Dallirhytis Kruglov & Starobogatov, 1989

Aksenova, Olga V., Vinarski, Maxim V., Itagaki, Tadashi, Ohari, Yuma, Oshida, Tatsuo, Kim, Sang Ki, Lee, Jin Hee, Kondakov, Alexander V., Khrebtova, Irina S., Soboleva, Alena A., Travina, Oksana V., Sokolova, Svetlana E., Palatov, Dmitry M., Bespalaya, Yulia V., Vikhrev, Ilya V., Gofarov, Mikhail Yu. & Bolotov, Ivan N., 2024, Taxonomy and trans-Beringian biogeography of the pond snails (Gastropoda: Lymnaeidae) of East Asia: an integrative view, Zoological Journal of the Linnean Society 201 (4), pp. 1-24 : 5-12

Genus Dallirhytis Kruglov & Starobogatov, 1989

Kruglov and Starobogatov 1989: 15.

Type species: Lymnaea petersi Dall, 1905

= Limnaea ovata var. atkaensis Dall, 1884 (by original designation).

Diagnosis: Shell medium in size, ovate-conical to almost ear-shaped, with well-developed acute spire ( Fig. 3A, B). Whorls are conspicuously inflated. Praeputium cylindrical, oblong, dark-pigmented; penis sheath rather short and compact; its length is 2.5–3.0 less than the praeputium length ( Fig. 4A). Penis with a (rudimentary) ring-shaped fixing swelling [ Walter (1969) calls it the ‘penial knot’]; prostate with a single internal fold.

Species richness: This is a monotypic genus. In addition to Dallirhytis atkaensis, Kruglov and Starobogatov (1989 , 1993) listed another species, Lymnaea petersi Dall, 1905 . However, we synonymize both species based on examination of samples of Ly. petersi kept in ZIN. We found that the conchological variability of Ly. petersi falls within the range of variability of D. atkaensis . The ranges of both taxa as accepted byKruglov and Starobogatov (1993) overlap almost completely. Dallirhytis atkaensis has a very characteristic shell appearance and can hardly be confused with another pond snail species of Beringia.

Distribution: A Beringian taxon known from Alaska, the Yukon Territory, northern British Columbia, and the Chukchi Peninsula ( Burch 1989, Kruglov 2005, Aksenova et al. 2023).