1969] Thompson — Microdontine Flies 79 
Microdontinae, not to the Cheilosinae as supposed by its author 
(Keiser, 1958). 
Since Rondani (1856-57) first divided the Syrphidae into super- 
generic groups, most authors have accepted the Microdontinae as a 
distinct and separate group. However, Williston (1886), Goffe 
(1952), and Wirth et al (1965) have treated it as a tribe in one or 
another subfamily. Williston placed the “tribe” Microdontini in the 
Syrphinae, and Goffe and Wirth et al have placed it in the Milesinae 
(Sphixinae Goffe). The relative ranking of a group depends on its 
position in the phylogeny of the whole group, so when one finds a 
group given two different rankings by different workers one expects 
to find differences in their phylogenies of the group. This is the case 
with the Microdontinae. Hull (1949) has placed the Microdontinae 
with the Eumerinae and Nausigasterinae in his first phylogenetic 
dichotomy of the Syrphidae; whereas Goffe (1952) considers the 
microdontines to have diverged long after the Syrphinae. 
These different views of the phylogeny of the Syrphidae can best 
be illustrated and compared by Hennig-type diagrams. The follow- 
ing diagrams (see text figure) illustrate the interpretations of Goffe 
(1952), Wirth et al (1965), and myself; I follow Hull (1949) 
except that I exclude the Eumerinae and Nausigasterinae from the 
Microdon line. Plan 1, my arrangement, clearly indicates that the 
Microdontinae should be considered the first divergence in the phylo- 
geny of the family. Only one character state (#8) could be used 
to place the microdontine divergence second. If the reduction of 
preabdominal segments in the male (character #8) is not convergent 
in the Microdontinae and Pipizini, then the Microdontinae would 
have to be considered to have arisen after the Syrphinae (Plan 2). 
Plan 2 explains Goffe’s (1952) groupings. However, it is difficult 
to follow Goffe’s “phylogenetic reasoning”, which seems inconsistent 
with the modern “synthetic” theory of evolution and systematics. 
This plan creates more convergences than it solves. It seems to me 
more logical to consider the reduction of a character — » in this case 
reduction of the abdominal segments in the male — as due to con- 
vergence than to suppose the development of a highly complex char- 
acter such as aphidophagous larvae to be convergent. 
Fig. 7, lateral view of male genitalia with axial system removed; 7a, 
lateral view of penis sheath and axial system; 8, ejaculatory apodeme and 
sac; 9-10, dorsal view of abdomen. Fig. 7, Paragodon paragoides, n. sp. 
(HT) ; 8. Microdon (C erioimicrodon) petiolatus Hull (HT) ; 9, Paragodon 
par ago des, n. sp. (HT) ; 10, Paragodon minutula van Doesburg (after 
van Doesburg, 1966). 
