Chamberlin and Berry (1930), reporting Utah specimens later determined (Pilsbry 1948) to be this species, listed it simply as "Pupoides. ... Species uncertain, probably new." Chamberlin and Berry (1931) reconsidered the same specimens that they had reported in 1930; in their 1931 publication they noted that these specimens "were first referred to P. hordaceus (Gabb) and then indicated [Chamberlin and Berry 1930] as probably new .... The species is here described as new." In this publication (Chamberlin and Berry 1931) the new name that they proposed for their Utah specimens was Pupoides eupleura. Gregg (1942) reported more specimens from Utah as Pupoides hordaceus. Pilsbry (1948) reassigned the specimens reported by Chamberlin and Berry (1930, 1931) to Pupoides hordaceus and placed the name Pupoides eupleura in synonymy with the former name. Chamberlin and Roscoe (1948) listed the species in Utah as "Pupoides hordaceous [sic] (Gabb)" and indicated "Pupoides eupleura Chamberlin and Berry" as a synonym.
Apparently no subspecies have been proposed in this species.
Status in Utah
Three occurrences, all historical at best, have been reported in Utah (Chamberlin and Berry 1930 [as "Pupoides ... Species uncertain, probably new"], Chamberlin and Berry 1931 [as "Pupoides eupleura, sp. nov."], Gregg 1942, Pilsbry 1948). None of the reports of the species in Utah has specified whether any live examples were found; thus, extant status in Utah has not been documented, even historically.
All reports of this species in Utah may be from Garfield County (Chamberlin and Berry 1930, Chamberlin and Berry 1931, Gregg 1942, Pilsbry 1948), although one of these localities has been vaguely stated as being in "Wayne and Garfield counties" (Chamberlin and Berry 1930, Chamberlin and Berry 1931). It is not unlikely that the species occurs elsewhere in southern Utah.
Pilsbry (1948) mentioned that the species occurs in "San Miguel Co., Colorado, near the Utah line" and documented this locality as "Dolores canyon near mouth of Gypsum Creek, San Miguel Co. (Junius Henderson, 1914)"; this Colorado locality suggests that the species may be found in San Juan County, Utah, as well. Records of this species from three of the four Arizona counties that adjoin Utah (Apache, Navajo, and Coconino counties, Arizona), where it is "most abundant" (Pilsbry 1948), also strongly suggests its occurrence in San Juan and Kane counties, Utah.
None of the reports of this species in Utah has provided any indication of numbers encountered or collected.
Threats to this species in Utah are unknown. Population trend in this species in Utah similarly is not known.
Inventory is needed to determine whether this species is extant in Utah at the three localities from which it is known historically. At least two of the three known Garfield County, Utah, localities are very near the boundary with Kane County; sites in adjacent Kane County should be searched for this species, and it should be looked for elsewhere in southern Utah, particularly in Wayne and San Juan counties, and also in Iron and Washington counties.
As with other pupillids, this is a minute and inconspicuous species, difficult to sample and easily overlooked. Thus, its rarity in Utah may be more apparent than real.
Habitats Utilized in Utah
None of the reports of this species in Utah has provided any information regarding habitat. Gregg's (1942) locality for the species, "along North Fork of Asay Creek", suggests a riparian situation; however, no details were given, and Gregg's specimen(s) may have been dead, perhaps drift material washed into and perhaps down the drainage.
Discussing the species throughout its range, Pilsbry (1948) wrote: "This is a species of the arid plateaus and foothills, not found in the humid upper zone of the mountains. It is known by specimens taken in the debris of streams or in Pleistocene or later deposits."