Catfish Corner: LakeTanganyika News Update (and Other Notes)
Author: Lee Finley
Catfish Corner: March 2007
In a previous column (“Good News From Lake Tanganyika,” TFH November 2006) I discussed work being done on Lake Tanganyikan Synodontis utilizing mitochondrial DNA techniques. The main part of the column was built around one study (Koblmuller, et al., 2006), but some additional work, available only in abstract form at that time, was also mentioned. This work has now been formally published (Day and Wilkinson, 2006) and I would like to make mention of this as a follow-up.
Notes from the Studies
First, I will note that the two studies were performed using different marker genes. While there were some differences encompassing non-Lake Tanganyikan species, the results for the endemic Lake Tanganyikan species basically came out the same: two clades, one consisting of S. multipunctatus and S. granulosus, and the other containing S. polli, S. petricola, and S. dhonti. The Day and Wilkinson study also includes a fish designated as S. cf. tanganaicae. This species, with or without a cf., was not included in the previous study. (Note: I had used the spelling tanganyicae in my previous column. See “Spelling Lesson” below). In any case, the fish listed as S. cf. tanganaicae is grouped together with S. polli, S. petricola, and S. dhonti.
Now, as previously noted, the above is very interesting but basically academic. What are some of the points to be drawn from this new paper that might be beneficial to us as aquarists? I will make a few comments that might be of potential interest…
Synodontis af. petricola
In addition to Synodontis petricola, Day and Wilkinson made note of a catfish they designate as Synodontis af. petricola and state that it is awaiting description. In that some of the collecting localities of this fish are the same as the new species of Synodontis, noted in Koblmuller et al. as Synodontis species novum, could this possibly be the same catfish? But…
Another catfish is also listed by Day and Wilkinson as Synodontis af. petricola*. They note that this catfish “…may also represent an undescribed species.” The two specimens of this fish were collected in localities shared by both of the fish that Koblmuller et al. mention, as well as the other S. af. petricola of Day and Wilkinson. So this basically means that when someone gets around to looking at these catfishes, anywhere from one to three new species could be the potential result. It may take a while, but it will be something to look forward to.
Lastly, Day and Wilkinson worked with 10 specimens of S. multipunctatus from four different localities in Tanzania, Zambia, and the Democratic Republic of Congo. They note, by the methodology they used, that there is little genetic variation between them. I will still stick with my original contention that the catfish that we know as S. multipunctatus, or S. cf. multipunctatus (at least hobby wise), will eventually prove to consist of more than just one species.
In the above piece I used the two abbreviations af. and cf. For those not familiar with these, I would like to make a brief note in regards to them.
af., or more commonly aff., is an abbreviation of the Latin term affinis. The definition for this is “having affinity with but not identical with.”
cf. is the abbreviation for the Latin term confer and means “to be compared with.”
While the two terms may seem somewhat similar in meaning, they are different in their usage. (Note: The offered definitions are from Procedure in Taxonomy, Third Edition, by E. T. Schenk & J. H. McMasters.)
Above I made mention of variants of the spelling of the Synodontis species name tanganyicae. There are currently two spellings that are in general use: tanganyicae (which I use) and tanganaicae (which is used in the Day and Wilkinson paper). A quick online search provides many more hits for the first spelling, but Internet search engine numbers are not the final arbiter of taxonomic correctness.
The origin of the problem with this species name (there, I avoided using either name!) is in the original description. The fish was originally described in 1936 by N. A. Borodin as a subspecies of Synodontis serratus. The name in question was appended as a third name. In the paper, spelling problems are rife, and both spellings, as above, are used in different places. To emphasize the point I will note that the spellings Synodontis and Sinodontis [sic] are also both used in the paper.
In any case, when DeVos and Thys van den Audenaerde (hereafter D&T) re-examined this “species” in 1998 they decided that it was not related to S. serratus and was in fact a valid species in its own right. In addition, they concluded that Max Poll had redescribed it under the name of S. lacustricolis. So Poll’s name became a synonym of this species, which had taken the species name tanganyicae. Now, with two spellings in place, how did D&T decide which was the proper one? But, let’s wait a minute, because there is actually a third spelling out there (are you confused yet?). In 1946, 1953, and 1971 Poll used the spelling “tanganicae.” As far as I can determine there is no reason given for this change of spelling.
So, with the above in place, D&T did the taxonomic equivalent of a “hanging chad” examination and concluded, based on an earlier paper (1931) by Borodin, that the “intent” had been to use tanganyicae, and they adopted this as the species name.
But all is not through. William Eschmeyer in his Catalog of Fishes suggests that the selection of name by D&T “…is apparently against the wishes of the original author…” and questions whether this is “…the first valid first reviser action.” But, he also questions (to no resolution) whether the amended name first used by Poll in 1946 might be valid (if he was acting as, I assume, a first reviser).
So where are we with the species name of this fish? Darn confused, that’s where. In making my own decision I will choose to follow the name in D&T (Synodontis tanganyicae)—at least until further notice.
The Symphysodon aequifasciatus and S. discus Dilemma
Although the spelling lesson is more than enough to cause this headache, it is not the primary reason.
The work on Synodontis covered herein (and the November, 2006 column) is more or less clear and straightforward. But in my last column I had made mention of two madtom catfishes (Noturus albater and N. maydeni) that were noted to be physically identical and separable only by the use of chromosome, protein, and DNA analysis. Good enough. I’m wrapping my head around this. Then I read a new cichlid taxonomy paper (yes, I like cichlids also). The pain began.
The paper dealt with the taxonomy of discus. I won’t go deeply into this (my friend Wayne Leibel will do so in his cichlid column), but the main head hurter is as follows: Symphysodon aequifasciatus and S. discus share the same DNA (by the method of analysis used) but are definable as separate species based on physical differences. So, here we have an exact reversal from the madtom situation (pass the aspirin please!). Where to go from here?
Wayne, who is well versed in such things (he does it, in part, for a living after all), provided me with a psychic aspirin of sorts. A lot of the conflict can be explained by the various methodologies used by different parties. Some of these are more precise, while others may be less so (generalized). It appears to kind of depend on where you want to go and how you want to do it. Many times comparisons of results done by such different techniques do basically conform; in other cases they do not. As I noted in the last column it is a brave new world and all things are not necessarily going to make (initial) sense. For those wanting a better explanation, check out Wayne’s “Cichlidophiles” column this month (p. 40).
Recommended Catfish Resources
The North American Native Fishes Association (NANFA) is generally, and specifically, a wonderful place to go if you have any interests at all that relate to the thrust of the group.
Christopher Scharpf, who is the group’s editor and membership coordinator, has just published part two of his outstanding and well-referenced 83-page work “Annotated Checklist of North American Freshwater Fishes, Including Subspecies and Undescribed Forms” in American Currents, Volume 32, Number 4, Fall (Nov.), 2006. Part one of the work was published in Volume 31, Number 4, Fall (Nov.) 2005 of the same publication.
For this mention here, the second part of the work is of importance in that it includes the catfishes. Chris offers six and a half pages on the topic, including both native and introduced species. Without any doubt this is the most current and comprehensive overview of the topic and belongs in the library of anyone with interests in this area. A great amount of information is provided for each catfish, including the meaning of the species name, the distribution, and the conservation status. In addition to this, many species have an additional “Note” section which provides additional valuable information in many areas of potential interest. Much of this latter material is via personal communication and therefore is most likely not to be found available in other sources.
Chris and NANFA are to be congratulated on the publication of this monumental work. This is now the starting place for similar future works.
For information regarding NANFA and membership therein, check out their website at www.nanfa.org/ or write to: NANFA, Membership Coordinator, 1107 Argonne Drive, Baltimore, MD 21218.
Day, J. J. & M. Wilkinson. 2006. “On the origin of the Synodontis catfish species flock from Lake Tanganyika.” Biology Letters, 2(4): 548-552 [plus two pages of supplemental material available online].
Koblmuller, S., C. Sturmbauer, E. Verheyen, A. Meyer & W. Salzburger. 2006. “Mitochondrial phylogeny and phylogeographyof East African squeaker catfishes (Siluriformes: Synodontis).” BMC Evolutionary Biology, 6 (49). Published online at: http://www.biomedcentral.com/1471-214816149 (last viewed 7/31/06).