Pseudobiceros hancockanus (Collingwood, 1876) Newman and Cannon, 1994
The diagnostic character for this species is the black background with an inner wide orange band and outer narrow white band.
External anatomy: This species is one of the largest pseudocerotid recorded and has a black background with two distinct marginal bands, an inner wide orange and an outer narrow white. The ventral side is grey becoming intense purple medially with the same marginal band of the dorsal side. The pseudotentacles are square and slightly ruffled. The cerebral cluster consists of hundreds of eyespost. Long pharynx with simple folds and two male gonopores well separated.
Internal anatomy: The male complex consists of two male gonopores, each one leading to an independent male system. Each system consist of unbranched vas deferens, an elongated and large seminal vesicle connected to a short and not coiled ejaculatory duct, an extremely small prostatic vesicle and an extremely small stylet housed in a shallow antrum. There is a single female system with a shallow antrum and a short vagina surrounded by the cement glands.
This species has been found in Heron Islands from the Great Barrier Reef to Laccadives, Japan, Singapore, and Philippines.
This is a common species found under ledges on the reef slope.
The location of the type material is unknown but there is a whole mount and a set of serial histological sections deposited at the Queensland Museum in Brisbane, Australia.
Newman & Cannon (1994) made the new combination Pseudobiceros hancockanus, based on the presence of the double male system and the type of pharynx. This species was included in to the group 2 because of the marginal bands, according to the categorization based on the color and color pattern created by the same authors. Within this group most of the species have a black background and bright colored marginal bands. Although P. uniarborensis has orange and white marginal bands, they are narrower plus an additional grey band.
Proceros hancockanus (Collingwood, 1876); Stylochopsis malayensis (Collingwood, 1876); Prostheceraeus hancockanus (Collingwood) Lang 1884; Pseudoceros malayensis (Collingwood) Bock 1913; Pseudoceros hancockanus (Collingwood, 1876).