PsylHdae of New Zealand — Tuthill 
85 
collecting in the northern section was rather 
too early in the season, and, on two of the 
three expeditions which I made into this area, 
the weather turned very bad; thus the repre- 
sentation from this area is rather poor. I am 
confident, therefore, that the number of 
species yet to be discovered in this area is 
quite large, especially as many of the plants 
which are restricted to this area are members 
of families or genera which are common hosts 
to psyllids elsewhere. The representation from 
the area south of this line is probably much 
better proportionately. Enough material was 
obtained there to indicate a large probable 
population on several groups of plants which 
are abundant in species and of which only a 
small percentage was examined. Olearia and 
Senecio are of particular interest in this regard. 
It appears that there are at least two distinct, 
parallel, evolutionary lines of psyllids on these 
plants and that they show a high degree of 
speciation and host specificity. One of these 
lines is represented by Trioza subacuta, T. 
doryphora, and T. subvexa, the other by T. 
crinita and T. scobina. As there are more than 
80 species of plants belonging to these and 
related genera of Compositae in New Zea- 
land, and as the majority of the 8 or 10 
species which were examined yielded more 
than one species of psyllid, it seems probable 
that the psyllid fauna associated with this 
group is very large. It is certainly one of the 
most interesting from an evolutionary stand- 
point. 
In the collecting, several remarkable ex- 
amples of localization of infestations were en- 
countered. The most extreme instance was 
that of Trioza hebicola, which was found on 
Hebe salicifolia at only one spot, although the 
host plant, which is very common through- 
out New Zealand, was examined throughout 
the season both before and after finding this 
one infestation. 
Another instance of localized distribution 
is that of Anomalopsylla insignita n.g., n.sp., 
which was taken on Shawia paniculata at one 
spot near Nelson and obtained nowhere else. 
As this is one of the most common hedge 
plants in the country, it seems probable that 
this psyllid is permanently limited, ecologi- 
cally, to such seaside areas as are little noticed. 
Just what the factors are which produce such 
localization is impossible to say until much 
more careful collecting has been done; 
theorizing at present would be futile although 
tempting. 
No parasitized specimens of native species 
were noticed, but parasitized nymphs of some 
of the Acacia-mhdihitmg Psylla were seen. 
Predators of three groups were quite active 
throughout the country, the larvae of Coc- 
cinellidae, Hemerobiidae, and Syrphidae be- 
ing common on infested plants. However, 
only one specimen of adult syrphid was ob- 
tained by rearing. The nomadic nature of my 
summer season largely precluded successful 
rearing of these voracious predators. 
The relationship of the fauna of New Zea- 
land to those of other parts of the world is of 
great interest, largely because of the relative 
present-day isolation of the islands. A few 
definite statements can be made now as re- 
gards the psyllid fauna. First, as has been 
mentioned previously by Heslop-Harrison 
(1949^), Ferris and Klyver were in error in 
stating that "There is no reason to suppose 
that any of them [the species they list from 
New Zealand] are introduced forms. . . 
Actually there is no doubt whatsoever that 
four of the five species which they assigned 
to Psyllia \Psylld\ and one of their species of 
Ctenarytaina are introduced from Australia. 
These species of Psylla have recently been 
placed in a separate genus by Heslop- 
Harrison, together with several Australian 
species and one from India. In my opinion, 
although these species form a natural group, 
it is one which properly constitutes a sub- 
genus. The remaining species assigned to 
Psylla by Ferris and Klyver (P. apicalis) and a 
new related species are of more doubtful 
affinities but are left in Psylla for the time 
being. 
The genus Ctenarytaina, however, shows a 
