Subulina octona is one of the land snail species that have been widely distributed as a result of human activities. I am not quite sure where the species originated. Pilsbry1 implied that the original range of S. octona was tropical America and indicated that it was introduced in Africa, Ceylon, East Indies and elsewhere. Schileyko gave the range of the genus as tropical Africa, Comora Islands, Central America and tropical South America.
Subulina octona is quite common in gardens, parks and alongside roads in Florida. I have found it in Pinellas County, north of Tampa and further south near Fort Myers. The snail pictured above was from the latter location. Elsewhere in the U.S., the species has been recorded from greenhouses. It has also been introduced to the Samoan Islands and was recently found in greenhouses in Prague, Czech Republic.
An empty shell of Subulina octona characterized by, in Pilsbry’s1 words, a "distinctly but not abruptly truncate columella [arrow]".
1. Pilsbry, H.A. 1946. Land Mollusca of North America (north of Mexico ). Vol. 2, part 1.
2. Schileyko, A.A. 1999. Treatise on Recent Terrestrial Pulmonate Molluscs. Part 4. Ruthenica, Supplement 2.