Microcystina microrhynchus Vermeulen, Liew & Schilthuizen

Vermeulen, Jaap J., Liew, Thor-Seng & Schilthuizen, Menno, 2015, Additions to the knowledge of the land snails of Sabah (Malaysia, Borneo), including 48 new species, ZooKeys 531, pp. 1-139 : 28-31

Taxon classification Animalia Stylommatophora Ariophantidae

Microcystina microrhynchus Vermeulen, Liew & Schilthuizen sp. n. Figure 24

Microcystina microrhynchus nomen nudum, Clements et al. 2008: 2761-2762; Schilthuizen et al. 2013: online supplementary data.

Microcystina sp. “BO-01”, Schilthuizen et al. 2002 a: 258; Schilthuizen et al. 2002b: 41-42; Schilthuizen and Vermeulen 2003: 96; Schilthuizen 2004: 94; Schilthuizen et al. 2011: 5.

Holotype. Malaysia, Sabah, Interior Province , Gua Pungiton ( RMNH.5003933 ).

Examined material from Sabah.

Interior Province. Upper Padas valley, Matang River South of Long Pasia (leg. J.J. Vermeulen, V 9815); Matang River South of Long Pasia, ridge on West bank (leg. J.J. Vermeulen, V 9824); Long Pasia (leg. T.S. Liew & Meckson, BOR/MOL 4355). Tenom (leg. M. Schilthuizen, BOR/MOL 3348). Crocker Range N.P., Gua Laing c. 12 km North of Keningau (leg. J.J. Vermeulen, V 1109, V 1114); West of the km 10 marker on the road Tambunan-Ranau, Mahua Waterfall (leg. J.J. Vermeulen & M. Schilthuizen, V 9749; leg. M. Schilthuizen, BOR/MOL 3137; leg. J. Schilthuizen, BOR/MOL 1081). Gunung Trusmadi slopes: Forestry chalet (leg. J.J. Vermeulen, V 13211); Gua Loloposon (leg. J.J. Vermeulen, V 13244). Pinangah valley, Batu Urun (= Bukit Sinobang) (leg. J.J. Vermeulen, V 7997, V 1143, V 1168, BOR/MOL 1067; leg. R. Haegens, V 5633; leg. M. Schilthuizen, BOR/MOL 1085). Pun Batu c. 30 km West of Sepulut (leg. J.J. Vermeulen, V 1284. Sepulut valley, Batu Punggul (leg. J.J. Vermeulen, V 1971; leg. M. Schilthuizen, BOR/MOL 1099); Batu Temurung (leg. J.J. Vermeulen, V 8041, BOR/MOL 1071; leg. M. Schilthuizen, BOR/MOL 1091); Bukit Tinagas, East end of Batu Punggul limestone (leg. J.J. Vermeulen & M. Schilthuizen, V 7629; leg. M. Schilthuizen, BOR/MOL 1096); Gua Pungiton (leg. J.J. Vermeulen & M. Schilthuizen, V 7548, BOR/MOL 1069); Gua Sanaron (leg. J.J. Vermeulen & M. Schilthuizen, V 7678; leg. M. Schilthuizen, BOR/MOL 1082, BOR/MOL 1098). Kudat Province. Balambangan Island, Kok Simpul (leg. J.J. Vermeulen & M. Schilthuizen, V 9530); South end, Batu Sireh (leg. J.J. Vermeulen & M. Schilthuizen, V 9544; leg. T.H. Liew, Sazilin & Ramlan, BOR/MOL 3689). Banggi Island, South end (leg. J.J. Vermeulen, V 1429; leg. M.A. Rahman, BOR/MOL 1094); Karakit Hill (leg. J.J. Vermeulen, V 1466; leg. J.J. Vermeulen & M. Schilthuizen, V 9470, V 9498); Pitas, Gua Mundau (leg. T.S. Liew & M. Schilthuizen, BOR/MOL 4370); Kg. Magnin (leg. T.S. Liew & M. Schilthuizen, BOR/MOL 4365). Sandakan Province. Meliau Range between 355-470 m (leg. T.S. Liew, M. Schilthuizen & A. van Til, BOR/MOL 3196, BOR/MOL 3197, BOR/MOL 3221). Kinabatangan valley, Batu Batangan (leg. M. Schilthuizen, BOR/MOL 1328); Batu Keruak 2 near Sukau (leg. J.J. Vermeulen & M. Schilthuizen, V 9790; leg. T.S. Liew & B. Elahan, BOR/MOL 1858, BOR/MOL 1892; leg. M. Sal verda & H. van Oosten, BOR/MOL 1322, BOR/MOL 1319); Hill Resang River (leg. M. Schilthuizen, BOR/MOL 1324); Batu Mawas (leg. T.S. Liew & M. Schilthuizen, BOR/MOL 1969, BOR/MOL 2004; leg. M. Schilthuizen, BOR/MOL 1325); Batu Materis (; leg. T.S. Liew & B. Elahan, BOR/MOL 2094, BOR/MOL 2126); Batu Pangi (leg. J.J. Vermeulen & M. Schilthuizen, V 9641; leg. J.P. King, BOR/MOL 1326); Batu Tai (not Bod Tai) near Gomantong (leg. J.J. Vermeulen & M. Schilthuizen, V 9582; leg. M. Schilthuizen, BOR/MOL 1321; leg. T.S. Liew & B. Elahan, BOR/MOL 1926); Batu Tomanggong Kecil (leg. J.J. Vermeulen & M. Schilthuizen, V 9713); Batu Tulug (Batu Putih) along road Lahad Datu-Sandakan, North of bridge over Kinabatangan River (leg. J.J. Vermeulen & H. Duistermaat, V 1500); Gomantong Hill 30 km South of Sandakan (leg. J.J. Vermeulen & H. Duistermaat, V 1631; leg. M. Schilthuizen, BOR/MOL 1080; leg. A. van Til, BOR/MOL 3122, BOR/MOL 3276, BOR/MOL 3292, BOR/MOL 3302, BOR/MOL 3309, BOR/MOL 3321, BOR/MOL 3344; leg. T.S. Liew & J.P. King, BOR/MOL 3649); Tandu Batu (leg. J.J. Vermeulen & M. Schilthuizen, V 9628); Batu Tomanggong Besar (leg. M. Schilthuizen, BOR/MOL 1074, BOR/MOL 1317; leg. T.S. Liew & B. Elahan, BOR/MOL 2263, BOR/MOL 2294); Batu Tomanggong Kecil (leg. M. Salverda & H. van Oosten, BOR/MOL 1327; leg. T.S. Liew & B. Elahan, BOR/MOL 2036, BOR/MOL 2064); Unnamed hill near Sukau Police Station (leg. M. Schilthuizen, BOR/MOL 1320; leg. T.S. Liew, BOR/MOL 2166; leg. T.S. Liew & B. Elahan, BOR/MOL 2197). Segama valley, North end of limestone ridge on East bank Tabin River (leg. J.J. Vermeulen & M. Schilthuizen, V 7780, BOR/MOL 1087); Tabin Wildlife Reserve (leg. T. Kimsin, BOR/MOL 735; leg. M. Schilthuizen, BOR/MOL 1086). Tawau Province. Batu Baturong c. 50 km W.S.W. Lahad Datu (leg. J.J. Vermeulen & H. Duistermaat, V 1853); North slope (leg. J.J. Vermeulen, V 7588). Danum Valley (leg. M. Schilthuizen, BOR/MOL 1068, BOR/MOL 1073, BOR/MOL 1077; leg. UMS students, BOR/MOL 1075; leg. H.A. Rutjes, BOR/MOL 1079, BOR/MOL 1083;; leg. T. Kimsin & H.N. Chai, BOR/MOL 1084). Gua Madai c. 40 km S.S.W. of Lahad Datu (leg. J.J. Vermeulen & H. Duistermaat, V 1724); N.E. End (leg. J.J. Vermeulen, V 7700, BOR/MOL 1093). Segama valley, hill N.W. of crossing road Sandakan-Lahad Datu with the Segama River (leg. J.J. Vermeulen & H. Duistermaat, V 1679); ‘Kirk’s Cave’ 8 km North of Lahad Datu (leg. J.J. Vermeulen, V 1214); limestone hill on North bank Segama River, near bridge of road Sandakan to Lahad Datu (leg. J.J. Vermeulen, V 7501); Sabahmas Cave (leg. J.J. Vermeulen, V 7458, BOR/MOL 1089). Tawau Hills Park (leg. J.P. King, BOR/MOL 1316). Semporna area, Segarong Hills, Bukit Pababola, 25 km E.S.E. of Kunak (leg. J.J. Vermeulen & H. Duistermaat, V 1767); Bod Gaya Island (leg. T.S. Liew, Abdul & Ladja, BOR/MOL 4761, BOR/MOL 4775, BOR/MOL 4789, BOR/MOL 4897, BOR/MOL 4908). Tawau Hills N.P., path up to Bukit Bombalai (leg. J.J. Vermeulen, V 13156). West Coast Province. Crocker Range N.P., km 54 marker on the road Kota Kinabalu-Tambunan, Gunung Mas (leg. J.J. Vermeulen & M. Schilthuizen, V 9766; leg. M. Schilthuizen, BOR/MOL 1090). Kinabalu N.P., Headquarters area near entrance (leg. J.J. Vermeulen, V 9775; leg. M. Schilthuizen, BOR/MOL 1092); Sayap (leg. M. Schilthuizen, J. Schilthuizen & F. Schilthuizen, BOR/MOL 1323); Summit trail between 1616-3089 m (leg. T.S. Liew & J. Lapidin, BOR/MOL 4040; leg. T.S. Liew, BOR/MOL 4063, BOR/MOL 4031, BOR/MOL 4035, BOR/MOL 4066, BOR/MOL 4051, BOR/MOL 4055); Kiau-Spurs route between 3024 and 3088 m (leg. T.S. Liew, J. Lapidin & Safrie, BOR/MOL 4034, BOR/MOL 4069, BOR/MOL 4029); Kotal’s route between 1952 and 3416 m (leg. T.S. Liew & Jasilin, BOR/MOL 4032, BOR/MOL 4033, BOR/MOL 4059, BOR/MOL 4062, BOR/MOL 4038, BOR/MOL 4039, BOR/MOL 4043); Mesilau trail between 1948 and 2356 m (leg. T.S. Liew & J. Lapidin, BOR/MOL 4054, BOR/MOL 4050, BOR/MOL 4056, BOR/MOL 4058, BOR/MOL 4067; leg. T.S. Liew, BOR/MOL 4028, BOR/MOL 4048, BOR/MOL 4053); Sayap - Nunuhon trail between 960 and 2944 m (leg. T.S. Liew, Dominik, J. Lapidin & Jasilin, BOR/MOL 4037, BOR/MOL 4041, BOR/MOL 4042, BOR/MOL 4046, BOR/MOL 4064); Serinsim (leg. M. Schilthuizen, BOR/MOL 3070); Serinsim-Numbuyukon trail between 700 and 1680 m (leg. T.S. Liew, BOR/MOL 4044, BOR/MOL 4049, BOR/MOL 4057, BOR/MOL 4065, BOR/MOL 4068); Monggis-Tambuyukon trail between 1016 and 2360 m (leg. T.S. Liew, BOR/MOL 4030, BOR/MOL 4045), BOR/MOL 4052). Kota Kinabalu, Kiansom (leg. UMS students, BOR/MOL 1095). Mantanani Group, Pulau Mantanani Besar (leg. T.H. Liew, BOR/MOL 3714); Pulau Mantanani Kecil (leg. T.H. Liew, BOR/MOL 3733).

Description.

Shell very small, thin, translucent, white, lenticular; spire almost flat or slightly elevated. Surface glossy. Whorls slightly convex. Protoconch: smooth, sometimes with a few inconspicuous, scattered radial riblets only. Teleoconch: Spiral sculpture absent. Radial sculpture teleoconch: growth lines inconspicuous, next to these widely but irregularly spaced, shallow grooves, often alternating with areas of a much finer, more dense but irregularly spaced striation; sometimes the latter striation is predominant. Umbilicus partly or entirely covered by a minute, triangular spur protruding from the columellar corner of the peristome; this spur lacking or inconspicuous in juveniles; umbilical region moderately concave. Dimensions: Height up to 1.7 mm; width up to 3 mm; diameters of the first three whorls 0.5-0.8 mm, 0.9-1.5 mm, 1.5-2.5 mm respectively; number of whorls up to 4 1/8; height aperture up to 1.4 mm; width aperture up to 1.7 mm.

Habitat in Sabah and distribution.

Rainforest, periodically dry, shrubby woodland, coastal woodland, secondary forest and other degraded vegetation; on limestone, sandstone and granitic soil, up to 3500 m alt. Sabah: common and widespread. Also in Brunei; Sarawak; Kalimantan. Endemic to Borneo.

Cross diagnosis.

Characterized among the Borneo Microcystina species with white shells by a complete lack of spiral striation. Usually it is also larger and has more rapidly expanding whorls.

Elsewhere, Lamprocystus vitreiformis Von Moellendorff, 1897, from Sumatra, Java, and Bali (see Vermeulen and Whitten 1998: 118) is most similar; Microcystina microrhynchus is characterized by the minute spur protruding from the columellar corner of the peristome and covering the umbilicus. Microcystina chionodiscus Vermeulen, 1996, from Bali (see Vermeulen and Whitten 1998: 115), has the first whorl consistently smaller (diameter 0.4-0.5 mm) than Microcystina microrhynchus .

Etymology.

The name refers to the spur covering the umbilicus [mikros (Gr.) = small; rhynchos (Gr.) = beak].