156 
Psyche 
[June 
Genus P arelectrentomum Roesler 
Parelectrentomum Roesler, 1940. Zool. Anz. 129:228. 
Diagnosis. — Differing from Electrentomum according to original 
description, by presence of first segment of Rs in hindwing, and rela- 
tively larger medial stem compared to medial branches in forewing. 
Type species. — P. prescum Roesler (Baltic amber). 
Phylogenetic relationships of the electrentomoid psocids 
Hennig (1966) has stressed the predictive value of phylogenetic 
classification and has emphasized that only apomorphous (derived) 
characters may be used for setting out monophyletic groups, while 
plesiomorphous (primitive) characters are useless for this purpose. 
Phylogenetic problems of two sorts (taxonomic levels) are con- 
sidered in this section. First, what are the phylogenetic relationships 
of the Electrentomoid families to other families of Psocoptera? 
Secondly, what are the phylogenetic relationships among the genera 
within the Family Troctopsocidae ? 
Enderlein (1911) placed Electrentomum as the sole representative 
of one branch of a basal dichotomy of the family Amphientomidae. 
Roesler (1944) recognized a distinct family Plaumanniidae for his 
genus Plaumannia { — Troctopsocus) and within the Amphiento- 
midae recognized a subfamily Electrentominae for Electrentomum 
and P arelectrentomum and a subfamily Compsocinae for Compsocus. 
The remainder of the Amphientomidae were placed in two sub- 
families, Amphientominae and Tineomorphinae. 
Pearman (1936) set up a group Amphientometae which would 
encompass the taxa mentioned above. 
We must decide first whether or not the Amphientometae is a 
phylogenetocally valid taxon, i.e. can it be characterized by at least 
a few apomorphous traits? 
The group Amphientometae may be diagnosed as follows (modified 
from Badonel, 1951): Adults with three tarsal segments, antennae 
with 15 segments, the flagellar segments annulated; labial palpi one- 
or two-segmented ; three, two, or no ocelli, well separated when 
present; forewings with pterostigma not thickened, with nodulus 
and second anal vein, and with apex rounded ; coxal organ reduced 
to the mirror. 
To this list may be added the following characters shared by a 
number of species of Amphientomidae with a number of species of 
electrentomoids, but not universal : Antennal socket sunk in a pit, the 
