Chapter 21 



Ostracoda (M\;odocopma) of Enewetak Atoll 



LOUIS S. KORNICKER 



Department of Invertebrate Zoology. National Museum 

 of Natural History:, Smithsonian Institution 

 Washington, D. C. 20560 



INTRODUCTION 



Ostracods in the superorder Myodocopa, excluding the 

 planktonic suborder Halocypridina, which is outside the 

 scope of the present rejjort, have not previously been 

 reported from Micronesia. A comprehensive checklist of 

 Ostracoda from southeast Asia (Hanai et al., 1980) is con- 

 cerned with the area between 25°N and 11°S latitude and 

 140°E and 85°E longitude. The area includes the western 

 edge of Micronesia, but a brief perusal of the checklist 

 revealed no listing of specimens from Micronesia. 



A small collection of Enewetak ostracods in the 

 suborder Myodocopina at the National Museum of Natural 

 History, Smithsonian Institution, contains members of all 

 five families that comprise the suborder (Table 1). 

 Although the sp)ecies in the collection are capable of swim- 

 ming, and do so occasionally, they spend most of their 

 existence crawling on, or burrowing in, the substrate. An 

 exception to this is members of the mainly pelagic genus 

 C\;pridina, which is represented in the collection by two 

 species. Some of the Enewetak specimens are illustrated in 

 Fig. 1. 



The feeding habits of the families differ: the Cylindro- 

 leberididae is composed of filter feeders, the Sarsiellidae 

 and Rutidermatidae of carnivores, the Philomedidae of 

 detritus feeders, and the Cypridinidae of scavengers, 

 detritus feeders, and also carnivores (Kornicker, 1975). 



BIOGEOGRAPHIC COMPARISONS 

 AT GENERIC LEVEL 



The genera Skogsbergia, Harbansus, Rutiderma, 

 Sarsiella, Parasterope, and Cy/iridro/eberis are worldwide in 

 distribution; only Parasterope is present in Antarctic waters 

 (Kornicker, 1975); and none has been reported from the 

 Arctic Ocean. 



TABLE 1 



Checklist of Enewetak Atoll Ostracoda 

 (Myodocopina) 



Phylum ARTHROPODA 

 Subphylum CRUSTACEA 

 Class OSTRACODA 



Superorder MYODOCOPA 

 Order MYODOCOPIDA 

 Suborder MYODOCOPINA 

 Superfamily CYPRIDINOIDEA 

 Family CYPRIDINIDAE 

 ■fCyprid/na spp. 

 '■\Parauargula sp. 

 '■fSkogsbergia sp. 

 Family PHILOMEDIDAE 



•fHarbansus sp. 

 Family RUTIDERMATIDAE 



'■fRutiderrrta sp. 

 Family SARSIELLIDAE 

 '■fAncohenia sp. 

 'tAnscottie//a sp. 

 '■fSarsiella sp. 

 Family CYLINDROLEBERIDIDAE 

 'fParasterope sp. 

 "fCy/indro/eberis sp. 



■ New Micronesian record, 

 t New Enewetak record. 



The pelagic genus Ci/pridina is primarily Indo-Pacific. 



Ancohenia is previously known from Maunalua Bay, 

 Oahu Island, Hawaii (Kornicker, 1976:7) and Vuna Point, 

 Taveuni, Fiji (Kornicker, 1981:12). 



Anscottiella has previously been collected off Ceylon 

 and Thailand (Poulsen, 1965:65; Kornicker, 1975:607; 

 Kornicker and McKenzie, 1976:348). 



Paravargula has previously been collected off the tip of 

 South Africa and from the East-Indian region (Poulsen, 

 1962:204; Kornicker, 1975:3). 



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