The freshwater crabs of Danum Valley Conservation Area in Sabah, East Malaysia, with a description of a new species of Thelphusula Bott, 1969 (Crustacea, Brachyura, Gecarcinucidae, Potamidae, Sesarmidae) Author Ng, Peter K. L. Author Ng, Paul Y. C. text ZooKeys 2018 760 89 112 http://dx.doi.org/10.3897/zookeys.760.24787 journal article http://dx.doi.org/10.3897/zookeys.760.24787 1313-2970-760-89 A93EB14C1AD140AD8E8284C040350651 A93EB14C1AD140AD8E8284C040350651 Isolapotamon ingeri Ng & Tan, 1998 Figure 6F Isolapotamon sp. - Ng and Goh 1987 : 328, pl. 3, D. Isolapotamon ingeri Ng & Tan, 1998: 66, figs 6 E-H , 7; Ng et al. 2008 : 163. Material examined. Holotype: male (44.3 x 33.3 mm) (ZRC 1997.0796), Sungei Tawau, Tawau Hills Park, Tawau, Sabah, coll. P. Yam, 14 December 1991. Paratypes: 1 female (41.4 x 31.0 mm) (ZRC 1997.0797), same data as holotype. Others: 1 male, 2 females, 1 juvenile (ZRC 2000.2217), Lower Segama River, Danum Valley Field Centre, Lahad Datu, Sabah, coll. K. Martin-Smith, June 1996; 1 male (57.4 x 44.8 mm) (ZRC 1997.0798), Sungei Palum Tambum, near Danum Valley Field Centre, Lahad Datu, Sabah, coll. K. Martin-Smith, August 1996; 5 males (largest 57.4 x 43.5 mm), 1 female (ZRC 1997.0799), Sungei Palum Tambun, near Danum Valley Field Centre, Lahad Datu, Sabah, coll. K.M. Martin-Smith, 9 October 1996; 1 female (ZRC 2000.2218), Sepat Kalisun, stream 200 m from 4°58'04.8"N , 117°48'56.5"E , Danum Valley Field Centre, Lahad Datu, Sabah, coll. H.H. Tan et al., 1 October 1996; 1 male, 2 females (ZRC 2000.2210), Sungei Bole Ketabil tributary, 4°57'33.5"N , 117°51'34.1"E , Danum Valley Field Centre, Lahad Datu, Sabah, coll. H.H. Tan et al., 2 October 1996; 1 male, 2 females (ZRC 2000.2220), Cabin Stream, 50 km on road to Danum Valley Conservation Area, drains from Bukit Rafflesia, Lahad Datu, Sabah, coll. H.H. Tan et al., 2 October 1996; 1 male (ZRC 2000.2221), West Eight, forest stream, 800 m into conservation area, tributary of Sungei Segama, Danum Valley Field Centre, Lahad Datu, Sabah, coll. H.H. Tan et al., 4 October 1996; 2 females (ZRC 2008.0431), Danum Valley Rainforest Lodge, 5°03'2.9"N , 117°34'34.8"E , Lahad Datu, Sabah, 3 October 1996; 1 female (56.0 x 42.0 mm) (ZRC 1989.3419), Sungei Madai, Madai Caves, Sabah, coll. R. Goh, 27 January 1985; 1 male (ZRC 1997.0802), Tawau, Sungei Matarid, Gua Madai, Jalan Madai, 4°43'8.7"N , 118°9'14.7"E , Tawau, Sabah, H.H. Tan et al., 6 October 1996. Colour. The colour in life is dark green overall (H.H. Tan, pers. comm.). Remarks. Isolapotamon ingeri belongs to the same group of species as I. kinabauense (Rathbun, 1904) and I. anomalum (Chace, 1938) (both from the Mount Kinabalu area in northern Sabah), with the distal part of the terminal segment of the G1 expanded and flap-like ( Ng and Tan 1998 ). Like these species, I. ingeri usually occurs in large streams and rivers with large rocks and fast flowing water.