Genus Cerodontha Rondani 
Genus Nemorimyza Frey 
Dizygomyza , subgenus Nemorimyza Frey, 
1946: 42. Type of genus: Agromyza 
posticata Meigen (Europe). 
Nemorimyza Nowakowski, 1962: 97. 
Hendel (1931: 30) included the 
obviously isolated leaf-mining species 
posticata , together with the cambium- 
boring tree feeders (now Phytobia ) , in 
the subgenus Dendromyza of his genus 
Dizygomyza . Frey proposed the 
subgenus Nemorimyza and Nowakowski 
(1962) raised this to full generic 
rank on the basis of the distinctive 
genitalia of N. posticata . 
The single species in our area, N. 
posticata (Meigen), has foretibia with 
lateral bristle, lunule silvery, and 
abdomen in male with anterior tergites 
yellow. 
Synopsis. Frons matt black, narrow, 
equal to width of eye, not projecting 
above eye in profile; 2 strong reclin- 
ate ors, 2 incurved ori; lunule small, 
semicircular; gena narrow, 0.10 height 
of eye; all antennal segments black, 
3d ovoid; mesonotum with 3+0 dc, 
shining black; wing length from 2.7 mm 
in male to 3.3 mm in female, costa 
extending strongly to vein M 1+2; legs 
largely black, foreknee yellowish; 
squama and fringe silvery white; 
halter yellow; male genitalia with 
aedeagus as in figures 537, 538. 
Host/Early Stages. Aster , Baccharis , 
Erecht ites , Solidago , possibly other 
Asteraceae. Larva forming large 
blotch mine with conspicuous feeding 
lines (fig. 539); puparium reddish 
brown, posterior spiracles on conical 
projections, each with 3 bulbs. 
Distribution. Widespread, probably 
present in all States; Canada, Costa 
Rica, Europe, Japan. 
References. Frick, 1959: 377; 
Spencer, 1969a: 161; 1981: 162. 
Cerodontha Rondani, 1861: 10. Type of 
genus: Chlorops denticornis Panzer, 
1806 (Europe). 
Traditionally this genus has been 
restricted to species with the third 
antennal segment having a spine (fig. 
549) or at least conspicuously angulate 
(Spencer, 1976a: fig. 314) and only one 
pair of scutellar bristles. However, 
Nowakowski (1962: 102) noted the 
similarity in the male genitalia of 
many species included in different sub- 
genera of Dizygomyza by Hendel (1931) 
and in Phytobia by Frick (1952a, 1959) 
and in particular the presence within 
the epandrium of a characteristic 
hooked or L-shaped paired structure in 
all species (fig. 578). Furthermore, 
all species he studied had hosts 
exclusively in the Monocotyledoneae in 
the four families Cyperaceae, 
Iridaceae, Juncaceae, and Poaceae. 
Nowakowski therefore proposed including 
all such species in a single "natural 
genus," and then after reporting of 
further revisionary studies in 1967 
and 1972, he produced a comprehensive 
monograph of European species of 
Cerodontha in 1973. In this, seven 
subgenera were recognized, treated in 
phylogenetic order: Icteromyza , 
Cerodontha , Xenophytomyza , Poemyza , 
Phytagromyza , Butomomyza , and 
Dizygomyza . All these subgenera are 
represented in the United States and 
no subgenera have been added elsewhere 
subsequently. Nowakowski* s concept 
has been followed by Spencer (1969a, 
1976a, 1977d) and is accepted here, 
but the possibility of future 
splitting of the genus is briefly 
discussed in part 2, p. 272. 
Cerodontha is a cosmopolitan genus, 
with species known in Alaska (Spencer, 
1969a), Chile, Australia (Spencer, 
1977d) , and New Zealand (Spencer, 
1976b). Nowakowski (1973) recorded 76 
species in Europe. Forty-two species 
have now been identified in the United 
States, of which 21 were recorded in 
California (Spencer, 1981). Ten new 
species are described here; 1 new 
87 
