Problems and possible difficulties in using this key.
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This is the first key that I am aware of in which the author has exhaustively listed the possible difficulties involved in using it. This is not to mean that these difficulties are permanent or insurmountable. It is hoped that greater knowledge and availability of material will gradually remove each of the problems listed here.
Pediobius has proven to be a difficult genus to characterize without leaving occasional exceptions. Hansson (2002) has made the most successful attempt at characterizing the genus, but I am aware of one series (Australian) that violates the definition.
Probably the first difficulty encountered by users of this key is in distinguishing Tetrastichines from other Eulophids. I have found it impossible to characterize Tetrastichines using universal or unique characters, or to even construct a simple logical formula or set of characters defining the group. Even the current solution, keying the subfamily to several different termini, is not entirely satisfactory because of the possibility of overlooked exceptions in every case. This problem will eventually be alleviated by keying Tetrastichines genus by genus (or genus-group) vs. the other subfamilies of Eulophidae, if no characters can be found to define the subfamily or divide it into significant groups.
Several Entedonine species constitute exceptions to the defining characters of the subfamily. These exceptions include species with numerous scutellar or submarginal vein setae. There is little I can do to alleviate this problem other than abolishing the use of subfamilies in this key, which is undesirable because it would probably reduce identification accuracy by adding complications difficult for the uninitiated to surmount. Fortunately, species violating both setal characters are not known from the Nearctic.
Certain Entedonine genera, namely Closterocerus, Omphale, and Perditorulus, are ultimately only identifiable once specimens have been slide-mounted, and even this sometimes works only for males. This problem is regrettable, but only partially avoidable. The other characters provided for distinguishing these genera are only reliable to a point, and any serious attempts at identification of these genera requires slide-mounting. With a certain level of expertise, species of these genera can be sight-identified without resorting to slide-mounting. This is only recommended for workers who know what they are doing. A key to genera constructed according to those principles would become large and unwieldy due to the vast number of species that would have to be dealt with, and even then it would be unsatisfactory due to the large number of undescribed species that would inevitably be encountered.
Achrysocharoides vs. Chrysocharis is a difficult couplet because no unique or universal character exists for either genus, other than the scutellar pits for Achrysocharoides. It is hoped that the set of characters provided can serve to separate the genera as accurately as possible. The best solution to this problem appears to be an effective gestalt for the two genera, and familiarity with species-groups. This may eventually be reflected in the key, but I know too little about exceptional species of these two genera to produce a satisfactory set of criteria regarding them.
Roger A. Burks
last updated: October 5, 2003