Hypselostoma sp. 1

Material examined.

Thailand • 2 shells; Trang Province, Kantang district, Yong Ling beach; 4 July 2014; J. U. Otani leg.; coll. PGB . Malaysia • 344 shells; Kelantan Province, 19 km south of Gua Musang; Oct. 1999; Hemmen leg.; coll. PGB .

Remarks.

Two samples from Thailand and Malaysia represent two different species, both of them probably most similar to H. burchi . Two specimens from Thailand are slightly more slender, lack interpalatal plica and have slightly narrower umbilicus. Specimens from Malaysia have slightly more detached and descending last whorl and they lack the interpalatal plica as well. Due to the absence of proper comparison material of H. burchi, we do not describe these taxa in this work.