122 
Psyche 
[March 
4-1 1 are hardly longer than quadrate and those more like M. theridii 
in which the third segment is fully twice as long as broad and the 
remaining segments are also clearly longer than broad. 
In the present group three species have been described and I 
know of no others. These are M. wagneri du Buysson, 1907, de- 
scribed from near Tijuca, State of Guanabara, Brazil; M. guianae 
Rohwer, 1923, (= hingstoni Richards, 1932) from Guyana (not 
British Columbia as stated by Rohwer) and M. myersi Turner, 1927, 
from Trinidad. M. wagneri has the apical portion of the clypeus 
considerably produced, a little upturned, and separated from the 
proximal part by a shallow depression. The mesoscutum is finely 
rugose. In color it is brownish-black, with head, pronotum, meso- 
scutum and metanotum reddish, legs testaceous. The nest is said to 
resemble that of M. theridii. M. guianae is testaceous with a few 
brown markings. The mesoscutum is clathrately sculptured. The 
nest is made of fibre and rotten wood with a pedicel 6 cm long. 
M. myersi is a brown species and the metanotum is hardly convex. 
The mesoscutum is smooth. The nest is said to resemble that of 
M. theridii but to include some small mud pellets. 
Biological Notes 
Nest Construction. In the same Costa Rican rain forests 1 where 
Microstigmus comes occurs so abundantly, the two nests of M. 
thripoctenus were obtained at heights of 4 and 7 feet above ground. 
One was found hanging beneath a palm frond tentatively identified 
as being of the genus Geonoma, and the other was suspended from 
the 12 cm long leaf of an unidentified vine. Both nests hung firmly 
from the approximate center of the leaf midrib (Fig. 1). Their 
pedicels, measuring 22 mm (Janzen nest) and 45 mm (Andrews 
nest) in length, increased in thickness toward the nest proper, from 
0.2 mm in diameter at the point of attachment to 0.8- 1.0 mm just 
above the nest entrance. 
At first glance, both nest bags appeared somewhat like greyish 
shriveled pears, but close examination revealed 5 distinct pouch-like 
lobes about the periphery of the lower half of each. One nest bag 
proper measured 11 mm long by 10 mm at greatest width (Janzen) ; 
the other was 12 mm long by 7 mm at its widest point (Andrews). 
The nest entrance, situated to one side of the pedicel attachment, 
was shielded in both nests by a distinctly protuberant hood-like over- 
hang. Such a hood is never present in M. co?nes nests. 
'See Matthews, 1968b, for a more nearly complete habitat description. 
