Tertiary and Quaternary fossil pyramidelloidean gastropods of Indonesia

The pyramidelloidean gastropods newly collected from one stratigraphic section and two spot localities in the Rembang anticlinorium (Middle Miocene, northeastern Java) are described and those of various ages in the collections of the Naturalis Biodiversity Center in Leiden are reviewed. A total of 111 species are covered in this paper; another 22 taxa dealt with by previous authors, of which the material was not available, are briefly commented on in an appendix. The “Rembangian” (Middle Miocene) assemblage consists of 89 species. Four are identified as formerly described species, namely Leucotina speciosa (Adams), Megastomia regina (Thiele), Exesilla dextra (Saurin) and Exesilla splendida (Martin); 52 are proposed as new; most of the others almost certainly represent previously undescribed species, but cannot be named because of inadequate material. Parodostomia jogjacartensis (Martin), Parodostomia vandijki (Martin) and Pyramidella nanggulanica Finlay, described from the Eocene deposits of Java, seem to be restricted to that epoch. The Neogene fauna appears to be composed almost entirely of extinct species. Only Leucotina speciosa (Adams), Megastomia regina (Thiele), Longchaeus turritus (Adams), Pyramidella balteata (Adams), Exesilla dextra (Saurin) and Nisiturris alma (Thiele) are still present in modern Indo-West Pacific faunas. Most Neogene species seem to be endemic of the Indonesian Archipelago; relationships with other West Pacific fossil faunas have been noted for only a few taxa. The relevance of shell characters in generic recognition, namely the protoconch type, the course and/or the inner lirations of the outer lip, and the sculpture (when present), are significant characters. None of them is genus-diagnostic in itself, but their combination distinguishes the various genera. On this basis, genera are revised and include only those species sharing the relevant characters of their respective type species. The new genera Bulimoscilla, Nisipyrgiscus, Turbolidium and Bulicingulina are introduced.