“In limestone caves at Jambusan, Borneo” [= Jambusan Hills, Bau, Sarawak].

Gunung Sebayat: ME 8005. Gunung Doya: ME 9699, ME 9148, ME 9179. Gunung Kapor: ME 3357, ME 3359, ME 3362, ME 8085, ME 8488, ME 9046, ME 9078, ME 9471. Lobang Angin: ME 9038, ME 9432. Gunung Batu: ME 3351, ME 3352, ME 3353, ME 8802.

Sarawak: Kuching, Serian, and Kapit divisions. Sabah: Sandakan, Tawau, and West Coast divisions. Endemic to Borneo.

Only dry shells were found during the surveys.

Figure 2. 

A Chamalycaeus specus (Godwin-Austen, 1889) ME 9046 Gunung Kapor B Pincerna globosa (H. Adams, 1870) ME 6979 Lobang Angin C Stomacosmethis hosei (Godwin-Austen, 1889) ME 1010 Gunung Batu D Stomacosmethis sadongensis (E. A. Smith, 1895) ME 8761 Gunung Kapor.

“Busan, near Sarawak, Borneo” [= Jambusan Hills, Bau, Sarawak].

Bukit Sekunyit: ME 1016, ME 6980. Gunung Doya: ME 1059, ME 9698, ME 8958, ME 9090. Gunung Kapor: ME 1004, ME 1015, ME 1053, ME 8489, ME 8974. Gunung Stulang: ME 5904. Lobang Angin: ME 1029, ME 6979, ME 8726, ME 8746, ME 8749, ME 9022. Gunung Batu: ME 1014, ME 1023, ME 1054, ME 8829.

Sarawak: Kuching, Serian, and Miri divisions. Sabah: West Coast Division. Endemic to Borneo.

Smith (1895) classified Pincerna globosa into five different forms: globosa, rabongensis, muluana, kinabaluana, and pygmaea, of which two forms were collected from Bau: globosa with a smaller yellowish orange shell while rabongensis has a larger yellow shell. The differences between the two forms may due to sexual dimorphism; hence, we considered these forms as synonyms. Living snails were observed foraging on the leaf surfaces of small trees and palms at the base of the limestone cliff.

“Busan Hills, Borneo” [= Jambusan Hills, Bau, Sarawak].

Gunung Doya: ME 1088, ME 9133. Gunung Kapor: ME 1024, ME 8084. Gunung Stulang: ME 5903. Gunung Batu: ME 1002, ME 1010, ME 7180, ME 8803.

Sarawak: Kuching and Serian divisions. Endemic to Borneo.

Living snails were observed foraging on the moderately wet vertical limestone rock surfaces that covered with lichens. The shell of this snail is always covered with calcareous dirt.

“Sadong, Sarawak”.

Gunung Kapor: ME 1003, ME 8761. Gunung Batu: ME 2896, ME 2900, ME 8804.

Sarawak: Kuching and Serian divisions. Endemic to Borneo.

This species differs from other Bornean species of Stomacosmethis by having a shell with dense, regular, rather low riblets on the shell instead of irregular low riblets. Living snails were observed foraging on wet vertical limestone rock surfaces covered with mosses and lichens.

“Busan Hills, Borneo” [= Jambusan Hills, Sarawak].

Gunung Doya: ME 8909, ME 9182. Gunung Batu: ME 0839, ME 2839.

Sarawak: Kuching and Miri division. Endemic to Borneo.

Only dry shells were found during the surveys.

Figure 3. 

A Craspedotropis borneensis (Godwin-Austen, 1889) ME 839 Gunung Batu B Cyclophorus perdix borneensis (Metcalfe, 1851) ME 8921 Gunung Doya C Ditropopsis everetti (E. A. Smith, 1895) ME 835 Gunung Kapor.

“Borneo”.

Gunung Sebayat: ME 8007. Bukit Sekunyit: ME 2631. Gunung Doya: ME 2675, ME 8921, ME 8947, ME 9169. Gunung Kapor: ME 2636, ME 2647, ME 8068, ME 8706, ME 8753, ME 8769, ME 9468. Gunung Stulang: ME 5905. Kampung Bunga Rampai: ME 2610, ME 5947. Kampung Padang Pan: ME 6667. Lobang Angin: ME 2648, ME 9183, ME 9483. Gunung Batu: ME 2633, ME 2642, ME 8805.

Sarawak: Kuching, Samarahan, Serian, Mukah, Kapit, and Miri divisions. Sabah: West Coast Division. Kalimantan: West, South, and East Kalimantan provinces. Distribution elsewhere. West Malaysia (Stoliczka 1872; Morgan 1885).

Living snails were observed foraging among leaf litter and plant debris near the cliff in lowland limestone forest.

“Rumbang, Sarawak” [= Rumbang Hills, Padawan, Sarawak].

Gunung Sebayat: ME 8009. Gunung Kapor: ME 0835, ME 0842, ME 8494, ME 9079, ME 9239.

Sarawak: Kuching Division. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in a limestone forest. It differs from other Bornean Ditropopsis species by having seven distinct lirae on the last whorl (one supra-peripheral, two peripheral, one basal, and three umbilical), instead of 4–6 lirae.

“Borneo, Sarawak”.

Gunung Doya: ME 0817, ME 8903, ME 9092, ME 9668. Gunung Kapor: ME 0737, ME 0780, ME 0784, ME 2949, ME 8069, ME 8490, ME 8768, ME 8783, ME 9047, ME 9609, ME 9841. Lobang Angin: ME 0791, ME 9083, ME 9134, ME 9275. Gunung Batu: ME 0783, ME 0796, ME 0800, ME 8808. Gunung Sebayat: ME 8008. Kampung Bunga Rampai: ME 0833, ME 0834. Kampung Padang Pan: ME 6668.

Sarawak: Kuching, Samarahan, Serian, Sibu, and Mukah divisions. Endemic to Borneo.

It differs from other Bornean Japonia species by the following combination of characters: more depressed medium-sized shell with wide umbilicus, last whorl with distinctly keeled periphery, with long, deciduous, slender, feather-like periostracal hairs along the first peripheral ridge and below the periphery. Shells of different local populations may vary: shells from near Jambusan have a smooth surface with very faint lirae; shells from near Lobang Angin have a distinctly keeled periphery (Fig. 4B); shells from non-limestone areas usually have a somewhat rounded periphery (Fig. 4A). Japonia similis (E. A. Smith, 1893) differs by having a larger, high spired shell with moderately wide umbilicus. Living snails were observed foraging among leaf litter and plant debris near the cliff in lowland limestone forest.

Figure 4. 

A Japonia barbata (L. Pfeiffer, 1855) ME 833 Kampung Bunga Rampai B Japonia barbata (L. Pfeiffer, 1855) ME 2141 Lobang Angin C Japonia bauensis sp. nov., ME 7231 paratype Gunung Kapor D Japonia bauensis sp. nov., MZU.MOL.20.02 holotype Gunung Doya.

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.

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.

Shell small, depressed-conical, dextral, rather solid. Colour brownish to yellowish white, translucent, shiny with or without prominent brown radiating markings. Suture impressed. Whorls 5¼, 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.

Shells of some populations (i.e., Gunung Kapor areas) without or with inconspicuous spiral lirae (Fig. 4C).

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.

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.

“Territorio di Sarawak”.

Gunung Doya: ME 9161. Lobang Angin: ME 9279. Gunung Batu: ME 2916.

Sarawak: Kuching Division. Endemic to Borneo.

Only dry shells were found during the surveys.

Figure 6. 

A Japonia metcalfei (Issel, 1874) ME 2916 Gunung Batu B Japonia mundyana (Godwin-Austen, 1889) ME 0838 Gunung Batu C Japonia rabongensis (E. A. Smith, 1895) ME 9080 Gunung Kapor D Leptopoma sericatum (L. Pfeiffer, 1851) ME 5900 Gunung Stulang E Leptopoma undatum (Metcalfe, 1851) ME 2684 Gunung Batu.

“Busan Hills, Borneo” [= Jambusan Hills, Bau, Sarawak].

Gunung Kapor: ME 0821, ME 8493, ME 9249. Gunung Batu: ME 0808, ME 0838.

Sarawak: Kuching Division. Endemic to Borneo.

It differs from other the Bornean Japonia species by having a considerably smaller shell with higher spire. Only dry shells were found during the surveys.

“Mount Rabong, West Sarawak”.

Gunung Kapor: ME 8492, ME 9080. Gunung Batu: ME 0824.

Sarawak: Kuching Division. Endemic to Borneo.

It is similar to Japonia metcalfei (Issel, 1874), but differs in having higher spire and narrower umbilicus. Only dry shells were found during the surveys.

“Borneo”.

Bukit Sekunyit: ME 1350. Gunung Doya: ME 1355, ME 8906, ME 9155. Gunung Kapor: ME 1290, ME 1347, ME 1352, ME 8070, ME 9232, ME 9403. Gunung Stulang: ME 5900. Gunung Batu: ME 1351, ME 1354, ME 1359, ME 8831.

Sarawak: Kuching, Serian, Kapit and Miri division. Sabah, Brunei Darussalam, Kalimantan: West, South, and East Kalimantan provinces. Endemic to Borneo.

“Borneo”.

Gunung Stulang: ME 5899. Kampung Padang Pan: ME 6723. Gunung Batu: ME 2684, ME 2686.

Sarawak: Kuching and Miri divisions. Sabah: Interior, Sandakan, Tawau, and West Coast divisions. Brunei Darussalam: Temburong District. Kalimantan: West and East Kalimantan provinces. Distribution elsewhere. Palawan (Vermeulen 1999).

“Java” [= Borneo (Metcalfe, 1851)].

Gunung Doya: ME 4744, ME 9144, ME 9192. Gunung Kapor: ME 3723, ME 4742, ME 4746, ME 5973, ME 8073, ME 8460, ME 8754, ME 8757, ME 8777. Lobang Angin: ME 4743, ME 8725, ME 8729, ME 8739, ME 9484. Gunung Batu: ME 4745, ME 4748, ME 8806.

Sarawak: Kuching, Samarahan, Serian, and Sibu divisions. Kalimantan: West Kalimantan Province. Endemic to Borneo.

Figure 7. 

A Opisthophorus biciliatus (Mousson, 1849) ME 8754 Gunung Kapor B Opisthophorus birostris (L. Pfeiffer, 1854) ME 8758 Gunung Kapor C Opisthophorus cavernae (Godwin-Austen, 1889) ME 8904 Gunung Doya D Opisthophorus euryomphalus (L. Pfeiffer, 1856) ME 8779 Gunung Kapor E Platyrhaphe linita (Godwin-Austen, 1889) ME 0881 Gunung Batu F Pterocyclos tenuilabiatus (Metcalfe, 1851) ME 5910 Gunung Batu.

Living snails were observed foraging among leaf litter and plant debris near the cliff in lowland limestone forest. It differs from other Bornean Opisthoporus species by having a moderately large shell, short sutural tube projecting upwards, and long, double, deciduous appendages along the first peripheral ridge and below the periphery that can be seen on a fresh shell.

“Sarawak, Borneo”.

Bukit Sekunyit: ME 4735. Gunung Doya: ME 1312. Gunung Kapor: ME 4731, ME 4736, ME 4737, ME 8072, ME 8495, ME 8755, ME 8758, ME 9605. Lobang Angin: ME 4738. Gunung Batu: ME 4732, ME 4734, ME 4739, ME 8830.

Sarawak: Kuching Division. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in lowland limestone forest. It differs from other Bornean Opisthoporus species by having a large shell, short sutural tube projecting downwards, and a thick brown periostracum can be seen on fresh shells.

“Sarawak proper, Borneo” [= Kuching, Sarawak].

Gunung Doya: ME 8904, ME 9093.

Sarawak: Kuching and Serian divisions. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in lowland limestone forest. It differs other Bornean Opisthoporus species by having a moderate shell, short sutural tube projecting upward, long Rhiostoma-like detached tuba.

“Borneo”.

Gunung Doya: ME 1295, ME 8905, ME 9113, ME 9157. Gunung Kapor: ME 1294, ME 1298, ME 1299, ME 8071, ME 8496, ME 8779. Gunung Batu: ME 1300, ME 1301, ME 2613, ME 8807.

Sarawak: Kuching Division. Kalimantan: West Kalimantan Province. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest. It differs from O. biciliatus by having a smaller shell without the hairy periostracum.

“Busan Hills, Borneo” [= Jambusan Hills, Bau, Sarawak].

Gunung Doya: ME 9700, ME 8908, ME 9094, ME 9175. Gunung Batu: ME 0881, ME 0882.

Sarawak: Kuching and Serian divisions. Endemic to Borneo.

This species is one of only four species of Platyrhaphe described from Borneo and the only one recorded from Sarawak. Living snails were observed foraging among leaf litter and plant debris near the cliff in lowland limestone forest. The shell is always covered with thick dirt.

“Borneo”.

Gunung Kapor: ME 8074, ME 9467. Gunung Stulang: ME 5901.

Sabah: West Coast, Interior, Sandakan, and Tawau divisions. SARAWAK: Kuching Division. Kalimantan: West Kalimantan Province. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

Singapore.

Bukit Sekunyit: ME 0462. Gunung Doya: ME 0543, ME 9695, ME 8898, ME 9089. Gunung Kapor: ME 0455, ME 0456, ME 0523, ME 0525, ME 8067, ME 8513, ME 8760, ME 8766, ME 8776. Kampung Padang Pan: ME 6672. Lobang Angin: ME 0463, ME 0524, ME 8735, ME 8742, ME 8748. Gunung Batu: ME 0459, ME 0526, ME 0535, ME 8799.

Sarawak: Kuching and Serian divisions. Sabah: Tawau Division. Distribution elsewhere. West Malaysia, Singapore, Bunguran (Indonesia) and Sirhassen (Indonesia) (Laidlaw 1949).

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

Figure 8. 

A Diplommatina adversa (H. Adams & A. Adams, 1851) ME 8799 Gunung Batu B Diplommatina busanensis Godwin-Austen, 1889 ME 8991 Gunung Doya C Diplommatina concinna H. Adams, 1872 ME 8745 Lobang Angin D Diplommatina isseli Godwin-Austen, 1889 ME 2869 Gunung Batu.

“Busan Hills, Borneo” [= Jambusan Hills, Bau, Sarawak].

Gunung Doya: ME 8902, ME 8991, ME 9088. Gunung Kapor: ME 0307, ME 0483, ME 0600, ME 8485, ME 9233, ME 9260, ME 9278. Gunung Batu: ME 0467, ME 8800.

Sarawak: Kuching Division. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

“Borneo”.

Gunung Sebayat: ME 8003. Bukit Sekunyit: ME 0464. Gunung Doya: ME 0544, ME 9696, ME 8992, ME 9087, ME 9101. Gunung Kapor: ME 0466, ME 0491, ME 0517, ME 0599, ME 8147, ME 8484, ME 9005, ME 9137, ME 9230. Gunung Stulang: ME 5902. Kampung Bunga Rampai: ME 0736. Kampung Padang Pan: ME 6671. Lobang Angin: ME 0515, ME 8745, ME 8981, ME 9024. Gunung Batu: ME 0512, ME 0538, ME 0540, ME 0597, ME 8797.

Sarawak: Kuching, Serian, and Miri divisions. Distribution elsewhere. Bunguran (Indonesia) (Smith 1874).

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

“Sarawak proper and Busan Hills, Borneo” [= Jambusan Hills, Bau, Sarawak].

Gunung Batu: ME 2869.

Sarawak: Kuching Division. Sabah: Interior and West Coast divisions. Endemic to Borneo.

Only dry shells were found during the surveys.

“Gua Madu, Kelantan”.

Gunung Sebayat: ME 8004. Gunung Doya: ME 0542, ME 9030, ME 9086, ME 9162. Gunung Kapor: ME 0475, ME 0532, ME 0598, ME 8486, ME 9004, ME 9028, ME 9076. Gunung Batu: ME 0534, ME 8798.

Sarawak: Kuching, Serian and Miri divisions. Distribution elsewhere. West Malaysia (Laidlaw 1949).

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

Figure 9. 

A Diplommatina maduana maduana Laidlaw, 1949 ME 9030 Gunung Doya B Diplommatina onyx Fulton, 1901 ME 9102 Gunung Doya C Diplommatina spinosa Godwin-Austen, 1889 ME 8801 Gunung Batu D Diplommatina toretos Vermeulen, 1993 ME 0536 Gunung Batu.

“Busan, N. Borneo” [= Jambusan Hills, Sarawak].

Gunung Doya: ME 0541, ME 9014, ME 9102, ME 9150. Gunung Kapor: ME 8487. Gunung Batu: ME 0484, ME 0537, ME 8888.

Sarawak: Kuching, Serian, and Miri divisions. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

“Cave exploration A, Borneo” [= Tupak Cave, Jambusan Hills (Cranbrook, 2013)].

Gunung Batu: ME 0522, ME 0539, ME 0596, ME 8801.

Sarawak: Kuching and Serian divisions. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

“SARAWAK. 1^st Div.: G. Pangga 3 km ENE of Bau”.

Gunung Doya: ME 0545. Gunung Batu: ME 0536.

Sarawak: Kuching, Serian and Miri divisions. Endemic to Borneo.

Only dry shells were found during the surveys.

“SARAWAK. 1^st Div.: G. Kapur 6 km SE of Bau”.

Gunung Doya: ME 8989, ME 9109, ME 9149. Gunung Kapor: ME 0274, ME 0277, ME 9002, ME 9206. Lobang Angin: ME 9171. Gunung Batu: ME 0273, ME 0276, ME 0331, ME 8796.

Sarawak: Kuching Division. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

Figure 10. 

A Opisthostoma ballorum Vermeulen, 1991 ME 9002 Gunung Kapor B Opisthostoma brachyacrum brachyacrum Thompson, 1978 ME 0353 Gunung Batu C Opisthostoma brachyacrum lambi (Vermeulen, 1991) ME 9003 Gunung Kapor D Opisthostoma cryptodon Vermeulen, 1991 ME 9084 Gunung Doya.

“BORNEO: Sarawak. Fourth Division. Limestone hill on the trail from the Niah River to Niah Cave, Batu Niah”.

Gunung Kapor: ME 0285. Gunung Batu: ME 0279, ME 0284, ME 0353.

Sarawak: Kuching and Miri divisions. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

“SARAWAK. 1^st Div.: W of Kpg. Lobang Batu 12.5 km S of Tebakang”.

Gunung Sebayat: ME 8002. Bukit Sekunyit: ME 0311. Gunung Doya: ME 0287, ME 9082, ME 9246. Gunung Kapor: ME 0281, ME 0310, ME 2875, ME 8978, ME 9003, ME 9077. Kampung Padang Pan: ME 6670. Lobang Angin: ME 9106, ME 9147, ME 9224.

Sarawak: Kuching, Serian and Kapit divisions. Sabah: Interior and West Coast divisions. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

“SARAWAK. 1^st Div.: W of Kpg. Lobang Batu 12.5 km S of Tebakang”.

Gunung Doya: ME 8901, ME 8988, ME 9084. Gunung Kapor: ME 0278, ME 9099, ME 9253. Lobang Angin: ME 8980, ME 9141. Gunung Batu: ME 0329.

Sarawak: Kuching and Serian divisions. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in lowland limestone forest.

“SARAWAK. 1^st Div.: G. Kapur 6 km SE of Bau”.

Gunung Kapor: ME 0263, ME 0352, ME 8483, ME 9205, ME 9250, ME 9267.

Sarawak: Kuching Division. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

Figure 11. 

A Opisthostoma planiapex Vermeulen, 1991 ME 9250 Gunung Kapor B Opisthostoma simile Vermeulen, 1991 ME 11471 Gunung Kapor C Opisthostoma tridens Vermeulen, 1991 ME 0333 Gunung Kapor.

“SARAWAK. 1^st Div.: G. Lelat 1 mile SW of Nyabet, 24 miles SSE of Kuching”.

Gunung Kapor: ME 9598, ME 11471, ME 11478.

Sarawak: Kuching Division. Endemic to Borneo.

Only dry shells were found during the surveys.

“SARAWAK. 1^st Div.: Kpg. Beratok along road Kuching-Serian”.

Gunung Kapor: ME 0333.

Sarawak: Kuching and Serian divisions. Endemic to Borneo.

Only dry shells were found during the surveys.

“Rumbang, Sarawak”.

Gunung Doya: ME 0248, ME 9013, ME 9244. Gunung Kapor: ME 0255. Lobang Angin: ME 0250, ME 8734, ME 8744, ME 9180. Gunung Batu: ME 0249, ME 0253, ME 0259, ME 8794.

Sarawak: Kuching and Serian divisions. Endemic to Borneo.

Living snails were observed foraging inside the rock crevices and cave walls, away from direct exposure to light. A single sinistral shell was found within the normal dextral populations.

Figure 12. 

A Plectostoma austeni (E. A. Smith, 1894) ME 8734 Lobang Angin B Plectostoma everetti (E. A. Smith, 1893) ME 8793 Gunung Batu C Plectostoma margaretchanae, sp. nov., MZU.MOL.20.06 paratype Gunung Batu D Plectostoma wallacei busauense (E. A. Smith, 1893) ME 9495 Gunung Doya E Plectostoma wallacei teinostoma (Vermeulen, 1994) ME 8899 Gunung Doya F Plectostoma wallacei wallacei Ancey, 1887 ME 5898 Gunung Stulang.

“Jambusan, N.W. Borneo” [= Jambusan Hills, Bau, Sarawak].

Gunung Doya: ME 8900, ME 9012, ME 9158. Gunung Batu: ME 0219, ME 0222, ME 2834, ME 8793.

Sarawak: Kuching Division. Endemic to Borneo.

Living snails were observed foraging on the moderately wet vertical limestone rock surfaces covered with mosses and lichens.

Holotype (SH 1.35 mm, SW 1.80 mm) (MZU.MOL.20.04), Malaysia, Sarawak, Kuching Division, Gunung Batu, limestone hill along Skio road, Jambusan, 2.4 miles E Bau, 1°23'50.65"N, 110°11'19.99"E, coll. M. E. Marzuki, 10.VII.2011. Paratypes: > 10 ex. (ME0000227), same data as holotype; 2 ex. (MZU.MOL.20.05), > 10 ex. (ME0000217), the same locality as holotype, coll. M. E. Marzuki, 11.III.2011.

It differs other Bornean Plectostoma species by having a tiny shell, long projecting tuba free from the spire, and a constriction with a transverse palatalis and transverse basalis. It is most similar to P. pyrgiscus (Vermeulen, 1994) and P. tuba (Vermeulen, 1994) but P. pyrgiscus has a higher spire of six whorls with widely spaced radial ribs, while P. tuba also has higher spire without spiral striation, but with a double peristome.

Shell spire conical with slightly convex sides. Apex not or slightly oblique. Whorls 4½, convex; last whorl rounded. Constriction with a transverse palatalis, and a transverse basalis. Tuba free from the spire, long projecting, abruptly narrowed towards the constriction, rounded below. Teleoconch: radial ribs on spire moderately spaced (six ribs/0.5 mm on the penultimate whorl), not sinuous, those close to tuba not sinuous; those on tuba widely spaced (three ribs/0.5 mm half-way), not or hardly sinuous below. Spiral striation present, distinct. Aperture hardly tilted with regards to coiling axis, circular to elliptical, peristome simple, distant from the spire; slightly spreading. Umbilicus open, 0.13 mm across. Dimensions: spire height 1.25–1.35 mm; spire width 1.00 mm, shell width (including tube) 1.60–1.80 mm; aperture height and width 0.47 mm.

Only known from the type locality. Living snails were observed foraging on the wet vertical limestone rock surfaces covered with mosses and lichens.

The specific epithet honours the Agronomist, Margaret Chan Kit Yok of Universiti Teknologi MARA, who was the mentor for the first author by providing valuable guidance for his malacological research in Sarawak.

Figure 13. 

Plectostoma margaretchanae sp. nov. A–C MZU.MOL.20.04 holotype A Basal view B Apertural view C Abapertural view D–F ME 0227, paratypes D Basal view E–F Apertural view.

“Busau, N.W. Borneo” [= Jambusan Hills, Bau, Sarawak].

Bukit Sekunyit: ME 2145. Gunung Doya: ME 9495.

SARAWAK: Kuching Division. Endemic to Borneo.

Living snails were observed foraging on the wet vertical limestone rock surfaces covered with mosses and lichens.

“SARAWAK. 1^st Div.: G. Pangga 3 km ENE of Bau”.

Gunung Doya: ME 0716, ME 8899, ME 9031, ME 9085. Gunung Kapor: ME 0234, ME 5972, ME 9204, ME 9213, ME 9251, ME 9842. Gunung Batu: ME 0226, ME 0229, ME 0703, ME 8795.

Sarawak: Kuching Division. Endemic to Borneo.

Living snails were observed foraging on the wet vertical limestone rock surfaces covered with mosses and lichens. Shells from Jambusan areas are very similar to Plectostoma dancei dispersum (Vermeulen, 1994) but differ by having a deep red shell colour and fine spiral striations on the shell surface.

“Borneo”.

Gunung Doya: ME 0239, ME 9697. Gunung Kapor: ME 0218, ME 0240, ME 0242, ME 0243, ME 0244, ME 2915, ME 8066, ME 8482, ME 8759, ME 8767, ME 8780. Lobang Angin: ME 0246, ME 8730, ME 8733, ME 8743. Gunung Batu: ME 0245, ME 0247. Gunung Stulang: ME 5898. Kampung Padang Pan: ME 6669.

Sarawak: Kuching and Serian divisions. Endemic to Borneo.

Living snails were observed foraging on the wet vertical limestone rock surfaces covered with mosses and lichens.

“Busan Hills, Borneo” [= Jambusan Hills, Bau, Sarawak].

Gunung Doya: ME 1114, ME 8946, ME 9112. Gunung Kapor: ME 1116, ME 9234. Gunung Batu: ME 1115, ME 1121, ME 8809.

Sarawak: Kuching and Serian divisions. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in lowland limestone forest. It differs from other Bornean Pupina species by having a smaller pearly white shell with a wide notch near the sutural margin.

Figure 14. 

A Pupina doriae Godwin-Austen, 1889 ME 8946 Gunung Doya B Pupina evansi Godwin-Austen, 1889 ME 9053 Lobang Angin C Pupina hosei Godwin-Austen, 1889 ME 1132 Gunung Batu D Rhaphaulus bombycinus (L. Pfeiffer, 1855) ME 9556 Lobang Angin E Rhaphaulus pfeifferi (Issel, 1874) ME 8741 Lobang Angin.

“From deposit in Cave A, Borneo” [= Tupak Cave, Jambusan Hills (Cranbrook, 2013)].

Gunung Sebayat: ME 8006. Gunung Doya: ME 1129. Gunung Kapor: ME 1127, ME 1130, ME 8786, ME 9254. Lobang Angin: ME 9053, ME 9203.

Sarawak: Kuching Division. Distribution elsewhere. Sirhassen, Natuna Islands (Smith 1894b).

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest. It differs from other Bornean Pupina species by having an intermediate size, globose, pale brown shell with a narrow notch near the sutural margin.

“Busan Hills, Borneo” [= Jambusan Hills, Bau, Sarawak].

Gunung Batu: ME 1132, ME 1134.

Sarawak: Kuching and Miri divisions. Sabah: Sandakan Division. Distribution elsewhere. Balabac and Palawan in Philippines (Kobelt and Möllendorff 1897).

Only dry shells were found during the surveys. It differs from other Bornean Pupina species by having a larger high spire dark brown shell with a wide notch near the sutural margin.

“Borneo, Sarawak”.

Gunung Kapor: ME 1098, ME 1099, ME 3358, ME 9017, ME 9215. Lobang Angin: ME 9556. Gunung Batu: ME 1100, ME 1103.

Sarawak: Kuching Division. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in lowland limestone forest. See remarks under Rhaphaulus pfeifferi (Issel, 1874).

“Territorio di Sarawak”.

Lobang Angin: ME 9556.

Sarawak: Kuching Division. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest. It differs from R. bombycinus by having a smaller shell with a less oblique spire and with a more spreading sutural tube.

“Wind Cave Passage 3, Wind Cave Nature Reserve, Bau, Sarawak, Malaysia”.

Lobang Angin: ME 0908, ME 8731, ME 8736.

Sarawak: Kuching Division. Endemic to Borneo.

Living snails were observed foraging on the wet vertical limestone rock surfaces covered with mosses and lichens.

Figure 18. 

A Georissa bauensis Khalik, Hendricks, Vermeulen & Schilthuizen, 2018 ME 8731 Lobang Angin B Georissa everetti E. A. Smith, 1895 ME 0906 Gunung Batu [not in natural colour, shell surface coated with platinum for examination under scanning electron microscope] C Georissa hosei Godwin-Austen, 1889 ME 8498 Gunung Kapor D Georissa hungerfordi Godwin-Austen, 1889, ME 11472 Gunung Kapor E Georissa leucococca Vermeulen, Liew & Schilthuizen, 2015 ME 9496 Gunung Doya.

“Rumbang, W. Sarawak”.

Gunung Batu: ME 0906.

Sarawak: Kuching and Miri divisions. Endemic to Borneo.

Only dry shells were found during the surveys.

“Borneo”.

Gunung Doya: ME 1478. Gunung Kapor: ME 8498.

Sarawak: Kuching Division. Endemic to Borneo.

Only dry shells were found during the surveys.

“Borneo”.

Gunung Kapor: ME 11472.

Sarawak: Kuching Division. Endemic to Borneo.

Only dry shells were found during the surveys.

“Malaysia, Sabah, Interior Province, Sepulut valley, Gua Pungiton”.

Gunung Doya: ME 9701, ME 9496.

Sarawak: Kuching and Serian divisions. Sabah: Interior and Tawau divisions. Endemic to Borneo.

Only dry shells were found during the surveys.

“Java”.

Kampung Padang Pan: ME 6828. Lobang Angin: ME 8982.

Sarawak: Kuching and Serian divisions. Distribution elsewhere. Sumatra to Java (Van Benthem-Jutting 1952)

This is the first record of this species in Borneo. Only dry shells were found during the surveys.

Figure 19. 

A Elasmias sundanum (Möllendorff, 1897) ME 8982 Lobang Angin B Lissachatina fulica (Bowdich, 1822) ME 9241 Gunung Kapor.

“L’ile de France” [= Mauritius].

Gunung Doya: ME 8920, ME 9228. Gunung Kapor: ME 8507, ME 9016, ME 9241.

Sarawak: Kuching, Samarahan, Serian, Sibu, Mukah and Miri divisions. Sabah: Kudat, West Coast, Interior, Sandakan and Tawau divisions. Kalimantan. Distribution elsewhere. Circumtropical (Vermeulen and Whitten 1998).

Living snails were observed foraging among leaf litter and plant debris near the cliff in lowland limestone forest. The species was firstly introduced into Sarawak in 1928 as poultry food and became pest a year later (Jarrett 1931). Apparently widespread throughout Borneo.

“L’ile Bourbon” [=La Réunion].

Gunung Sebayat: ME 8013. Gunung Doya: ME 2905, ME 9704, ME 8928, ME 8948, ME 9036. Gunung Kapor: ME 0753, ME 2877, ME 2948, ME 8506, ME 9043, ME 9229, ME 9248. Lobang Angin: ME 9105, ME 9276. Gunung Batu: ME 2835, ME 2841, ME 2870, ME 8821.

Sarawak: Kuching, Serian, Sibu, and Miri divisions. Sabah: Interior, Sandakan, Tawau, and West Coast divisions. Distribution elsewhere. Circumtropical (Vermeulen and Whitten 1998).

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest. Introduced species. Widespread throughout Borneo.

Figure 20. 

A Allopeas clavulinum (Potiez & Michaud, 1838) ME 0753 Gunung Kapor B Allopeas gracile (T. Hutton, 1834) ME 2942 Gunung Kapor C Opeas didyma (Westerlund, 1883) ME 9096 Gunung Kapor D Paropeas achatinaceum (L. Pfeiffer, 1846) ME 5977 Gunung Kapor.

“Mirzapoor, India”.

Gunung Doya: ME 8929, ME 8949, ME 9035. Gunung Kapor: ME 0312, ME 1229, ME 2942, ME 2943, ME 8149, ME 8504, ME 8970, ME 9011, ME 9069. Kampung Padang Pan: ME 6681. Lobang Angin: ME 9135, ME 9263. Gunung Batu: ME 2842, ME 2866, ME 8822.

Sarawak: Kuching, Serian, Mukah, and Miri divisions. Sabah: Interior, Kudat, Sandakan, Tawau, and West Coast divisions. Kalimantan: West Kalimantan Province. Distribution elsewhere. Circumtropical (Vermeulen and Whitten 1998).

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest. Introduced species. Widespread throughout Borneo.

“Malakka, Singapore”.

Gunung Kapor: ME 9096, ME 9237.

Sarawak: Kuching Division. Distribution elsewhere. West Malaysia and Singapore (Westerlund 1887)

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

“Java”.

Gunung Kapor: ME 2876, ME 2878, ME 2946, ME 2951, ME 5977, ME 8086, ME 8505, ME 8785, ME 8964. Lobang Angin: ME 8983, ME 9172, ME 9269. Gunung Batu: ME 8823.

Sarawak: Kuching, Serian, Kapit, and Miri divisions. Labuan, Sabah: Sandakan and West Coast divisions. Kalimantan: West Kalimantan Province. Distribution elsewhere. South to East Asia, South-east Asia, Pacific Islands (Naggs 1994; Vermeulen and Whitten 1998).

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest. Widespread throughout Borneo.

“Gunong Kapor, Bau District, Sarawak”.

Gunung Doya: ME 2906, ME 8930, ME 8950, ME 8993. Gunung Kapor: ME 8150, ME 8503, ME 9050. Gunung Batu: ME 2838, ME 2843, ME 2871, ME 8819.

Sarawak: Kuching and Serian divisions. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

Figure 21. 

A Platycochlium sarawakense Laidlaw, 1950 ME 8993 Gunung Doya B Gulella bicolor (T. Hutton, 1834) ME 9095 Gunung Kapor C Succinea obesa Martens, 1867 ME 2903 Gunung Batu.

“Mirzapoor, India”.

Gunung Kapor: ME 9095.

Sabah: Interior, Kudat, Tawau, and West Coast divisions. Sarawak: Kuching, Samarahan, Serian, Sibu, and Miri divisions. Distribution elsewhere. South to East Asia, Malay Archipelago (Vermeulen and Whitten 1998).

Only dry shells were found during the surveys. Introduced species.

“Oestliches Java, am See von Grati bei Passuruan gesammelt”.

Gunung Batu: ME 2903, ME 8820.

Sarawak: Kuching Division. Distribution elsewhere. Sumatra, Java, and Madura, Indonesia (Van Benthem-Jutting 1952).

Only dry shells were found during the surveys. The shells from Bau match the descriptions of Succinea obesa Martens, 1867 sensu Van Benthem-Jutting (1952). Two other species, namely Succinea borneensis Pfeiffer, 1853 and Succinea subrugata Pfeiffer, 1853, were described from Borneo. However, the original descriptions of these two species were not detailed enough for species identification.

“Kuching, Mt. Penrissen, and Mt. Santubong, N.W. Borneo”.

Gunung Doya: ME 8922. Lobang Angin: ME 9054.

Sarawak: Kuching and Sibu divisions. Endemic to Borneo.

It is an arboreal semi-slug which can also be found in lowland peat swamp forests.

Figure 22. 

A Damayantia carinata Collinge, 1901 ME 9054 Lobang Angin B Hemiplecta densa (A. Adams & Reeve, 1850) ME 9241 Gunung Doya C Macrochlamys infans (L. Pfeiffer, 1854) ME 2854 Gunung Batu D Macrochlamys saintjohni (Godwin-Austen, 1891) ME 9900 Gunung Kapor E Macrochlamys tersa (Issel, 1874) ME 9620 Gunung Kapor F Vitrinula glutinosa (Metcalfe, 1851) ME 8782 Gunung Kapor.

“Philippine Islands”.

Gunung Doya: ME 8892, ME 9160. Gunung Kapor: ME 2581, ME 4723, ME 4724, ME 5971, ME 8079, ME 8791, ME 9243. Gunung Stulang: ME 5907. Kampung Padang Pan: ME 6674. Lobang Angin: ME 9485. Gunung Batu: ME 4725, ME 4726, ME 8833.

Sarawak: Kuching Division. Labuan, Sabah: Sandakan Division. Kalimantan: West and East Kalimantan provinces. Distribution elsewhere. Philippines and Indonesia: Java and Sumatra (Mousson 1857; Smith 1895).

Further study is needed to clarify the taxonomic status of this species together with Hemiplecta humpreysiana (I. Lea, 1840).

“Sarawak, Borneo”.

Gunung Batu: ME 1858, ME 2854.

Sarawak: Kuching Division. Labuan: Endemic to Borneo.

Only dry shells specimens were found during the surveys. It differs from Macrochlamys tersa (Issel, 1874) by having a white shell without spiral sculpture or only with very fine spiral grooves. The taxonomic status and occurrence of M. infans in Java and Bali were discussed in Vermeulen (1996).

“Busan Hills, Borneo”.

Gunung Sebayat: ME 8011. Gunung Doya: ME 3053, ME 9111, ME 9184. Gunung Kapor: ME 3850, ME 8509, ME 9208, ME 9240, ME 9900. Gunung Batu: ME 2837.

Sarawak: Kuching Division. Distribution elsewhere. Palawan (Smith 1895).

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest. It differs from other Bornean Macrochlamys species by having a small reddish brown shell with well-spaced fine spiral grooves.

“Borneo”.

Gunung Doya: ME 8936, ME 8957, ME 9037. Gunung Kapor: ME 2880, ME 2882, ME 2945, ME 3040, ME 8089, ME 8771, ME 8966, ME 9048, ME 9620. Kampung Padang Pan: ME 6680. Lobang Angin: ME 9142, ME 9152, ME 9272. Gunung Batu: ME 1858, ME 2855, ME 2868, ME 8827.

Sarawak: Kuching, Serian, and Miri divisions. Sabah: Kudat, West Coast, Interior, and Tawau divisions. Endemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest. It differs from other Bornean Macrochlamys species by having a moderately sized pale brown shell with very fine closely spaced spiral grooves.

Holotype (SH 1.38 mm, SW 1.75 mm) (MZU.MOL.20.06), Malaysia, Sarawak, Kuching Division, 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. Paratypes: 1 ex. (ME0009154), same data as the holotype; 9 ex. (ME0009165), Bukit Sokwang (Site 1), northern site of Gunung Doya, limestone hill along Skio road, 2.05 miles E Bau, 1°23'52.11"N, 110°10'27.93"E, coll. M. E. Marzuki, 22.IV.2017; 6 ex. (ME0009168), 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, 22.IV.2017; 2 ex. (ME0002899), Gunung Batu, limestone outcrop along Skio road, Jambusan, 2.4 miles E Bau, 1°23'50.65"N, 110°11'19.99"E, coll. M. E. Marzuki, 23.VI.2010; 4 ex. (ME0001757), the same locality, coll. M. E. Marzuki, 11.III.2011; 1 ex. (ME0008889), the same locality, coll. M. E. Marzuki, 10.II.2017; 2 ex (ME0002899), 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, 23.VI.2010; 2 ex. (ME0001762), 2 ex. (MZU.MOL.20.07), South Flank of Bukit Akud, near Kampung Beratok, Serian-Kuching road, 14 miles NW Serian, 1°18'23.26"N, 110°24'15.07"E, coll. M. E. Marzuki, 21.VI.2010; 7 ex. (ME0007020), small limestone outcrop at Kampung Beratok, Serian-Kuching road, 14.3 miles NW Serian, 1°18'41.05"N, 110°24'37.13"E, coll. M. E. Marzuki, 27.XII.2015; 1 ex. (ME0011489), Lobang Angin (Site 1), limestone outcrop near Sungai Sarawak Kanan, 1.75 miles W of Bau, 1°24'48.14"N, 110°8'12.21"E, coll. M. E. Marzuki, 15.IV.2017; 6 ex. (ME0008138), Limestone escarpment near Kampung Benuk, 8.2 miles SW Kota Padawan, coll. M. E. Marzuki, 13.IX.2017.

Figure 23. 

A Microcystina arabii, sp. nov., MZU.MOL.20.06 Holotype Gunung Batu B Microcystina atoni, sp. nov., MZU.MOL.20.11 Paratype Gunung Batu C Microcystina kilat, sp. nov., MZU.MOL.20.19 Paratype Gunung Batu D Microcystina lirata, sp. nov., MZU.MOL.20.15 paratype Gunung Kapor.

It differs from Microcystina sinica Möllendorff, 1885, Microcystina oswaldbrakeni sp. nov., and Microcystis bunguranensis Smith, 1894 by having cancellated sculpture on the shell surface.

Shell very small, thin, translucent, white, straw yellow to brown; spire distinctly elevated, conical with convex sides or depressed-ovoid; apex rounded. Surface with a silky to glossy lustre. Whorls convex, periphery rounded. Last whorl with a thin, inconspicuous peripheral thread coinciding with the suture of the penultimate whorl. Number of whorls < 4¼. Protoconch: with a fine, moderately spaced spiral striation consisting of rows of minute spiral grooves crossed by equally strong radial riblets which are arranged in a cancellated pattern towards the teleoconch. Teleoconch moderately spaced spiral striation consisting of rows of minute spiral grooves crossed by equally strong radial riblets which are arranged in a cancellated pattern. Radial sculpture teleoconch of very fine, densely spaced radial riblets, oblique, predominant at the peripheral region and inconspicuous at the umbilical region. Aperture: lunulate. Peristome simple; somewhat thickened and reflected on the columellar side, not thickened nor reflected on the basal and palatal side. Umbilicus open, narrow, partly covered; umbilical region moderately concave. Dimensions: shell height < 1.38 mm; shell width < 1.75 mm; diameters of the first three whorls 0.38–0.42 mm, 0.75–0.83 mm, and 1.17–1.29 mm, respectively; aperture height < 0.67 mm; aperture width < 0.92 mm.

Figure 24. 

Microcystina arabii sp. nov. A–F MZU.MOL.20.07 Paratype A Apertural view B Apical view, C Basal view D Enlargement of the apical side showing the apex E Enlargement of the body whorl showing the shell sculpture F Enlargement of the basal side of the shell.

The shells of this species display high variability in terms of colour and height/width ratio.

It is known from the Bau and Padawan-Serian limestone hill clusters. Only dry shells specimens were found during the surveys.

The specific epithet honours Mr. Abang Arabi Abang Aimran, Chief Wildlife Warden of Sarawak Forestry Corporation, who has contributed significantly to the conservation of wildlife in Sarawak.

Holotype (SH 1.38 mm, SW 2.46 mm) (MZU.MOL.20.10), Malaysia, Sarawak, Kuching Division, Gunung Batu, limestone outcrop along Skio road, Jambusan, 2.4 miles E Bau, 1°23'50.65"N, 110°11'19.99"E, coll. M. E. Marzuki, 10.VII.2011. Paratypes: 1 ex. (MZU.MOL.20.11), 1 ex. (ME0009903), same data as the holotype.

It is similar to Microcystina chionodiscus Vermeulen, 1996 and Microcystina striatula Vermeulen, Liew & Schilthuizen, 2015 in terms of the shell shape, but does not have the spiral striations on the protoconch and teleoconch. It is also different from Microcystina microrhynchus Vermeulen, Liew & Schilthuizen, 2015 and Microcystina kilat sp. nov. in lacking shell grooves and radial sculptures, and with an open but narrow umbilicus.

Figure 25. 

Microcystina atoni sp. nov. A–F MZU.MOL.20.10 Holotype A apertural view B apical view C basal view D enlargement of the apical side showing the apex E enlargement of the teleoconch showing the shell sculpture F enlargement of the basal side of the shell.

Shell very small, thin, translucent, white, lenticular, spire almost flat or slightly elevated. Surface with a slightly silky lustre. Whorls slightly convex. Number of whorls < 4. Protoconch dull, without spiral and radial threads. Teleoconch with spiral sculpture absent. Radial sculpture teleoconch: growth lines very fine, inconspicuous. Aperture lunulate. Peristome simple; somewhat thickened and reflected on columellar side, not thickened nor reflected on basal and palatal side. Umbilicus open, narrow; columellar wall very thick; umbilical region concave. Dimensions: shell height < 1.38 mm; shell width < 2.46 mm; diameters of the first three whorls 0.50 mm, 1.00 mm, and 1.58 mm, respectively; aperture height < 1.00 mm; aperture width < 1.25 mm.

It is known from the Bau limestone hill clusters only. Only dry shells were found during the surveys.

The specific epithet honours Mr. Zolkipli Mohamad Aton, Chief Executive Officer of Sarawak Forestry Corporation, Controller of Wildlife and Controller of National Parks and Nature Reserves, who has contributed significantly to the conservation of wildlife in Sarawak.

Holotype (SH 1.33 mm, SW 2.42 mm) (MZU.MOL.20.18), Malaysia, Sarawak, Kuching Division, Lobang Angin (Site 2), limestone outcrop near Sungai Sarawak Kanan, 1.75 miles W of Bau, 1°24'51.01"N, 110°8'13.48"E, coll. M. E. Marzuki, 16.IV.2017. Paratypes: 1 ex. (ME0009430), same data as Holotype; 5 ex. (ME0009898), 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; 1 ex. (ME0001764), Lobang Angin (Site 1), limestone outcrop near Sungai Sarawak Kanan, 1.75 miles W of Bau, 1°24'48.14"N, 110°8'12.21"E, coll. M. E. Marzuki, 11.III.2011; 1 ex. (ME0009273), Lobang Angin (Site 3), limestone outcrop near Sungai Sarawak Kanan, 1.75 miles W of Bau, 1°24'54.96"N, 110°8'13.62"E, coll. M. E. Marzuki, 23.IV.2017; 5 ex. (ME0001829), 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, 11.III.2011; 2 ex. (ME0009895), the same locality, coll. M. E. Marzuki, 23.VI.2010; 6 ex. (ME0008088), the same locality, coll. M. E. Marzuki, 17.IX.2016; 1 ex. (ME0010477), the same locality, coll. M. E. Marzuki, 7.VIII.2008; 1 ex. (ME0009902), the same locality, coll. M. E. Marzuki, 8.IV.2017; >10 ex. (ME0009899), Fairy Caves (Site 2), south part of Gunung Kapor, 4 miles SW Bau, 1°22'56.09"N, 110°6'58.82"E, coll. M. E. Marzuki, 8.IV.2017; 9 ex. (ME0009646), the same locality, coll. M. E. Marzuki, 7.I.2018; 24 ex. (ME0009001), Buddha Caves (Site 3), north part of Gunung Kapor, 3 miles SW Bau, 1°23'26.51"N, 110°7'10.02"E, coll. M. E. Marzuki, 9.IV.2017; 2 ex. (ME0009897), Bukit Sokwang (Site 1), northern site of Gunung Doya, limestone hill along Skio road, 2.05 miles E Bau, 1°23'52.11"N, 110°10'27.93"E, coll. M. E. Marzuki, 22.IV.2017; 4 ex. (ME0008943), 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, 22.IV.2017; 2 ex. (MZU.MOL.20.19), >10 ex. (ME0009904), Gunung Batu, limestone hill along Skio road, Jambusan, 2.4 miles E Bau, 1°23'50.65"N, 110°11'19.99"E, coll. M. E. Marzuki, 10.VII.2011; 1 ex. (ME0001767), the same locality, coll. M. E. Marzuki, 23.VI.2010; 10 ex. (ME0001699), Limestone escarpment near Kampung Benuk, 8.2 miles SW Kota Padawan, 1°18'41.43"N, 110°17'32.03"E, coll. M. E. Marzuki, 20.VIII.2008; 8 ex. (ME0001770), small limestone outcrop at Kampung Beratok, Serian-Kuching road, 14.3 miles NW Serian, 1°18'41.05"N, 110°24'37.13"E, coll. M. E. Marzuki, 21.VI.2010; 7 ex. (ME0006997), Gua Raya, along Kampung Skuduk-Chupak, 8.8 miles SE Siburan, 1°14'23.29"N, 110°25'49.05"E, coll. M. E. Marzuki, 1.I.2016; 3 ex. (ME0009455), Serian Division, Gunung Storib, small northern peak of Gunung Silabor, 15 miles S Serian, 0°57'30.75"N, 110°30'3.00"E, coll. M. E. Marzuki, 22.IX.2017; 6 ex. (ME0001773), Gunung Suka, Limestone outcrop near Kampung Picsing, Tebakang-Tebedu road, 8.45 miles SW Serian, 1°8'5.08"N, 110°26'53.30"E, coll. M. E. Marzuki, 20.VI.2010.

Figure 26. 

Microcystina kilat, sp. nov. A–F MZU.MOL.20.18 Holotype A apertural view B apical view C basal view D enlargement of the apical side showing the apex E enlargement of the body whorl showing the shell sculpture F enlargement of the basal side of the shell.

It differs from Microcystina callifera Vermeulen, Liew & Schilthuizen, 2015, in having a shell without spiral sculpture. The shell with an umbilicus that is entirely covered by a callus separates this new species from Microcystina microrhynchus Vermeulen, Liew & Schilthuizen, 2015 from Sabah.

Shell very small, thin, translucent, white, lenticular, spire almost flat or slightly elevated. Surface with shiny or a slightly silky lustre. Whorls slightly convex. Number of whorls < 4. Protoconch smooth, sometimes with a few inconspicuous, scattered radial grooves only. Teleoconch: spiral sculpture absent. Radial sculpture teleoconch growth lines inconspicuous, next to these inconspicuous to distinct, densely placed shallow grooves, often at irregular intervals. Aperture lunulate. Peristome simple; somewhat reflected on the columellar side, not thickened nor reflected on the basal and palatal side. Umbilicus entirely covered by callus; columellar wall thickened; umbilical region is moderately concave. Dimensions: shell height 1.33–1.85 mm; shell width 2.42–3.70 mm; diameters of the first three whorls 0.42 mm, 0.79 mm, and 1.50 mm, respectively; aperture height < 1.08 mm; aperture width < 1.25 mm.

It is known from the Bau-Padawan limestone hill clusters. Only dry shells were found during the surveys.

From the Malay kilat, meaning shiny, in reference to the shell surface of the new species.

Holotype (SH 0.77 mm, SW 1.35 mm) (MZU.MOL.20.14), Malaysia, Sarawak, Kuching Division, Buddha Caves (Site 3), north part of Gunung Kapor, 3 miles SW Bau, 1°23'26.51"N, 110°7'10.02"E, coll. M. E. Marzuki, 9.IV.2017. Paratypes: 2 ex. (MZU.MOL.20.15), >10 ex. (ME0009214), same data as the holotype; 1 ex. (ME0006721), small limestone escarpment near Kampung Padang Pan, 15 miles SW Bau, 1°19'24.07"N, 110°3'46.34"E, coll. M. E. Marzuki, 27.IX.2015; 2 ex. (ME0008774), 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, 22.IV.2017; 4 ex. (ME0009166), Lobang Angin (Site 2), limestone outcrop near Sungai Sarawak Kanan, 1.75 miles W of Bau, 1°24'51.01"N, 110°8'13.48"E, coll. M. E. Marzuki, 16.IV.2017; 3 ex. (ME0008979), 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, 8.IV.2017; >10 ex. (ME0009235), Fairy Caves (Site 2), south part of Gunung Kapor, 4 miles SW Bau, 1°22'56.09"N, 110°6'58.82"E, coll. M. E. Marzuki, 8.IV.2017.

It differs from Microcystina circumlineata (Möllendorff, 1897) by having a smaller white shell with somewhat punctured-like secondary spiral grooves in between moderately spaced spiral threads.

Shell very small, rather thin, translucent, white, lenticular, spire moderately elevated. Surface with a silky lustre. Whorls slightly convex. Number of whorls < 4¼. Protoconch with a fine, moderately spaced spiral striation consisting of rows of minute, rather sharply outlined pits which are arranged in a cancellated pattern towards the teleoconch. Teleoconch: spiral sculpture present with very distinct, moderately spaced, continuous elevated spiral threads. In between these very fine, two rows of low, somewhat punctured-like secondary spiral grooves. Radial sculpture of teleoconch very fine as well as irregularly spaced growth lines. Periphery rounded; suture shallow. Aperture lunulate. Peristome simple; somewhat thickened and reflected on the columellar side, not thickened nor reflected on the basal and palatal side. Umbilicus open, narrow, partly covered by reflected peristome; umbilical region is moderately concave. Dimensions: shell height < 1.17 mm; shell width < 1.92 mm; diameters of the first three whorls 0.60 mm, 0.90 mm, and 1.37 mm, respectively; aperture height < 0.83 mm; aperture width < 0.83 mm.

It is known from the Bau limestone hill clusters only. Only dry shells were found during the surveys.

From the Latin lirata, in reference to the prominent spiral sculpture of the shell.

Figure 27. 

Microcystina lirata, sp. nov. A–F MZU.MOL.20.14 Holotype A apertural view B apical view C basal view D enlargement of the apical side showing the apex E enlargement of the body whorl showing the shell sculpture F enlargement of the basal side of the shell.

Holotype (SH 1.79 mm, SW 1.99 mm) (MZU.MOL.20.16), Malaysia, Sarawak, Kuching Division, 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. Paratypes: 2 ex. (MZU.MOL.20.17), >10 ex. (ME0002268), same data as the holotype; 6 ex. (ME0001758), Gunung Batu, limestone outcrop along Skio road, Jambusan, 2.4 miles E Bau, 1°23'50.65"N, 110°11'19.99"E, coll. M. E. Marzuki, 23.VI.2010; 1 ex. (ME0003275), the same locality, coll. M. E. Marzuki, 10.VII.2011; 4 ex. (ME0008818), the same locality, coll. M. E. Marzuki, 10.II.2017; 1 ex (ME0010295), Gua Tupap, Northern Gunung Batu Complex, Jambusan, 2.51 miles E Bau, Kuching Division, 1°24'21.25"N, 110°11'21.70"E, coll. M. E. Marzuki, 26.XII.2018; >10 ex. (ME0001751), 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, 10.VII.2011; 3 ex (ME0007194), 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, 17.IX.2016; 1 ex. (ME0010478), the same locality, coll. M. E. Marzuki, 10.II.2017; 1 ex. (ME0011473), Fairy Caves (Site 2), south part of Gunung Kapor, 4 miles SW Bau, 1°22'56.09"N, 110°6'58.82"E, coll. M. E. Marzuki, 8.IV.2017; 2 ex. (ME0008012), Gunung Sebayat, limestone hill near Bengoh resettlement scheme, along Jambusan-Semadang road, 10 miles SE Bau, 1°18'24.54"N, 110°15'21.80"E, coll. M. E. Marzuki, 13.IX.2016; 10 ex. (ME0001796), Gunung Suka, Limestone outcrop near Kampung Picsing, Tebakang-Tebedu road, 8.45 miles SW Serian, 1°8'5.08"N, 110°26'53.30"E, coll. M. E. Marzuki, 20.VI.2010.

Figure 28. 

A Microcystina oswaldbrakeni, sp. nov., MZU.MOL.20.17 Paratype Gunung Batu B Microcystina paripari, sp. nov., ME 1746 Paratype Gunung Batu C Microcystina physotrochus Vermeulen, Liew & Schilthuizen, 2015 ME 9072 Gunung Kapor D Microcystina seclusa Godwin-Austen, 1891 ME 8153 Gunung Kapor.

It differs from Microcystina seclusa Godwin-Austen, 1891 in having a smaller shell with a silky surface that is covered by well-spaced faint spiral grooves and a closed umbilicus. This species also similar to Microcystina arabii sp. nov., see Remarks under that species.

Shell very small, thin, translucent, brown; conical-ovoid with convex sides, spire elevated, apex rounded. Surface with a glossy lustre. Whorls convex, rounded or slightly angular. Number of whorls < 5½. Protoconch with very fine, moderately spaced spiral striation consisting of rows of minute spiral grooves crossed by inconspicuous radial riblets towards the teleoconch. Teleoconch: spiral sculpture obsolete or with densely spaced, continuous, inconspicuous, narrow spiral grooves above the periphery but rather well-spaced below the periphery. Radial sculpture inconspicuous, oblique, widely but irregularly spaced, growth lines. Aperture lunulate. Peristome simple; somewhat reflected on columellar side, not thickened nor reflected on basal and palatal side. Umbilicus open, narrow, partly, or almost closed by reflected peristome; umbilical region is moderately concave. Dimensions: shell height < 1.79 mm; shell width < 1.99 mm; diameters of the first three whorls 0.42 mm, 0.74 mm, and 1.05 mm, respectively; aperture height < 0.73 mm; aperture width < 1.05 mm.

Figure 29. 

Microcystina oswaldbrakeni, sp. nov. A–F MZU.MOL.20.16 Holotype A apertural view B apical view C basal view D enlargement of the apical side showing the apex, E enlargement of the teleoconch showing the shell sculpture F enlargement of the basal side of the shell.

It is known from the Bau and Serian-Padawan limestone hill clusters. Only dry shells were found during the surveys.

The specific epithet honours Mr. Oswald Braken Tisen, Deputy Chief Executive Officer of Sarawak Forestry Corporation, who has contributed significantly to the conservation of wildlife in Sarawak.

Holotype (SH 1.25 mm, SW 2.08 mm) (MZU.MOL.20.12), Malaysia, Sarawak, Kuching Division, Fairy Caves (Site 2), south part of Gunung Kapor, 4 miles SW Bau, 1°22'56.09"N, 110°6'58.82"E, coll. M. E. Marzuki, 7.I.2018. Paratypes: 2 ex. (MZU.MOL.20.13), 7 ex. (ME0009647), same data as the holotype; >10 ex. (ME0009329), the same locality, coll. M. E. Marzuki, 8.IV.2017; 1 ex. (ME0003845), 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, 11.III.2011; 2 ex. (ME0009469), the same locality, coll. M. E. Marzuki, 8.IV.2017; 2 ex. (ME0008510), the same locality, coll. M. E. Marzuki, 10.II.2017; 2 ex. (ME0001761), the same locality, coll. M. E. Marzuki, 23.VI.2010; 1 ex. (ME0001749), 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, 10.VII.2011; 1 ex. (ME0009677), 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; 37 ex. (ME0009044), Buddha Caves (Site 3), north part of Gunung Kapor, 3 miles SW Bau, 1°23'26.51"N, 110°7'10.02"E, coll. M. E. Marzuki, 9.IV.2017; 1 ex. (ME0000783), Gunung Batu, limestone outcrop along Skio road, Jambusan, 2.4 miles E Bau, 1°23'50.65"N, 110°11'19.99"E, coll. M. E. Marzuki, 11.III.2011; >10 ex. (ME0001746), same locality, coll. M. E. Marzuki, 10.VII.2011.

It differs from Microcystina muscorum Van Benthem-Jutting, 1959 and Microcystina gratilla Van Benthem-Jutting, 1950 in having a shell without spiral striations on both the protoconch and teleoconch.

Shell very small, thin, translucent, straw yellow to brown, lenticular, spire moderately elevated. Surface with a glossy lustre. Whorls slightly convex. Number of whorls < 4. Protoconch smooth, sometimes with a few inconspicuous, corrugation at the suture. Teleoconch without spiral sculpture. Radial sculpture on teleoconch: inconspicuous growth lines, then next to these with distinct, well-spaced to densely spaced, shallow grooves, sometimes the latter striation is predominant. Aperture lunulate. Peristome simple; somewhat thickened and reflected on columellar side, not thickened nor reflected on basal and palatal side. Umbilicus open, narrow; umbilical region is moderately concave. Dimensions: shell height < 1.25 mm; shell width < 2.08 mm; diameters of the first three whorls 0.13 mm, 0.21 mm, and 0.25 mm, respectively; aperture height < 0.75 mm; aperture width < 0.92 mm.

It is known from the Bau limestone hill clusters only. Only dry shells were found during the surveys.

The specific epithet paripari is in reference to the type locality, Gua Pari-pari, and is the Malay word for fairies.

Figure 30. 

Microcystina paripari, sp. nov. A–F MZU.MOL.20.12 Holotype A apertural view B apical view C basal view D enlargement of the apical side showing the apex E enlargement of the teleoconch showing the shell sculpture F enlargement of the basal side of the shell.

“Malaysia, Sabah, Sandakan Province, Kinabatangan Valley, Batu Keruak 2, near Sukau”.

Gunung Doya: ME 8953. Gunung Kapor: ME 2262, ME 2264, ME 2265, ME 2266, ME 9072, ME 9098, ME 9256. Lobang Angin: ME 9174. Gunung Batu: ME 2263.

Sarawak: Kuching, Bintulu, and Miri divisions. Enemic to Borneo.

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

“Borneo, cave-earth”.

Gunung Doya: ME 8933, ME 8954. Gunung Kapor: ME 8153, ME 9209. Gunung Batu: ME 0439, ME 2261.

Sarawak: Kuching Division. Endemic to Borneo.

Only dry shells were found during the surveys. It differs from Microcystis bunguranensis Smith, 1894 from Natuna Island by having a larger and higher spire shell (Smith 1894b).

“Borneo”.

Gunung Doya: ME 1620, ME 8915, ME 9114. Gunung Kapor: ME 1617, ME 1618, ME 1619, ME 8080, ME 8508, ME 8782, ME 8967, ME 9407. Kampung Padang Pan: ME 6675. Lobang Angin: ME 8728, ME 8750, ME 9023. Gunung Batu: ME 1621, ME 4785, ME 4983, ME 8832.

Sarawak: Kuching, Sibu, Mukah, Kapit, and Miri divisions. Kalimantan: West Kalimantan Province. Endemic to Borneo.

This species exhibits high variability in shell form, ranging from high to low spire and in colour from pale to dark brown.

“Timor”, Indonesia.

Bukit Sekunyit: ME 4905. Gunung Batu: ME 4906, ME 8828.

Sabah: Interior, West Coast, Kudat and Sandakan divisions. Sarawak: Kuching, Samarahan, Sibu, Mukah, Kapit, and Miri divisions. Distribution elsewhere. Southeast mainland Asia to Indo-Australian archipelago, South America (Reeve 1851; Vermeulen and Whitten 1998).

Probably an introduced species. The species is known only from disturbed habitats.

Figure 31. 

A Bradybaena similaris (Férussac, 1821) ME 4906 Gunung Batu B Chloritis tomentosa (L. Pfeiffer, 1854) ME 8917 Gunung Doya C Landouria winteriana (L. Pfeiffer, 1842) ME 8078 Gunung Kapor D Ganesella acris (Benson, 1859) ME 8963 Gunung Kapor E Amphidromus angulatus Fulton, 1896 ME 4632 Gunung Kapor F Amphidromus cf. similis Pilsbry, 1900 ME 8756 Gunung Kapor.

“Sarawak, Borneo”.

Gunung Doya: ME 8917, ME 9164. Gunung Kapor: ME 1532, ME 1549, ME 8077, ME 9266. Kampung Padang Pan: ME 6683. Gunung Batu: ME 1540, ME 1547, ME 1548.

Sarawak: Kuching Division. Labuan: Kuraman Island. Distribution elsewhere. Sumatra (Bock 1881; Van Benthem-Jutting 1959).

Only dry shells were found during the surveys. This species is different from Bradybaena similaris (Férussac, 1822) in having very fine hair pits that cover the shell surfaces and a slightly angular peristome between the columellar and basal sides.

“Java”.

Bukit Sekunyit: ME 1580. Gunung Kapor: ME 1579, ME 1583, ME 1584, ME 5979, ME 8078, ME 8778, ME 9226. Lobang Angin: ME 9274.

Sarawak: Kuching and Miri divisions. Distribution elsewhere. Indo-Australian archipelago (Vermeulen and Whitten 1998).

The shells from Bau are similar to the syntype of Plectotropis kraepelini Leschke, 1914, ZMH 98416 [= Landouria winteriana (Pfeiffer, 1842)]. For further details, see Nurinsiyah et al. (2019: 10–17)

“Teria Ghát montium Khasiæ” [= Khasi Hills, Teria Ghat, India].

Gunung Doya: ME 8916. Gunung Kapor: ME 1561, ME 1562, ME 1564, ME 1567, ME 1570, ME 8512, ME 8773, ME 8963, ME 9041. Kampung Padang Pan: ME 6682. Lobang Angin: ME 8939, ME 8977. Gunung Batu: ME 1565.

Sarawak: Kuching and Miri divisions. Sabah: Tawau, Sandakanm, and West Coast divisions. Distribution elsewhere. South to Southeast Asia mainland, Sumatra to Java (Benson 1859; Crosse 1879; Smith 1887; Van Benthem-Jutting 1959).

“Sarawak”.

Gunung Doya: ME 8919, ME 9176, ME 9191. Gunung Kapor: ME 4611, ME 4632, ME 8075, ME 8789, ME 9045, ME 9223. Lobang Angin: ME 4631. Gunung Batu: ME 4612, ME 4630.

Sarawak: Kuching and Miri divisions. Endemic to Borneo.

Only dry shells were found during the surveys. This species is similar to Amphidromus thalassochromus Vermeulen & Junau, 2007 and Amphidromus coeruleus Clench & Archer, 1932 in terms of shell shape and colour pattern on the shell surface. However, it differs from A. thalassochromus by having a rounded last whorl at the periphery and it differs from A. coeruleus in having a somewhat obese shell with a short spire.

“Sadong, West Sarawak”.

Gunung Doya: ME 8918, ME 8923. Gunung Kapor: ME 3724, ME 4160, ME 4595, ME 4596, ME 4597, ME 5970, ME 8076, ME 8752, ME 8756, ME 9242. Gunung Batu: ME 4599.

Sarawak: Kuching Division. Endemic to Borneo.

The shells from Bau are different from Pilsbry’s Amphidromus similis in having a shell with a translucent white callus and parietal wall.

“Barrakpore, Indiæ” [= Barrackpore, West Bengal, India].

Gunung Doya: ME 8931, ME 8951, ME 9034. Gunung Kapor: ME 1910, ME 1926, ME 8156, ME 8787, ME 9009, ME 9026. Gunung Stulang: ME 5896. Kampung Padang Pan: ME 6678. Lobang Angin: ME 8986, ME 9021, ME 9268. Gunung Batu: ME 1912, ME 8813.

Sarawak: Kuching, Serian, and Miri divisions. Sabah: Interior, Sandakan, Tawau, and West Coast divisions. Kalimantan (Vermeulen et al. 2015). Distribution elsewhere. Africa and South Asia mainland to Indo-Australian archipelago, Europe (Godwin-Austen 1882; Vermeulen and Whitten 1998; Preece and Naggs 2014).

Figure 32. 

A Kaliella barrakporensis (L. Pfeiffer, 1852) ME 9009 Gunung Kapor B Kaliella busauensis (E. A. Smith, 1895) ME 1892 Gunung C Kaliella calculosa (Gould, 1852) ME 1863 Gunung Kapor D Kaliella doliolum (L. Pfeiffer, 1846) ME 9074 Gunung Kapor.

“Busau, Sarawak” [= Jambusan Hills, Bau, Sarawak].

Gunung Sebayat: ME 8304. Gunung Doya: ME 9702, ME 8990. Gunung Kapor: ME 1880. Lobang Angin: ME 9259, ME 9264. Gunung Batu: ME 1868, ME 1873, ME 1892.

Sarawak: Kuching Division. Endemic to Borneo.

Only dry shells were found during the surveys. It differs from other Bornean Kaliella species by having a higher dark brown spired shell with a cancellated shell surface due to the prominent spiral grooves and oblique radial riblets.

“Tahiti” [= Tahiti Island, French Polynesia].

Bukit Sekunyit: ME 1885. Gunung Doya: ME 1865, ME 8932, ME 8952, ME 8995. Gunung Kapor: ME 1863, ME 1898, ME 1911, ME 8973, ME 9049, ME 9238. Kampung Padang Pan: ME 6722. Lobang Angin: ME 8747, ME 9177, ME 9259. Gunung Batu: ME 1866, ME 8816.

Sarawak: Kuching, Serian and Miri divisions. Sabah: Interior, Sandakan, Tawau, and West Coast divisions. Distribution elsewhere. South Asia mainland to Indo-Australian archipelago and Pacific Islands (Vermeulen et al. 2015).

The juvenile shell of this species is similar to Kaliella barrakporensis (Pfeiffer, 1852) and K. busauensis (Smith, 1895), but it differs from the two species by having a lower conical, brittle, whitish shell with moderately spaced spiral striae above the periphery.

“Sibonga, island of Zebu” [= Sibonga, Cebu Island, Philippines].

Gunung Kapor: ME 1851, ME 1874, ME 1895, ME 9010, ME 9074, ME 9252.

Sarawak: Kuching, Serian, and Miri divisions. Sabah: Interior, Kudat, Sandakan, Tawau, and West Coast divisions. Distribution elsewhere. Southeast Asia mainland to Indo-Australian archipelago and Pacific Islands (Vermeulen et al. 2015).

Living snails were observed foraging among leaf litter and plant debris near the cliffs in a lowland limestone forest.

“Lomma-Lomma (Viti)” [= Loma Loma, Fiji].

Bukit Sekunyit: ME 1884. Gunung Doya: ME 1877, ME 9703, ME 8934, ME 8959, ME 8996. Gunung Kapor: ME 1860, ME 1896, ME 1909, ME 8154, ME 8499, ME 8975, ME 9007, ME 9073. Kampung Padang Pan: ME 6677. Lobang Angin: ME 8738, ME 8987, ME 9146. Gunung Batu: ME 1855, ME 1893, ME 1913, ME 8817.

Sarawak: Kuching, Serian, and Miri divisions. Sabah: Interior, Kudat, Sandakan, Tawau, and West Coast divisions. Kalimantan: South Kalimantan Province. Distribution elsewhere. South-east Asia to Australia and the Pacific Islands (Vermeulen and Whitten 1998).

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

Figure 33. 

A Kaliella microconus (Mousson, 1865) ME 1855 Gunung Batu B Kaliella micula (Mousson, 1857) ME 9650 Gunung Kapor C Kaliella platyconus (Möllendorff, 1897) ME 8814 Gunung Batu D Kaliella scandens (Cox, 1871) ME 1928 Gunung Kapor.

“Insula Balie” [= Bali Island, Indonesia].

Gunung Kapor: ME 9650.

Sarawak: Kuching Division. Distribution elsewhere. Peninsular Malaysia to Lesser Sunda, Indonesia (Vermeulen and Whitten 1998).

Only dry shells were found during the surveys. It differs from K. scandens by having a larger shell with wider whorls that rapidly increase in size. For further details on the differences between this species and K. dendrobates (Tillier & Bouchet, 1989), see Vermeulen et al. (2015: 105).

“Java”, Indonesia.

Gunung Batu: ME 8814.

Sarawak: Kuching and Samarahan divisions. Distribution elsewhere. Sumatra to Sumbawa, Indonesia (Vermeulen and Whitten 1998).

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest. The shells from Bau are the first record of this species in Borneo. This species is different from Kaliella barrakporensis (Pfeiffer, 1852) and Kaliella accepta (Smith, 1895) in having a low conical shell with wider whorls.

“Port Macquarie, east coast of Australia”.

Bukit Sekunyit: ME 1883. Gunung Doya: ME 1882, ME 8935, ME 9033, ME 9110. Gunung Kapor: ME 1897, ME 1928, ME 8155, ME 8500, ME 9008, ME 9025, ME 9075, ME 9486. Lobang Angin: ME 8985, ME 9202, ME 9277. Gunung Batu: ME 1875, ME 8835.

Sarawak: Kuching, Serian, and Miri divisions. Sabah: Interior, Sandakan, Tawau, and West Coast divisions. Kalimantan: exact location was not mentioned in Vermeulen et al. (2015). Distribution elsewhere. South-east Asia to Australia and the Pacific Islands (Vermeulen et al. 2015).

“Antipolo bei Manila, Luzon” [= Antipolo, Luzon Island, Philippines].

Gunung Batu: ME10290.

Sarawak: Kuching and Miri divisions. Sabah: Tawau and West Coast divisions. Distribution elsewhere. Philippines, Java, Sulawesi to Timor, Indonesia (Solem 1957).

Only dry shells were found during the surveys.

Figure 34. 

A Beilania philippinensis (C. Semper, 1874) ME 10290 Gunung Batu B Philalanka jambusanensis, sp. nov., ME 1879 Paratype Gunung Batu C Philalanka kusana (Aldrich, 1889) ME 5897 Gunung Batu D Philalanka moluensis (E. A. Smith, 1893) ME 0443 Gunung Doya [not in natural colour, shell surface coated with platinum for examination under scanning electron microscope].

Holotype (SH 2.78 mm, SW 3.11 mm) (MZU.MOL.20.20), Malaysia, Sarawak, Kuching Division, Gunung Batu, limestone outcrop along Skio road, Jambusan, 2.4 miles E Bau, 1°23'50.65"N, 110°11'19.99"E, coll. M. E. Marzuki, 10.VII.2011. Paratypes: 1 ex. (ME0001879), same data as holotype.

It differs from Philalanka thienemanni Rensch, 1932, by having a shell with spiral striations only on the first 1½ whorls above the peripheral thread and a narrowly open umbilicus. This species is different from Philalanka micromphala Van Benthem-Jutting, 1952 in having a high conical white shell with no spiral sculpture above the periphery.

Shell very small, dextral, thin, translucent, white; spire conical-ovoid. Surface with a shiny lustre. Whorls flat or with slightly convex sides, rounded. Number of whorls 4¾. Protoconch whorls convex with moderately spaced spiral striations consisting of 4–6 rows of inconspicuous spiral threads towards the teleoconch. Teleoconch with no spiral sculpture above periphery, well-spaced below periphery, fine spiral threads present except in the umbilical region. Radial sculpture on the teleoconch consisting of densely spaced, fine, slightly oblique growth lines. Last whorl with a distinct peripheral thread coinciding with the suture of the penultimate whorl. Aperture: peristome simple; somewhat reflected and thickened on columellar side, not thickened nor reflected on basal or palatal side. Umbilicus open, narrow; umbilical region moderately concave. Dimensions: shell height 2.78 mm; shell width 3.11 mm; diameters of the first three whorls 0.61 mm, 1.22 mm, and 1.78 mm, respectively; shell aperture height 1.11 mm; shell aperture width 1.67 mm.

Figure 35. 

Philalanka jambusanensis, sp. nov. A–F MZU.MOL.20.20 Holotype. A Apical view B Basal view, C Enlargement of the apical side showing the apex D Enlargement of the teleoconch showing the shell sculpture E Enlargement of the basal side of the shell.

It is only known from the type locality. Only dry shells were found during the surveys.

The specific epithet jambusanensis is from the name of Jambusan, where the specimens were found.

“Kusan and Penggiron districts in South-eastern Borneo” [= Kusan and Pangeran in South Kalimantan, Indonesian Borneo].

Gunung Doya: ME 8956, ME 9115. Gunung Kapor: ME 2238, ME 2244, ME 2249, ME 8157, ME 8501, ME 8788, ME 9029. Gunung Stulang: ME 5897. Lobang Angin: ME 8737, ME 9181, ME 9270. Gunung Batu: ME 2252, ME 2254.

Sarawak: Kuching, Serian, Kapit, and Miri divisions. Sabah: Interior, Kudat, Sandakan, Tawau, and West Coast divisions. Kalimantan: Exact location was not mentioned in Vermeulen et al. (2015). Distribution elsewhere. West Malaysia to Papua (Vermeulen et al. 2015).

Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

“Molu or Mulu Mountains, N. Borneo”.

Gunung Doya: ME 0443.

Sarawak: Kuching and Miri divisions. Sabah: Interior, Sandakan, Tawau, and West Coast divisions. Endemic to Borneo.

Only dry shells were found during the surveys.

“Malaysia, Sabah, West Coast Province, Crocker Range, Kiansom Waterfall”.

Gunung Doya: ME 8927, ME 8945, ME 8994. Gunung Kapor: ME 1734, ME 1760, ME 1927, ME 8976, ME 9042, ME 9067, ME 9262, ME 9641. Kampung Bunga Rampai: ME 0741. Lobang Angin: ME 9265. Gunung Batu: ME 1756, ME 1763, ME 8836.

Figure 36. 

A Paralaoma angusta Vermeulen, Liew & Schilthuizen, 2015 ME 9641 Gunung Kapor B Paralaoma sarawakensis, sp. nov., ME 2269 Paratype Gunung Doya C Charopa sp. “argos” ME 8593 Gunung Doya.

Sarawak: Kuching and Serian divisions. Sabah: West Coast Division. Kalimantan: South Kalimantan Province. Endemic to Borneo.

This is the first record of this species in Sarawak. Living snails were observed foraging among leaf litter and plant debris near the cliffs in a lowland limestone forest. The shells from Bau are slightly larger and more obese than the shells from Sabah. Dimensions: Height < 1.65 mm; width < 2.37 mm; diameters of the first three whorls 0.41 mm, 0.93 mm, and 1.65 mm, respectively; number of whorls < 4½; aperture height < 0.93 mm; aperture width < 1.24 mm.

Figure 37. 

Paralaoma angusta Vermeulen, Liew & Schilthuizen, 2015 A–F ME 1763 A apertural view B apical view C basal view D enlargement of the apical side showing the apex E enlargement of the body whorl showing the shell sculpture F enlargement of the basal side of the shell.

Holotype (SH 1.27 mm, SW 2.00 mm) (MZU.MOL.20.21), Malaysia, Sarawak, Kuching Division, 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, 22.IV.2017. Paratypes: 1 ex. (ME0008944), same data as holotype; 7 ex. (ME0008010), Gunung Sebayat, limestone hill near Bengoh resettlement scheme, along Jambusan-Semadang road, 10 miles SE Bau, 1°18'24.54"N, 110°15'21.80"E, coll. M. E. Marzuki, 13.IX.2016; >10 ex. (ME0002234), Bukit Sekunyit, limestone quarry near Batu Kitang, Kuching-Bau road, 7.2 miles E Bau, 1°25'46.81"N, 110°15'47.20"E, coll. M. E. Marzuki, 10.III.2011; 4 ex. (ME0002269), 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, 10.VII.2011; 8 ex. (ME0002230), Gunung Batu, limestone outcrop along Skio road, Jambusan, 2.4 miles E Bau, 1°23'50.65"N, 110°11'19.99"E, coll. M. E. Marzuki, 23.VI.2010; 5 ex. (ME0002235), the same locality, coll. M. E. Marzuki, 11.III.2011; 9 ex. (ME0002257), the same locality, coll. M. E. Marzuki, 10.VII.2011; >10 ex. (ME0002229), Fairy Caves, south part of Gunung Kapor, 4 miles SW Bau, Kuching Division, 1°22'53.97"N, 110°7'2.29"E, coll. M. E. Marzuki, 11.III.2011; 2 ex. (ME0009211), Fairy Caves (Site 2), south part of Gunung Kapor, 4 miles SW Bau, 1°22'56.09"N, 110°6'58.82"E, coll. M. E. Marzuki, 8.IV.2017; 1 ex. (ME0009261), Buddha Caves (Site 3), north part of Gunung Kapor, 3 miles SW Bau, 1°23'26.51"N, 110°7'10.02"E, coll. M. E. Marzuki, 9.IV.2017; 1 ex. (ME0002233), South Flank of Bukit Akud, near Kampung Beratok, Serian-Kuching road, 14 miles NW Serian, 1°18'23.26"N, 110°24'15.07"E, coll. M. E. Marzuki, 21.VI.2010; 2 ex. (ME0006975), Gua Raya, along Kampung Skuduk-Chupak, 8.8 miles SE Siburan, 1°14'23.29"N, 110°25'49.05"E, coll. M. E. Marzuki, 1.I.2016; 2 ex. (MZU.MOL.20.22), >10 ex. (ME0007998), North side of Gua Raya, along Kampung Skuduk-Chupak, 8.3 miles SE Siburan, 1°14'35.10"N, 110°25'51.08"E, coll. M. E. Marzuki, 17.IX.2016; >10 ex. (ME0000430), Limestone escarpment near Kampung Benuk, 8.2 miles SW Kota Padawan, 1°18'41.43"N, 110°17'32.03"E, coll. M. E. Marzuki, 27.X.2008; >10 ex. (ME0002258), the same locality, coll. M. E. Marzuki, 22.VI.2010; >10 ex. (ME0002256), the same locality, coll. M. E. Marzuki, 9.III.2011; 7 ex. (ME0007966), the same locality, coll. M. E. Marzuki, 13.IX.2016; 3 ex. (ME0009461), the same locality, coll. M. E. Marzuki, 22.IX.2017; 1 ex. (ME0002231), Serian Division, Gua Sireh, Bukit Nambi, limestone outcrops near Kampung Taee, 7 miles W Serian, 1°10'36.18"N, 110°27'53.81"E, coll. M. E. Marzuki, 21.VI.2010; 6 ex. (ME0002232), Gunung Suka, Limestone outcrop 7.5 km from Kampung Picsing, Tebakang-Tebedu road, 8.45 miles SW Serian, 1°8'5.08"N, 110°26'53.30"E, coll. M. E. Marzuki, 20.VI.2010; >10 ex. (ME0009386), Gunung Silabur, limestone hill near Kampung Lobang Batu, 15 miles S Serian, 0°57'22.63"N, 110°30'9.36"E, coll. M. E. Marzuki, 22.IX.2017; 2 ex. (ME0000644), Miri Division, limestone outcrop near logging road, Baram Valley, 3.5 miles SW Long Bemang, 11 miles NE Long Lama, 3°49'50.36"N, 114°33'15.09"E, coll. M. E. Marzuki, 4.XI.2012; 1 ex. (ME0002751), Small limestone outcrop near Bemang-Bedian Junction, 5.4 miles E Long Lama, 3°46'15.701"N, 114°28'52.693"E, coll. M. E. Marzuki, 16.VIII.2013.

Figure 38. 

Paralaoma sarawakensis, sp. nov. A–F MZU.MOL.20.21 Holotype A apertural view B apical view C basal view D enlargement of the apical side showing the apex E enlargement of the teleoconch showing the shell sculpture F enlargement of the basal side of the shell.

It differs from ‘Charopa’ lafargei Vermeulen & Marzuki, 2014 of West Malaysia, by having a depressed-conical shell and a protoconch with fine, moderately spaced, spiral striations consisting of rows of minute striae which are arranged in a dashed-line pattern towards the teleoconch.

Shell very small, dextral, rather solid, translucent, white; spire depressed. Surface with a silky lustre. Whorls slightly convex. Number of whorls < 4¼. Protoconch with a fine, moderately spaced, spiral striation consisting of rows of minute, striae are crossed by well-spaced radial grooves arranged in a dashed-line pattern towards the teleoconch. Teleoconch: spiral sculpture present with very distinct, moderately spaced, continuous striae arranged as dashed lines. Radial sculpture of teleoconch consisting of well-spaced, coarse, orthocline, slightly sinuous, high narrow ribs which reach down to the spiral ridge and are fused to it; interstices with inconspicuous radial grooves. Periphery rounded, slightly angular; suture deep. Aperture lunulate. Peristome simple; somewhat reflected on columellar side, not thickened nor reflected on basal or palatal sides. Umbilicus open, narrow; umbilical region moderately concave. Dimensions: Shell height < 1.27 mm; shell width < 2.00 mm; diameters of the first three whorls 0.17 mm, 0.20 mm, and 0.23 mm, respectively; aperture height < 0.67 mm; aperture width < 1.00 mm.

It has a wide distribution in Sarawak. Living snails were observed foraging among leaf litter and plant debris near the cliffs in a lowland limestone forest and in a lowland non-limestone forest.

The specific epithet sarawakensis is derived from the name of Malaysian State of Sarawak.

Not applicable.

Gunung Doya: ME 8593, ME 8998. Kampung Padang Pan: ME 9491. Gunung Kapor: ME 9896, ME 9136. Gunung Batu: ME 7177, ME 1890. Lobang Angin: ME 9039, ME 9138.

Sarawak: Kuching and Miri divisions. Sabah: Exact location was not mentioned in Clements et al. (2008). Endemic to Borneo.

This species was recorded in Clements et al. (2008) as Charopa argos. This species will be described in a separate publication on Sabah land snails. Living snails were observed foraging among leaf litter and plant debris near the cliff in lowland limestone forest. It differs from other Bornean Charopa species by its prominent, rather deep, well-spaced radial grooves crossing the spiral striae at more or less regular intervals on the shell surface.

Figure 39. 

Charopa sp. “argos”. A–F MZU.MOL.20.08 A apertural view B apical view C basal view D enlargement of the apical side showing the apex E enlargement of the teleoconch showing the shell sculpture F enlargement of the basal side of the shell.

“Busan Hills, Borneo” [= Jambusan Hills, Bau, Sarawak].

Gunung Doya: ME 1600, ME 8913, ME 9015, ME 9159. Gunung Kapor: ME 1595, ME 1596, ME 1598, ME 1599, ME 8082, ME 8457, ME 9056, ME 9217. Gunung Batu: ME 1597, ME 4861, ME 8811.

Sarawak: Kuching and Sri Aman divisions. Endemic to Borneo.

Another form of this species was described by Smith (1895) as concolor from Sri Aman, Sarawak.

Figure 40. 

A Dyakia busanensis Godwin-Austen, 1891 ME 9015 Gunung Doya B Dyakia subdebilis E. A. Smith, 1895 ME 1602 Gunung Kapor C Rhinocochlis nasuta (Metcalfe, 1851) ME 8740 Lobang Angin D Quantula striata (Gray, 1834) ME 8792 Gunung Kapor.

“Sarawak”.

Gunung Sebayat: ME 8303. Gunung Kapor: ME 1602.

Sarawak: Kuching Division. Endemic to Borneo.

According to MolluscaBase, this is a “Taxon inquirendum”. This species was placed as junior synonym of Dyakia regalis (Benson, 1850) by Laidlaw (1963). However, the shells from Bau are different from Dyakia regalis (Benson, 1850) in having a straw-yellow to light brown shell with a shiny surface below the periphery.

“Busan, near Sarawak, Borneo” [= Jambusan Hills, Bau, Sarawak].

Gunung Doya: ME 8961. Gunung Kapor: ME 1630, ME 8968. Gunung Batu: ME 1628, ME 1629.

Sarawak: Kuching and Miri divisions. Endemic to Borneo.

Only dry shells were found during the surveys. This species is different from both Xesta baramensis Kobelt, 1897 and Vitrinula moluensis (E. A. Smith, 1893) in having a shell with a wide, pale brown band encircling the periphery. Anatomical studies by Godwin-Austen (1891) confirmed the placement of this species in the genus Everettia.

Figure 41. 

A Everettia cutteri (H. Adams, 1870) ME 8968 Gunung Doya Kapor B Everettia microrhytida, sp. nov., MZU.MOL.20.25 Holotype Gunung Batu C Everettia minuta, sp. nov., MZU.MOL.20.23 Holotype Gunung.

Holotype (SH 12.14 mm, SW 22.00 mm) (MZU.MOL.20.25), Malaysia, Sarawak, Kuching Division, Gunung Batu, limestone outcrop along Skio road, Jambusan, 2.4 miles E Bau, 1°23'50.65"N, 110°11'19.99"E, coll. M. E. Marzuki, 10.II.2017. Paratypes: 1 ex. (MZU.MOL.20.26), the same locality as holotype, coll. M. E. Marzuki, 10.VII.2011; 1 ex. (ME0006829), small limestone escarpment near Kampung Padang Pan, 15 miles SW Bau, 1°19'24.07"N, 110°3'46.34"E, coll. M. E. Marzuki, 27.IX.2015; 2 ex. (ME0003498), small limestone outcrop at Kampung Beratok, Serian-Kuching road, 14.3 miles NW Serian, 1°18'41.05"N, 110°24'37.13"E, coll. M. E. Marzuki, 21.VI.2010; 6 ex. (ME0009145), Lobang Angin (Site 3), limestone outcrop near Sungai Sarawak Kanan, 1.75 miles W of Bau, 1°24'54.96"N, 110°8'13.62"E, coll. M. E. Marzuki, 23.IV.2017; 1 ex. (ME0009845), the same locality, coll. M. E. Marzuki, 12.V.2018.

This species is similar to Everettia consul (Pfeiffer, 1854) in terms of general shape and size. However, it differs from E. consul by lacking spiral sculpture and having only very fine (sometimes inconspicuous), somewhat wrinkled, puncture-like sculpture on both the apical and apertural sides. Everettia consul, on the other hand, has a shell with a more elevated spire and its shell surface has densely placed radial threads and somewhat cut by irregularly spaced spiral grooves.

Figure 42. 

Everettia spp. A–C Everettia minuta, sp. nov., MZU.MOL.20.24 Paratype A Enlargement of the apical side showing the apex B Enlargement of the teleoconch showing the shell sculpture C Enlargement of the basal side of the shell D–F Everettia microrhytida, sp. nov., MZU.MOL.20.26 Paratype D Enlargement of the apical side showing the apex E Enlargement of the teleoconch showing the shell sculpture F Enlargement of the basal side of the shell.

Shell moderately large, rather thin, translucent, pale to dark brown, spire slightly elevated. Surface with a glossy lustre. Whorls convex. Number of whorls < 6¼. Protoconch: almost smooth, spiral striation absent with inconspicuous radial threads near the suture. Teleoconch with no: spiral sculpture but with very fine, inconspicuous, somewhat wrinkled, puncture-like shell sculptures on both apical and apertural sides. Radial sculpture of teleoconch very fine as well as inconspicuous growth lines, most conspicuous radial threads near the suture and below periphery. Periphery round; suture shallow. Aperture lunulate. Peristome simple; somewhat thickened and reflected on columellar side, not thickened nor reflected on basal and palatal sides. Umbilicus open, narrow; sometimes partly covered by reflected peristome; umbilical region moderately concave. Dimensions: shell height < 12.58 mm; shell width < 22.13 mm; diameters of the first three whorls 1.60 mm, 2.55 mm, and 4.90 mm, respectively; aperture height < 8.94 mm; aperture width < 11.66 mm.

It is known from the Bau and Serian-Padawan limestone hill clusters. Living snails were observed foraging among leaf litter and plant debris near the cliff in a lowland limestone forest.

From the Greek mikro rytídes, meaning extremely small wrinkles, in reference to the shell sculpture.

Holotype (SH 5.72 mm, SW 10.00 mm) (MZU.MOL.20.23), Malaysia, Sarawak, Kuching Division, 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, 8.IV.2017. Paratypes: 7 ex. (ME0008965), same data as the holotype; 1 ex. (MZU.MOL.20.24), the same locality as the holotype, coll. M. E. Marzuki, 23.VI.2010; 5 ex. (ME0001512), the same locality, coll. M. E. Marzuki, 11.III.2011; 1 ex. (ME0001513), Gunung Batu, limestone outcrop along Skio road, Jambusan, 2.4 miles E Bau, 1°23'50.65"N, 110°11'19.99"E, coll. M. E. Marzuki, 11.III.2011; 4 ex. (ME0009139), Lobang Angin (Site 1), limestone outcrop near Sungai Sarawak Kanan, 1.75 miles W of Bau, 1°24'48.14"N, 110°8'12.21"E, coll. M. E. Marzuki, 15.IV.2017; 1 ex. (ME0009222), Lobang Angin (Site 2), limestone outcrop near Sungai Sarawak Kanan, 1.75 miles W of Bau, 1°24'51.01"N, 110°8'13.48"E, coll. M. E. Marzuki, 16.IV.2017; 1 ex. (ME0009466), Serian Division; Gunung Storib, small northern peak of Gunung Silabor, 15 miles S Serian, 0°57'30.75"N, 110°30'3.00"E, 22.IX.2017.

The new species is similar to Everettia jucunda (Pfeiffer, 1863), E. bangueyensis (Smith, 1895) and E. jucundior Liew, Vermeulen & Schilthuizen, 2009 from Sabah. Everettia jucunda differs by having a larger shell (< 17.3 mm wide), with one and half more whorls. Everettia jucundior differs by having a larger shell (< 19.5 mm wide) with slightly shouldered whorls. Everettia bangueyensis differs by having a smaller shell (< 9.0 mm wide), and a flat spire with slightly shouldered whorls.

Shell small, rather thin, translucent, pale brown, spire moderately elevated. Surface with a glossy lustre. Whorls convex. Number of whorls < 5¼. Protoconch almost smooth, spiral striation absent with inconspicuous radial threads near the suture. Teleoconch: spiral sculpture with inconspicuous, densely placed spiral grooves on both apical side and apertural sides. Radial sculpture almost smooth, with inconspicuous radial threads near suture and below periphery. Periphery round; suture slightly depressed. Aperture lunulate. Peristome simple; continuous, somewhat sinuous, thickened, and reflected on columellar side, not thickened nor reflected on basal and palatal sides. Umbilicus narrow, partly covered by the reflected peristome; umbilical region moderately concave. Dimensions: shell height < 7.62 mm; shell width < 13.17 mm; diameters of the first three whorls 1.45 mm, 2.40 mm, and 4.34 mm, respectively; aperture height < 4.65 mm; aperture width < 6.58 mm.

Known from the Bau and Serian-Padawan limestone hills. Only dry shells were not found during the surveys.

From the Latin minuta, meaning small, in reference to the smaller shell compare to other species of Everettia from Sarawak.

“Borneo”.

Gunung Doya: ME 1637, ME 8911.

Sarawak: Kuching, Serian and Miri divisions. Sabah: West Coast and Tawau divisions. Kalimantan: West Kalimantan Province. Distribution elsewhere. Sumatra (?) (Van Benthem-Jutting, 1959).

Only dry shells were found during the surveys. The shells from Bau have a more depressed shell than the shells from Niah.

Figure 43. 

A Geotrochus conicoides (Metcalfe, 1851) ME 8911 Gunung Doya B Geotrochus subscalaris Vermeulen, Liew & Schilthuizen, 2015 ME 1636 Gunung Kapor C Videna bicolor (Martens, 1864) ME 8732 Lobang Angin D Videna timorensis (Martens, 1867) ME 8972 Gunung Kapor E Exrhysota brookei (A. Adams & Reeve, 1848) ME 8790 Gunung Kapor.

“Malaysia, Sabah, Sandakan Province, Kinabatangan valley, Batu Pangi”.

Gunung Kapor: ME 1636.

Sarawak: Kuching Division. Sabah: West Coast Division. Endemic to Borneo.

This is the first record of this species in Sarawak. No living snail was found during the surveys. The shells from Bau are more depressed than the shells from Sabah.

“Im mittleren Sumatra” [= Central Sumatra].

Bukit Sekunyit: ME 1202. Gunung Doya: ME 3356, ME 8910, ME 9032, ME 9116. Gunung Kapor: ME 1199, ME 1205, ME 3361, ME 8775, ME 9225, ME 9844. Kampung Bunga Rampai: ME 1198. Lobang Angin: ME 8732, ME 9271. Gunung Batu: ME 1106, ME 1203, ME 1209, ME 8825.

Sarawak: Kuching, Serian, Sibu, Mukah, Kapit, and Miri divisions. Sabah: Interior and West Coast divisions. Kalimantan: West and South Kalimantan provinces. Distribution elsewhere. Sumatra to Lesser Sunda (Vermeulen and Whitten 1998).

Living snails were observed foraging on wet rotten wood surfaces and crown of a plant of the limestone cliff. It differs from V. timorensis (Martens, 1867) by having a medium-sized dark brown shell with wide umbilicus and a smooth shell surface. This is the most common Videna species in Sarawak.

“Timor, im Innern bei Okabiti, in Waldern” [= near Okabiti, Timor Island].

Gunung Doya: ME 1228, ME 9163, ME 9193, ME 9405. Gunung Kapor: ME 1179, ME 1222, ME 1226, ME 3360, ME 5976, ME 8090, ME 8458, ME 8762, ME 8972. Kampung Padang Pan: ME 6724. Lobang Angin: ME 8984, ME 9404. Gunung Batu: ME 1224, ME 8824.

Sarawak: Kuching Division. Sabah: Tawau Division. Distribution elsewhere. Peninsular Malaysia to Indo-Australian archipelago (Maassen 2001).

Living snails were observed foraging on wet rotten wood surfaces at the base of the limestone cliff. It differs from V. bicolor (Martens, 1864) by having a pale brown smaller shell with narrower umbilicus and shell surface striated with conspicuous spiral grooves.

“Mountains of Borneo”.

Gunung Kapor: ME 8083, ME 8790.

Sarawak: Kuching, Sibu, Kapit and Miri divisions. Sabah: Sandakan, Tawau and East Coast divisions. Kalimantan: West, South, and East Kalimantan provinces. Endemic to Borneo.

This is the largest native land snail species in Borneo. For further details on the generic and familial placement of this species, see Sutcharit et al. (2019: 2).

“Busan Hills, Borneo” [= Jambusan Hills, Bau, Sarawak].

Bukit Sekunyit: ME 2850. Gunung Doya: ME 8955, ME 8999, ME 9156. Gunung Kapor: ME 2879, ME 2881, ME 2947, ME 5978, ME 8087, ME 8459, ME 8770, ME 8969. Kampung Padang Pan: ME 6679. Lobang Angin: ME 8751, ME 9398. Gunung Batu: ME 2840, ME 2867, ME 8815.

Sarawak: Kuching, Serian and Miri divisions. Distribution elsewhere. Lombok (Smith 1899).

Living snails were observed foraging on the leaf surfaces of small trees and palms at the base of limestone cliffs.

Figure 44. 

A Microcystis dyakana Godwin-Austen, 1891 ME 8770 Gunung Kapor B Rahula raricostulata (E. A. Smith, 1893) ME 8938 Lobang Angin C Phaedusa borneensis (L. Pfeiffer, 1854) ME 8784 Gunung Kapor.

“Busau or Busan, Sarawak” [= Jambusan Hills, Bau, Sarawak].

Gunung Doya: ME 8937, ME 8962. Gunung Kapor: ME 0860, ME 1508, ME 9097, ME 9207. Lobang Angin: ME 8938, ME 9221. Gunung Batu: ME 1891.

Sarawak: Kuching and Serian divisions. Endemic to Borneo.

Only dry shells were found during the surveys. It differs from Rahula delopleura Vermeulen, Liew & Schilthuizen, 2015, by having a shell with distinct, prominent spiral lirae on the protoconch.

“Sarawak, Borneo”.

Gunung Doya: ME 2904, ME 8912, ME 9153. Gunung Kapor: ME 2890, ME 2891, ME 2892, ME 2893, ME 2944, ME 5975, ME 8784, ME 9257. Gunung Batu: ME 2897, ME 2898.

Sarawak: Kuching, Serian, and Miri divisions. Endemic to Borneo.

Living snails were observed foraging on the moderately wet vertical limestone rock surfaces covered with lichens.

“Jamaica”.

Gunung Doya: ME 8942, ME 8997. Gunung Kapor: ME 8151, ME 8502, ME 9006, ME 9027, ME 9070. Kampung Padang Pan: ME 6830. Lobang Angin: ME 9140, ME 9173.

Sarawak: Kuching, Bintulu, Miri, and Limbang divisions. Sabah: Sandakan Division. Distribution elsewhere. Circumtropical (Pilsbry 1920–1921).

Only dry shells were found during the surveys. It differs from P. circumlitum (Hedley, 1897) and P. orcella (Stoliczka, 1873) in having a higher spired shell with an umbilicus that is partly or entirely covered by the reflected peristome. This species also differs from P. pulvisculum (Issel, 1874) in having a larger shell with spiral lirae on shell surfaces.

Figure 45. 

A Ptychopatula dioscoricola (C. B. Adams, 1845) ME 9070 Gunung Kapor B Ptychopatula orcella (Stoliczka, 1873) ME 8925 Gunung Doya C Pupisoma moleculina (Van Benthem-Jutting, 1940) ME 9051 Gunung Kapor D Pupisoma pulvisculum (Issel, 1874) ME 9055 Gunung Kapor E Boysidia salpinx F. G. Thompson & Dance, 1983 ME 8781 Gunung Kapor.

Figure 46. 

Living snails from Bau A Japonia barbata (L. Pfeiffer, 1855) ME 8768 Gunung Kapor B Opisthophorus euryomphalus (L. Pfeiffer, 1856) ME 8779 Gunung Kapor C Opisthophorus biciliatus Mousson, 1849 ME 8754 Gunung Kapor D Opisthophorus birostris (L. Pfeiffer, 1854) ME 8755 Gunung Kapor. All not to scale.

“Penang island”.

Gunung Doya: ME 8925.

Sarawak: Kuching Division. Sabah: Tawau Division. Distribution elsewhere. Malay Peninsula, Indo-Australian archipelago (Vermeulen and Whitten 1998).

Only dry shells were found during the surveys. It differs from Ptychopatula circumlitum (Hedley, 1897) and P. dioscoricola (C. B. Adams, 1845) by having irregularly spaced ribs on shell surfaces (visible at 40 × magnification). This is probably the first record of sinistral form for species in the Genus Ptychopatula. For further details, see Pilsbry (1920–1921: 29).

Figure 47. 

Living snails from Bau A Cyclophorus perdix borneensis (Metcalfe, 1851) ME 8753 Gunung Kapor B Platyrhaphe linita (Godwin-Austen, 1889) ME 9700 Gunung Doya C Stomacosmethis sadongensis (E. A. Smith, 1895) ME 8761 Gunung Kapor D Pincerna globosa (H. Adams, 1870) ME 8749 Lobang Angin. All not to scale.

“Forest between the village of Tjisolok and the hot springs (Tjipanas) some miles inland, south coast of West Java”.

Gunung Kapor: ME 9051, ME 9212.

Sarawak: Kuching Division. Sabah: Sandakan Division. Distribution elsewhere. Peninsular Malaysia, Sumatra, and Java (Van Benthem-Jutting 1940; Vermeulen and Raven 1998; Maassen 2000).

This is the first record of this species in Sarawak. Only dry shells were found during the surveys.

Figure 48. 

Living snails from Bau A Chamalycaeus specus (Godwin-Austen, 1889) ME 11867 Lobang Angin B Plectostoma wallacei wallacei Ancey, 1887 ME 8767 Gunung Kapor C Plectostoma austeni (E. A. Smith, 1894) ME 8794 Gunung Batu D Plectostoma everetti (E. A. Smith, 1893) ME 8793 Gunung Batu. All not to scale.