Sampling the depth: New data on the Caecidae (Mollusca, Gastropoda) from northeastern Papua New Guinea

The Caecidae J. E. Gray, 1850 collected from several deep-water stations of the BIOPAPUA, PAPUA NIUGINI and KAVIENG expeditions carried out by the Muséum national d’Histoire naturelle, Paris, are revised. About 200 specimens of this family were collected, belonging to three genera and 20 species, i.e., Caecum Fleming, 1813 (15 species), Mauroceras Vannozzi, 2019 (three species) and Parastrophia de Folin, 1869 (two species). Five species are described as new: Caecum restrictum n. sp., C. miliarium n. sp., C. microannulatum n. sp., C. lozoueti n. sp. and C. temporale n. sp. All recorded species are illustrated. Except for C. miliarium n. sp., occurring in large number in the type locality and showing the complete growth sequence, all species are represented by few specimens, often in poor condition. With the addition of the five new species and the new record of Caecum dakuwaqa Pizzini, Raines & Vannozzi, 2013, the inventory of the Caecidae known from northeastern Papua New Guinea reached 43 species. Furthermore, an indeterminate specimen, possibly belonging to an undescribed species, is illustrated.