Contributions to the Knowledge of the Alpheid Shrimp 
of the Pacific Ocean 
Part VI. Prionalpheus, a New Genus of the Alpheidae 1 
Albert H. Banner and Dora May Banner 2 
In the extensive collections of shrimp upon 
which this series of papers is based, there are 
three fragmentary specimens in which the mouth 
parts are entirely unlike those of any other 
genus of the family Alpheidae. These are of 
two species but, because of the fragmentary 
condition of the specimens, only one of the 
species is named. The specimens were collected 
in Fiji and the Society Islands while the senior 
author was there under a grant from the Bernice 
P. Bishop Museum, Honolulu. The study has 
been supported by grants from the National 
Science Foundation (NSF-G 1754 and NSF-G 
3863). 
Prionalpheus gen. nov. 
DIAGNOSIS: Body form usual, similar to Al- 
pheopsis; rostrum present and small; supra-, 
extra-, and infracorneal teeth lacking; anterior 
carapace projecting to cover corneas from dorsal 
and lateral view, flat, not inflated to form orbital 
hoods; antennules and antennae normal for fam- 
ily; mandibles without a trace of molar process, 
incisor process greatly expanded and consisting 
of five strong teeth, the most anterior tooth of 
left mandible developed as an awl-shaped proc- 
ess that slides within almost closed tube formed 
by corresponding portion of right mandible; 
maxillulae with middle lobe moderately or 
greatly expanded, inner lobe bearing strong 
spines; maxillae reduced in size, endites greatly 
reduced, palp present, scaphognathite relatively 
small and narrow; first maxilliped with endite 
large and rounded, endopod without apparent 
segmentation, exopod well developed but with- 
out any basal exite, epipodites present; second 
maxilliped with basal article of endopod ap- 
parently united with basipodite and large, next 
1 Contribution No. 132, Hawaii Marine Laboratory. 
Manuscript received November 1, 1958. 
2 Department of Zoology and Entomology, Univer- 
sity of Hawaii, Honolulu. 
article somewhat to greatly reduced, penultimate 
article not greatly expanded and ultimate article 
rounded in outline rather than short and later- 
ally expanded; third maxillipeds not markedly 
different from those of other genera; only one 
cheliped known, similar in form to those of 
Alp he op sis equalis Coutiere; second legs with 
carpus divided into three or four articles; fol- 
lowing legs slender, elongate with biunguiculate 
dactylus; pleura of sixth abdominal somite artic- 
ulated; telson and uropods normal; no anal 
tubercles; branchial formula apparently includ- 
ing five pleurobranchs, no arthrobranchs, and 
epipodites only on first and second maxilliped. 
TYPE SPECIES: Prionalpheus triarticulatus , 
described below. 
DISCUSSION: Even without both chelae of the 
first pair, there can be no doubt that this genus 
belongs to the family Alpheidae. This is shown 
by the development of the sole chela on the 
first walking legs and the chelate second legs 
with a multiarticulate carpus, by the whole body 
form, by the development of the carapace to 
cover the orbits of the eyes, by the development 
of the antennules and antennae, as well as by 
less important characteristics like the form of 
the third legs, the development of articulated 
pleura of the sixth abdominal segment, and the 
form of the telson and uropods. If it were not 
for the unique development of the mouth parts, 
these species would fall into the genus Al- 
pheopsis without modification of the generic 
description. 
However, no mouth parts like these have 
been described for any species of any genus of 
the family. In Coutiere’s thesis ( 1899 : 153 - 173 ) 
the mouth parts of the members of the family 
were shown to have little variation, with the 
possible exception of the third maxilliped. No 
subsequent publication has shown any greater 
differences in the inner mouth parts, although 
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