THE REDISCOVERY AND PROBABLE 
PHYLOGENETIC POSITION OF 
PSILOPSOCUS (PSOCOPTERA) 
By Edward L. Mockford 
Illinois State Normal University 
Normal, Illinois 
The genus Psilopsocus has posed a puzzle to students of the Psocop- 
tera since the time of its discovery. The original description by 
Enderlein (1903:305) was based on a single specimen. Although 
adequate for identification, this description does not permit the genus 
to be placed beyond suborder in recent classifications. Enderlein 
placed Psilopsocus in the Mesopsocidae, but gave no reasons for this. 
Roesler (1944), apparently without re-examining the type, erected 
a new family for this genus and placed it in the group Epipsocetae on 
the basis of similarity of the lacinia in the Epipsocidae and Psilopso- 
cidae. 
It is the purpose of this paper to describe a new species of Psilopsocus 
from the Philippine Islands, to add to the knowledge of the morph- 
ology of the genus, and to re-interpret its phylogenetic position. 
Genus Psilopsocus Enderlein, 1903. 
In addition to the characters included by Enderlein in the original 
description, the following characters are probably important in 
delimiting this genus: 
1. Male phallic sclerotizations in the form of a simple frame with 
no indication of external parameres (fig. 2.). 
2. Ovipositor valvulae complete, i.e. three pairs. 
3. Female subgenital plate with a slender central process (fig. 1.). 
4. Female paraproct with a decided elongation of the posterior 
margin (fig. 3.). 
5. Male paraproct with a pointed apical process on its posterior 
margin (fig. 8.). 
6. Labrum not of the Epipsocus type, lacking a pair of diagonal 
strap-like sclerites. 
The character mentioned by Enderlein of lack of junction of the 
Explanation of Plate 5 
Psilopsocus nebulosus n. sp. Fig. 1, $, subgenital plate. Fig.2, $, hypandri- 
um and phallic frame. Fig. 3, $, left paraproct. Fig. 4, 9, sclerites of 9th 
abdominal sternite (dorsal view). Fig. 5, 9, ovipositor valvulae. Fig. 6, $, 
lacinial tip. Fig. 7, $, tarsal claw. Fig. 8, $, right paraproct. Fig. 9, $, 
tip of pedicel (Ped.) and base of first flagellar segment (fl). 
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