Cycloporus venetus Neuman & Cannon, 2002 (12mm)

Featured Invertebrate Data


Frequency on Okinawa: Collection Data:
[brackets indicate range for all Okinawa-collected specimens of the species]

Species Account:

        Cycloporus venetus is considered to be rare on Okinawa as I have collected only two individuals, although I've photographed two additional individuals over a period of more than twenty years of Okinawa diving.

        The following original description of Cycloporus venetus and discussion is from Neuman & Cannon (2002).

Diagnosis. - Blue with narrow median white stripe and wide yellow margin, tentacular bumps with a black spot.

Remarks. - No other Cycloporus has such a unique colour pattern.

Habitat & distribution. - Rare from Exmouth, WA.


It is apparent that flatworms belonging to the family Euryleptidae are more common than previously thought. In general, these polyclads are smaller than the more conspicuous pseudocerotids and may have been overlooked. Furthermore, several of these animals were found closely associated with their prey, colonial ascidians, and have not been found roaming about like the larger pseudocerotids.

Identification of Cycloporus species has proven to be problematic since there are few reliable taxonomic characters. It appears that pattern is the most reliable character available to separate species, however, the colour of animals varies depending on what they consume. Many animals appeared to be generally dark brown owing to the dark brown food particles in the gut diverticula. The relative number of cerebral and tentacular eyes is also a useful character to differentiate some species although the exact number of eyes was found to vary intra-specifically. The reliability of the number of lateral intestinal branches as a taxonomic character is questionable: they were extremely hard to see in the wholemounts especially if the animals were sexually mature and full of eggs in the swollen, branching oviducts. Details of the reproductive anatomy have not been given here as there is no information from the previous literature for comparison.

        There are a series of photographs of Cycloporus venetus on-line via Google.


Literature Cited:

        I've added a second page w/ a series of images of the species.

        In addition, I've added a link to the current and past featured invertebrates via a list and thumbnails.

Page Date: 01 May '18
Page Modification Date: 01 May '18
Digitally manipulated photo
Copyright © 2018 Robert F. Bolland