162 
PACIFIC SCIENCE, Vol. XII, April, 1958 
The first species, S. quadrispinosus , was repre- 
sented in the Siboga collections by three ma- 
ture and two immature specimens; the second, 
S. quadridens , by a sole ovigerous specimen 
lacking the large chela. 
In this collection there is a single pair of 
specimens in good shape (although the male 
is lacking the small chela) which exhibits a 
perplexing confusion of the supposedly dis- 
tinguishing characteristics of the two species 
as separated by de Man. 
Rostrum and orbital hoods : Both specimens 
are very similar to S. quadridens , with the 
orbital teeth heavy and inflated. 
Antennular peduncles : In both specimens the 
antennular peduncle is assymetrically devel- 
oped, with the total lengths of the peduncles 
approximately the same, but with the basal 
article of one about 1.3 times the length of 
the other; however, in general appearance the 
articles are slender as reported for S. quadri- 
spinosus. The stylocerite, to the contrary, is 
shorter and heavier like that of S . quadridens. 
Antennae: In the male the scaphocerite is 
shorter than that of S. quadrispinosus (which 
had the shorter scaphocerite of the two spe- 
cies), while in the female it is longer than 
S . quadridens. The carpocerite is shorter in the 
male than S. quadridens (which had the shorter 
carpocerite), while in the female the article is 
long as in S. quadrispinosus. 
Large chela: In S. quadrispinosus , the only 
species with the large chela described, the 
chela had a breadth of 0.34 its length, the 
fingers occupied the distal 0.27 of the length 
(recalculated from de Man), and there was a 
rounded-to-acute tooth above the dactylar 
articulation. In both of these specimens the 
proportions are exactly the same, with the 
breadth 0.25 the length, and with the fingers 
occupying the distal 0.26 the entire length of 
the chela. In the male the tooth above the 
the dactylar articulation is heavy and very 
conspicuous; in the female it is less pro- 
nounced and more gradually rounded. 
Small chela: This is present only in the fe- 
male, where the carpus equals 0.33 the length 
of the chela; the chela is 3 times as long as 
broad, with the fingers occupying the distal 
0.4. These proportions are close to those of 
S. quadrispinosus , but not exactly the same. 
Third leg: In the merus, where the greatest 
differentiation occurs, the male is 3 times as 
long as broad, like S. quadridens , and the fe- 
male is 3.8 times as long as broad, like S. 
quadrispinosus. 
Sixth abdominal segment: In the male the 
lateral teeth are narrow and acute like S. 
quadrispinosus , while in the female they are 
broader and more rounded like S. quadridens. 
Telson: The proportions are given in the 
table below: 
S. quadri- S, 
MALE 
Length/breadth 1.3 
at base 
FEMALE 
1.3 
spin os us 
1.5* 
quadridens 
1.4* 
Breadth at base ^ 
Breadth at tip 
2.0 
2. 1-2.2 
2.0 
Length/breadth 2.3 
2.5 
3. 2-3.4 
2.8 
at tip 
(*Ratios calculated from other 
ratios.) 
From this it can be seen that the telson 
most closely approached that described for 
S. quadridens. 
In summation, the specimens at hand are 
quite similar to S. quadridens in five character- 
istics, and to S. quadrispinosus in five other 
characteristics. Even if these were not a co- 
habiting pair — which they probably were, 
considering that they were collected together 
— their essential similarities would not permit 
them to be considered as other than a single 
species. Their similarities to both S. quadri- 
spinosus and S. quadridens should establish their 
close relationship to both of de Man’s species 
and their variable and inconsistent differences 
with both of de Man’s nominal species de- 
stroys the validity of de Man’s criteria for 
separation of the two forms. The only con- 
clusion that may be drawn logically is that 
S. quadridens is a synonym (by page priority 
in the original description) for S. quadrispino- 
sus and that S. quadridens is a variable species. 
