1945] 
Observations on Rhachiocrema 
109 
OBSERVATIONS ON THE SUBGENUS 
RHACHIOCREMA (HYMENOPTERA: FORMICID^) 
WITH THE DESCRIPTION OF A NEW 
SPECIES FROM BORNEO 
By Wm. S. Creighton 
Dept, of Biology, City College, C.C.N.Y. 
Of the several subgenera of Crematogaster perhaps the least 
known is Rhachiocrema. The species which belong to this sub- 
genus possess enormously developed epinotal spines. These 
arise from a relatively narrow thorax but project rearward at a 
very wide angle so that the distance between their tips exceeds 
the width of the head or gaster. Up to the present Rhachiocrema 
has been represented by only two species, wheeleri from the 
British Solomon Islands and paradoxa from New Guinea. This 
paper carries the description of a third species from Borneo. 
References to Rhachiocrema in the literature are scattered and 
brief. As far as can be determined it has been mentioned only 
three times since its original description. It is regrettable that 
two of these references contain serious factual errors. In one 
case the error has gone uncorrected for more than twenty years. 
This is not surprising in view of the rarity of the species in- 
volved. It has recently been my good fortune to receive a small 
collection of ants taken in New Guinea by Pvt. Howard Levy, 
Sn.C., a former City College student. This collection contained 
four species of Crematogaster, three of which have a bearing on 
the status of Rhachiocrema. A study of these specimens and a 
review of the literature both indicate that considerable clarifica- 
tion is needed in the case of this subgenus. 
Rhachiocrema was erected as a subgenus by Mann in 1919 
( 1 ) . Among the ants which he collected in the British Solomon 
Islands was a remarkable Crematogaster taken in the mountains 
on the island of Malaita. He described this insect as the species 
wheeleri and designated it as the type of the new subgenus 
Rhachiocrema. The only other member of the subgenus cited 
by Mann was paradoxa , a species from New Guinea which 
Emery had described in 1894 (2). In view of subsequent events 
