Additions to the knowledge of the land snails of Sabah (Malaysia, Borneo), including 48 new species Author Vermeulen, Jaap J. Author Liew, Thor-Seng Author Schilthuizen, Menno text ZooKeys 2015 531 1 139 http://dx.doi.org/10.3897/zookeys.531.6097 journal article http://dx.doi.org/10.3897/zookeys.531.6097 1313-2970-531-1 C845838EC9124BD8AB4E07980F91959E C845838EC9124BD8AB4E07980F91959E Taxon classification Animalia Architaenioglossa Cyclophoridae Ditropopsis tyloacron Vermeulen, Liew & Schilthuizen sp. n. Figure 12 Ditropopsis sp. "BO-02" , Schilthuizen et al. 2002 : 257-258. Holotype . Malaysia , Sabah , Tawau Province , Danum Valley Conservation Area ( RMNH5003920 ). Examined material from Sabah. Tawau Province. Danum Valley Conservation Area (leg. UMS students, V 9880, BOR/MOL 313). Description. Shell very small, rather thick, somewhat translucent, white to pale (yellowish) green. Surface shiny or glossy. Spire almost flat, but apex protruding, slightly oblique. Sculpture. Radial sculpture: fine growth lines, locally grading into fine, densely placed riblets. Spiral sculpture on the last whorl: 6 very distinct cords: 1 supraperipheral and 1 peripheral, the latter widest and widely projecting, 1 basal and 3 umbilical; next to these a fine spiral striation on the lower surface. Sculpture continuing up to the peristome, but close to the peristome distorted and partly obliterated by densely placed, low radial riblets and increasingly coarse spiral threads. Aperture. Peristome simple, not expanded, distinctly constricted in fully adult shells, parietal side attached to the penultimate whorl in fully adult shells, basal side angular, slightly to distinctly drawn out. Dimensions. Height 1.4-1.65 mm; width 2.5-2.8 mm; h/w 0.52-0.56; umbilicus measured over the basal spiral cord 33-37 % of the shell width; number of whorls c. 4; height aperture 0.7-0.9 mm; width aperture 0.8-0.9 mm. Figure 12-13. 12 Ditropopsis tyloacron sp. n. 12A Frontal view, shell 1.6 mm high 12B Frontal view, shell 1.5 mm high 12C Umbilical view (12A, 12C Malaysia, Sabah, Tawau Province, Danum Valley Conservation Area, RMNH.5003920, holotype; 12B Indonesia, Kalimantan Selatan, Meratus Mountains, c. 18 Km East of Barabai, Nateh near Batu Tangga, V 3003) 13 Ditropopsis constricta sp. n. 13A Frontal view, shell 1.5 mm high 13B Umbilical view (Malaysia, Sabah, Interior Province, Sepulut valley, Gua Sanaron, RMNH.5003919, holotype). Habitat in Sabah and distribution. Primary forest on limestone soil, rarely on sandstone, 0-600 m alt. Sabah: S.E. part. Also in Kalimantan, East part. Endemic to Borneo. Cross diagnosis. Well characterized among Sabah Ditropopsis by the low, almost flat spire with only the apex protruding. In Kalimantan the Sabah form (illustrated) locally grades into series with relatively smooth, large shells and with the supraperipheral and umbilical ridges partly or entirely missing. Such shells look a little like Ditropopsis imadatei and Ditropopsis cincta , but have a flatter spire and a wider umbilicus. Elsewhere, Ditropopsis moellendorfii Boettger, 1891 and Ditropopsis papuana E.A. Smith, 1897 have similarly flat shells, but the first has a double peristome, and the second a more rounded spire. Etymology. The name refers to the shape of the apex [tulos (Gr.) = knob; akros (Gr.) = at the top; a knobhead, therefore].