142 
PACIFIC SCIENCE, Vol. XIV, April I960 
TABLE 2 
Variations in the Chelae of Athanas marshallensis Chace 
LEFT CHELA RIGHT CHELA 
SEX 
CARAPACE 
LENGTH 
2 y n g 
5' EL £ ^ 
to 3 T3 p 
( in proportion to palm ) 
Merus 1/b | 
i 
Palm 1/b 
p ^ o g 
D P-. *r cd 
'S 3 S 
h-j ^ C/5 
C/5 5/3 
( in proportion to palm ) 
Merus 1/b 
Palm 1/b 
9 
3.1 mm. 
0.6 
1.0 
1.0 
1.4 
4.0 
2.7 
0.5 
1.0 
1.1 
1.5 
3.7 
2.5 
$ 
3.5 mm. 
0.5 
1.0 
0.8 
1.2 
3.8 
3.0 
0.4 
1.0 
0.6 
1.2 
3.8 
3.6 
9 
3.6 mm. 
0.5 
1.0 
1.0 
1.4 
4.0 
3.4 
0.4 
1.0 
0.6 
1.2 
4.0 
3.3 
9 
3.7 mm. 
0.3 
1.0 
0.9 
1.3 
4.5 
3.5 
0.3 
1.0 
0.8 
1.3 
3.8 
2.8 
9 
4.5 mm. 
0.3 
1.0 
0.4 
1.0 
3.0 
3.0 
0.3 
1.0 
0.6 
1.1 
3.3 
3.7 
9 
4.6 mm. 
0.4 
1.0 
0.8 
1.4 
3.5 
3.1 
0.3 
1.0 
0.6 
1.2 
3.2 
3.4 
9 
5.2 mm. 
0.4 
1.0 
0.4 
1.1 
3.3 
3.1 
0.4 
1.0 
0.4 
0.9 
3.0 
3.2 
2 
4.3 mm. 
0.3 
1.0 
0.2 
0.9 
3.0 
2.7 
0.2 
1.0 
0.2 
0.9 
2.8 
3.0 
2 
4.6 mm. 
0.2 
1.0 
0.2 
0.9 
2.5 
3.0 
0.2 
1.0 
0.2 
0.9 
2.5 
3.0 
2 
5.3 mm. 
0.3 
1.0 
0.3 
1.0 
2.7 
2.3 
0.3 
1.0 
0.2 
0.9 
2.5 
3.2 
genus, it appears wiser to place A. sibogae in 
synonymy. 
Indeed, A. jedanensis may also be found to be 
a synonym. In this species the chief distinction, 
when the differences in the chelae are ruled out, 
is the absence of the infracorneal spine. If this 
is variable, as it is in A. areteformis, then there 
is but one species. However, as in this small 
collection no transitional forms were found, 
A. jedanensis has been retained. 
distribution: A. parvus has been reported 
from the type locality, in Indonesia, and from 
southern Japan; A. sibogae only from Indonesia. 
Specimens in the present collections came from 
various places on the reef flats in from 1 to 6 
feet of water and were largely from dead coral 
heads. There were seven specimens from Tonga, 
and four from Samoa. 
Athanas marshallensis Chace 
Fig. 2 
Athanas marshallensis Chace, 1955. Proc. U. S. 
Nat. Mus. 105(3349): 17-20, fig. 8. 
DISCUSSION: All the 11 specimens available 
were collected in a single narrow habitat at 
Eniwetok, Marshall Islands, under loose coral 
boulders resting on a sandy substrate in the in- 
tertidal zone where they were collected together 
with Alpheus strenuus Dana, Salmoneus tricris- 
tatus Banner, and S. sibogae (de Man). It is 
noteworthy that in similar habitats in other 
archipelagoes producing widespread A. strenuus 
this species was not collected; all specimens 
known have been collected solely from the 
northern Marshall Islands. 
In this series of specimens the usual changes 
in form of the chelae with size and sex are 
found. Table 2 gives the changes in proportion 
with size of all specimens collected; Figure 2 b-d 
shows the changes with growth in the female 
and the chela of a mature male for contrast. 
The proportions show that the chelae of the 
large male are quite symmetrical; it is possible 
that the chelae of very large females, larger than 
those represented in the collection, may also be- 
come symmetrical. 
The differences between this species and A. 
rhothionastes Banner are discussed under the 
latter species. This species may prove to be a 
synonym of A. esakii Kubo but at present the 
two forms appear to be distinct; this is discussed 
under A. esakii. 
DISTRIBUTION : As stated above all specimens 
of this .species have been collected from the 
northern Marshall Islands. 
Athanas rhothionastes sp. nov. 
Fig- 3 
TYPE SPECIMENS: Holotype, a 12 mm. (4.8 
mm. carapace length) ovigerous female; allo- 
type, a male of the same size; paratypes from 
the same locality, at end of surge channels, edge 
of reef front, leeward (western) side, Canton 
