MARINE AMPHIPODA IN MICRONESIA — BARNARD 543 



Material: Abbott station 141-D-3 (1). 



Remarks: It is questionable that this species is a Phonexes be- 

 cause of the telson lacking the hooks seen in P. gammaroides and P. 

 lessoniae. It may prove that the telson is the only qualitative fea- 

 ture distinguishing Pleonexes from Ampithoe because the widening 

 of the sixth article on pereopods 3-5 is quantitative and occasionally 

 approached by several species of Ampithoe. The mouthparts are 

 similar to P. gammaroides (Sars, 1895, pi. 207) except for the mandible 

 and lower lip, figured herein. The mouthparts are quite distinct 

 from those of P. lessoniae (Hmiey, 1954). This specimen differs from 

 any known species of Ampithoe by its peculiar second gnathopods. 



Distribution : If aluk Atoll, Caroline Islands. 



Family Podoceridae 

 Genus Podocerus Leach 



To gain any concept of this genus and the limits of variation 

 within a species is nearly impossible at the present time as seen in 

 the following discussion and J. L. Barnard's (1962a) remarks. The 

 earliest described species, P. brasiliensis (Dana, 1853), P. lobatus 

 (HasweU, 1885), P. laevis (Haswell, 1885), and P. cristatus (Thomson, 

 1879), were not well detailed. Apparently overlooked in the last 3 

 species were the proper configurations of the teeth on male gnathopod 

 2. Later identifications of P. laevis by Walker (1904) and Chilton 

 (1926) differ completely in the respective absence and presence of 3 

 widely separated teeth on the male gnathopod 2 palm; Walker's 

 figure is more like the original description. Chilton's (1926) figure 

 of male gnathopod 2 on P. cristatus establishes the species. On the 

 other hand J. L. Barnard's (1959) figiu-e of P. brasiliensis probably 

 shows a younger stage of this same gnathopod, yet he was able to 

 distinguish P. brasiliensis as a common harbor-dwelling, noncristate 

 amphipod from a related cristate species, occurring more commonly 

 in the open sea. The latter resembles P. cristatus in the dorsal keel 

 but bears only one palmar tooth on gnathopod 2. Pirlot (1938) 

 showed the wide variation in dorsal carination of two other species, 

 hence demonstrating its uselessness. For the time being we must 

 resort to gnathopodal configurations as specific criteria. Pirlot's 

 (1938) figure of P. lobatus most certainly appears distinct from Has- 

 well's original figures. The commonly reported P. brasiliensis has 

 never been refigured since it was redescribed by Walker (1904) as P. 

 synaptochir, except by J. L. Barnard (1959). Indeed Barnard's iden- 

 tification may be erroneous and the specimens might be named as P. 

 variegatus Leach. K. H. Barnard (1916) suggested that P. variegatus 

 and P. brasiliensis may be identical, a reasonable opinion. 



