Taxonomy of Fossil Tanaidaceans
University of Washington
In 1974, I described a fossil tanaidacean from the famous Middle Pennsylvanian (Carboniferous), Mazon Creek faunas, which I named Cryptocaris hootchi (see Schram, 1974b). I had several excellent specimens from private fossil collections that I used to study and illustrate the species. However, when I came time to select a holotype, there was only one specimen in the collections of the Field Museum that I thought just might serve as a type. It was a strange and aberrant specimen, and it figured hardly at all in the description and reconstruction of the species. The policy of the Field Museum then, and I still think it a good one, was not to designate holotypes from private collections, unless the owner donated it to an established museum. None of the amateur collectors wanted to part with their specimens, so I decided in the end to use the Field Museum specimen as the holotype. The wisdom of doing this was verified soon thereafter within a few years when those specimens in private collections all vanished.
Jürgen Sieg, in 1980, decided that the genus Cryptocaris warranted a separate family, the Cryptocarididae, and so erected it within his new fossil infraorder Anthracocaridomorpha Sieg, 1980c. Another family, Anthracocarididae Schram, 1979, was included within this infraorder.
By the late 1980s, the Field Museum had accumulated 1,000s of additional specimens from the Mazon Creek localities, including additional specimens of tanaidaceans. Furthermore, the most important specimens from the original 1974 work had re-emerged at an auction of fossil specimens, and by fortuitous chance a knowledgeable amateur collector was there, Mrs. Helen Asher of Peoria, Illinois, who recognized the specimens, purchased them, and donated them to the Field Museum. In 1989, I realized that the aberrant holotype specimen of Cryptocaris hootchi had nothing to do with the concept of the fossil tanaidacean species. It was in fact a specimen of a species in another class of crustaceans. The name-bearing specimen, which had not figured in the original description, had nothing to do with the species concept of the fossil tanaidacean from the Mazon Creek biotas. I was thus confronted with a problem over what to do.
After consulting with a number of colleagues knowledgeable about systematics and taxonomic nomenclature, I decided to do the following. First, the original fossil tanaidacean -- then without a name or a holotype -- was in 1989 named Eucryptocaris asherorum, with one of the rediscovered specimens that strongly figured in the original description and reconstruction designated as the holotype (see Schram, 1989).
Subsequently, Michael Emerson and I in our monograph on fossil remipede crustaceans, determined that the problematic holotype specimen, bearing the name Cryptocaris hootchi, had to become the holotype of a species of fossil remipede, fully "described" and illustrated by Emerson and Schram, 1991. This remipede species, Cryptocaris hootchi, sits together with Tesnusocaris goldichi in the fossil family Tesnusocarididae Brooks, 1955, in the order Enantiopoda Birshtein, 1960, in the class Remipedia Yager, 1981. There is no perceived need right now to erect a separate family for this Cryptocaris.
By doing this, however, I unknowingly created a problem with regard to Sieg's 1980 erection of a family Cryptocarididae. What is the status of that family group name? Nomenclaturally, it is not available.
However, do we need a family here? I believe Sieg was wrong to erect that family to begin with. It was based entirely on plesiomorphic features, i.e., there were no diagnostic apomorphies (and at least the most important of these features was never actually seen -- Sieg only "believed" the feature had to be there). Sieg's family diagnosis reads:
"Im wesentlichen met der Diagnose der Unterordnung uebereinstimmend; wahrschienlich mit Stielaugen; Uropoden zweiästig, Exo- und Endopodit jeweils [my emphasis] aus zwei plattenformig verbreiterten Gliedern bestehend (?)."
Jeweils ("for the time being") indeed! This supposedly diagnostic feature has never been verified. I myself would not have erected this a family at all, based on the condition of the specimens and the state of the knowledge of the taxa then [and still true today]. Thus, I believe that Eucryptocaris asherorum should simply remain as a species in one of three genera within the Anthracocarididae Schram, 1979. Thus, as regards the fossil tanaidaceans, nothing more probably needs to be done. If some future revision of the Anthracocaridomorpha determines that Anthracocaris, Ophthalmapseudes, and/or Eucryptocaris deserve separate families, they can be erected at that time.
A problem may arise, however, if someone decides that the remipede genus Cryptocaris deserves a family separate from the genus Tesnusocaris. If that should ever happen, that person will have to go to the International Commission of Zoological Nomenclature to suppress Cryptocarididae Sieg, 1980c.
What should I have done? I have conferred with both the President of the International Commission, Prof. Alessandro Minelli, and a member of the International Secretariat for Zoological Nomenclature, Dr. Philip Tubbs. Both gentlemen admit this is one of the most intractable cases they have ever encountered, and it probably should have been handled through the international commission from the very first. They both indicated that I should have asked the commission to suppress the original holotype of Cryptocaris hootchi. I could then have designated a new holotype and thus kept the name originally attached to the Mazon Creek tanaidacean.
Be that as it may, I have two choices now. First, I could go to the International Commission, still ask for the suppression of the original holotype, and start all over again with designating a new holotype for the Mazon Creek tanaidacean under the old name, Cryptocaris hootchi, and create a new name for the fossil remipede. This, however, would only cause further confusion, since Eucryptocaris asherorum is now coming into accepted use as the name for the Mazon Creek tanaidacean (e.g., see Hay, 1997). The other alternative is leave things as they are now. This would involve going to the commission only if I (or someone else) believed a new family name was needed for the fossil remipede, since Cryptocarididae Sieg, 1980c is not available.
Consequently, the taxonomy of the fossil tanaidaceans as it now stands is given below.
ORDER TANAIDACEA Dana, 1849
SUBORDER ANTHRACOCARIDOMORPHA Sieg, 1980c
FAMILY ANTHRACOCARIDIDAE Schram, 1979
FAMILY NIVEOTANAIDAE Polz, 2005
SUBORDER APSEUDOMORPHA Sieg, 1980c
SUPERFAMILY CRETITANAOIDEA Schram et al., 1986
FAMILY CRETITANAIDAE Schram et al., 1986
SUPERFAMILY JURAPSEUDOIDEA Schram et al., 1986
FAMILY JURAPSEUDIDAE Schram et al., 1986
SUBORDER TANAIDOMORPHA Sieg, 1980c
FAMILY ALAVATANAIDAE Vonk & Schram, 2007
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