Synonymy

The existence of more than one name (synonym) for a taxon is not uncommon and can arise for a number of reasons:

Due to the re-combination of a name.
We examine this in How to record a Parenthetic Author.
Due to the recognition that two previously published species are actually the same, or that two names actually refer to the same species.
It is this latter case that we deal with here.

The two broad categories of synonymy are:

Synonymy	Description
Homotypic / Objective	Two or more synonyms are derived from the same Type specimen In Taxonomy Type specimens are specimens selected to typify the described species. They are made available (often in museums) for study by Taxonomists. The Type Series is all specimens on which the description of a new species or genus is based. The Holotype is the single specimen published as "the Type" by the Name Author. An Isotype is a duplicate specimen of the Holotype collected at the same place and time as the Holotype. The Syntype is one of two or more specimens cited by the author when no Holotype was designated or it is any one of two or more specimens originally designated as Types. The Neotype specimen is selected as the Type where the original Types are known to be destroyed. Paratypes are the non-Holotype Syntypes. (the same holotype). Also known as objective or nomenclatural synonyms as the basis for recognizing synonymy is empirical (the same type specimen was used to define the species). Example In 1910 Wood described a new zoological species Gus hus Wood, 1910 and in 1950 Brown described Jus kus Brown, 1950. In 2004 another scientist realized that Brown had used the same Holotype In Taxonomy the definitive Type specimen on which a scientific name of a species is based. as Wood and that the two names refer to the same species. In this case: The currently accepted name is Gus hus Wood, 1910 as it has priority (it was published first). The scientific name Jus kus Brown, 1950 would remain exactly as it is as no re-combination has taken place, but it would be considered a homotypic synonym of Gus hus Wood, 1910 and would not be a currently accepted name. Recording a homotypic or objective synonym Homotypic or objective synonymy occurs when the same Holotype In Taxonomy the definitive Type specimen on which a scientific name of a species is based. was used to define two (or more) scientific names. Note: A re-combined name (when a species name is combined with a different genus name) is a special case of Homotypic synonymy and is dealt with in How to record a Parenthetic Author. In the following example: Both names were recorded as currently accepted: In other situations only one or neither name will be recorded as currently accepted. When considering the example below, it is only important to ensure that the scientific name with Priority In Taxonomy, where two or more scientific names are synonyms, the Name that was published before the others is said to have Priority and is the Currently Accepted Name for a species. is the currently accepted name. Note: Where names are in a synonymous relationship, only one can be currently accepted. On the Primary Citation tab for each name, Is Original Name?: (Original Name) is set to Yes. This may or may not be the case in practice. Note: Only the name with priority can be recorded as the Original Name. For example: In 1910 Wood described a new zoological species Gus hus Wood, 1910. This was a currently accepted name: On the Primary Citation tab this name is specified as the original name: Is Original Name?: (Original Name) is set to Yes. In 1950 Brown identified Jus kus Brown, 1950. This too was a currently accepted name: On the Primary Citation tab this name is specified as the original name: Is Original Name?: (Original Name) is set to Yes. In 2004 another scientist realized that Brown had used the same holotype as Wood and that the two names refer to the same species. In this case: The currently accepted name would be Gus hus Wood, 1910 as it has priority. The scientific name Jus kus Brown, 1950 would remain exactly as it is - no re-combination has taken place - but it would be considered a homotypic synonym of Gus hus Wood, 1910. This will be the junior synonym in this relationship. Note: Only one scientific name can be the currently accepted name. It is not possible to create a synonymous relationship between two names that are both currently accepted, and trying to do so will generate a warning message. Therefore: Ensure that the scientific name with priority is the currently accepted name (Gus hus Wood, 1910 in this example). Next ensure that the other scientific name is NOT the currently accepted name (Jus kus Brown, 1950 in this example): Select Unknown from the Currently Accepted?: (Currently Accepted Name) drop list. A message displays: Click OK. Note: See Pending tab for an explanation of what happens to heterotypic synonyms that are moved to the Pending tab. The All Synonyms tab disappears from the Jus kus record. Note: Only the record for the currently accepted name has the All Synonyms tab and is able to list all synonyms. Select the Primary Citation tab and if Is Original Name?: (Original Name) is set to Yes, select Unknown from the drop list. Save the record. In the record for the currently accepted name (Gus hus Wood, 1910 in this example): Select the Homotypics tab. Attach the Jus kus Brown, 1950 record in the Name: (Homotypic Names and Combinations) field. The default under Combination/Other: (Homotypic Names and Combinations) is Combination. Delete this and replace with Other. Save the record. If we now display the Jus kus record, we find that Currently Accepted?: (Currently Accepted Name) is automatically set to No and that Current Name: (Currently Accepted name) points to the Gus hus record: If we check the All Synonyms tab in Gus hus we find that Jus kus is added to the Synonyms List and identified as a Homotypic synonym: Tip: See below for an alternative method to record synonyms.
Heterotypic / Subjective	Two or more synonyms are derived from different type specimens. Also known as subjective or taxonomic synonyms as the basis for recognizing synonymy is a matter of opinion. Example In 2002 Wood described a new zoological species Cus dus Wood, 2002 and in 2003 Brown described Vus wus Brown, 2003 (using different type specimens). In 2004 another scientist decided that these two names actually refer to the same species. In this case: The currently accepted name would be Cus dus Wood, 2002 as it has Priority In Taxonomy, where two or more scientific names are synonyms, the Name that was published before the others is said to have Priority and is the Currently Accepted Name for a species.. Vus wus Brown, 2003 would remain exactly as it is as no re-combination has taken place, but it would be considered a heterotypic synonym of Cus dus Wood, 2002 and would not be a currently accepted name. Recording a heterotypic or subjective synonym Heterotypic or subjective synonymy occurs when different type specimens are used to define two (or more) scientific names. For example: In 1910 Wood identified a new zoological species Gus hus Wood, 1910. This was a currently accepted name: On the Primary Citation tab this name is specified as the original name: Is Original Name?: (Original Name) is set to Yes. In 1950, and using a different Type specimen In Taxonomy Type specimens are specimens selected to typify the described species. They are made available (often in museums) for study by Taxonomists. The Type Series is all specimens on which the description of a new species or genus is based. The Holotype is the single specimen published as "the Type" by the Name Author. An Isotype is a duplicate specimen of the Holotype collected at the same place and time as the Holotype. The Syntype is one of two or more specimens cited by the author when no Holotype was designated or it is any one of two or more specimens originally designated as Types. The Neotype specimen is selected as the Type where the original Types are known to be destroyed. Paratypes are the non-Holotype Syntypes. to Wood, Brown identified Jus kus Brown, 1950. This too was a currently accepted name: On the Primary Citation tab this name is specified as the original name: Is Original Name?: (Original Name) is set to Yes. In 2004 another scientist decided that though the type specimens were different these two names really refer to the same species. In this case: The currently accepted name would be Gus hus Wood, 1910 as it has Priority In Taxonomy, where two or more scientific names are synonyms, the Name that was published before the others is said to have Priority and is the Currently Accepted Name for a species.. The scientific name Jus kus Brown, 1950 would remain exactly as it is - no re-combination has taken place - but it would be considered a heterotypic synonym of Gus hus Wood, 1910. This will be the junior synonym in this relationship. Note: Only one scientific name can be the currently accepted name. It is not possible to create a synonymous relationship between two names that are both currently accepted, and trying to do so will generate a warning message. Therefore: In Jus kus Brown, 1950 (the Junior synonym in this relationship because Gus hus Wood, 1910 was published first): On the Primary Citation tab, check whether Is Original Name?: (Original Name) is set to Yes. If so, select Unknown from the drop list. On the Classification tab, select No from the Currently Accepted?: (Currently Accepted Name) drop list. The Current Name: (Currently Accepted Name) field becomes available: Enter Gus hus Wood 1910 in Current Name: (Currently Accepted name) and click Attach beside the field (or press the TAB key). A message displays indicating that Jus kus Brown is to become a heterotypic synonym of Gus hus Wood: Click OK and then save the record. The All Synonyms tab disappears from the Jus kus record. Note: Only the record for the currently accepted name has the All Synonyms tab and is able to list all synonyms. If we check the All Synonyms tab in Gus hus we find that Jus kus is added to the Synonyms List and identified as a Heterotypic synonym: Tip: See below for an alternative method to record synonyms.

Synonymy

Description

Homotypic / Objective

Two or more synonyms are derived from the same Type specimen In Taxonomy Type specimens are specimens selected to typify the described species. They are made available (often in museums) for study by Taxonomists. The Type Series is all specimens on which the description of a new species or genus is based. The Holotype is the single specimen published as "the Type" by the Name Author. An Isotype is a duplicate specimen of the Holotype collected at the same place and time as the Holotype. The Syntype is one of two or more specimens cited by the author when no Holotype was designated or it is any one of two or more specimens originally designated as Types. The Neotype specimen is selected as the Type where the original Types are known to be destroyed. Paratypes are the non-Holotype Syntypes. (the same holotype).

Also known as objective or nomenclatural synonyms as the basis for recognizing synonymy is empirical (the same type specimen was used to define the species).

Example

In 1910 Wood described a new zoological species Gus hus Wood, 1910 and in 1950 Brown described Jus kus Brown, 1950. In 2004 another scientist realized that Brown had used the same Holotype In Taxonomy the definitive Type specimen on which a scientific name of a species is based. as Wood and that the two names refer to the same species. In this case:

The currently accepted name is Gus hus Wood, 1910 as it has priority (it was published first).
The scientific name Jus kus Brown, 1950 would remain exactly as it is as no re-combination has taken place, but it would be considered a homotypic synonym of Gus hus Wood, 1910 and would not be a currently accepted name.

Recording a homotypic or objective synonym

Homotypic or objective synonymy occurs when the same Holotype In Taxonomy the definitive Type specimen on which a scientific name of a species is based. was used to define two (or more) scientific names.

Note: A re-combined name (when a species name is combined with a different genus name) is a special case of Homotypic synonymy and is dealt with in How to record a Parenthetic Author.

In the following example:

Both names were recorded as currently accepted:
In other situations only one or neither name will be recorded as currently accepted. When considering the example below, it is only important to ensure that the scientific name with Priority In Taxonomy, where two or more scientific names are synonyms, the Name that was published before the others is said to have Priority and is the Currently Accepted Name for a species. is the currently accepted name.
Note: Where names are in a synonymous relationship, only one can be currently accepted.
On the Primary Citation tab for each name, Is Original Name?: (Original Name) is set to Yes.
This may or may not be the case in practice.
Note: Only the name with priority can be recorded as the Original Name.

For example:

In 1910 Wood described a new zoological species Gus hus Wood, 1910.
This was a currently accepted name:
On the Primary Citation tab this name is specified as the original name: Is Original Name?: (Original Name) is set to Yes.
In 1950 Brown identified Jus kus Brown, 1950.
This too was a currently accepted name:
On the Primary Citation tab this name is specified as the original name: Is Original Name?: (Original Name) is set to Yes.
In 2004 another scientist realized that Brown had used the same holotype as Wood and that the two names refer to the same species. In this case:
- The currently accepted name would be Gus hus Wood, 1910 as it has priority.
- The scientific name Jus kus Brown, 1950 would remain exactly as it is - no re-combination has taken place - but it would be considered a homotypic synonym of Gus hus Wood, 1910. This will be the junior synonym in this relationship.
  Note: Only one scientific name can be the currently accepted name. It is not possible to create a synonymous relationship between two names that are both currently accepted, and trying to do so will generate a warning message. Therefore:

Ensure that the scientific name with priority is the currently accepted name (Gus hus Wood, 1910 in this example).
Next ensure that the other scientific name is NOT the currently accepted name (Jus kus Brown, 1950 in this example):
1. Select Unknown from the Currently Accepted?: (Currently Accepted Name) drop list.
  A message displays:
Click OK.
Note: See Pending tab for an explanation of what happens to heterotypic synonyms that are moved to the Pending tab.
The All Synonyms tab disappears from the Jus kus record.
Note: Only the record for the currently accepted name has the All Synonyms tab and is able to list all synonyms.
Select the Primary Citation tab and if Is Original Name?: (Original Name) is set to Yes, select Unknown from the drop list.
Save the record.

In the record for the currently accepted name (Gus hus Wood, 1910 in this example):

Select the Homotypics tab.
Attach the Jus kus Brown, 1950 record in the Name: (Homotypic Names and Combinations) field.
The default under Combination/Other: (Homotypic Names and Combinations) is Combination. Delete this and replace with Other.
Save the record.

If we now display the Jus kus record, we find that Currently Accepted?: (Currently Accepted Name) is automatically set to No and that Current Name: (Currently Accepted name) points to the Gus hus record:

If we check the All Synonyms tab in Gus hus we find that Jus kus is added to the Synonyms List and identified as a Homotypic synonym:

Tip: See below for an alternative method to record synonyms.

Heterotypic / Subjective

Two or more synonyms are derived from different type specimens.

Also known as subjective or taxonomic synonyms as the basis for recognizing synonymy is a matter of opinion.

Example

In 2002 Wood described a new zoological species Cus dus Wood, 2002 and in 2003 Brown described Vus wus Brown, 2003 (using different type specimens). In 2004 another scientist decided that these two names actually refer to the same species. In this case:

The currently accepted name would be Cus dus Wood, 2002 as it has Priority In Taxonomy, where two or more scientific names are synonyms, the Name that was published before the others is said to have Priority and is the Currently Accepted Name for a species..
Vus wus Brown, 2003 would remain exactly as it is as no re-combination has taken place, but it would be considered a heterotypic synonym of Cus dus Wood, 2002 and would not be a currently accepted name.

Recording a heterotypic or subjective synonym

Heterotypic or subjective synonymy occurs when different type specimens are used to define two (or more) scientific names.

For example:

In 1910 Wood identified a new zoological species Gus hus Wood, 1910.
This was a currently accepted name:
On the Primary Citation tab this name is specified as the original name: Is Original Name?: (Original Name) is set to Yes.
In 1950, and using a different Type specimen In Taxonomy Type specimens are specimens selected to typify the described species. They are made available (often in museums) for study by Taxonomists. The Type Series is all specimens on which the description of a new species or genus is based. The Holotype is the single specimen published as "the Type" by the Name Author. An Isotype is a duplicate specimen of the Holotype collected at the same place and time as the Holotype. The Syntype is one of two or more specimens cited by the author when no Holotype was designated or it is any one of two or more specimens originally designated as Types. The Neotype specimen is selected as the Type where the original Types are known to be destroyed. Paratypes are the non-Holotype Syntypes. to Wood, Brown identified Jus kus Brown, 1950.
This too was a currently accepted name:
On the Primary Citation tab this name is specified as the original name: Is Original Name?: (Original Name) is set to Yes.
In 2004 another scientist decided that though the type specimens were different these two names really refer to the same species. In this case:
- The currently accepted name would be Gus hus Wood, 1910 as it has Priority In Taxonomy, where two or more scientific names are synonyms, the Name that was published before the others is said to have Priority and is the Currently Accepted Name for a species..
- The scientific name Jus kus Brown, 1950 would remain exactly as it is - no re-combination has taken place - but it would be considered a heterotypic synonym of Gus hus Wood, 1910. This will be the junior synonym in this relationship.
  Note: Only one scientific name can be the currently accepted name. It is not possible to create a synonymous relationship between two names that are both currently accepted, and trying to do so will generate a warning message. Therefore:

In Jus kus Brown, 1950 (the Junior synonym in this relationship because Gus hus Wood, 1910 was published first):

On the Primary Citation tab, check whether Is Original Name?: (Original Name) is set to Yes. If so, select Unknown from the drop list.
On the Classification tab, select No from the Currently Accepted?: (Currently Accepted Name) drop list.
The Current Name: (Currently Accepted Name) field becomes available:
Enter Gus hus Wood 1910 in Current Name: (Currently Accepted name) and click Attach beside the field (or press the TAB key).
A message displays indicating that Jus kus Brown is to become a heterotypic synonym of Gus hus Wood:
Click OK and then save the record.
The All Synonyms tab disappears from the Jus kus record.
Note: Only the record for the currently accepted name has the All Synonyms tab and is able to list all synonyms.
If we check the All Synonyms tab in Gus hus we find that Jus kus is added to the Synonyms List and identified as a Heterotypic synonym:
Tip: See below for an alternative method to record synonyms.

Note: Where names are synonymous (and by definition interchangeable), only one of the names is identified as the currently accepted name.

It is also possible to record a synonym using the All Synonyms tab in the record of the currently accepted name:

Using the All Synonyms tab to record synonyms

First ensure that the junior synonym is not recorded as being a currently accepted name (i.e. Currently Accepted?: (Currently Accepted Name) should be set to Unknown or No).

For example:

In 1910 Wood identified a new zoological species which was called Gus hus Wood, 1910.
This was a currently accepted name:
On the Primary Citation tab this name is specified as the original name: Is Original Name?: (Original Name) is set to Yes.
In 1950, and using a different Holotype In Taxonomy the definitive Type specimen on which a scientific name of a species is based. to Wood, Brown identified Jus kus Brown, 1950.
This too was a currently accepted name:
On the Primary Citation tab this name is specified as the original name: Is Original Name?: (Original Name) is set to Yes.
In 2004 another scientist decided that though the type specimens were different these two names really refer to the same species. In this case:
- The currently accepted name would be Gus hus Wood, 1910 as it has Priority In Taxonomy, where two or more scientific names are synonyms, the Name that was published before the others is said to have Priority and is the Currently Accepted Name for a species..
- The scientific name Jus kus Brown, 1950 would remain exactly as it is - no re-combination has taken place - but it would be considered a heterotypic synonym of Gus hus Wood, 1910. This will be the junior synonym in this relationship.

In Jus kus Brown, 1950 (the Junior synonym in this relationship because Gus hus Wood, 1910 was published first):

On the Primary Citation tab, check whether Is Original Name?: (Original Name) is set to Yes. If so, select Unknown from the drop list.
On the Classification tab, select Unknown from the Currently Accepted?: (Currently Accepted Name) drop list.
Click OK if a message similar to the following displays:
Save the record.
On the All Synonyms tab of Gus hus Wood, 1910, enter Jus kus Brown 1950 in the Name: (Details) field and click Attach (or press the TAB key).
Jus kus Brown, 1950 is added to the List and automatically identified as a Heterotypic synonym:
Note: If we were recording a homotypic relationship, we'd select Homotypic from the Kind of Synonym: (Details) Lookup List or we would have added Jus kus Brown, 1950 on the Homotypics tab.
Save the record.

If we check the Jus kus Brown, 1950 record we find that Currently Accepted?: (Currently Accepted Name) is set to No and Current Name: (Currently Accepted name) points to Gus hus Wood, 1910: