Land snails and slugs of Bau limestone hills, Sarawak (Malaysia, Borneo), with the descriptions of 13 new species Author Marzuki, Mohammad Effendi bin Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, 94300, Kota Samarahan, Sarawak, Malaysia & Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, Jalan UMS, 88450, Kota Kinabalu, Sabah, Malaysia fendiemz@gmail.com Author Liew, Thor-Seng https://orcid.org/0000-0002-9437-5924 Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, Jalan UMS, 88450, Kota Kinabalu, Sabah, Malaysia thorsengliew@gmail.com Author Mohd-Azlan, Jayasilan Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, 94300, Kota Samarahan, Sarawak, Malaysia text ZooKeys 2021 2021-04-27 1035 1 113 http://dx.doi.org/10.3897/zookeys.1035.60843 journal article http://dx.doi.org/10.3897/zookeys.1035.60843 1313-2970-1035-1 ED19022EA1704DB79587FEFE15D07854 4C2258D4EE6754488B9280D3AB0447A1 Japonia bauensis sp. nov. Figures 4C, D , 5 Material examined. Holotype (SH 5.84 mm , SW 8.00 mm) (MZU.MOL.20.02), Malaysia , Sarawak, Kuching Division , Gunung Doya , limestone hill near Sungai Sebuyoh , 3.4 miles SE Bau , 1°22'57.24"N , 110°11'39.42"E , coll. M. E. Marzuki , 7.I.2018 . Paratypes : 1 ex. (ME0000817), the same locality as Holotype, coll. M. E. Marzuki , 10.VII.2011 ; 1 ex. (ME0009667), Bukit Sokwang ( Site 3), northern site of Gunung Doya , limestone hill along Skio road, 2.05 miles E Bau , 1°23'49.87"N , 110°10'32.14"E , coll. M. E. Marzuki , 7.I.2018 ; 4 ex. (ME0008907), the same locality, coll. M. E. Marzuki , 22.IV.2017 ; 1 ex. (ME0009167), Bukit Sokwang ( Site 2), northern site of Gunung Doya , limestone hill along Skio road, 2.05 miles E Bau , 1°23'45.69"N , 110°10'35.04"E , coll. M. E. Marzuki , 22.IV.2017 ;> 10 ex. (ME0000743), Fairy Caves ( Site 1), south part of Gunung Kapor , 4 miles SW Bau , 1°22'53.76"N , 110°7'4.34"E , coll. M. E. Marzuki , 18.VIII.2007 ;> 10 ex. (ME0000779), the same locality, coll. M. E. Marzuki , 11.III.2011 ; 4 ex. (ME0005974), the same locality, coll. M. E. Marzuki , 21.II.2015 ;> 10 ex. (ME0007231), the same locality, coll. M. E. Marzuki , 27.X.2008 ; 2 ex. (MZU.MOL.20.03), the same locality, coll. M. E. Marzuki , 27.X.2008 ; 6 ex. (ME0008491), the same locality, coll. M. E. Marzuki , 10.II.2017 ; 1 ex. (ME0009216), the same locality, coll. M. E. Marzuki , 8.IV.2017 . Differential diagnosis. It differs from Japonia barbata (L. Pfeiffer, 1855) by having a smaller shell (shell height: 5.84-6.20 mm vs. 6.25-9.25 mm; shell width: 8.0-8.88 mm vs. 9.5-15.8 mm). In addition, it has very short feather-like periostracal hairs along the first peripheral ridge, while J. barbata has five-times longer feather-like periostracal hairs. Description. Shell small, depressed-conical, dextral, rather solid. Colour brownish to yellowish white, translucent, shiny with or without prominent brown radiating markings. Suture impressed. Whorls 51/4 , convex, regularly increasing in diameter. Periphery rounded, slightly angular at ultimate whorl. Protoconch: smooth, dark brown, more or less rounded without spiral striae. Teleoconch with radial sculpture consisting of very fine transverse growth lines all over the shell. Spiral sculpture with seven spiral ridges, three above periphery, two along periphery, one below periphery, and one near base. Spiral striae absent. Aperture almost circular, somewhat oblique, parietal area between two spiral ridges below periphery and near base. Peristomes double, with prominent outer peristome except for the supra-columellar site, with a distinct notch near suture, inner peristome slightly expanded. Periostracum thin, corneous, and smooth with very short, deciduous, slender, feather-like hairs along first peripheral ridge and below periphery in fresh condition. Umbilicus: open, moderately wide, 1.80-2.00 mm in diameter. Dimensions: Shell height 5.84-6.20 mm; shell width 8.0-8.88 mm; Aperture height and width 2.60 mm. Remarks. Shells of some populations (i.e., Gunung Kapor areas) without or with inconspicuous spiral lirae (Fig. 4C ). Geographic distribution and habitat. Bau and Serian-Padawan limestone hill clusters. Living snails were observed foraging among leaf litter and plant debris near the cliff in lowland limestone forest. Etymology. For Bau District, where the specimens were found. Figure 5. Japonia bauensis sp. nov., ME 7231 paratype. Enlargement of the body whorl showing the shell sculpture.