VALIDITY OF THE SPECIES NAME TRIPODUS LAEVIS BRADSHAW, 1969

                     

        Stig M. Bergström1 and Guillermo L. Albanesi2

 

1 Department of Geological Sciences, The Ohio State University, 155 S. Oval Mall, Columbus, OH 43210, USA <stig@geology.ohio-state.edu>

2 CONICET (UNC – Argentina), Ibidem 1 <galbanesi@arnet.com.ar>

 

The conodont Tripodus laevis Bradshaw, 1969 has figured prominently in the ongoing discussion of the definition of the base of the global Middle Ordovician Series (Webby 1998) and the FAD of this species (referred to as T. combsi Bradshaw, 1969) in the Whiterock Narrows section, Monitor Range, Nevada has recently been proposed as GSSP for the base of this series (see proposal in the Ordovician Stratigraphy Discussion Group Web site). The names T. combsi and T. laevis have been used in several recent contributions for the same multielement conodont species, and the fact that different authors use a different species designation for the same biozonal index species is likely to cause confusion not only among non-conodont workers. The purpose of this communication is to clarify that based on the latest edition (1999) of the International Code of Zoological Nomenclature (1999), T. laevis is the only valid name of this species. The pertinent facts are as follows.

 

1. Tripodus laevis and Acodus combsi were both described in the same paper by Bradshaw (1969) based on specimens from the Fort Peña Formation of the Marathon area, Texas. She used single-element taxonomy.

 

2. Based on collections from the Ibex area, Utah, Ethington and Clark (1981, p. 110-112) recognized that Bradshaw’s (1969) T. laevis and Scolopodus alatus described by her in the same paper belong to the same conodont apparatus. They also included a previously undescribed and unnamed oistodiform element in the multielement apparatus and the complete apparatus was described as including paltodiform, drepanodiform, distacodiform, trichonodelliform, and oistodiform elements. In their multielement revision of this species, they picked the name T. laevis. In doing so, not only did they suppress S. alatus to the status of a junior synonym of T. laevis but also, and this is important, as First Reviser(s), they established that the proper name of the species with this multielement apparatus is T. laevis. According to ICZN Article 24.2.1 “When the precedence between names or nomenclatural acts cannot be objectively determined, the precedence is fixed by the action of the first author citing in a published work those names or acts and selecting from them; this author is termed the “First Reviser”. Further, ICZN Article 24.2.2. states that “If two or more names, different or identical, and based on the same or different species, or two or more nomenclatural acts, are published on the same date in the same or different works, the precedence of the names is fixed by the First Reviser…” Also, it should be mentioned that ICZN Article 23.6  states that “In accordance with the Principle of Priority the first nomenclatural act taken in respect of a name or a nominal taxon to achieve any of the following constitutes the only valid such act: i.e., acts taken under the First Reviser Principle [Art. 24.2]…”.

 

3. Apparently unaware of the actions taken in the monograph by Ethington and Clark (1981), Stouge (1984, p. 76) described the same species in multielement taxonomy based on material from western Newfoundland.  He used the name Acodus combsi Bradshaw, 1969 and listed Bradshaw’s (1969) T. laevis and Scolopodus alatus in his synonymy list.

Furthermore, he stated “Acodus combsi s.f. is the prioniodontiform, Scolopodus alatus Bradshaw s.f. is the trichonodelliform, and Tripodus laevis s.f. is the tetraprioniodontiform.” Hence it is quite obvious that Stouge (1984) was dealing with the same multielement species as Ethington and Clark (1981).  Apart from the inclusion of the prioniodontiform element in the apparatus, Stouge’s concept of the species is closely similar to that of Ethington and Clark (1981). Because Ethington and Clark (1981) as First Revisers established the species name of this taxon, Stouge’s use of the designation T. combsi is taxonomically incorrect (ICZN Art. 24.2), and this name has become a junior synonym of T. laevis.  It should be noted that Stouge’s inclusion of an additional element in the apparatus clearly cannot change the species name established on the First Reviser principle. We conclude that following the most recent edition of ICZN, the only valid name for this species is T. laevis. This name can be changed only if it becomes clear that somewhere in the world, one of the elements in its apparatus has been described earlier than Bradshaw’s1969 paper, or if can be established that T. laevis is a homonym of another Tripodus species, which is most unlikely.

 

References

 

Bradshaw, L. E. 1969. Conodonts from the Fort Peña Formation (Middle Ordovician), Marathon Basin, Texas. Journal of Paleontology, v. 43, 1137- 1168.

Ethington, R. L. and Clark, D. L. 1981. Lower and Middle Ordovician conodonts from the Ibex area, western Millard County, Utah. Brigham Young University Geology Studies, v. 28(2), 160 pp.

Stouge, S. S. 1984. Conodonts of the Middle Ordovician Table Head Formation, western Newfoundland. Fossil and Strata, v. 16, 145 pp.

Webby, B. 1998. Steps toward a global standard for Ordovician stratigraphy. Newsletter on Stratigraphy, v. 36(1), p.1-33.