<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-us" lang="en-us"> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-15" /> <link rel="stylesheet" type="text/css" href="sdd1.css"> </head> <body bgcolor="#ffffff"> <a name="PageTop"></a> <p /> <h2><a name="SDD_Part_0_Introduction_and_Prim"></a> SDD Part 0: Introduction and Primer to the SDD Standard </h2> <p /> <h3><a name="2_4_Dichotomous_keys"></a><a name="2_4_Dichotomous_keys_"></a> 2.4 Dichotomous keys. </h3> <h4><a name="2_4_1_Traditional_dichotomous_ke"></a> 2.4.1 Traditional dichotomous keys. </h4> <p /> Dichotomous keys (Box 2.3.1) are specialised identification tools comprising fragments of descriptive data arranged in couplets forming a branching tree. Each fragment (lead) comprises a small (occasionally verbose) natural-language description. Each node in the tree typically has two branches (dichotomy) but may have three (trichotomy) or more branches. Several differing formats of dichotomous keys are traditionally used. <p /> <h4><a name="Box_2_4_1_Typical_dichotomous_ke"></a> Box 2.4.1 - Typical dichotomous keys </h4> <p /> <p /> <div align="center"> <table bgcolor="#ddddff" border="0" cellpadding="5" style="border-collapse: collapse" bordercolor="#111111" width="80%" id="table7" > <tr> <td width="409" style="border-left-style: solid; border-left-width: 1px; border-top-style: solid; border-top-width: 1px"> <b>Key to Ascomycete genera</b></td> <td align="right" style="border-right-style: solid; border-right-width: 1px; border-top-style: solid; border-top-width: 1px"> </td> </tr> <tr> <td width="409" style="border-left-style: solid; border-left-width: 1px; border-top-style: solid; border-top-width: 1px"> <br> Ascus unitunicate</td> <td align="right" style="border-right-style: solid; border-right-width: 1px; border-top-style: solid; border-top-width: 1px"> </td> </tr> <tr> <td width="409" style="border-left-style: solid; border-left-width: 1px"> Clypeus present around ostiolar neck</td> <td align="right" style="border-right-style: solid; border-right-width: 1px"> </td> </tr> <tr> <td width="409" style="border-left-style: solid; border-left-width: 1px"> Clypeus poorly developed</td> <td align="right" style="border-right-style: solid; border-right-width: 1px"> <i>Glomerella</i></td> </tr> <tr> <td width="409" style="border-left-style: solid; border-left-width: 1px"> Clypeus well developed</td> <td align="right" style="border-right-style: solid; border-right-width: 1px"> <i>Hyllachora</i></td> </tr> <tr> <td width="409" style="border-left-style: solid; border-left-width: 1px"> Clypeus lacking</td> <td align="right" style="border-right-style: solid; border-right-width: 1px"> </td> </tr> <tr> <td width="409" style="border-left-style: solid; border-left-width: 1px"> Ascus widest in middle</td> <td align="right" style="border-right-style: solid; border-right-width: 1px"> <i>Physalospora</i></td> </tr> <tr> <td width="409" style="border-left-style: solid; border-left-width: 1px"> Ascus clavate or cylindrical</td> <td align="right" style="border-right-style: solid; border-right-width: 1px"> <i>Glomerella</i></td> </tr> <tr> <td width="409" style="border-left-style: solid; border-left-width: 1px"> Ascus bitunicate</td> <td align="right" style="border-right-style: solid; border-right-width: 1px"> </td> </tr> <tr> <td width="409" style="border-left-style: solid; border-left-width: 1px"> Ascostroma uniloculate</td> <td align="right" style="border-right-style: solid; border-right-width: 1px"> <i>Guignardia</i></td> </tr> <tr> <td width="409" style="border-left-style: solid; border-left-width: 1px; border-bottom-style: solid; border-bottom-width: 1px"> Ascostroma muliloculate</td> <td align="right" style="border-right-style: solid; border-right-width: 1px; border-bottom-style: solid; border-bottom-width: 1px"> <i>Botryosphaeria</i></td> </tr> </table> </div> <br> <div align="center"> <table bgcolor="#ddddff" border="1" cellpadding="5" style="border-collapse: collapse" bordercolor="#111111" width="80%" id="table8"> <tr> <td style="border-left-style: solid; border-left-width: 1px; border-right-style: none; border-right-width: medium; border-top-style: solid; border-top-width: 1px; border-bottom-style: none; border-bottom-width: medium" colspan="3"> <b>Key to Australian skinks in the genus <i>Ctenotus</i></b></td> </tr> <tr> <td width="50" style="border-left-style: solid; border-left-width: 1px; border-right-style: none; border-right-width: medium; border-top-style: solid; border-top-width: 1px; border-bottom-style: none; border-bottom-width: medium">1</td> <td style="border-left-style: none; border-left-width: medium; border-right-style: none; border-right-width: medium; border-top-style: solid; border-top-width: 1px; border-bottom-style: none; border-bottom-width: medium">Dark upper lateral zone with one or more distinct series of pale spots or blotches along the body</td> <td width="114" valign="bottom" align="right" style="border-left-style: none; border-left-width: medium; border-right-style: solid; border-right-width: 1px; border-top-style: solid; border-top-width: 1px; border-bottom-style: none; border-bottom-width: medium">2</td> </tr> <tr> <td width="50" style="border-left-style: solid; border-left-width: 1px; border-right-style: none; border-right-width: medium; border-top-style: none; border-top-width: medium; border-bottom-style: none; border-bottom-width: medium">1a</td> <td style="border-style: none; border-width: medium">Dark upper lateral zone obscurely mottled or uniform with at most a few pale spots anteriorly</td> <td width="114" valign="bottom" align="right" style="border-left-style: none; border-left-width: medium; border-right-style: solid; border-right-width: 1px; border-top-style: none; border-top-width: medium; border-bottom-style: none; border-bottom-width: medium">3</td> </tr> <tr> <td width="50" style="border-left-style: solid; border-left-width: 1px; border-right-style: none; border-right-width: medium; border-top-style: none; border-top-width: medium; border-bottom-style: none; border-bottom-width: medium">2</td> <td style="border-style: none; border-width: medium">Fewer than 25 lamellae under the fourth toe; supralabials 7-8 (usually 7); prefrontals separated</td> <td width="114" valign="bottom" align="right" style="border-left-style: none; border-left-width: medium; border-right-style: solid; border-right-width: 1px; border-top-style: none; border-top-width: medium; border-bottom-style: none; border-bottom-width: medium"> <i>C. arcanus</i></td> </tr> <tr> <td width="50" style="border-left-style: solid; border-left-width: 1px; border-right-style: none; border-right-width: medium; border-top-style: none; border-top-width: medium; border-bottom-style: none; border-bottom-width: medium">2a</td> <td style="border-style: none; border-width: medium">More than 25 lamellae under the fourth toe; supralabials 8-9 (usually 8); prefrontals usually in contact</td> <td width="114" valign="bottom" align="right" style="border-left-style: none; border-left-width: medium; border-right-style: solid; border-right-width: 1px; border-top-style: none; border-top-width: medium; border-bottom-style: none; border-bottom-width: medium"> <i>C. alleni</i></td> </tr> <tr> <td width="50" style="border-left-style: solid; border-left-width: 1px; border-right-style: none; border-right-width: medium; border-top-style: none; border-top-width: medium; border-bottom-style: none; border-bottom-width: medium">3</td> <td style="border-style: none; border-width: medium">Pale mid-lateral stripe passes over the hindlimb to continue along the tail </td> <td width="114" valign="bottom" align="right" style="border-left-style: none; border-left-width: medium; border-right-style: solid; border-right-width: 1px; border-top-style: none; border-top-width: medium; border-bottom-style: none; border-bottom-width: medium"> <i>C. inornatus</i></td> </tr> <tr> <td width="50" style="border-left-style: solid; border-left-width: 1px; border-right-style: none; border-right-width: medium; border-top-style: none; border-top-width: medium; border-bottom-style: solid; border-bottom-width: 1px">3a</td> <td style="border-left-style: none; border-left-width: medium; border-right-style: none; border-right-width: medium; border-top-style: none; border-top-width: medium; border-bottom-style: solid; border-bottom-width: 1px">Pale mid-lateral stripe extends to groin, then continues along the front edge of the hindlimb</td> <td width="114" valign="bottom" align="right" style="border-left-style: none; border-left-width: medium; border-right-style: solid; border-right-width: 1px; border-top-style: none; border-top-width: medium; border-bottom-style: solid; border-bottom-width: 1px"> <i>C. coggeri</i></td> </tr> </table> <p /> <p /> <div align="center"> <table bgcolor="#ddddff" cellspacing="2" cellpadding="2" style="border-collapse: collapse" bordercolor="#111111" width="80%"> <tr> <td colspan="4" align="left" style="border-left-style: solid; border-left-width: 1px; border-top-style: solid; border-top-width: 1px; border-right-style: solid; border-right-width: 1px; border-bottom-style: solid; border-bottom-width: 1px"><b>Key to <i>Aira</i> naturalized in Australia</b></td> </tr> <tr> <td style="border-left-style: solid; border-left-width: 1px" width="5%" height="35" rowspan="3" valign="top">1.</td> <td width="50%" height="15" valign="top">Inflorescence open and spreading</td> <td style="border-right-style: solid; border-right-width: 1px" width="45%" height="15" valign="top">2</td> </tr> <tr> <td width="50%" height="15" valign="top">Inflorescence dense and spike-like</td> <td style="border-right-style: solid; border-right-width: 1px" width="45%" height="15" valign="top"><b>*</b><b>A. praecox</b></td> </tr> <tr> <td width="50%" height="10" valign="top"></td> <td style="border-right-style: solid; border-right-width: 1px" width="45%" height="10" valign="top"></td> </tr> <tr> <td style="border-left-style: solid; border-left-width: 1px" width="5%" height="35" rowspan="3" valign="top">2.</td> <td width="50%" height="15" valign="top">Pedicels 3-8 times spikelet length</td> <td style="border-right-style: solid; border-right-width: 1px" width="45%" height="15" valign="top">3</td> </tr> <tr> <td width="50%" height="15" valign="top">Pedicels up to 3 times spikelet length</td> <td style="border-right-style: solid; border-right-width: 1px" width="45%" height="15" valign="top">4</td> </tr> <tr> <td width="50%" height="10" valign="top"></td> <td style="border-right-style: solid; border-right-width: 1px" width="45%" height="10" valign="top"></td> </tr> <tr> <td style="border-left-style: solid; border-left-width: 1px" width="5%" height="35" rowspan="3" valign="top">3.</td> <td width="50%" height="15" valign="top">Spikelets c. 3.5 mm long</td> <td style="border-right-style: solid; border-right-width: 1px" width="45%" height="15" valign="top"><b>*A. provincialis</b></td> </tr> <tr> <td width="50%" height="15" valign="top">Spikelets c. 2 mm long</td> <td style="border-right-style: solid; border-right-width: 1px" width="45%" height="15" valign="top"><b>*A. elegantissima</b></td> </tr> <tr> <td width="50%" height="10" valign="top"></td> <td style="border-right-style: solid; border-right-width: 1px" width="45%" height="10" valign="top"></td> </tr> <tr> <td style="border-bottom-style: solid; border-bottom-width: 1px; border-left-style: solid; border-left-width: 1px" width="5%" height="35" rowspan="3" valign="top">4.</td> <td width="50%" height="15" valign="top">Spikelets 2-2.5 mm long</td> <td style="border-right-style: solid; border-right-width: 1px" width="45%" height="15" valign="top"><b>*A. cupaniana</b></td> </tr> <tr> <td width="50%" height="15" valign="top">Spikelets 2.5-3.2 mm long</td> <td style="border-right-style: solid; border-right-width: 1px" width="45%" height="15" valign="top"><b>*A. caryophyllea</b></td> </tr> <tr> <td style="border-bottom-style: solid; border-bottom-width: 1px" width="50%" height="10" valign="top"></td> <td style="border-right-style: solid; border-right-width: 1px; border-bottom-style: solid; border-bottom-width: 1px" width="45%" height="10" valign="top"></td> </tr> </table> </div> </div> <p /> <p /> <p /> <h3><a name="2_4_2_SDD_representation_of_dich"></a> 2.4.2 SDD representation of dichotomous keys </h3> <p /> While dichotomous keys can be presented in various formats, the essential elements of all dichotomous keys are identical. Each consists of a tree of questions, each with two (or occasionally more) possible choices, each choice leading to another question or a taxon. <p /> A dichotomous key rendered in SDD requires three essential items: the names of the taxa being described, a set of questions (leads) used to separate the taxa, and the nodes defining the structure of the leads. <p /> A simple SDD instance document for dichotomous key data has the basic structure shown below and in Example 2.4.2. <p /> There are at least two different ways of generating a dichotomous key in a well structured SDD instance document, using statements or questions, these will be dealt with separately. <p /> <img alt="identificationkey.gif" src="http://wiki.tdwg.org/twiki/static/_publish/identificationkey.gif" /> <p /> <h4><a name="Example_2_4_2_Dichotomous_keys_w"></a> Example 2.4.2 - Dichotomous keys within SDD </h4> <p /> <table bgcolor="#ddddff" border="0" width="100%" cellpadding="5" cellspacing="5" style="border-collapse: collapse" bordercolor="#111111"> <p /> <tr> <td> <p /> <pre> <Datasets> <TechnicalMetadata> ... information about the generator (Technical metadata) </TechnicalMetadata> <Dataset> <TaxonNames> ... naming the entities described (Taxon names) </TaxonNames> <IdentificationKeys> <IdentificationKey> ... the dichotomous key structure (see below) </IdentificationKey> </IdentificationKeys> </Dataset> </Datasets> </pre> <p /> </td> </tr> <p /> </table> <p /> <h3><a name="2_4_3_Dichotomous_keys_using_sta"></a> 2.4.3 Dichotomous keys using statements </h3> <p /> A dichotomous key structured with statements consists mostly of the elements <lead> and <result>. <Lead> points to another couplet while <Result> points to a taxon name. <p /> <h4><a name="Example_2_4_3_Structure_of_dicho"></a> Example 2.4.3 - Structure of dichotomous keys within SDD (statements) </h4> <p /> <table bgcolor="#ddddff" border="0" width="100%" cellpadding="5" cellspacing="5" style="border-collapse: collapse" bordercolor="#111111"> <p /> <tr> <td> <p /> <pre> <IdentificationKey id="key1"> <Representation> <Label>Key to Australian Aira Using statements </Label> </Representation> <Leads> <Lead id="lead1"> <Statement> <Label>Inflorescence open and spreading </Label> </Statement> </Lead> <Result> <Statement> <Label>Inflorescence dense and spike-like </Label> </Statement> <TaxonName ref="t1"/> </Result> <Lead id="lead2"> <Parent ref="lead1"/> <Statement> <Label>Pedicels 3-8 times spikelet length </Label> </Statement> </Lead> <Lead id="lead3"> <Parent ref="lead1"/> <Statement> <Label>Pedicels up to 3 times spikelet length </Label> </Statement> </Lead> <Result> <Parent ref="lead2"/> <Statement> <Label>Spikelets c. 3.5 mm long </Label> </Statement> <TaxonName ref="t2"/> </Result> <Result> <Parent ref="lead2"/> <Statement> <Label>Spikelets c. 2 mm long </Label> </Statement> <TaxonName ref="t3"/> </Result> <Result> <Parent ref="lead3"/> <Statement> <Label>Spikelets 2-2.5 mm long </Label> </Statement> <TaxonName ref="t4"/> </Result> <Result> <Parent ref="lead3".> <Statement> <Label>Spikelets 2.5-3.2 mm long </Label> </Statement> <TaxonName ref="t5"/> </Result> </Leads> </IdentificationKey> </pre> <p /> </td> </tr> <p /> </table> <p /> <p /> <h3><a name="2_4_4_Dichotomous_keys_using_que"></a> 2.4.4 Dichotomous keys using questions </h3> <p /> When a dichotomous key in an SDD instance document is structured with questions the statements act as answers to questions rather than independent statements. <p /> <h4><a name="Example_2_4_4_1_Structure_of_dic"></a> Example 2.4.4.1 - Structure of dichotomous keys within SDD (questions) </h4> <p /> <table bgcolor="#ddddff" border="0" width="100%" cellpadding="5" cellspacing="5" style="border-collapse: collapse" bordercolor="#111111"> <p /> <tr> <td> <p /> <p /> <pre> <IdentificationKey id="key1"> <Representation> <Label>Key to Ascomycete genera</Label> </Representation> <Question> <Label>Is the ascus unitunicate</Label> </Question> <Leads> <Lead id="lead1"> <Statement> <Label>yes, unitunicate</Label> </Statement> <Question> <Label>Is a clypeus present</Label> </Question> </Lead> <Lead id="lead2"> <Statement> <Label>no, bitubinate</Label> </Statement> <Question> <Label>Is ascostroma uniloculate</Label> </Question> </Lead> <Lead id="lead3"> <Parent ref="lead1"/> <Statement> <Label>yes, clypeus present around ostiolar neck</Label> </Statement> <Question> <Label>Is clypeus well developed</Label> </Question> </Lead> <Lead id="lead4"> <Parent ref="lead1"/> <Statement> <Label>no, clypeus lacking</Label> </Statement> <Question> <Label>Is ascus widest in middle</Label> </Question> </Lead> <Result> <Parent ref="lead3"/> <Statement> <Label>clypeus poorly developed</Label> </Statement> <TaxonName ref="taxon1"/> </Result> <Result> <Parent ref="lead3"/> <Statement> <Label>clypeus well developed</Label> </Statement> <TaxonName ref="taxon2"/> </Result> <Result> <Parent ref="lead4"/> <Statement> <Label>ascus widest in middle</Label> </Statement> <TaxonName ref="taxon3"/> </Result> <Result> <Parent ref="lead4".> <Statement> <Label>ascus clavate or cylindrical</Label> </Statement> <TaxonName ref="taxon1"/> </Result> <Result> <Parent ref="lead2"/> <Statement> <Label>ascostoma uniloculate</Label> </Statement> <TaxonName ref="taxon4"/> </Result> <Result> <Parent ref="lead2"/> <Statement> <Label>ascostoma multiloculate</Label> </Statement> <TaxonName ref="taxon5"/> </Result> </Leads> </IdentificationKey> </pre> <p /> </td> </tr> <p /> </table> <p /> For more information on defining taxon names using the <TaxonNames> element, see the topic <a href="taxonnames.html">Defining taxon names</a>. <p /> Note that taxa can also be arranged into hierarchies. See the topic <a href="taxonhierarchies.html">Defining taxon hierarchies</a> for more information. <p /> <Scope> describes the taxon or set of taxa to which the description applies. <p /> The <Result> element may include a <Subkey> element, which points to another complete dichotomous key. This allows a main/subkey arrangement, for example a key to the genera of a family with results leading to a subkey identifying the species within each genus. <p /> <h4><a name="Example_2_4_4_2_Subkeys_within_S"></a> Example 2.4.4.2 - Subkeys within SDD dichotomous keys. </h4> <p /> <table bgcolor="#ddddff" border="0" width="100%" cellpadding="5" cellspacing="5" style="border-collapse: collapse" bordercolor="#111111"> <p /> <tr> <td> <p /> <p /> <pre> <IdentificationKeys> <IdentificationKey id="key 1"> <Representation> <Label>Key to genera</Label> </Representation> <Leads> <Lead id="lead1"> <Statement> <Label>Inflorescence open and spreading</Label> </Statement> </Lead> <Result> <Statement> <Label>Inflorescence dense and spike-like</Label> </Statement> <Subkey ref="key 2"/> (key to species of first genus)) </Result> . . . etc. </IdentificationKey> </IdentificationKeys> </pre> <p /> </td> </tr> <p /> </table> <p /> <p /> -- DonovanSharp - 01 Jun 2006 <p /> <p /> </body></html>