158 



SAMUELSON AND NISHIDA 



TABLE 8 



Proportions of Indigenous and Adventive Species for 



Groups Represented on Enewetak Atoll 



'Forty-one are indigenous to Enewetak; 54 are adventive. 



of those endemic to Micronesia. These figures will certainly 

 change as studies continue on this and adjacent faunas. 



ARACHNIDA 



The Micronesian arachnid fauna is partially studied, 

 though the spiders and mites remain incompletely sur- 

 veyed. The Amblypygi just enter the Micronesian area 

 at Palau, with one Papuan-Malayan species reported, 

 Charon grai^i Gervais (Takashima, 1950), 



Scorpionida 



Marshalls 2, Enewetak 1 — The Hormurus we list for 

 Enewetak is widely distributed in the Pacific and also 

 occurs from China to Australia. The tropicopolitan 

 Isometrus macuhtus (DeGeer) is reported for the Marshalls, 

 Gilberts, Palau; it is commonly found in dwell- 

 ings but is not yet reported for Enewetak. Micronesian 

 fauna, studied by Chapin (1957), comprises three species. 

 A second Hormurus of mainly Australian-Mclanesian distri- 

 bution reaches Palau. 



Pseudoscorpionida 



Marshalls 10, Enewetak 3 — Seven of the 10 pseudo- 

 scorpions reported for the Marshalls are restricted to 

 Micronesia. Two of these are endemic to the Marshalls but 



are not reported for Enewetak; they are Gari/pus omatus 

 Beier (Bikini) and Xenolpium oceanicurr) latum (Beier) (Lac, 

 Ujae, Utirik). The Lechi>tia we list for Enewetak is re- 

 stricted to atolls or low islands, including the Carolines 

 (Ulithi) and Marcus Island. Nesidiochernes maculatus Beier 

 is restricted to the eastern Carolines (Kosrae) and 

 Marshalls and is not yet repwrted for Enewetak. Three 

 species are either widespread in Micronesia or at least 

 recorded from distant localities. One of these is the 

 Haplochernes we list for Enewetak. The three extra 

 Micronesian taxa comprise Oratemnus samoanus whartoni 

 Chamberlin reported for Enewetak, western Carolines, and 

 Okinawa; the nominate O. s. samoanus Beier of mainly 

 Polynesian distribution; and a species of Geogar\;pus also 

 occurring on Taiwan. Micronesian fauna, studied by Beier 

 (1957), comprises 45 species or subspecies of which all 

 arc confined to the Pacific basin. 



Opiliones 



Marshalls 1, Enewetak — Only one species, Zaimoxis 

 solitGha (Roewer), is recorded for the Marshalls; its distri- 

 bution is restricted to the eastern Carolines (Ponape) and 

 Marshalls (Jaluit). Micronesian fauna, studied by Goodnight 

 and Goodnight (1957), comprises six endemic species in 

 five genera. One genus, Parasamoa, is endemic to Ponape 

 and is related to a Samoan genus and also to another in 

 the Seychelles; the remaining four genera have representa- 

 tives in the Malayan subregion. 



Araneae 



Marshalls 19, Enewetak 12 — Spiders reported for the 

 Marshalls are widespread (9 species), distributed in the 

 Malayan subregion and Pacific (3), confined to Oceania (5), 

 or undetermined (2). Of the species we list for Enewetak, 

 the Araneus. Chiracanthium. Flacillula, Heteropoda, 

 Latrodectus, Smehngopus. and Vitia are widespread; the 

 Masteria. two Opopaea. and Sc\;todes are confined to 

 Oceania; and the Erigone is of unknown distribution, as it 

 is unidentified. At least five of the 12 spiders reported for 

 Enewetak also occur in Hawaii, a probable avenue for the 

 introduction of some of the adventive species. Roewer 

 (1963) treated seven families of Micronesian spiders total- 

 ing 13 species, 10 of which are restricted to Micronesia; 

 eight of the species we treat for Enewetak are not included 

 in Roewcr's treatment. 



Acari 



Many additional records are expected for the Marshalls; 

 suborders are treated below. 



Gamasida (Mesostigmata): Marshalls 4, Enewetak 

 1 — Laelaps echidnina Berlese and L. nuttalli Hirst are 

 reported for the Marshalls but not Enewetak; both are 

 associated with Rattus and are cosmopolitan or nearly so. 

 The Ornithonyssus we list for Enewetak is not identified, 

 but the only species thus far reported for Micronesia is the 



