Major Group: Gastropoda
Order: Basommatophora
Family: Glacidorbidae
This order is represented in Australian freshwaters by a single family, Glacidorbidae. |
Descriptive Features: shell coiled, dextral, flat or near flat-spire or planispiral, orthostrophic to hyperstrophic
wide, shallow umbilicus
operculum present, circular to oval, mulitspiral to paucispiral, central to eccentric nucleus
radula with large central teeth, lateral teeth, marginal teeth absent
head-foot with long cephalic tentacles with eyes in middle of bases (only Glacidorbis known)
foot posteriorly bifid, anteriorly with lateral processes
snout short and very broad
hermaphroditic (simultaneous or protandric)
Size: small to minute, most species diameter <= 2mm, Benthodorbis pawpela <= 4mm
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Glacidorbis circulus |
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Tasmodorbis punctatus |
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Taxonomic Checklist: Genera
Benthodorbis pawpela Smith (formerly Glacidorbis pawpela)
Benthodorbis fultoni Ponder & Avern
Glacidorbis 12 species
Striadorbis pedderi Smith (formerly Glacidorbis pedderi)
Striadorbis (2 species)
Tasmodorbis punctatus Ponder & Avern
*Glacidorbis costatus Ponder & Avern is assumed extinct due to draining of wetlands. |
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Distribution: Vic, NSW, Tas, S WA, SA
Sensitivity Rating: SIGNAL grade 5
Functional Feeding Group: predators, scavengers |
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Huon River, Tahune Tas |
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Ecology: Instream habitat: Glacidorbidae species inhabit swamps, bogs, streams and rivers where they are normally found on macrophytes, moss, roots, pieces of wood, or under stones (rarely). Benthodorbis live on the soft sediment on the beds of lakes. Glacidorbis occidentalis and G. hedleyi can occur in intermittent habitats whereas most other species live in permanent to semi-permanent streams or swamps.
Feeding ecology: Glacidorbis snails are probably carnivores preferring crushed or wounded invertebrates, including bivalves, snails, beetle larvae and amphipods. G. occidentalis is known to ingest large numbers of Pinus pollen grains but it is not known if this is done selectively or accidentally.
Habit:
Life history: Glacidorbis hedleyi, Glacidorbis occidentalis and Benthodorbis pawpela display brooding of the young. A brood pouch usually contains 33-218 shelled veligers, 65-83ìm in diameter. Glacidorbis occidentalis young develop into mature females. Veligers are present soon after adults emerge. Small snails appear during late winter to early spring, reaching adult size by summer. Glacidorbis hedleyi is the only species known so far to have the unusual reproductive mode where protandric males must copulate before turning into females. |
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Information Sources: Ponder & Avern 2000, Ponder 1986, 2001, 2013, Smith 1992, 1996, Beesley 2008, Bunn et al. 1989
Key to Genera: Ponder & Avern 2000
Key to Species: none |
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