Mesomphix - Button Snails (Family Zonitidae)
Button Snails have mostly globose to subglobose shells with the last whorl noticeably expanded. The apertural lip is not reflected and tends to oblique and ovate (like a lop-sided wide mouth grin). They are umbilicate to slightly rimate.
They can be confused for immature Mesodon shells as both have unreflected lips. But the expansive outer whorl of Mesomphix is an important clue and is its mostly oval aperture compared to the rounded aperture of Mesodon.
Up to eight species of Button snails may be found in Indiana. The actual status and how many there are is undetermined. As with other genera, a thorough re-examination of museum specimens and wide collections of fresh specimens is needed. Dourson (2010) and Hotopp et al. (2013) provide more information.
Up to eight species of Button snails may be found in Indiana. The actual status and how many there are is undetermined. As with other genera, a thorough re-examination of museum specimens and wide collections of fresh specimens is needed. Dourson (2010) and Hotopp et al. (2013) provide more information.
The eight species all have some museum records and are (in order of number of counties and with presence/absence as a state species in NatureServe noted):
Mesomphix cupreus, Copper Button Snail (29 counties, state-listed in NS)
Mesomphix friabilis, Brittle Button Snail (13 counties, state-listed in NS)
Mesomphix vulgatus, Common Button Snail (11 counties, state-listed in NS)
Mesomphix capnodes, Dusky Button Snail (8 counties, not state-listed in NS)
Mesomphix perlaevis, Smooth Button Snail (7 counties, not state-listed in NS)
Mesomphix inornatus, Plain Button Snail (5 counties, state listedNS
Mesomphix globosus, Globose Button Snail (2 counties, state-listed in NS)
Mesomphix anurus, Frog Button (1 county, not state-listed in NS)
In general, these species tend to prefer wooded hillsides associated with leaf litter and other organic matter, but also may be found in associated areas.
Speculative Key based on Burch (1962) but excludes Mesomphix anurus and M. globosus [also be sure to consult descriptions and images in Dourson 2010, Dourson 2015, and at Hotopp et al. 2013]
1a. perforate to narrowly umbilicate – go to 2
1b. wider, 1/12 – 1/5 – go to 4
2a. first several whorls nearly smooth – go to Mesomphix inoratus
2b. first several whorls of spire strongly sculptured with growth wrinkles – go to 3
3a. shell rather dull, sculpture of spiral papillae well developed (papillae shown below) – go to Mesomphix vulgatis
3b. shell more glossy, sculpture of spiral papillae not well developed – go to Mesomphix perlaevis
4a. shell sculptured with distinct spiral rows of papillae, shell larger, more than 29 mm in diameter, spiral papillae not well developed – go to Mesomphix capnodes
4b. shell sculpture indistinct – go to 5
5a. umbilicus 1/6-1/5 of the shell diameter – go to Mesomphix cupreus
5b. umbilicus about 1/10 the shell diameter – go to Mesomphix friabilis
image of Mesomphix cupreus
Copper Button Snail
Mesomphix cupreus (Rafinesque, 1831)
Mesomphix friabilis (W. G. Binney, 1857)
Brittle Button Snail
Mesomphix friabilis (W. G. Binney, 1857)
Mesomphix vulgatus H. B. Baker, 1933
Common Button Snail
Mesomphix vulgatus H. B. Baker, 1933
papillae shown below
image of Mesomphix capnodes
Dusky Button Snail
Mesomphix capnodes (W. G. Binney, 1857)
image of Mesomphix perlaevis
Smooth Button Snail
Mesomphix perlaevis (Pilsbry, 1900)
image of Mesomphix inornatus
Plain Button Snail
Mesomphix inornatus (Say, 1821)
image of Mesomphix globosus
Globose Button Snail
Mesomphix globosus (MacMillan, 1940)
image of Mesomphix anurus
Smooth Button Snail
Mesomphix anurus
