Mollusca (Snails and Clams)

07/11 Quick guide to common New Zealand freshwater Mollusca Prepared by Brian Smith (2007)

Sphaeriidae

YES

Is the shell <6 mm & pale?

Bivalvia NO (clams) Cucumerunio YES Hyriidae Does the shell have distinct nodules & ridges?

note: juvenile Echyridella NO have distinct ridges present

Echyridella

YES

Is the shell composed of 2 halves & cockle- like? generally restricted to Melanoides thermally (exotic) influenced waters YES NO

Is the shell strongly elongated (tips may Gastropoda be broken) & (snails & distinctive striae limpets) present? shell dark & smoothly coiled, up to 30 mm

Prosobranchia

YES NO Melanopsis

Is an operculum Melanopsidae present, & the shell always spired? YES

NO Is the shell smoothly coiled, with a large white mantle on the ventral surface?

NO usually <12 mm, may have spines

Hydrobiidae

Potamopyrgus Continued overleaf

Continued from previous page shell up to 12 Latia mm Latiidae

Pulmonata YES Is the shell black, & oval to rounded, dorsally? YES NO pale, shell sub- Ancylidae parallel sided, Ferrissia Does the shell lack a YES Is the shell dorsally; <5 mm distinct spire, or domed & does the specimen limpet-like? look limpet-like? NO

Gyraulus NO Planorbidae (in part) YES

shell spire of Is the shell <5 mm dia, & variable height shell flattened like a coin? Planorbella (exotic) YES NO Is the shell very thin & brittle, & the blunt end smooth with fine grooves?

NO shell up to 30 mm Planorbarius dia; (exotic)

digitate process

Physa Physidae (exotic)

YES Does the YES shell open on Is a digitate process present the left hand on inner mantle opening; side? shell never with carina? NO

NO Planorbidae Lymnaeidae (in part) shell spire rounded Glyptophysa to carinate

Lymnaea (exotic) striations at right angles to growth lines

YES

Pseudosuccinea (exotic) Is the spire acute & YES elongate? Are there striations at NO right angles to growth lines, & the body shape not noticeably bulbous?

NO Austropeplea image courtesy of S. Moore, Landcare This Quick guide was funded by Terrestrial and Freshwater Biodiversity Information System (TFBIS) programme number 194 .