour, I m. AM C149774, 19 October 1985, Site 10. 168, Kiu Tsui Chau (W of Tai Ngam Tsui), Port Shelter, 6 m. Depth range: 1-12 m.

Reference:
• Rudman, W.B. & Darvell, B.W. (1990) Opisthobranch molluscs of Hong Kong. Part 1. Goniodorididae, Onchidorididae, Triophidae, Gymnodorididae, Chromodorididae, (Nudibranchia). Asian Marine Biology, 7: 31-79

Best wishes,
Bill Rudman & Brian Darvell

Rudman, W.B. & Darvell, B.W., 2002 (Mar 11) Hong Kong Plocamopherus ceylonicus. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6071

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