Identifying freshwater mussels in coastal NSW

Basket shells Corbicula australis (top) are more symmetrical than freshwater mussels Hyridella drapeta (bottom).
Photo: Hugh Jones, OEH.

Adult shells vary in size from about 50 to 200 mm in length but most shells fit snugly in the palm of your hand. The shell colour of mussels ranges from brown to black, although it can be green in young shells.

Freshwater mussels should not be confused with basket shells, another common bivalve which inhabits coastal rivers. Basket shells are small and triangular, reaching a maximum size of about 15 mm. The external shell of basket shells is usually orange while the internal surface has a purplish tinge.

MUSSELpdb is a comprehensive online database documenting specimen collections from major museums around the world. Use the database, together with information in the table below, to identify mussels in NSW.

Hyridella australis Distribution in NSW: All streams. Most common in lower reaches Microhabitat: Areas of still-slow current often in soft sediment. Found in alcoves near streambanks and behind logs, undercut banks, and impoundments behind weirs Appearance: Angular, glossy-black, oblong-shaped shell. Heavy v-shaped sculpturing on beaks of small shells. Maximum shell length 90 mm.
Hyridella depressa Distribution in NSW: All streams except the Hunter and Shoalhaven rivers Microhabitat: Slow-moderate currents in sand or gravel of glides and pools Appearance: Elongated dark brown shell. Fine beak sculpture on small shells. Maximum shell length 70 mm.
Hyridella drapeta Distribution in NSW: Absent or rare in the Hawkesbury-Nepean River and south of the Shoalhaven River Microhabitat: Slow-moderate currents in sand or gravel of glides and pools Appearance: Oval with smoothly curved outline, brown to slate-grey, never glossy. Fine beak sculpture on small shells. Maximum shell length 90 mm.
Hyridella narracanensis Distribution in NSW: Upper reaches of Genoa River Microhabitat: Moderate currents, often buried in sand or gravel. Small, shallow permanently flowing streams with intact riparian vegetation Appearance: Almond-shaped, small shell, olive-purple brown. Heavy beak sculpture on small shells. Maximum shell length 60 mm.
Cucumerunio novaehollandiae Distribution in NSW: North from the Hunter River Microhabitat: Moderate-strong currents, often in boulder-stabilised habitats on outer bends; pools at the base of riffles and cascades Appearance: Large, elongated, brown-black shell. Tear-shaped nodules on posterior surface of shell. Maximum shell length 200 mm.
Alathyria pertexta Distribution in NSW: Richmond River upstream of Coraki Microhabitat: Ranges from still waters to fast-flowing runs; pools and impoundments Appearance: Heavy, elongated-oval shell, brown-black. Beak sculpture absent. Maximum shell length 160 mm.
Alathyria profuga Distribution in NSW: Manning, Karuah, Hunter and Shoalhaven rivers Microhabitat: Slow-moderate current regimes Appearance: Solid, oval shell, brown to grey-green. Beak sculpture absent. Maximum shell length 120 mm.
Velesunio ambiguus Distribution in NSW: Patchy distribution: Richmond, Clarence, Upper Macleay (Apsley River), Hawkesbury-Nepean rivers; western creeks of Shoalhaven River; Snowy River Microhabitat: Still water or slow current areas in pools, farm dams, impoundments, lower reaches of rivers. Inhabits temporary creeks; broad environmental tolerance Appearance: Oval, occasionally globose, light shell, yellow to dark brown. Beak sculpture absent. Maximum shell length 100 mm.