Alpheid Shrimp, V — Banner and Banner 
At h anas dubius Banner, 1956. Pacif. Sci. 10(3): 
323, fig. 2a— h. 
DISCUSSION: These four nominal species were 
all described on the basis of a few specimens, 
as listed in the introduction: Coutiere had two 
females, one incomplete, for A. naifaroensis; 
one complete male and one incomplete female 
for A. areteformis; Ramadan had one female for 
A. erythraeus; I had nine specimens from Sai- 
pan. Since the original description several more 
specimens have been reported for A. areteformis 
(Chace, 1955: 21; Balss, 1915: 30) and for 
A. naifaroensis (de Man, 1922: 16; Barnard, 
1950: 731) and no more specimens have been 
reported for A. erythraeus. 
The four species were separated by various 
characteristics. A. naifaroensis differed from A. 
areteformis seemingly only in the presence of 
infracorneal spines (the chela of the male had 
never been observed ) . For his species, Ramadan 
listed a number of differences that would dis- 
tinguish it from A. areteformis: 1. The visible 
portion of the first article of the antennular 
peduncle he stated was considerably longer than 
the sum of the other two in A. areteformis and 
about equal to the sum in A. erythraeus. Ap- 
parently this is in error, for Coutiere does not 
state or show such a relationship, and in speci- 
mens that are plainly A. areteformis the relation- 
ship is as it is described for A. erythraeus. 2. The 
lateral corneal spine "is not as well developed" 
in A. erythraeus as in A. areteformis. 3. The 
chela of the female in A. erythraeus is like that 
of the male A. areteformis (although Ramadans 
plate does not show this condition); the dactyl 
and fixed finger had low teeth. 
A. dubius was distinguished from A. arete- 
formis principally by the forms of the male and 
female chelae with the fingers on the male being 
slender and straight more like the female A. 
areteformis, and the palm on the female being 
broader; also the ischium on the male and 
female carried spines which apparently were 
lacking in the female A. areteformis. 
In the present collections there are 25 speci- 
mens that can be referred to this complex; 
unfortunately, many of them are small or in- 
complete. 
These specimens are found to be variable in 
all characteristics that have been used for the 
139 
separation of these species. The rostrum reaches 
from near the end of the second antennular 
article to the middle of the third; in some the 
basal portion has parallel sides, in others the 
rostrum has an almost uniform taper to the tip. 
The supracorneal teeth are well developed and 
acute in some, while in others they are shorter 
and more rounded, like the condition depicted 
for A. dubius; the cleavage between the base of 
the rostrum and supracorneal spines also varies 
in depth and definition. All but five specimens 
lack the infracorneal tooth; however, on these 
five the tooth varies from considerably smaller 
to larger than that depicted for A. naifaroensis. 
In the collection are three specimens from Tonga 
from the same location, two without teeth and 
the third carrying a small but definite tooth. 
Similar variations can be seen in the length 
ratios of the antennular articles, and at least 
within narrow limits, in the development of the 
lateral spine of the scaphocerite. 
In the series many of the specimens lack the 
chelae. The females all show the type illustrated 
for A. naifaroensis and A. dubius. In this ap- 
pendage the merus varies from 2.5 to 3.3 times 
as long as broad, with the two sides showing 
asymmetry and the larger specimens in general 
with the higher ratios; the length-breadth ratio 
of the carpus runs from 0.7 to 1.1; the palm, 
2.0 to 2.7; the palm varies from 1.3 to 1.8 times 
the length of the fingers. All specimens have 
from three to five spines on the ischium. One 
female of 3.3 mm. carapace length had slight 
teeth on the dactylus, similar to those described 
by Ramadan. 
Of the males all specimens but one also had 
a chela as described for A. dubius and female of 
A. areteformis with a slender merus, with the 
length from 1.6 to 3.0 times the breadth; the 
carpus somewhat elongate, 0.8 to 1.0 times as 
long as broad; the palm from 1.4 to 2.6 times as 
long as broad, and the palm 1.4 to 1.8 times the 
length of the fingers. However, the largest of all 
males, with a carapace length of 3.2 mm. had 
the form described for the male A. areteformis, 
with short curved fingers, a heavy cylindrical 
palm 3.3 times the length of the fingers. This 
specimen came from the same collection (BE-11) 
as did two larger females and a small male 
(carapace length of 2.2 mm.) with a typically 
