Identification Characteristics:
Medium-sized mussel with a very thick, leaf-shaped shell. The interior of the shell is deeply concave near the hinge area. The umbo (apex) is inflated and curves forward. The dorsal surface of the shell has wrinkles and bumps. The posterior and ventral regions of the shell typically exhibit only rough growth lines. There are approximately ten ridge-like wrinkles on the posterior dorsal region. Two prominent ridges run parallel from the umbo to the posterior edge of the shell. The shell surface is dark brown, and the nacre (mother-of-pearl) is white with a bluish iridescence.
Biology and Ecology:
Inhabits rivers in mountainous regions, preferring a soft substrate of mud and sand.
Distribution:
- Within Vietnam: Mountainous regions, midlands of the Northeast, and the Red River Delta.
- Global: Endemic to Vietnam.
Value:
Of scientific value, used as a food source, and its thick shell is suitable for button making and mother-of-pearl inlay.
Conservation Status:
An endemic species currently facing significant exploitation. Prior to 1975, it was commonly found in the rivers of the Red River Delta. After 1975, particularly from 1990 to the present, the development of handicrafts using the mussel shell, led to increased harvesting, resulting in a noticeable decline in numbers, potentially up to 20%. Before 1975, the distribution area of this mussel extended throughout the Red River Delta, covering an area of 15,000 km². Currently, due to overexploitation and pollution of rivers in the delta and midlands, the distribution area has shrunk to approximately 2,000 km².
Assessment:
VU (Vulnerable) B2a,b,e + 3d.
Conservation Measures:
Included in the Vietnam Red Book and the list of protected species by the fisheries sector since before 1996. Recommendations: restrict harvesting, protect against river water pollution. Conduct supplementary research, including artificial breeding.