Originally this species was reported from the state as Pupa corpulenta by Binney (1886). It has also been called Vertigo parietalis in Utah (Jones 1940a). Chamberlin and Jones (1929) called the subspecies corpulenta the chubby snail and the subspecies parietalis the long-toothed snail.
Three subspecies, Vertigo modesta insculpta, Vertigo modesta corpulenta and Vertigo modesta parietalis, have been reported from Utah. The taxonomic validity of these subspecies, particularly corpulenta and parietalis is doubtful under the modern concept of a subspecies. According to Pilsbry (1939), "[t]here are numerous forms and mutations [of this species], some of them apparently subspecies characteristic of definite areas; others, such as parietalis, often occur associated with various races in the same populations. The subspecific taxonomy is more or less arbitrary." In discussing some morphological characteristics of parietalis, Pilsbry states: "As forms with the parietalis teeth occur in some places associated with both corpulenta and with shells having the contour of typical modesta, the subspecific status can hardly be allowed this form." The type locality for the taxon parietalis is Ogden Canyon, Weber County, but corpulenta is recorded from the same locality and possibly from the same specimen lot (Henderson and Daniels 1917).
Status in Utah
Eleven Utah occurrences of this species have been published. In north-central Utah, occurrences are concentrated in the central and southern portions of the Wasatch Range, in Weber, Salt Lake, Wasatch and Utah counties, and in the Uinta Mountains in Summit County, but other populations are known in Sevier County in central Utah and Kane and San Juan counties in southern Utah (Binney 1886, Pilsbry and Vanatta 1900, Ferriss 1920, Chamberlin and Jones 1929, Chamberlin and Berry 1930, Berry 1931, Jones 1940a, Woolstenhulme 1942a, 1942b). The San Juan County records represent the only occurrence of the subspecies insculpta in Utah.
Reported numbers of Utah specimens of this species are: 6 (Jones 1940a), 3 (Woolstenhulme 1942a), and 2 (Woolstenhulme 1942b).
Some populations, especially those in the Wasatch Mountains, are potentially threatened by development and associated loss of habitat.
No records of this species in Utah are available since 1942. Inventory in the Wasatch Mountains is needed in order to reveal distributional patterns and habitat use in this rapidly developing area. Inventory is also needed in southern Utah to clarify the distribution and taxonomic relationships of the subspecific taxa in the state.
This minute species is likely overlooked by most surveys. For example, Clarke (1993) conducted extensive surveys in the Ogden Canyon vicinity, the type locality of the taxon parietalis, but possibly overlooked Vertigo modesta, reporting only large species of the genus Oreohelix.
Habitats Utilized in Utah
Chamberlin and Jones (1929) reported specimens from "swampy ground".