Hypselostoma annamiticum Möllendorff, 1900

Figs 111 C, 116, 154

Hypselostoma annamiticum Möllendorff, 1900: 133.

Hypselostoma annamiticum — Möllendorff 1901 a: 50; Fischer and Dautzenberg 1904: 408; Pilsbry 1917: 180–181; Zilch 1984: 161; van Benthem Jutting 1950: 41.

Hypselostoma annamiticum altius Pilsbry, 1917: 181, pl. 31, figs 11–13. syn. nov.

Hypselostoma annamiticum altius — van Benthem Jutting 1950: 41; Schileyko 2011: 3.

Hypselostoma annamiticum annamiticum — Schileyko 2011: 3.

Type material examined.

Vietnam • holotype of H. annamiticum annamiticum; “ Phuc-Son, Touranne, Annam ”; ex. coll. Möllendorff; SMF 4871 • 11 paratypes of H. annamiticum annamiticum; same data as for the holotype; ex. coll. Möllendorff; SMF 4872 • 1 paralectotype of H. annamiticum altius; from the type locality; ANSP 45167 .

Type localities.

“ Phuc-son ”, Vietnam ( H. annamiticum annamiticum), “ Annam (Fruhstorfer) ”, Vietnam ( H. annamiticum altius).

Differential diagnosis.

This species is superficially similar and geographically approximate to A. turritus sp. nov., but the suture of this species is shallower, the shell is more slender, the umbilicus is wider and the apertural dentition is also different (no concrescent barriers on the parietal side in the new species vs angulo-parietal lamella in H. annamiticum).

Distribution.

This species is known only from Annam, Vietnam.

Remarks.

Holotype of H. annamiticum annamiticum has a vestigial lamella between the columellar lamella and angulo-parietal lamella. Some paratypes do not have this lamella or it is further less developed, sometimes also located much deeper inside the aperture. In some specimens, upper palatal plica has an additional palatal tubercle which is sometimes connected with the former. Hypselostoma annamiticum altius is synonymised with the nominotypical subspecies since we could observe no morphological differences. The fact that it is higher than the nominotypical subspecies (Pilsbry 1917) does not seem to justify its distinctness.