The red-rimmed melania, scientific nameMelanoides tuberculata, is a species of freshwater snail with an operculum, a parthenogenetic, aquaticgastropodmollusk in the family Thiaridae. The common name comes from the presence of reddish spots on the otherwise greenish-brown shell. The species name is sometimes spelled Melanoides tuberculatus, but this is incorrect because Melanoides Olivier, 1804 was clearly intended to be feminine because it was combined with the feminine specific epithetfasciolata in the original description. This species is native to northern Africa and southern Asia, but it has been accidentally introduced in many other tropical and subtropical areas worldwide. It has also been accidentally introduced to heated aquaria in colder parts of the world.
Shell description
This species has an elongate, conical shell, which is usually light brown, marked with rust-colored spots. An operculum is present. In some places, such as in Israel, the shells are colored in black or dark brown, probably to help conceal the snail on the background of the basalt rocks of the Sea of Galilee. The average shell length is about 20–27 mm or 30–36 mm, but exceptional specimens may be up to 80 mm long. Shells of this species have 10–15 whorls.
Distribution
This species is native to subtropical and tropical northern Africa and southern Asia. ;in Africa:
This species has become established outside of its natural range in large part through the activities of aquarists. These snails were imported to the United States by the aquarium trade as early as the 1930s. Established populations exist from Florida to Texas, and the species may still be expanding its range in the West and Northeast. Some of these exotic populations have become very large, with densities of 10,000 per square metre being reported from the St. Johns River in Florida. In some cases red-rimmed melanias are believed to have a negative impact on native snail populations. The nonindigenous distribution includes the United States: Arizona; San Francisco Bay, California; Colorado; Florida; Hawai'i; Louisiana; Montana; North Carolina; Nevada; Oregon; Utah; Texas, and Fall River County in South Dakota,
Although normally a freshwater snail, this species is very tolerant of brackish water, and has been recorded in waters with a salinity of 32.5 ppt. It is however a warm-climate species. It appears to prefer a temperature range of 18 to 25 °C or of 18 to 32 °C. Research has been conducted to determine the snail's lethal high water temperature, which is about 50 °C. This information is helpful in the disinfection of fishing gear and research equipment, which otherwise may inadvertently spread the snails to uninfested waters. This species is resistant to low oxygen levels. The pollution tolerance value is 3.
Red-rimmed melania females are both parthenogenic and ovoviparous. Females can be recognized by their greenish coloured gonads while males have reddish gonads. Under good conditions, females will produce fertilised eggs that are transferred to a brood pouch where they remain until they hatch. Melanoides tuberculata has 1–64 embryos in its brood pouch. Snails will begin reproducing at a size as small as 5 mm or 10 mm in length and broods may contain over seventy offspring. The size of the shell of the parent at peak release of juveniles is 20.0 mm. The size of juveniles at birth is 1.2-2.2 mm. Melanoides tuberculata grows to a similar size as Tarebia granifera, are similar in size at first birth and juvenile output. It is a r-strategist species.
Parasites
Melanoides tuberculata is known to carry certain parasites which can be dangerous to humans. Pinto & de Melo compiled a checklist of 37 species of trematode parasites from this species of snail. Eleven of those trematodes are also parasites of human. These snails serve as first intermediate host for parasites which include:
This species is a host for a trematode parasite which has been found to infect an endangered species of fish in Texas, the fountain darter.
Agricultural pests
Red-rimmed melanias can sometimes be an agricultural pest species, as has been reported on Chinese cabbage plantations in Hong Kong.
Aquaria
Red-rimmed melanias are quite commonly found in freshwater aquaria, but opinion in the hobby is divided between those who see them as a pest species, and those who value their usefulness as algae-eaters and substrate-cleaners. Among aquarists, these snails are known as Malayan livebearing snails or Malayan/Malaysian trumpet snails.
