Perotrochus pseudogranulosus: Perotrochus pseudogranulosus is a recently described medium-sized slit shell, previously confused with P. caledonicus Bouchet & Metivier, 1982. Due to the well-known existence of a « smooth » and a « pustulose » form with apparently no intergrades, there has been a long suspicion that Perotrochus species from around New Caledonia, previously all attributed to P. caledonicus, might actually be a species complex of at least two species. Indeed, an investigation using both morphology and molecular sequencing of the COI barcoding gene revealed in 2015 that the two were distinct species. The « smooth » form with unbeaded to weakly beaded spiral ribs but lacking in significant pustulation matches the type series of P. caledonicus, whereas the « pustulose » form with strongly beaded ribs is a separate species described as P. wareni Anseeuw, Puillandre, Utge & Bouchet, 2015. Surprisingly however, a further previously undescribed species was detected from the Coral Sea material ~ P. pseudogranulosus. Perotrochus pseudogranulosus is rather similar to P. caledonicus but can be distinguished by a more conical shell with much more flattened basal disc, the presence of a characteristic strong metallic lustre on the shell surface, and a more regular « checkerboard » pattern under the selenizone. The spiral cords tend to be finely beaded, especially above the selenizone, hence the specific epithet. Phylogenetic reconstructions using the COI gene suggest it is in fact most closely related not to P. caledonicus but to P. deforgesi Metivier, 1990, which is sister to the P. caledonicus ~ P. wareni group. The original description was based only from materials collected from the Coral Sea and restricted to the Chesterfield Plateau; but seeing a number of specimens has turned up in the shell trade throughout the past years with the locality data near New Caledonia, its true distribution may extend to as far as western New Caledonia. Presumably a carnivorous grazer feeding mostly sponges like other pleurotomariids, it inhabits rather deep water around -300~500m deep. Typical shell diameter around 40mm., extremely large specimens may exceed 55mm. This species appears to be rare in the shell trade market, much rarer than either P. caledonicus or P. wareni, most likely due to its main habitat in the Coral Sea is too remote for regular visits to be made.