>Andrew,
>   I originally meant the question in the sense that Harry answered it:
>what is the largest and smallest gastropod, bivalve, etc. in various
>regions.  I was not thinking of largest numbers of taxa or species
>diversity.  Sorry for the confusion.
>   I also realize that some may not consider some organisms as belonging to
>a certain continent.  The giant squids may have been caught far enough
>from a coast that someone might consider them pelagic or bethnic organisms
>and not belonging to a particular continental fauna.  I leave such fine
>points up to the person answering the question.

Harry's more perceptive...

OK, to my knowledge, from the described NZ fauna:

Largest marine gastropod: Charonia tritonis (Linne 1758), 350x178mm
(finding of a Syrinx aruanus
       {Turbinellidae} near Auckland was a hoax)
Smallest marine gastropod: Orbitestella parva (Finlay 1924), h 0.3mm d 0.6mm
Largest fluvial gastropod: Glyptophysa variabilis (Gray 1843), h 25mm
(Planorbidae) {Lymnaea stagnalis
        larger, but introduced}
Smallest fluvial gastropod: Hadopyrgus brevis Climo 1974, up to 1.5mm
(Hydrobiidae)
Largest terrestrial gastropod: Placostylus bollonsi Suter 1908, 100mm
Smallest terrestrial  gastropod: Phrixgnathus serratocosta Webster
1906, h 0.75, d 1.0 (Punctidae)
Largest marine bivalve: Atrina zelandica (Gray 1835), 405mm... NOT
related to A. pectinata (L 1767), by
       the way
Smallest marine bivalve: Benthocardiella striatula Powell 1931,
0.54mm (Condylocardiidae)
Largest fluvial bivalve: Hyridella menziesi (Gray 1843), 100mm
Smallest fluvial bivalve: Pisidium casertanum (Poli 1791) intro, P.
hodgkini (Suter 1905), both 4.5mm
Largest poyplacophoran: Eudoxochiton nobilis (Gray 1843), 110mm
Smallest polyplacophoran: Ischnochiton luteoroseus Suter 1907, 5mm
Aplacophora sl: no idea
Largest scaphopod: Fissidentalium zelandicum (Sowerby 1860), 88mm
Smallest scaphopod: Cadulus teliger Finlay 1927, 5.1mm
Largest monoplacophoran: Micropilina tangaroa Marshall 1990, 1.5mm
Smallest monoplacophoran: M. rakiura Marshall 1998?
Largest cephalopod: Architeuthis dux Steenstrup 1857
Smallest cephalopod: Pterygioteuthis giardi H Fischer 1895, 30mm
(smallest I know of)
Largest benthic cephalopod: Octopus vulgaris (=O. maorum Hutton
1880), arms to 1.4m length
Smallest benthic cephalopod: Robsonella huttoni Benham 1943, appx
10cm diameter & length

Sizes taken mostly from Powell 1979, which will be out-of-date. Bruce
Marshall's papers, many on micros, don't cover anything smaller or
larger than the list above.
--
Andrew Grebneff
165 Evans St, Dunedin 9001, New Zealand
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