Gastrocopta rogersensis Nekola and Coles, 2001
Rogers' Snaggletooth Snail
Basis for Listing
Only recently described as a distinct species (Nekola and Coles 2001), Rogers’ Snaggletooth snail (Gastrocopta rogersensis) is limited to three disjunct areas of occurrence: the Ozarks and surrounding limestone districts; the middle Ohio River valley; and the Upper Mississippi River valley. Only four Minnesota sites for this species have been documented, all restricted to the Paleozoic Plateau in Fillmore, Houston, and Winona counties. Due to the limited number of documented populations in Minnesota, its restricted range in the state, and its sensitivity to fire management practices utilized within its habitat, Rogers’ Snaggletooth was listed as a species of special concern in 2013.
Rogers’ Snaggletooth possesses a shell ranging from 1.8-2.6 mm (0.07-0.10 in.) in height, with 5-6 whorls. The shell is brown-yellow in color. It is most easily distinguished from the similar-looking Wing Snaggletooth (Gastrocopta procera) by the shape of the angulo-parietal lamella (the ‘teeth’ at the opening of the shell): In Rogers’ Snaggletooth, the angular and parietal lobes are parallel, separated by a channel, and rectangular in outline; while in Wing Snaggletooth they converge, creating a triangular structure (Nekola and Coles 2001).
In Minnesota, Rogers’ Snaggletooth is restricted to dry bedrock bluff prairies and cedar glades (sedimentary bedrock outcrop) within The Blufflands Subsection of the Paleozoic Plateau Section of the Eastern Broadleaf Forest Province. It favors very xeric sites, where it is limited to the thin layers of decomposing grass litter that accumulate around and under loose rocks. In the Ozarks, this species can also inhabit dry and wooded carbonate bedrock cliffs and outcrops (Nekola and Coles 2001).
Biology / Life History
Little specifically is known about the life-history behavior of Rogers’ Snaggletooth. Field observations suggest that this species is a generalist consumer of fungus, and perhaps algae, that cover decaying pieces of plant leaf litter. Because individuals at all stages of development may be found at any given time within a colony, it is likely that they reproduce throughout the growing season, with individuals taking no more than eight weeks to reach adult maturity from hatching. It is also likely that individuals are able to live longer than one growing season. Like many other land snails within the Pupillidae, it is also likely that Rogers’ Snaggletooth can reproduce via selfing, whereby male and female gametes from the same hermaphroditic individual are able to join to create viable offspring. Because of this, it is possible for a single individual to found a new colony.
Genetic analyses document that Rogers’ Snaggletooth represents a species that is intermediate between members of the central and eastern USA Wing Snaggletooth group and some members of the subgenus Immersidens from the Sonoran Desert and adjacent regions (in particular the Shortneck Snaggletooth [G. dalliana]; Nekola et al. 2012).
Although essentially limited to prairie habitats, Rogers’ Snaggletooth has proven to be highly sensitive to fire disturbance, with population sizes decreasing by orders of magnitude for many years (and perhaps decades) following events (Nekola and Coles 2001; Nekola 2002). Because they prefer dry sites with very low-productivity, it takes at least this amount of time for leaf litter accumulations to return to the pre-burn levels that will support healthy populations of this species.
Conservation / Management
Because of the ubiquitous use of rapid return-interval fire management by public and private conservation organizations, many potential sites for this species in southeastern Minnesota have already been damaged and may no longer support Rogers’ Snaggletooth. However, it is hoped that healthy colonies persist on unmanaged lands elsewhere in the region. Maintenance of these sites will require hand removal of encroaching woody plants in combination with low levels of large herbivore grazing to maintain grassland without the use of fire. Pre-management surveys of newly acquired properties will be essential to determine species presence, monitor population size, and identify those sites which are inappropriate for rapid return-interval prescribed burns.
Conservation Efforts in Minnesota
No specific activities have been taken to ensure the long-term survival of Rogers’ Snaggletooth within the state. However, one of the known sites for this species is in Great River Bluffs State Park, which should offer the species some protection.