IDENTIFICATION OF THE CYSTISCIDAE AND MARGINELLIDAE FOUND ON  SYDNEY BEACHES

The species tabulated below are recorded in the  Australian Museum collection as being beach collected.  The remaining members of the family occur in sufficiently deep water to not be washed up on beaches.  The diagnostic features used here are only diagnostic within this group of species, not within the Cystiscidae and Marginellidae as a whole, and they need to be used in conjunction with the descriptions and photographs of the individual species.  For an explanation of the terminology, see the introductions to Cystiscidae and Marginellidae.

 

Family Cystiscidae

  •  Shells less than 4 mm in length

  •  No margin on outside of outer lip, except in one species

  • At least four plaits on the columella, upper ones often weak or absent

Species

Diagnostic features

Adult size

Beach occurrence

Cystiscus angasi

Most common of the NSW cystiscid species; up to 8 plaits/lirae on the columella

2 - 3 mm

Common

Cystiscus subauriculata

Broad, lip flared; 5-7 plaits/lirae on the columella

1.5 2 mm

Uncommon

Gibberula subbulbosa

Lirate inside outer lip; lirae extend deep into aperture.  Columella with 5-7 plaits/lirae

2.5 - 4 mm

Common

Granulina nympha

Egg shaped; the only cystiscid with an external varix. 

1.3 2 mm

Common

Pugnus parvus

Cylindrical shape, dense spiral threads

1.5 - 2 mm

Very uncommon

Family Marginellidae

  • Four plaits on columella

  • Outer lip thickened externally to create margin

Species

Diagnostic features

Adult size

Beach Occurrence

Serrata mustelina

Elongate, brown bands

7 mm

Uncommon

Alaginella ochracea

Distinctive biconic shape

3 - 4 mm

Moderately common

Austroginella muscaria

Largest marginellid species in NSW.  The only species over 10 mm in length.

10 -16 mm

Common

Austroginella johnstoni

Very similar to A. muscaria, separated mainly on size.  Base heavily calloused.

6 - 9 mm

Common, sometimes abundant

Austroginella tasmanica

More elongate and higher spire than A. muscaria and A. johnstoni

7 - 10 mm

Common

Mesoginella turbinata

Usually ribs on dorsum

5 - 10 mm

Common to abundant

Mesoginella olivella

Narrower than M. turbinata, but very variable.

5 - 10 mm

Moderately common

Mesoginella translucida

Taller spire than other Mesoginella species; may be quite like Austroginella johnstoni, but distinguished by lip shape. 

5 - 8 mm

Common to abundant

Mesoginella victoriae

Strongly constricted at base, elliptical in outline.

3.8 5 mm

Uncommon

Mesoginella strangei

Distinguished by size; more slender than A. ochracea

2.5 3.5 mm

Uncommon

Ovaginella ovulum

Egg shaped, variable in size

5.5 10 mm

Very uncommon


Copyright Des Beechey 2003