Synspilus A Junior Synonym of melanurus?

[Bas Pels]

monophyletic means from a single ancestor, fullstop.

I wonder how it is possible a species comes from a single ancestor. And I don't mean to say each individual has a mother and a father, but evolution is something for groups.

A population of any species is a gene pool. After all the individuals crossbreed with each other, and the best fitting - or lucky - ones survive. If the circumstances change, the gene pool shifts, resulting in a change in the average characteristics of the individuals in said populations.

Looking at the single ancestor idea from another point of view - genetics, and especially inbreeding, a species which started with a father and a mother will not survive long - this species does not have enough genetic variation to survive. Generally, a population which has shrunk to less than 50 unrelated individuals is in danger of extinction due to inbreeding. Obviously, some specioes are more resilient than others, and therefore 50 can mean anthing from 10 to over 100, I think.

However, one could state that in a gene pool all individuals may be considered as descendants of 1 ancestor a 1000 generations back - but in that case, the ancestor is - by definition - not part of the species, as is lived a thousand generations before the species started to emerge.

So, the meaning of 'ancestor' in the above can not be 1 individual. It must be a population.

Going back to Willem - when a population starts to change into another species, this will result in the absense of the original population. But if we believe species are real - and not something people thought up, in orderto understand nature (which is what I think) the original species itself will not have to go extinct, just because 1 population changed.

I think we have a lot of situations where 1 species descended from another species - while both still excist. Obviously, in many cases the new species will be better adapted and be the cause the original speces will go extinct, but this will not have to be the case - a natural barrier can excist, or the new species is not better adapted everywhere. And even if the old species will be replaced, this will take time. So even in that case, both species coexcist - for a geological while

[cichla]

Well, the study by Mcmahan et al. is indeed a valuable contribution to the alpha-taxonomy of the Middle American cichlids. Anyway, I agree with Willem that Heros melanurus is not a synomym of Paraneetroplus melanurus but just the original combination. It might be connected with the 'layout' as Rico speculate. More serious is, however, that the authors list the taxa Cichlaurus hicklingi Fowler 1956 Heros melanopogon Steindachner 1864 as synonyms without discussion. They not even mention the sources why they doing so. In a re-description it is necessary to discuss all possible synonyms. Or at least to cite the source, where these taxa established as sysnonyms.

As one, who like numerical taxonomy, I miss a clear description of how they calculate the distance matrix. They used 'non-parametric statistical methods' to prevent the influence of 'unbalanced nature of the data'. But the MDS is non-parametric only insofar as it treats the metric distances as ranks. So, its also necessary to correct the original data for e.g. small sample size. And the 'group average hierarchical cluster analyses' is not 'non-parametric'. Besides the inappropriate description of the statistical methods the results are still valid and it is refreshing to see that modern statistical procedures are used in taxonomy of our beloved cichlids from Middle Amrica.

To include these species in Paraneetroplus based only on analysis of Cyt b (which itself is often challenged as a source for phylogenies within Perciformes). It is well known that the topology of phyloegenetic trees often changed when additional sequences or morphological data are incorporated. This is why I believe that Paraneetroplus in this sense will not survive. But who know

[Tachymarptis]

monophyletic means from a single ancestor, fullstop.

I wonder how it is possible a species comes from a single ancestor. And I don't mean to say each individual has a mother and a father, but evolution is something for groups.

So, the meaning of 'ancestor' in the above can not be 1 individual. It must be a population.

Of course, this is one of the approximations needed by cladism. But even as an approximation, this is not always true. Species may originate from a full interspecific hybridization, sometimes between two markedly different species. This may occur in case of a major ecological or geographical sudden change, which leads to cross-breeding between two populations previously isolated by environmental or behavioral conditions.

[Rico Morgenstern]

By the way: paraphyletic groups are by definition not natural. The real question is: should named genera always be natural groups?

Willem, I have referred to the word sense, not to any definition when using the term 'natural'. That only monophyletic groups can be natural, is exactly what I have called into question.

My example was somewhat imprecise, in fact it was a certain population of S. galiliaeus galilaeus that gave rise to the Barombi flock. In your cladogramm, S. galilaeus galilaeus would have to be inserted for Aequidens and he Barombi species for Cichlasoma.



Another question is to what extent the trees obtained in a study reflect the real relationships of the included taxa at all. Of course the probality increases with the number of taxa/specimens (molecular studies are often based of single or few specimens of each species) and characters, but how can we be sure that the characters used are at all suitable and/or - in the case of morphological analyses - correctly coded into character states.

However, let's return to the work, which does not actually deal with these questions.

Anyway, I agree with Willem that Heros melanurus is not a synomym of Paraneetroplus melanurus but just the original combination. It might be connected with the 'layout' as Rico speculate. More serious is, however, that the authors list the taxa Cichlaurus hicklingi Fowler 1956 Heros melanopogon Steindachner 1864 as synonyms without discussion. They not even mention the sources why they doing so. In a re-description it is necessary to discuss all possible synonyms. Or at least to cite the source, where these taxa established as sysnonyms.

It would of course be desirable to discuss the status of H. melanopogon and C. hicklingi, especially since this has never been done. The former was synonymized by Regan (1905), the latter (with C. synspilum) by Miller (1966). However, their status has never been questioned since. And as the material examined by McMahan & al. covers the whole range including the type localities (the origin of the H. melanopogon types is not exactly known, but according to Günther [1868] it is probably Lake Petén; C. hicklingi was described from a tributary of the Belize River; it is self-evident from the description and figure that it is the same species) of all four nominal taxa it is clear the synonymy is to be accepted.

If another combination than the valid one is a synonym or not is a matter of interpretation. Furthermore, I have observed that there is a general misunderstanding, what exactly a synonym is.

The glossary of the code defines a synonym as:

Each of two or more names of the same rank used to denote the same taxonomic taxon.

This means, Cichlasoma synspilum is not only a synonym of P. melanurus, but P. melanurus is also a synonym of C. synspilum.

The principle of binominal nomenclature (Article 5.1) says:

The scientific name of a species, and not of a taxon of any other rank, is a combination of two names (a binomen), the first being the generic name and the second being the specific name.

Article 28:

Change of generic assignment. An available species-group name, with change in gender ending if required [Art. 34.2], becomes part of another combination whenever it is combined with a different generic name.

So when a name of the species is a combination of two names, a changed combination is another name and may therefore be considered a synonym. The definition cited above does not even prevent misapplied names from being synonyms. However, when cited, these must be clearly marked as misidentificatons to avoid confusion.

[Willem Heijns]

Rico,

Just out of curiosity: what is a natural group sensu Morgenstern?

With regard to the Barombi Mbo fauna: how do we know that the population of S. galileus galileus you mention is the ancestor of the species flock in this craterlake? Or could it have been a "galileus-type" fish?

And finally about synonyms: ICZN art. 50.1 says: "the author of a name is the person who first publishes it" In our case: if Heros melanurus GÜNTHER 1862 is synonymized with Paraneetroplus melanurus, which author and date should be fixed for the latter name?

[cichla]

Here in the discussion some are mixing things which have only minor connections. Like taxonomy and classification, species monophyly and monophyletic groups.

1)synonyms are names given for the same taxon (Mayr, 1969). What you are meaning Rico is (I guess) the bibliographic account. This is indeed called (unfortunately) ''Synonymy'' in some text books. However, it has 'nothing' to do with the synonym in the taxonomic sense.
Concerning the paper by MCMAHAN et al: I miss a discussion of all synonyms. At least they have to list the source where these taxa are synonymized.
2)monophyly of species: Almost all taxonomists agree that the majority of species are not monophyletic in the strict sense. This is indeed a challenge for the a classification of the phylogenetic school. This is why species are treated by some participants as ''individuals'' (in a kind of metaphysical instead of physical sense). Hence, paraphyletic species are accepted by the majority of ichthyologists (see Kullander 1999)
3)Monophyly of a group: Polyphyletic groups are un-natural units and rejected by all schools of classification. And were rejected long before the strict phylogenetic classification was developed. Paraphyletic groups are, however, natural groups and are not rejected by the evolutionary school of classification. And there are even papers (currently published) by followers of the phylogenetic school which incorporate paraphyletic groups for both schools of classification.

The explanation of the phylogenetic application by Willem is informative (reading it, will prevent you to study many text books )

And yes, in the strict sense of Hennig's phylogenetic systematic the ancestor species has to be re-named if a part of it developed to a new species. This is why I think - at least at species level - it is not applicable.

I like a lively discussion.
Greetings, IS

[Rico Morgenstern]

ust out of curiosity: what is a natural group sensu Morgenstern?

A natural group would then simply require that the included populations (or taxa, if higher categories are concerned) are "naturally" (that is by natural reproduction) descended from a common ansestor, but it would not necessarily have to contain all of them.

With regard to the Barombi Mbo fauna: how do we know that the population of S. galileus galileus you mention is the ancestor of the species flock in this craterlake? Or could it have been a "galileus-type" fish?

Of course nobody was there when the lake was formed and colonized by fishes. However, in the example scenario, the assumption that it was a "galilaeus-type" fish would make S. galilaeus (the trinomen was an error of mine, though the most closely related population referred by Schliewen would be referrable to the subspecies galilaeus according to Trewavas 1983) even polyphyletic. And even if galilaeus was split into several 'cryptic' species, the para- or polyphyly of the genus Sarotherodon was retained.

I fully concur with Patrick's view that cladistics should be seen as not more, but also not less, than an useful tool.

And yes, in the strict sense of Hennig's phylogenetic systematic the ancestor species has to be re-named if a part of it developed to a new species. This is why I think - at least at species level - it is not applicable.

I agree, and - with regard to the implications on binominal nomenclature - I would even extend this to genus level. Remember that the Linnean nomenclature was not intended as an end in itself, but as a practical reference system. And this, I fear, is getting lost by recognizing taxa only if they are monophyletic clades.

And finally about synonyms: ICZN art. 50.1 says: "the author of a name is the person who first publishes it" In our case: if Heros melanurus GÜNTHER 1862 is synonymized with Paraneetroplus melanurus, which author and date should be fixed for the latter name?

Of course I know this was a rhetorical question, let's nevertheless look what the Code says:

50.3.2. Change in generic combination of a species-group name does not affect its authorship (see Article 51.3 for the use of parentheses to indicate changed combinations).

51.3. Use of parentheses around authors' names (and dates) in changed combinations. When a species-group name is combined with a generic name other than the original one, the name of the author of the species-group name, if cited, is to be enclosed in parentheses (the date, if cited, is to be enclosed within the same parentheses).

It's Paraneetroplus melanurus (Günther, 1862)

There are several ways to cite additionally the author of a new combination, one is suggusted in the Code:

Recommendation 51G. Citation of person making new combination. If it is desired to cite both the author of a species-group nominal taxon and the person who first transferred it to another genus, the name of the person forming the new combination should follow the parentheses that enclose the name of the author of the species-group name (and the date, if cited; see Recommendation 22A.3).

Other methods include separation of species name and author by comma, semicolon or colon, or adding "new combination" etc.

However, this all is of minor importance, see article 51.1 (emphasis by myself):

51.1. Optional use of names of authors. The name of the author does not form part of the name of a taxon and its citation is optional, although customary and often advisable.

To bring back the discussion from philosophical matters and terminology to the actual topic of the MCMahan paper:

Though fully convinced of the identity of the species, I'm nevertheless somewhat surprised that nobody here advocates for their distinctness, since until a few days ago both synspilus and melanurus (generic names deliberately omitted to avoid confusion) were maintained.

Finally, I find Juan Miguel's consideration to apply the results from McMahan & al. to Thorichthys affinis and T. meeki absolutely worthy to be discussed in this context. The distributional pattern and habitat preferences are comperable (except for the more extended range of Thorichthys in Northern Yucatán) and the two forms are indeed more similar to each other than each of them to other species of the genus. However, in several relatively recent works dealing with the species level taxonomy of Thorichthys (i.e. Rivas 1962, Hasse 1981, Miller & Taylor 1984 and Miller 2006) they are recognized as distinct on the basis of comprehensive material. Therefore they should not be synonymized without a careful study of intraspecific variability.

[michi tobler]

Hi all,
this is an interesting discussion! By definition, natural groups are monophyletic groups, I concur with Willem. But while higher taxonomic groups (genera, families, etc.) should - by convention - be natural, i.e. include all descendants from a common ancestor, biological species do not necessarily need to be monophyletic...
Cheers, m

[Willem Heijns]

As much as I like to go back to the original subject of the topic (and I will) I have to say a few more things about the naming terminology (since you brought that up Rico ).

My question on the authorship was not rhetorical. I believe authorship and dates are assigned to names (at any level). In our case the name melanurus (a species group name) has Günther as author and 1862 as date. The name Heros was likewise created by Heckel in 1840. And the name Paraneetroplus by Regan in 1905. Any combination of the specific name melanurus with any generic name (Heros, Cichlasoma, Paraneetroplus) does not change that and creates no synonyms. The ICZN states (art. 5.1): the scientific name of a species is a combination of names, the first being the generic name and the second being the specific name. (my boldface). All rules and regulations (including synonymy) in the ICZN are aimed at the names on the defined levels i.e. species-goup names, etc (and not at the combination of names). There is no article in the Code that says anything about the status and validity of scientific names (the combinations), except art 50.3.2 about the authorship. That is also logical because a change in generic assignment does not change the specific name (except for the ending), nor does it change the authorship and thus can not create a synonym.

Your question about retaining the names synspila and melanura (as members of Vieja in my view ) has answered itself with your remark about affinis and meeki. Although many (including me) suspected the two species to be the same, we waited to adopt the "new" name until a "careful study of intraspecific variability" had been published.

[cichla]

Dear all.
Parneetroplus, Vieja or Cichlasoma :
''It is often not appreciated that much of taxonomy, across all levels, is determined by community consensus rather
than strict rules. For example, the decision to recognize a collection of individuals or populations as a species is
frequently debated. Likewise, both the recognition (or not) of a supraspecific taxon and the level applied (e.g., genus,
tribe, family) is usually subjective because there are many ways to divide up a phylogenetic tree and apportion taxa.''
Hedges (2011): http://www.mapress.com/zootaxa/2011/f/zt02867p068.pdf
It is just subjective where we chop the phylogenetic tree.
Greetings, IS

[Rico Morgenstern]

All rules and regulations (including synonymy) in the ICZN are aimed at the names on the defined levels i.e. species-goup names, etc (and not at the combination of names). There is no article in the Code that says anything about the status and validity of scientific names (the combinations), except art 50.3.2 about the authorship.

Willem, how would all this fit to homonyms in the species group? What about the seven festae, the eight moorii or the 28(!) ansorgii established by Boulenger. Are they homonyms for the species-group name and author being identical? And what's the difference then between primary and secondary homonyms if the status of combinations is not a subject of the Code? And there are many other provisions related to combinations.

In conclusion I would still say that there are no provisions in the Code that would unambiguously exclude altered combinations (and misapplied names as well) from being synonyms, nor are they excluded by the definitions of "synonym" and "name" in the glossary (see Art. 89.1 for relevance).

[Willem Heijns]

Been away to Bonnie Scotland for a few weeks and, believe it or not, I did not take the Code with me.

Now that I'm back I checked the famous book and found that species group names are only homonyms if they are established in combination with the same generic name (Art. 53.3). So the seven festae, the eight moorii and the 28 ansorgii are in no danger of being homonyms, provided they were all assigned to different genera. I did not check their generic assignments though.

The difference between primary and secondary homonyms is merely the original combination (primary) or the subsequent (after being assigned to another genus originally) combination (secondary) with the same generic name.

I don't believe combinations as such are subject to availability and/or validity under the Code. Article 11 only deals with names (of any rank). This view is also illustrated in article 13.4 which states that combined description of a new genus group taxon and new species is deemed to confer availability on each name (my boldface). This obviously relates to the genus group name and the species group name separately.

[Rico Morgenstern]

Oops, I thought I had won

No, joking aside: Of course I know that the 'ansorgiis' etc. are no homonyms, I just wanted to challenge your statement about importance of authorship and combinations being no subject to the code. What I tried to point out is, that validity (and also availability; see, e. g. Art. 11.9.3) can well be affected by combination, and this is of course regulated by the code, as the example of homonyms in the species group shows.

Anyway, if you look at the definition and scope of the code (Arts 1.1 and 1.2.), at the Principle of Binominal Nomenclature (Art. 5.1) and at the definitions of 'name' and 'taxon' in the Glossary, you will find that (1) the code is about naming of taxa, (2) 'name' includes scientific names, i.e. the combinations, and (3) the name of a taxon at the species rank is a combination of a generic name and a specific name. And as the definition of the term 'synonym' ("Each of two or more names of the same rank used to denote the same taxonomic taxon") is linked to taxa, it does not exclude changed combinations (and not even misidentifications). Even if the definition of 'synonym' would be altered into: "Each of two or more names of the same rank established for the same taxonomic taxon", this would not exclude the original combination from being a synonym. What you seem to have in mind is perhaps "Each name at the same rank established for the same taxonomic taxon except the one determined as valid, regardless of its combination in the case of the species group". In fact this is the meaning of of the term 'synonym' (in taxonomy) by conventional use (and I agree that it is often useful to quote only such names), but not by any provision in the code.

Well, Willem, even if we do some hairsplitting here (may the other forum members forgive us ), I actually like this discussion. Nevertheless I think we can stop here and agree on a draw. Otherwise we could perhaps quote the entire code here and would finally still adhere on our views.

[Willem Heijns]

I was never in this discussion to win or lose or reach a draw. I am always triggered to read more and learn from it. This topic really did that. And why stop? You said you like it (as did I) and, judging from the number of reads (close to 600) many people were interested. A pity they did not contribute though.

Anyway, rounding this up: The original question was: does a new (generic) combination make the old combination a synonym? We have not reached a conclusive answer to this question. Technically it is possible, but it certainly is no common practice. An omission of the Code?

[cichla]

Dear Willem, Dear Rico, Dear all,
well, I think, there are two different things: (A) synonyms (two or more names given for the very same species) and (B) Synonymy (a chronological list of scientific names given for a particular species). The later is better called ''bibliography''. Unfortunately, both (A+B) have the very same (or almost identical) term in text books about taxonomy and nomenclature. This is why confusion may arise. So, I think, it is not necessary to 'quote the entire code' but just differentiate between the two things.

In our case Cichlasoma synspilum Hubbs 1935 is a synonym of Heros melanurus Günther 1862. But Cichlasoma melanurum (Günther 1862) is not a synonym of Heros melanurus Günther 1862. It is just an alternative combination.

Greetings, IS

By the way, I am still missing a confidential source for the synonyms Heros melanopogon Steindachner 1864 and Cichlaurus hicklingi Fowler 1956 for Heros melanurus Günther 1862. In the paper by McMahan et al (2011) I couldn't find any source.

[Rico Morgenstern]

I was never in this discussion to win or lose or reach a draw. I am always triggered to read more and learn from it.

It`s of course not about to win or to lose, this was only a joke. I have the same intention as you, Willem! However, I do not think that we can find much more in the code what helps to interprete the term 'synonym'.

As to the question, if a new combination makes the original one a synonym, I also think - technically spoken - yes. At least I find it no violation of the code to denote the original combination (or any other combination) as synonym, and this is what you have initially brought up. What is useful in practise, that's a different matter. The definition of 'synonym' in the code should perhaps be more precise. On the other hand, to what extent is this a nomenclatoral problem at all? Most questions concerning synonyms are rather taxonomic, and taxonomy is not subject to the code. Insofar, it is of course advisable to oriantate according to practical use.

well, I think, there are two different things: (A) synonyms (two or more names given for the very same species) and (B) Synonymy (a chronological list of scientific names given for a particular species). The later is better called ''bibliography''.

Kullander, in his famous book on the Peruvian cichlids (1986), distinguished between synonymy and (Peruvian) bibliography and listed the original combination under the former subheading whenever there are more specific names given to a species, but without subhaeding where this is not the case, compare, e. g., Astronotus ocellatus and A. crassipinnis. This would fit the interpretation: "Each of two or more names of the same rank established for the same taxonomic taxon".

By the way, I am still missing a confidential source for the synonyms Heros melanopogon Steindachner 1864 and Cichlaurus hicklingi Fowler 1956 for Heros melanurus Günther 1862. In the paper by McMahan et al (2011) I couldn't find any source.

After checking some sources about Friedrichsthal's (the collector of the H. melanopogon types) travels, I find it now - contrary to earlier statemants here and elsewhere in the forum - unlikely (though not excluded) that Lake Petén is the type locality for this and other nominal species described from his collection. Günther's conclusion is merely based on the fact that Salvin had collected the same species in Lake Petén and the then very incomplete knowledge on distribution of the species, all of which are now known to be widespread in Southern Mexico, Belize und Guatemala. Friedrichsthal's species have obviously been collected during his last travel (1840/41) in Yucatán. He entered the peninsula via Bacalar and went to Campeche, where he took his residence for some month. He then mostly explored the northern part of the Yucatán peninsula, where none of the species collected by him, except 'C.' urophtalmus, occurs. Also, provided that all species were sent together to Vienna (I shall send an inquiry to the NMW), they must have been collected at the beginning of his travel, as one of them - Parachromis friedrichsthalii - was described still in 1840. The material may thus have come from near Bacalar or from somewhere on the way to Campeche. Unfortunately, there is no detailed travelogue since Friedrichsthal died soon after his return to Austria.

[cichla]

In the book ''The Cichlids of Surinam'' Kullander & Nijssen used the 'correct' form (in the nomenclature sense): first the original combination, then the synonyms and then the bibliography.

In the language the term 'synonym' is used in a broader sense and means a word having the same (or almost the same) meaning as one or some other words. But in nomenclature there are only ''objective'' and ''subjective'' synonyms. An alternative combinations (for instance, a species taxon is transferred to another genus) does not constitute (in my point of view) a synonym in the strict nomenclature sense.

Rico, your findings about Friedrichsthal and the possible confusion of type localities are interesting. However, I am still left with my question about a reasonable source where Heros melanopogon and Cichlaurus hicklingi are proofed to be synonyms. McMahan et al (2011) did a good and convincing job for Cichlasoma synspilum Hubbs 1935, but not for the other taxa.

[cichla]

Few words about paraphyletic groups:

''...the principle that any classificatory group defined should be 'monophyletic', ... '', ''This principle has been shown to be zero ... we can add nothing to these discussion, except to say that this 'principle' has resulted in the mechanical production of several new families because the older, larger families cannot be shown to fulfill its (discredited) criterion.'' Cullen & Walters (2006).

''Cladistic classification neglects important evolutionary processes'' Hörandl & Stuessy (2010)

Paraphyletic groups are not 'un-natural' per se and not so bad as thought (Brummit 2003). Why is it then, that paraphyletic groups are strictly rejected by some taxonomists. The answer is given by Brummit (2003) who summed up after a decade of defending paraphyletic taxa (2003: 804): ''... it is that although literally hundreds of fellow taxonomists have told me that they agree with what I say, I have persuaded very few to say the same things in public. ... One comment which made me particularly sad came from a systematic botany graduate research school. Although everybody there secretly believed with everything I said in the 2002 paper, they all knew that if they said so publicly they would never get a job in systematics.''

Greetings, IS