Identification:
Morphological Characteristics:
Medium-sized clam. Shell relatively short, wide, with a sharp, abruptly pointed apex. Shell moderately thick, with a low umbonal region. The anterior margin is evenly rounded; the ventral margin is straight, slightly concave in the middle; the dorsal margin is slightly curved downwards. The outer shell surface is smooth in the anterior region; at the apex, short, parallel longitudinal ridges and “chi”-shaped nodular rows are visible. The posterior shell section has large, parallel longitudinal grooves extending to the tip.
Shell color: dark brown. Nacreous layer: white with iridescent, five-colored sheen.
Biology and Ecology:
Inhabits mountainous rivers, preferring soft, muddy, or sandy bottoms.
Distribution:
Within Vietnam: Cao Bang (Bang River), Thua Thien – Hue, South Central Coast (Phuc Son).
Global: Endemic to Vietnam.
Value:
Significant scientific and culinary value.
Conservation Status:
Endemic species with fragmented distribution, currently experiencing heavy exploitation. Prior to 1975, the species was common in the Bang River (Cao Bang). Since 1975, particularly from 1990 to the present, due to its culinary value, the annual exploitation rate has increased significantly, leading to a noticeable decline in population, possibly up to 20%. The pre-1975 distribution encompassed Cao Bang, the Central and South Central regions. Currently, the area has shrunk due to heavy exploitation and the pollution of rivers. Surveys and interviews with local people in 2000 and 2001 on the Bang River (Cao Bang) did not yield any live specimens of this species.
IUCN Red List Category: VU B2a,b,e + 3d.
Conservation Measures:
Included in the Vietnamese Red Book and the list of protected species of the Fisheries sector before 1996. Recommendations: restrict exploitation, protect against river water pollution. Further research including artificial breeding is recommended.