MARINE AMPHIPODA IN MICRONESIA — BARNARD 471 



Table 1. — List of Indo-Pacific tropical gammaridean Amphipoda from the literature 

 (* = Known epifaunal intertidal species; all others arc subtidal, benthic, or of 

 unknown ecolog}'; species in parentheses are dubious. See J. L. Barnard, 

 1958, for references) — Continued 



Composition of the collections. — The collections are divided 

 into two major groui^s, those of Dr. Abbott from Ifaluk Atoll, with 

 794 specimens and those of Dr. Reish from Eniwetok, Bikini, and 

 Majuro Atolls, with 851 specimens. Although the collections are 

 similar in size, their relative compositions differ remarkably. Reish's 

 collections were screened through a mesh of 0.5 mm. ; hence a number 

 of small species found in the Abbott collections apparently were lost. 

 Of the 48 identified species in the two collections, only 17 were found 

 in both, 23 were found only in the Ifaluk material and 8 were found 

 only in the Eniwetok material. Many of the 23 from Ifaluk are 

 small species, such as Colomastix, leucothoids, anamixids, and small 

 gammarids. The 10 most abundant species from both collections are 

 shown in table 2. Only 5 of these, according to their ubiquity indices 

 (3 or above), are truly Indo-Pacific cosmopolitan forms. The re- 

 maining 5, so far have been reported only from the Pacific east of 

 Indonesia and 3 of these have been discovered only in Micronesia. 

 None of the top 10 is a new species and so most of the 5 Pacific forms 

 may be endemic and not penetrate westward into the Indian Ocean. 



Eleven of the 38 minor species, of lesser abundance than the top 

 10, are new. Of the remaining 26 species, probably 9 are truly pan- 

 Indo-Pacific and pan-tropical as follows: Leucothoella bannwarthi, 

 Leucothoides pottsi, Colomastix pusilla, Elasmopus brasiliensis, Maera 

 inaequipes, Hyale media, Dexaminoides orientalis, Eurystheus atlanticus, 

 and Paragrubia vorax. None of these was exceptionally abundant in 

 the Micronesian collections. 



Four of the new species appear to be inquilines associated with 

 sessile animals of the substrate and probably feeding semiparasitically 

 upon them. They are in the gen^vs^, Azotostoma, Anamixis, and Leuco- 

 thoe. The remaining new species are described in the genera Ronco, 

 Lembos, Elasmopus, Beaudettia, Pleonexes, Liagoceradocus, Megam- 

 phopus, and Podocerus. 



