NOTES ON ALASKAN COLLEMBOLA 
I. A NEW GENUS AND SPECIES OF 
THE FAMILY ISOTOMIDAE 1 
By Kenneth A. Christiansen 
Biological Laboratories, Harvard University 
This is the first in a series of papers on the Collembola 
fauna of northern Alaska. The material on which this paper 
is based was collected by Dr. Neal A. Weber while holding 
a contract with the Office of Naval Research and while sta- 
tioned in the Alaskan Arctic under the support of the Arctic 
Research Laboratory. 
I wish to thank Dr. Marie Hammer and Dr. Harlow B. 
Mills for their helpful suggestions concerning this work. 
Weberacantha, n. gen. 
Anurophorini, facies superficially proisotomid. Body 
somewhat elongate. Head prognathous, slightly narrower 
than second thoracic segment; antennae four-jointed, fourth 
joint about twice as long as third and slightly swollen, with- 
out retractile apical bulb, and with well-developed blunt 
olfactory setae ; eyes eight on each side on a pigmented field ; 
P.A.O. elongate, elliptical, with flap-like margins. 
First thoracic segment reduced, not imbricate. All other 
body segments clearly imbricate. No marked ankylosis of 
of abdominal segments. Sometimes division between fifth 
and sixth segments obscure; all other intersegmental mem- 
branes clearly visible. Fourth abdominal segment distinctly 
longer than third, and longer than fifth and sixth taken to- 
gether. Sixth abdominal segment downwardly skewed from 
fifth, and almost completely hidden by the latter when viewed 
from above. Fifth abdominal segment dorsally with a num- 
ber of short stout spines. Anus ventrally directed. Furcula 
1 Published with a grant from the Museum of Comparative Zoology 
at Harvard College. 
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