Hypselostoma piconis van Benthem Jutting, 1949
“The nearest relatives of the species are Hypselostoma tubiferum (Benson) as to the arrangement of the teeth and H. annamiticum Möllendorff as to the general shape, except the tubiferous portion of the ultimate whorl which has only a very short free part. Hypselostoma piconis is so distict from any of the known species of this genus, that there is no doubt we have to do with a new species.” (Benthem-Jutting, 1949)
Benthem-Jutting (1949) original descriptions on Hypselostoma piconis – “Shell moderately conical, the spire about as high as the diameter of the last whorl (previous to the trumpet). Last whorl produced into a trumpet-shaped aperture, free from the spire, running forward and a little obliquely upward. The peristome and the vertical axis make an angle about 45°. Dark brown, thin little transparent, somewhat glossy. Surface finely striated in spiral direction, with a cross-striation parallel with the lines of growth. Whorls 4, convex, separated by a well impressed suture. The last whorl bears a conspicuous, although not sharp, peripheral keel. This keel is rendered even more conspicuous by slight impressions in the shell above and below it, which cause it stand out a little more prominently. The peripheral keel is continued on the free part of the aperture, becoming more cord-like on this part of the shell. The base of the shell is angular around the widely open umbilicus. This edge is also continued as a ridge on the free part of the ultimate whorl. Together with two other ridges, originating from the suture and about halfway between the suture and the base of the columellar side, these ridges give the trumpet a more or less quadrangular aspect. Top mamillar. Peristome continuous. Aperture indistinctly tetragonal, provided with 5 teeth within. Angular and parietal lamella are combined into one lobed tooth. Besides there are one columellar lamella an two palatal plicae. Of the latter, the lower one faces the parietal + angular tooth, the upper one is opposite the columellar tooth. In the corner between the angular + parietal and the columellar lamella there is a smaller tooth, presumably the supra columellar lamella. Teeth not puckered.”
Hypselostoma piconis – “Dimensions: Max. diam. (including aperture) 3.7-3.8 min. diam. 2.3-2.4, height 1.8 mm.” (Benthem-Jutting, 1949)
Type locality – “Sungei Siput, Perak” (Benthem-Jutting, 1949)