Key to Families of Australian Aquatic Molluscs


This large phylum is divided into several classes of which only the Bivalvia (bivalved molluscs) and Gastropoda (snails and slugs) are found in inland waters.


Bivalved molluscs occur commonly in marine and estuarine environments.  Four families are known from Australian inland waters.  Identification to Bivalvia is relatively easy based on the bi-valved shell which covers the whole body, but care should be taken, especially with small specimens, to check the animal is not a crustacean of class Conchostraca (clam shrimp) Ostracoda (mussel-shrimp or seed-shrimp), or Cladocera (water flea).  These animals have a bi-valved carapace and may superficially resemble bivalved molluscs, but within the carapace is a shrimp-like body with several pairs of jointed legs.

The four freshwater bivalve families are:

1 Hyriidae (Freshwater mussels)

A family restricted to South America and Australasia.  Found throughout mainland Australia and central-north Tasmania, absent from southern Tasmania.  Some species are endemic to particular catchments whilst others are cosmopolitan.  The first larval stage is the minute, bivalved glochidium, ectoparasitic on the gills, fins, or general body surface of various fish.

2 Corbiculidae (Orb-shell mussels)

Found in Asia, Australia and Oceania, with isolated introductions in other parts of the world.  A tropical to subtropical group.  There are two distinct species groups in Australia.  The first (genera Batissa and Polymesoda) inhabit fresh and estuarine coastal streams of northern Australia, and are closely related to forms found in south-east Asia.  The second (genus Corbicula, endemic subgenus Corbiculina) are found throughout Australia except for Tasmania and the southern part of Western Australia.

3 Sphaeriidae (Pea shell mussels, pea shells, fingernail clams)

A little studied but cosmopolitan family of small bivalves.  Previously, many names were based on minute differences in the shell and on geographic distribution.  Some species are widespread throughout Australia but others are confined to small regions or in some cases to a single body of water.

4 Mytilidae (Mussels)

The cosmopolitan family which includes the marine mussels.  Several species are estuarine and some may be found in near-fresh water, but never entirely away from marine influence.

Identification to family can be based on the shell.  The Hydriidae and Mytilidae are elongate mussels with the beak of the shell at one end.  Corbiculidae and Sphaeriidae are sub-circular.  Hydriid larvae (glochidium larvae), parasitic on freshwater fish, are keyed separately in this key.


The aquatic gastropod families divide into two subclasses, the gill-breathing Prosobranchia are related to marine snails, the lung-breathing (or secondarily gilled) Pulmonata are related to land snails.  Eleven prosobranch families and nine pulmonate families are recorded from Australian inland waters.

Almost all species are shelled and recognisably snail-like, but one family (Onchidiidae) of marine, air-breathing slugs extends into estuaries and damp terrestrial situations near the sea.

Identification to class Gastropoda is relatively easy based on the snail-like shell and/or the presence of a pulmonate lung in the mantle cavity.  Larvae of Helicopsychidae, a family of caddis-fly (Insecta: Trichoptera) construct a helical case which resembles a snail shell, and could be mistaken for molluscs.  The trichopteran case is composed of sand grains and the animal inside is a typical insect larva with segmented body and three pairs of legs.

The identification of gastropods to family level can be difficult because the families are defined on internal anatomical structures.  There are few readily observable characters, other than those of the shell, but shells vary as much within as between families.  Adult whole animals can be identified using a combination of shell (and operculum) plus external body characters, but juveniles and shells alone are not always identifiable to the family level.

Character systems useful for identifying gastropod families include:

1   Shell coiling (dextral, sinistral, flat, or not-coiled)

2   Operculum presence/absence

3   Shell shape (spired, globose, turbinate, etc.) and spire height

4   Shell patterning (ridges, striations, colour patterns, etc.)

5   Tentacle and eye position

Some species will key easily to family level, but others may be difficult.

Posted By: Site Admin Last Updated: Aug 8, 2012 Views: 8641
Key Author(s): CSIRO Entomology Key Version: 1.1
South Australian Pasture Selection key

Key for South Australia

Posted By: Site Admin Last Updated: Oct 22, 2008 Views: 8635
Key Author(s): Stuart Brown Key Publisher: CSIRO Key Version: 1.0
Campbell Island Larval Chironomidae Key

Campbell Island/Motu Ihupuku lies 700 km south of New Zealand’s mainland, the most Campbell Island/Motu Ihupuku lies 700 km south of New Zealand’s mainland, the most southerly of the five New Zealand Subantarctic groups.

There are two identification keys to the freshwater invertebrate taxa of Campbell Island. This key is for identifying the freshwater Chironomidae larvae of Campbell Island to genus or species level.

The key is suitable for users that have basic knowledge in invertebrate identification or animal biology.

The keys were made possible by funding from the Terrestrial and Freshwater Biodiversity Information System (TFBIS) Programme.

How to cite the key:  McMurtrie, S.A.; Sinton, A.M.R.; & Winterbourn, M.J.; 2014. Lucid identification key to the freshwater Chironomidae of Campbell Island. EOS Ecology, Christchurch.

Go to the website:

Key Author(s): McMurtrie, S.A.; Sinton, A.M.R.; & Winterbourn, M.J. Key Version: 1.0

Posted By: Site Admin Last Updated: Jul 9, 2014 Views: 8628
Key Author(s): McMurtrie, S.A.; Sinton, A.M.R.; & Winterbourn, M.J. Key Version: 1.0
The Key to Pythium species

The key is presented as a guide to identifying Pythium to the species level. It is a modification of that created by Anna van der Plaats-Niterink (Van der Plaats-Niterink, A. J. 1981. Monograph of the genus Pythium. Studies in Mycology. Baarn, Centraalbureau voor Schimmelcultures. Monograph No. 21:242). Some but not all species of Pythium are included. This key is only a guide and diagnostic tool to assist in the identification of Pythium species. To learn more about identifying Pythium species, culturing Pythium, and Pythium in general visit and work through the Module set. 

Be flexible in your interpretation of what you observe and observe cultures over time. As you gain experience through looking at many different Pythium cultures, you will begin to be able to differentiate sporangia from oogonia, slightly inflated filamentous sporangia from hyphae, and recognize proliferating sporangia. At first, just reading descriptions is confusing, but the more cultures you observe the process will become much easier.

The key was built using the Lucid Builder program. When you open the key, the window is divided into four sections: features available, features chosen, entities remaining and entities discarded. The culture characteristics are present in the Lucid key as “features”. Pythium species are present as “entities”.

As you look at Pythium cultures, check off the characters you observe on the character checklist. Check off characters by expanding the options beneath each main heading of the “features available” section and click on the empty box next to the character you have observed in your culture. When a character is selected, a check mark will be placed next to that character in the “features available” section. These selected characters will also be copied into the “features chosen” section. In order remove a feature chosen, simply click the checked box next to the unwanted character, and it will become unchecked again.  Lastly, as you select the characters you are observing, Pythium species are discarded into the “entities discarded” section, leaving fewer and fewer “entities remaining,” or possible Pythium species.

To help you identify Pythium species, images of the characters are available in the Lucid key. To view these images, make sure that “image thumbnails” is selected under the view tab. Simply expand the contents of the “features available” section and click on the thumbnails to enlarge the images. 

Be flexible in using the key. If you are not certain of a characteristic, select one option for that characteristic and see where the key takes you. When you have eliminated most species, examine the description of the species to which you are led and see if it fits. If the descriptions do not match what you have observed, go back and select a different option for that characteristic and other questionable characters and examine the description of the species to which you come.


Gary W. Moorman, Ph.D.
Department of Plant Pathology and Environmental Microbiology
The Pennsylvania State University
111 Buckhout Laboratory
University Park, PA 16802
Phone: 814-863-7401
Email: [email protected]

Sara May
Department of Plant Pathology and Environmental Microbiology
The Pennsylvania State University
220 Buckhout Laboratory
University Park, PA 16802
Phone: 814-865-2204
Email: [email protected]

Kathleen M. Ayers
Department of Plant Pathology and Environmental Microbiology
The Pennsylvania State University
220 Buckhout Laboratory
University Park, PA 16802
Email: [email protected]

Posted By: Site Admin Last Updated: May 21, 2014 Views: 8624
Key Author(s): Gary W. Moorman, Ph.D., Sara May, Kathleen M. Ayers Key Version: 1.0
Antarctic Marine Dinoflagellates

Antarctic Marine Dinoflagellates

Posted By: Site Admin Last Updated: Aug 24, 2016 Views: 8622
Key Author(s): Australian Antarctic Division
Dung Beetles of eastern NSW - Amphistomus subkey

How to identify the Scarabaeinae of eastern New South Wales

A subkey to the Key to the Dung Beetles of eastern New South Wales

Australian Museum

Posted By: Site Admin Last Updated: Apr 21, 2016 Views: 8613
Key Author(s): Rebecca Harris and Dr Chris Reid Key Publisher: Australian Museum Key Version: 1.0
Queensland Pasture Selection Tool

A pasture selection tool.

Posted By: Site Admin Last Updated: Nov 10, 2008 Views: 8609
Key Author(s): Stuart Brown Key Publisher: CSIRO Key Version: 1.0
Key to Orders of Trichomycetes

Trichomycetes are a cosmopolitan group of fungi and protists that grow obligately in the guts of insects, crustaceans, and millipedes that live in freshwater, marine, or terrestrial habitats. The taxonomy of these organisms is based primarily on morphology of the vegetative thallus; spore type and dimensions; host; and habitat.

Posted By: Site Admin Last Updated: Jul 27, 2016 Views: 8582
Key Author(s): R.W. Lichtwardt, University of Kansas, Lawrence KS USA and D.B. Strongman, Saint Mary’s University, Halifax NS Canada Key Version: 1.0
Key to Families of Adult Australian Aquatic Coleoptera (Beetles)

Coleoptera (beetles) is the most speciose of all the insect orders.  The majority of the approximately 120 families known from Australia are terrestrial but around 14 are wholly aquatic or strongly associated with water and a further 5 include some aquatic or semi-aquatic species.  This key identifies these 19 families but may not distinguish members of this set from all other, terrestrial, beetles.

Coleoptera undergo holometabolous development, meaning there is an abrupt change of body form at the final moult.  It is convenient to deal with adults and larvae in separate keys.

The chief distinguishing feature of adult beetles is that the front wings form hardened elytra.  The elytra cover and protect the membranous flying wings, which are rolled and folded underneath the elytra at rest.  The elytra meet at the midline of the abdomen, never overlapping as do the hemelytra of some hemipteran bugs.  Functionally, the body of an adult beetle is peculiarly divided not into head, thorax and abdomen as in most other insects, but head, prothorax and hind-body.  The hind-body comprises the pterothorax and abdomen, fused broadly together.  Beetle mouthparts usually are of biting type.  The adult head sometimes has two ocelli but never three, an often none.  The abdominal sternum often displays a reduced number of visible sclerotised plates (sternites).  The first few are reduced and concealed beneath the hind coxae, and the terminal segments usually are telescoped into the apex of the abdomen.

Identification to family level can be partly achieved on gross features such as size and shape, but in many cases requires a careful examination of external morphology.  There is much variation of body form within many families and large-scale characters can readily be misleading.  On the other hand it is never necessary to examine internal characters in order to identify a specimen to family level.

The Australian aquatic and semi-aquatic beetles fall into three suborders: Myxophaga (1 family: Microsporidae), Adephaga (6 families: Carabidae through Gyrinidae in the key), and Polyphaga (12 families: Hydrophilidae through Brentidae in the key).  Myxophaga is a small suborder comprising minute, globose beetles.  Adephaga includes a wide range of body sizes and two general body shapes: one in which the head, prothorax and hindbody are well separated from each other, the other in which they fit closely together to give a smooth lateral outline and overall a boat-shaped appearance.  Polyphaga includes all these shapes and more.

A few families are instantly recognisable on the basis of unique characters.  Most specimens, however, will fall readily into one of several not necessarily closely related families and then may require close examination for final placement.

Posted By: Site Admin Last Updated: Aug 9, 2012 Views: 8568
Key Author(s): CSIRO Entomology Key Version: 1.1
Key to the Goodeniaceae of Western Australia

This key allows identification of all species of the fanflower family (Goodeniaceae) in Western Australia.


We are grateful to many friends and colleagues working at the WA Herbarium for supplying diverse data, images, maps, ideas, and taxonomic and computing expertise that have made the development of this data set possible. In particular we wish to thank Rob Davis and Mike Hislop, Steve Dillon, for their help with taxonomic queries. John Huisman for the use of his camera, microscope. Thanks also go to Kelly Shepherd for her help and advice.  Karina Knight for her help and encouragement throughout the project. Images available here come from the WA Herbarium’s online plant information system, FloraBase, and represent the work of a team of dedicated volunteers. The maps, also part of FloraBase, represent specimens held at the WA Herbarium. 

Posted By: Site Admin Last Updated: Apr 20, 2016 Views: 8558
Key Author(s): Chris Hollister and Kevin Thiele Key Publisher: Department of Environment and Conservation WA Key Version: 1.0
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