The slugs and semislugs of Sabah, Malaysian Borneo (Gastropoda, Pulmonata: Veronicellidae, Rathouisiidae, Ariophantidae, Limacidae, Philomycidae)

As a part of an inventory of the terrestrial malacofauna of the Malaysian state of Sabah (northern Borneo), the slugs and semislugs were given particular attention. Except for several exotic and presumed exotic species, slugs and semislugs are generally rare and infrequently encountered, mostly at high altitudes, where several short-range endemics appear to exist. We describe one new species, viz: Ibycus rachelae nov. spec. (Ariophantidae). We furthermore present new records and characters for identification of other species, namely: the veronicellids Laevicaulis alte (Férussac, 1821), Valiguna flava (Heynemann, 1885), and Semperula wallacei (Issel, 1874), the rathouisiid Atopos punctata Collinge, 1902, the ariophantids Microparmarion pollonerai Collinge & Godwin Austen, 1895, M. simrothi Collinge & Godwin Austen, 1895, Parmarion martensi Simroth, 1893, and Philippinella möllendorffi (Collinge, 1899), the limacid Deroceras reticulatum (Müller, 1774), and the philomycids Meghimatium striatum (Van Hasselt, 1824), M. uniforme Laidlaw, 1937, and M. pictum (Stoliczka, 1872). For the genus Meghimatium, our taxonomy is based on a molecular phylogenetic reconstruction, which we present. Finally, we provide reports and illustrations on several species for which the available material is currently insufficient for formal identification, namely, an unidentified Atopos (Rathouisiidae), for which only juveniles (preying on Opisthostoma) were found, a second unidentified Atopos (Rathouisiidae) and an unidentified Microparmarion (Ariophantidae) for each of which only a single adult was available, as well as an unidentified Parmarion (Ariophantidae) known only from a photograph.