Quilted melania

Quilted melania (Tarebia granifera) is a freshwater gastropod up to 35mm in length, native to South-east Asia. This invasive species can withstand near marine salinities and poses a threat both ecologically and economically, through its ability to outcompete native species for space and resources, and damage aquatic infrastructure by restricting pipelines. A popular aquarium animal, its introduction internationally is likely due to both unintentional release from the trade, and intentional release as a method of controlling native snail populations. It is a host to the medically significant parasite, Paragonimus westermani (oriental lung fluke). Quilted melania, has successfully colonised estuaries, rivers, streams, canals and ponds across America, Hawaii, South Africa, and Israel.

The quilted melania, while generally thin and conical, may have a pale to dark brown body whorl, with a brown or black spire. Additionally, the shell may be smooth or covered in nodules and ribs. In conjunction with its variable physical appearance, the quilted melania colonises a diverse habitat of sediment, rock, aquatic plants, and artificial structures within both estuarine and freshwater ecosystems, resulting in a difficult biosecurity risk to manage.

Reporting

If you think you have seen a quilted melania in NSW, please take several clear, high-resolution photos of the shell. For identification, we need to see the:

1. Shell size – please include something for reference (e.g. a coin, ruler)
2. Shell colour and markings
3. Close-up of the shell opening and operculum (lid-like structure).

Please send photos to aquatic.biosecurity@dpird.nsw.gov.au, along with details of when and where the shell was seen.

Identification

Key features

• Conical and narrow with 8-12 whorls
• Up to 35mm in length
• Shell pale to dark brown body whorl with a brown or black spire
• Smooth or covered in radial ribs and nodules

Known locations

• Not in Australia

Habitat

• Estuaries, freshwater rivers, streams, canals, and ponds.
• Can acclimate to near marine salinity, and briefly tolerate extreme temperatures
• Inhabits sediment, rock, aquatic plants, and infrastructure
• Survives up to 3 days of air exposure at 25°C

Vectors

• Release from aquarium trade
• Contaminated boats, trailers and fishing gear
• Intentional introduction

Impacts

• Displaces and outcompetes native species for resources.
• Fouls infrastructure such as water intake pipes
• Increases maintenance costs for utilities and industry.

Similar native species

These native species may be confused with the quilted melania. These species do not need to be reported.

Australian mud whelk (Batillaria australis)

Key features

• Medium to dark brown shell covered in defined nodules and ridges
• Elongate, conical shell, typically 30mm in length, up to 49mm

Known locations

• Very common along East Coast of Australia

Habitat

• Estuarine environments, typically mud flats, river mouths, and mangrove swamps