Stomacosmethis kelantanensis expansus (Foon & Liew, 2017)

Pall-Gergely, Barna, Sajan, Sheikh, Tripathy, Basudev, Meng, Kaibaryer, Asami, Takahiro & Ablett, Jonathan D., 2020, Genus-level revision of the Alycaeidae (Gastropoda, Cyclophoroidea), with an annotated species catalogue, ZooKeys 981, pp. 1-220 : 1

Stomacosmethis kelantanensis expansus (Foon & Liew, 2017)

Alycaeus expansus Foon & Liew, 2017: 25-37, figs 7N, 16, 31I.

Remarks.

Alycaeus expansus Foon & Liew is most similar to A. clementsi and Stomacosmethis kelantanensis . Foon and Liew (2017) do not explain the differences between A. expansus and the other two taxa, but mention that the characteristic features of this species are the obtuse ultimate whorl, the strongly expanded peristome, the thick operculum and the animal colouration. Based on the photographs in the original description it is difficult to understand what the authors meant by "obtuse ultimate whorl", because the general shell and body whorl shape do not differ conspicuously from the other two taxa; it was supposed to mean the more rounded-looking ultimate whorl, especially for shells from the type locality (Junn Kitt Foon, pers. comm. 2020 June). Contrary to the original description, the peristome of S. kelantanensis is even more expanded than that of A. expansus . The animal colouration and the operculum thickness are characters which should not be used as distinguishing characters at the species level, especially because thickness of shell or operculum is highly dependent on the environment. Therefore, this taxon is treated as a subspecies of S. kelantanensis .

Alycaeus expansus Foon & Liew, 2017 is a primary homonym of Alycaeus expansus Heude, 1890. To our knowledge, the older name has not been used in this combination since 1899, thus no replacement name for Alycaeus expansus Foon & Liew, 2017 is necessary.