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>There is for example a publication of 1901, in which a new genus is described, consisting of two species. The first issue concerns the type species (I'll call it here 'Species 1'). In its description, twelve specimens are mentioned and each briefly described. These specimens are however a heterogenous assembly of two different species with clearly different morphological traits.<
This type of problem is addressed by choosing a lectotype. By designating one of the twelve specimens as the type specimen, you will stabilize the concept of the species and of the genus.
The difficulty comes in chosing which specimen to designate. If no one has done much work on either species in the type lot, and there is little use of the genus name, then it does not matter much. If the genus has been used for one of the forms, it would promote stability to designate a lectotype in agreement with conventional usage. Likewise, you can promote stability if a younger genus or species name is in current use for one of the species by designating a representative of the other species as the lectotype. Conversely, if one of the species seems readily assigned to an existing, older genus and you think that the name deserves oblivion, you could designate a lectotype that would make the name a subjective junior synonym.
It is important to explicitly state that you are selecting a lectotype. Vague statements, especially in literature that pre-dates the standardization of rules, lead to confusion-is the author just expressing his opinion of how the name ought to be applied, or is he trying to formally designate a particular specimen as the type?
Another source of confusion comes from statements in the genus description. Some people have argued that, for genera with no type species designated, that if one species seems clearly to have played a major role in the creation of the generic description, then it is the type. However, I believe that this is incorrect and designation of a type species remains necessary. Hopefully, the designation will reflect such indications in the generic description, but sometimes it has not. For example, Campanile as originally described included both the giant Eocene gastropod species and the modern Australian species. The genus description mentioned soft part features, not known for the fossil taxa. However, the earliest designation of a type species that I know of selected the Eocene one. Thus, if the original description of the genus ephasized features of one of the two species included in the original type series, it would be a good idea to select that one as a lectotype.
The fact that an additional species, probably not congeneric, was included under the genus name does not affect its status. As long as a genus name can be unambiguously tied to a particular species that does not have an earlier name assigned to it, the genus is nomenclaturally valid.
Dr. David Campbell
Old Seashells
University of Alabama
Biodiversity & Systematics
Dept. Biological Sciences
Box 870345
Tuscaloosa, AL 35487-0345 USA
bivalve@mail.davidson.alumlink.com
That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa
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