This is the central key in this series of linked Keys to Australian
Aquatic Macro-Invertebrates. The
key is designed to identify any specimen to a level corresponding approximately
to Phylum or Class.
For most major invertebrate groups this key points directly to a
family-level subkey. For arthropod
taxa, it points to a Key to Arthropoda as an intermediate-level key.
Groups for which no subkey is provided can be identified further using
the notes and illustrations given against the relevant terminating taxon in this
key. In most cases, these notes allow identification to family
level, but a few taxa, namely rotifers, gastrotrichs and nematodes, are taken
only to ordinal level.
This set of keys was prepared mainly from the primary and secondary
taxonomic literature and from existing dichotomous keys.
Expert advice and assistance was sought in some cases.
References and acknowledgments with respect to each key are given in the
text which accompanies that key.
These keys cover the free-living macroscopic invertebrate taxa known to
occur in Australian inland waters, including introduced taxa.
Taxa represented in fresh or saline, running or still, permanent or
ephemeral inland waters are included, but wholly marine taxa which may extend
into upper estuarine habitats, and wholly terrestrial taxa some species of which
extend into intermittently wet habitats, have generally been omitted from the
The aim has been to key free-living organisms to family level.
Only higher-level identification is provided for (i) taxa in which all
species are obligate parasites, (ii) taxa mainly comprised of organisms too
small to be retained by a 250mm mesh sorting sieve, and (iii) semi-aquatic,
damp-soil and semi-marine (upper estuarine) taxa.
Some taxa are not taken to family level because the taxa are poorly
known. For these the key runs to
whatever level can be achieved on current knowledge. For example, phylum Nematoda is taken only to order (and then
only by way of taxon notes) and part of Platyhelminthes is taken only to
Our aim has been to cover the whole of Australia, but not all source
documents specify whether offshore territories, etc, are included.
Thus, coverage of tropical/subtropical island territories, and
Antarctic/sub-antarctic territories may not be complete for some taxonomic
Our aim has been to cover all inland waters: fresh or salt, flowing or
still, including marshlands and temporary waters. The dividing line between riverine and estuarine habitats is
hazy, as are also the line between marine littoral and coastal saltmarsh and
that between wetlands generally and damp terrestrial environments.
At genus or species level the decision what to include or exclude could
be problematic, but at family level it is less so. For the most part, families which are strongly represented in
marginally-aquatic environments also include one or more truly aquatic species,
and thus are included in the keys. Where
this is not the case we err on the side of including taxa which might be found
in aquatic samples. Where sources
differ as to whether a family has aquatic members we treat it as if it has.
The idea behind an interactive key is to identify a specimen by
eliminating all the taxa to which it cannot belong. Identificatory characters may be taken in any order
convenient to the user. The first
character in the present key (character one when the characters are listed in
Lucid natural order) exemplifies the method but is somewhat unusual in
that it asks for a first impression (gestalt) of the specimen.
Most other characters are more specific. Some specimens can be identified to a single taxon on the
basis of gestalt but most cannot. For
example, medusoid jellyfish are instantly recognisable as such, but
flatworm-like animals occur in many phyla apart from Platyhelminthes.
By selecting 'jellyfish' all taxa except Cnidaria would be eliminated; by
selecting 'flatworm' taxa such as Bryozoa and Porifera would be eliminated, but
further characters would be needed to reduce the list which remains.
Throughout these keys, character codings have been written so as to
retain every taxon which has, looks as if it has, or might reasonably be
mistaken as having the attribute in question.
For this reason it would be inappropriate to take the attribute
codings from these keys and to read them as if they represented a true
description of the taxon. Identificatory
character attributes are not character states in the conventional sense.
They deal with specimens not taxa. Their
totality is not a valid description of the taxon to which an identified specimen
Errors in and omissions from these keys should be referred to Peter
Cranston (email@example.com) but most of the blame lies with John Trueman (firstname.lastname@example.org).
Keys prepared at CSIRO Division of Entomology, Black Mountain
Laboratories, PO Box 1700, Canberra, ACT 2601, AUSTRALIA
by Ben M. Gunn, John W.H. Trueman, Sophia Dimitriadis and Peter S.
Cranston, with funding from the Land and Water Resources Research and
Development Corporation, Inc.
Lucid Software developed by
at the The University of Queensland,
Brisbane, Qld 4072.