Melanoides tuberculata
(red-rimmed melania)

Preferred Common Name

• red-rimmed melania

Other Scientific Names

• Melanoides tuberculatus
• Thiara tuberculata

International Common Names

• English: Malaysian trumpet snail

• Domain: Eukaryota
•     Kingdom: Metazoa
•         Phylum: Mollusca
•             Class: Gastropoda
•                 Subclass: Caenogastropoda
•                     Order: Sorbeoconcha
•                         Unknown: Cerithioidea
•                             Family: Thiaridae
•                                 Genus: Melanoides
•                                     Species: Melanoides tuberculata

Melanoides tuberculata is a tropical freshwater gastropod belonging to the Thiaridae family which is placed in clade Sorbeoconcha of the Caenogastropoda according to the classification of Bouchet and Rocroi (2005). It was described in the eighteenth century by Müller (1774) from the Coromandel region, India. Since its first description, many new species names have been given, as a consequence of substantial morphological variability, and subsequently synonymized with M. tuberculata (Starmühlner, 1976b). However, the shell of M. tuberculata exhibits an amazing morphological variation (general shape, background colour, ornaments and sculptures) that can simply be revealed by bleaching shells and which allows defining discrete morphs (several dozen described morphs), (Pointier, 1989; Facon et al., 2003). This variation has been shown to be heritable in the morphs studied (Pointier et al., 1992). These different morphs display very different life-history traits (Pointier et al., 1992; Facon et al., 2008).

M. tuberculata has a turreted shell with rounded body whorls that are ornamented with spiral grooves and sometimes axial undulating ribs well marked on the middle and upper whorls. The shells are pale to dark brown with numerous reddish brown flames and spots. However, characteristics of the shell (general shape, background colour, ornaments and sculptures) can vary according to the morphs considered (Facon et al., 2003). The spire is usually twice the length of the aperture or more (Morrison, 1954). The aperture is oval-shaped and the operculum is paucispiral, with the nucleus near the base (Morrison, 1954; Thompson, 1984). The head is tongue-like and constricted on its ventral side to give rise to the foot. The tentacles arise from just above this constricted area and are long and slender. M. tuberculata can reach up to a mean adult size of 20-40 mm depending on the morphs considered and environmental conditions (Pointier, 1989), but Murray (1975) reported individuals 70-80 mm in shell length in Texas.

In 1927, M. tuberculata was found in various regions of Asia and Africa. Since then, it quickly invaded the whole inter-tropical belt mainly as a result of the trade in aquatic plants used in aquariophily (Madsen and Frandsen, 1989; Glaubrecht, 2000). Its invasion history in the Neotropics is well documented. Accidental introduction was first mentioned in America (Texas) in 1964 (Murray, 1964), and this was followed by rapid expansion. It was reported in Puerto-Rico and Florida in 1966, Panama in 1971, Venezuela in 1972, the Lesser Antilles (Dominique Island) and Louisiana in 1975, Honduras, Martinique and Guadeloupe Islands in 1979, Mexico and Dominican Republic in 1980 (Pointier and McCullough, 1989; Pointier, 1999). Later, other South-American countries were colonized, including Colombia, Peru, Ecuador, Brazil and Argentina (Fernandez et al., 2003). Today, most of the Neotropical area must be considered as either invaded or on the way to be so (Pointier, 1999; Quintana et al., 2000). Invasion dynamics have been thoroughly studied in some areas, such as the French West Indies (for further information, see Pointier, 1989, 1993, 1999; Pointier and Guyard, 1992; Pointier and Jourdane, 2000; Pointier et al., 1989, 1992,1993). Its expansion in the Australian and Pacific areas is more poorly documented. For instance, Riech (1937) recorded M. tuberculata in the Pacific islands in 1937, but its absence is not certain before this date. 

The consequences of the invasion of the Neotropical area, especially in some Caribbean islands, may be considered as a benefit for public health, because this snail has eliminated or strongly reduced populations of Biomphalaria glabrata, the main snail host of intestinal schistosomiasis (Pointier and Théron, 2006). However, it has to be noted that the impact of M. tuberculata on B. glabrata is variable according to the type of aquatic habitat (Pointier et al., 1993). Positive results have been obtained in dasheen-marshes (Prentice, 1983), water-cress beds (Pointier and Guyard, 1992), ponds (Pointier, 1989) and springs (Pointier et al., 1991) where B. glabrata was eliminated but the biological control failed in the marshy forest located behind mangroves in Guadeloupe and this area is still an active focus of schistosomiasis (Pointier and Jourdane, 2000; Pointier and Théron, 2006).

• Invasive in its native range
• Proved invasive outside its native range
• Has a broad native range
• Abundant in its native range
• Highly adaptable to different environments
• Is a habitat generalist
• Capable of securing and ingesting a wide range of food
• Highly mobile locally
• Benefits from human association (i.e. it is a human commensal)
• Long lived
• Fast growing
• Has high reproductive potential
• Reproduces asexually
• Has high genetic variability

• Changed gene pool/ selective loss of genotypes
• Negatively impacts aquaculture/fisheries
• Reduced native biodiversity
• Threat to/ loss of native species

• Competition - monopolizing resources
• Competition - smothering
• Pest and disease transmission
• Herbivory/grazing/browsing
• Hybridization
• Parasitism (incl. parasitoid)
• Predation
• Rapid growth

• Highly likely to be transported internationally accidentally
• Highly likely to be transported internationally deliberately
• Highly likely to be transported internationally illegally
• Difficult to identify/detect as a commodity contaminant
• Difficult to identify/detect in the field
• Difficult/costly to control