Comment on the proposed conservation of the usage of the generic name of Drosophila Fallén, 1823 (Insecta, Diptera)

The nomenclature of the genera related to Drosophila, as
used in recent taxonomic papers, is based on the paper of Sturtevant
(1942). However, Throckmorton (e.g. 1962) and subsequent authors
recognised that the taxonomic relationships within the group are partly
different and showed them on cladograms, without suggesting
nomenclatural changes. Now it is quite apparent that the conception of
Throckmorton is, in principle, correct and its modifications are
presently discussed. After forty seven years, time is now more than
mature to reflect the changes in the nomenclature. If the Commission
maintains Drosophila funebris (Fabricius, 1787) as type species of the genus Drosophila Fallén, there are two possibilities how to reflect the situation: 1. Sophophora Sturtevant,
1939 would be elevated to the rank of genus and consequently many
geneticists, physiologists, etc. would have to adopt the name Sophophora melanogaster for
their favourite research subject. 2. Alternatively, more than ten
currently independent genera would be connected with the genus Drosophila (see comment by P. Štys, BZN 65(2): 144). In this case, the currently independent genera Scaptomyza, with about fifteen subgenera, and probably Hypselothyrea, Phorticella and Zaprionus, with two subgenera each, would become part of the genus Drosophila. It is evident that the names of these genera, and/or their subgenera, could not then be used as genus-group names.

 On the other hand, accepting the proposition to use the name Drosophila s. s. for the genus based on D. melanogaster Meigen,1830 would also bring various constraints, as discussed in BZN 65(1) and 65(2). Apparently there is no perfect solution and I do not intend to anticipate the decision of the Commission. However, if D. melanogaster is to be accepted as type species of the genus Drosophila, the name of the present subgenus Drosophila (based on Musca funebris Fabricius, 1787) has to be changed at the same time. This nomenclatural act needs a comment.

 Apparently no suitable genus-group name, other than Drosophila, has ever been used for the present type species D. funebris. The only available name, Oinopota Kirby in Kirby and Spence, 1815, is based on Musca cellaris Linnaeus, 1758. Type material of M. cellaris does not exist. Although Meigen (1830) considered M. cellaris synonymous with M. funebris Fabricius, 1787, most subsequent authors have not accepted this synonymy and M. cellaris is considered a nomen nudum (e.g. Brake & Bächli, 2008). Moreover M. cellaris was not originally included in Drosophila and, in my opinion, cannot become the type species of the taxon currently known as Drosophila s.str.

 There are several genus-group names used for various subordinate taxa of the present genus Drosophila. The names Idiomyia Grimshaw, 1901 and Hypenomyia Grimshaw,
1901 should not be taken into consideration; they have been used for
endemic Hawaian species now considered by many authors, including Brake
& Bächli (2008), to belong to the genus Idiomyia Grimshaw,
although this arrangement is not unequivocally accepted. Consequently
the two names used by Duda, 1923 are the candidates. In the application
(BZN 64(4): 239), the name Chaetodrosophilella Duda, 1923 (p. 40) is suggested for the present subgenus Drosophila (anticipated there to be raised to the genus level). However, Chaetodrosophilella has been used as a valid name only once before, notably for the group based on, and including only, Drosophila quadrilineata de Meijere, 1911 from southeast Asia and Micronesia, and has already been replaced by Chaetodrosophila Duda,
1924a in his subsequent publication. Therefore I do not consider it
very suitable for a subgenus of several hundred species. The other
genus-group name used by Duda, 1923 (p. 47) is Spinulophila. Duda soon transferred to Spinulophila the common cosmopolitan species immigrans Sturtevant, 1921 (misidentified as ‘tripunctata Loew, 1862: Becker, 1908’ by Duda, 1924a, but recognized as ‘D. immigrans Sturtevant
?’ by Duda, 1924b), which is often used as an object of genetic,
physiological and ecological research, and the term ‘immigrans group’
has been commonly used for more than sixty years (Sturtevant, 1942) for
a group currently comprising almost 100 species. The ‘immigrans group’ is close to the ‘funebris group’ and all taxonomic treatments show that they are congeneric. Furthermore Spinulophila has been, from the very beginning, used for a group which is not monotypic.

 Other genus-group names used for subordinate taxa of the present Drosophila (Acrodrosophila Duda, 1924a, Spinodrosophila Duda, 1924a, Sordophila Wheeler,
1949, disregarding unjustified emendations) are younger. They are also
apparently disqualified because they represent groups of one to several
species limited to one of the zoogeographical regions (considering the
Holarctic region as a single unit). The same applies to the names
presently used for the other extant subgenera of Drosophila, which moreover represent taxa unrelated to Drosophila funebris.

In summary: if the name Drosophila were to be used for the genus based on D. melanogaster Meigen, 1830, I suggest giving the present subgenus Drosophila the name Spinulophila Duda, 1923 (although this name does not have page priority over Chaetodrosophilella Duda, 1923), mainly because Spinulophila originally
represents a well known group of numerous species, including one
cosmopolitan species and several others important for genetic research,
the group being clearly congeneric with D. funebris (Fabricius, 1787), type species of Drosophila.

Additional references

Brake, I. & Bächli, G. 2008. Drosophilidae (Diptera). World catalogue of insects, vol. 9. 412 pp. Apollo Books, Stenstrup. [including quotations of further relevant papers].

Duda, O. 1924a. Beitrag zur Systematik der
Drosophiliden unter besonderer Berücksichtigung der paläarktischen u.
orientalischen Arten (Dipteren). Wiegmann’s Archiv für Naturgeschichte (A), 90(3): 172–234.

Duda, O. 1924b. Revision der europäischen Arten der Gattung Drosophila Fallén (Dipt.). Entomologiske Meddelelser, 14: 246–313.

Grimshaw, P.H. 1901. Diptera. Pp. 1–92, pls.1–3 in Sharp, D. (Ed.), Fauna Hawaiiensis, 3(1). University Press, Cambridge.

Throckmorton, L.H. 1962. The problem of phylogeny in the genus Drosophila. The University of Texas Publication, 6205: 207–343.