Shell relatively small, with a conical spire issuing from a rather broad base. The wide aperture is not disjunct, but adnate to the preceding whorl. Shell is reddish-brown and opaque. First 1.5 whorls lack ornamentation, progressing into weakly striated and ribbed subsequent ultimate whorls. Last whorl (of 5) ends straight or partially descending. Whorl peripheries rounded except for a conspicuous peripheral keel on the ultimate whorl, with a similar keel encircling the umbilicus. Umbilicus rather wide and open. Aperture wide, with separated angular and parietal lamellae;
columella, upper and lower palatal teeth large, infraparietal, basal and interpalatal teeth small. Peristome continuous, thickened and expanded. Height: 2.9-3.4 mm, Breadth: 2.6-3.1 mm, Apertural height: 1.4-1.6 mm [among type series and references of Benthem-Jutting, 1949].
H. serpa resembles
Gyliotrachela modesta in general form, but the latter differs in its disjunct ultimate whorl and lesser-developed apertural armature. == Distribution and threats ==