Pseudoceros bolool Newman and Cannon, 1994
The diagnostic character of this species is the even black coloration on the dorsal surface.
External anatomy: Even black dorsal surface with velvet appearance. Ventrally, the animal is light gray, darker towards the margins. The pseudotentacles are made by simple folds of the anterior margin. There is cerebral cluster formed by about 60 eyespots in a clear area. Small branched pharynx pseudoceros-type with elaborated folds.
Internal anatomy: An elongated and oblong seminal vesicle connected to a coiled ejaculatory duct, and a round prostatic vesicle. A wide male antrum housing a short stylet. The female system consists of a shallow antrum and a tubular and extended vagina surrounded by cement glands.
This species has been found in Heron Island and One Tree Island in Australia and Madang in Papua New Guinea. It was also found in the Caribbean, specifically on the rocky shore of XXX in Curaçao.
This species has been found on the reef crest under the boulders associated to encrusting colonial tunicates and under the coral rubble of the reef slope.
The holotype is a whole mount of an entire specimen and the paratype is a set of serial histological sections deposited at the Queensland Museum in Brisbane, Australia.
Newman & Cannon (1994) included this species into the group 1 distinguished by an even color, according to the categories created by the same authors based on the color pattern. There are few cotyleans with an even color background like P. periviolaceus with a purple dorsal surface located in the same category. Hyman (1959) described Pseudoceros ater which also shows a dark even coloration, however, the author stated that the presence of a simple pharynx suggests that this species belongs to the genus Pseudobiceros (Newman & Cannon 1994). P. bolool is frequently found together with the nudibranch Dendrodoris nigra which also shows an even black coloration suggesting a possible case of mimicry.