The Giant South American Snail, Megalobulimus Oblongus (Muller)

Based on data furnished by Torres (1950), Mead (1961) called attention to the giant South American snail as destined to become an important pest. Because tropical conditions of south Florida are similar to those where this snail has already been introduced, we should be aware of this plant feeder’s existence and be ready to eradicate it before it gains a foothold in Florida. Like the giant African snail (Achatina fulica Bowdich), this species may be confused by non-malacologists with non-plant-feeding tree snails (Bulimulidae) since they have similar shell shapes. Adults (Fig. 1) are much larger than Florida’s largest tree snails (Orthalicus spp.), and their thick, bright pink lip is distinctive from both tree snails and the giant African snail. Juveniles show a trace of pink at the base of the columella, and are thin-shelled, unlike native species of equivalent size. Other distinguishing characters include ribbed surface sculpture and solid coloration (Fig. 7), rather than microscopic striations and vertical stripes. Although this South American species is unrelated to the giant African snail, it appears to occupy a similar ecological niche (Bequaert 1948). Data on host preferences are scant, but the giant South American snail is believed to be, like the giant African snail, a serious plant pest requiring quarantine measures. This snail has been introduced into a few Caribbean islands as a food source (Bequaert 1948). Formerly, it was placed in the genus Strophocheilus (family Strophocheilidae), but Leme (1973) placed it along with several other species in the monogeneric family Megalobulimidae based on important anatomical differences. These include possession of a buccal fringe, a pulmonary septum, and a pre-rectal valve in the intestine. Based on the orientation and structure of the kidney, Leme postulates that this group is the most primitive of the order Stylommatophora.