Aoridae from the Hancock Expedition — Myers 
505 
Fig. 6. Microdeutopus hancocki sp. nov. salinas 
bay, costa rica. $ Paratype: a, head. 
Microdeutopus trichopus sp. nov. isabela island, 
Galapagos. $ Paratype: b, head. 
Neomegamphopus roosevelti Shoemaker 
Shoemaker, C R. 1942. Smithson. Misc. 
Coll. 101 (11) : 36 — 38, fig. 13. 
Myers, A. A. 1968. Crustaceana 14(2) : 127— 
130 . 
Fig. 5 a-c, f 
identification: Specimens agree well with 
Shoemaker’s (1942) description, but the first 
male peraeopod (Fig. 5 a-c, /) exhibits great 
plasticity of form, with the carpopodite tooth 
arising distally or, as in some very large speci- 
mens, from midway along the posterior margin. 
Intermediates occur according to size, suggesting 
that in some, but not all, specimens the relative 
position of the tooth varies according to the 
stage of development of the animal. The pro- 
popodite also varies; in some specimens it is 
broad with the posterior margin convex, in 
others it is narrow with the posterior margin 
concave. 
distribution: N. roosevelti is in this study 
shown to be widely distributed along the Pacific 
coasts of the Americas, in Mexico (Isabel 
Island), Costa Rica (Playa Blanca and Salinas 
Bay), Panama (Bahia Honda), and Galapagos 
(Espanola) . The species reaches its most north- 
erly point of distribution in the Pacific in the 
type locality (Magdalena Bay, Baja California) 
(Shoemaker, 1942). It is also known from the 
Atlantic, off the coasts of Venezuela (Myers, 
1968) and Florida (unpublished observations). 
DISCUSSION 
All five genera recorded are here included in 
the family Aoridae, even though it is difficult 
to separate this family from the Photidae 
(Barnard, 1959). The genera Amphideutopus 
and Neomegamphopus are particularly difficult 
to allocate since they show relationships with 
the Photidae in the form of the head and 
mandible, but have the gnathopod and par- 
agnath characteristic of the Aoridae. Following 
Barnard (1962) who included Neomegam- 
phopus in the Aoridae, Amphideutopus is here 
also regarded as a member of that family since 
for practical purposes the enlarged first gnath- 
opoda may be taken as the common feature 
which unites these genera within the Aoridae. 
Barnard has suggested that this feature probably 
indicates some basic difference in axial gradi- 
ents between the two groups. 
REFERENCES 
Barnard, J. L. 1959. In: Ecology of Amphi- 
poda and Polychaeta of Newport Bay, Cali- 
fornia. Contr. Allan Hancock Fdn. Paper 
21:1-106, pis. 1-14. 
\96\a. Relationship of California am- 
phipod faunas in Newport Bay and in the 
open sea. Pac. Nat. 2(4) :166-186, figs. 1-2. 
I96lb. Gammaridean Amphipoda from 
depths of 400-6000 m. Galathea Rept. 5:23- 
128, figs. 1-83. 
