oct. 4, 1923 ROHWER: NEW PEMPHREDONINE WASPS 369 
funicles, nearly 2 mm. in diameter, black, lustrous, with a metallic and 
iridescent sheen. 
Type in the U. 8. National Herbarium, no. 1,135,662, collected in a moisti 
wooded ravine in the mountains near Ahuachapan, Salvador, altitude about 
1000 meters, January, 1922, by Paul C. Standley (no. 19782). Also collected 
in the region of Finca Colima, Sierra de Apaneca, Departamento de 
Ahuachapain, Standley 20074. 
Two other species of Plewropetalum are known from Central America, 
P. sprucei (Hook. f.) Standl., which ranges from Veracruz to Ecuador, and 
P. pleiogynum (Kuntze) Standl. (Celosia plerogyna Kuntze, Rev. Gen. PI. 
541. 1891). In the North American Flora’ the latter was referred to the 
genus Celosia, but further study of the material indicates that it is really a 
species of Pleuropetalum. 
Pleuropetalum calospermum has sepals of about the same size as those of 
P. pleiogynum, but in the latter the seeds are half as large, much more numer- 
ous, and on slender funicles. From P. spruce the Salvadorean plant is 
distinguished by its much larger sepals and capsules. | 
ENTOMOLOGY.—Three new Pemphredonine wasps (Hymenoptera). 
S. A. Rouwer, Bureau of Entomology. 
Two of the species described below have been recently received 
from correspondents who are anxious to use the specific name in 
connection with some observations on habits of the species. 
Microstigmus guianensis, new species. 
This species seems to be very close to M. theridii Ducke, which has been 
recorded from French Guiana by Buysson,! but it does not agree with the 
description in all ways, especially in the sculpture of the mesoscutum. 
Female.—Length 2.5 mm. Clypeus gently convex, the anterior margin 
broadly and gradually rounded; interocular quadrangle somewhat higher 
than broad; head shining, polished; the ocelli in an acute triangle; flagellum 
slightly thickening apically, the first joint distinctly longer than the second, 
which is slightly longer than the third; dorsal surface of the pronotum polished, 
the anterior margin with a sharp carina; mesoscutum coarsely reticulate, the 
posterior margin with a transverse carina; the scutellum with four strong 
carinae which meet medianly and form a transverse pyramid, the posterior 
face of which has a triangular shaped area bounded by striae; posterior 
margin of the scutellum with a strong, high carina; dorsal area of the propo- 
deum irregularly reticulate on a granular surface, the margin bounded by a 
U-shaped carina; mesepisternum granular and with a few irregular raised 
lines; sides of the propodeum with a few oblique striae; posterior face of the 
propodeum with coarse reticulations; petiole short, carinate laterally ; abdomen 
polished; stigma oval, its greatest width slightly longer than the first abscissa 
of the radius. Head rufo-ferrugineous; clypeus, mandibles and lower part of 
face stramineous; thorax, legs and petiole stramineous; the top of the scutellar 
$21:98. 1917. 
1Ann. Soc. Ent. France, 76:29. 1907. 
